Department of Chemistry

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Studies on the Metabolism of Lactose, Melibiose, Sucrose and Raffinose by Erwin/a Chrysanthemi
(University of Fort Hare, 1995) Mabinya, Leonard Vuyani
One of the challenging problems for a bacterial cell is to detect chemical changes that constantly occur in its environment, and to regulate and integrate its metabolism in response to such changes. The primary function of many cellular activities in these organisms is directed towards this task. These activities may include transport processes‚ cellular locomotion and chemotaxis, and the secretion of digestive enzymes (Saier, 1977; Dills et al.‚ 1980; Postma and Lengeler, 1985; Mitchell, 1985).
Separation of Bi, Ca, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn, Ti, V and Zn in soil samples using thenoyltri:fluoroacetone as the most selective single ligand by the appropriate use of solvent extraction under the optim~m pH conditions
(University of Fort Hare, 2003-01) Mamela, Mojalefa Daniel
In this investigation, three soil samples collected from non-arid land were qualitatively analysed using both the electron microscopy and AAS methods and elements such as Bi, Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sn Ti, V and Zn were positively identified in each of them. However, the electron microscopy method also revealed the presence of Na, K and Mg in these samples. Due to the logistical problems our scope of analysis was restricted to the first sixteen elements only.
Variation in the essential oil composition of calendula officinalis L
(University of Fort Hare, 2008) Okoh, Omobola
Variations in the yield and composition of the essential oils from Calendula officinalis L. cultivated in Alice (Eastern Cape) are reported. Essential oils were obtained by hydrodistillation using the Clevenger apparatus and analysis was performed by GC-MS. The yield in essential oil revealed a maximum at the full-flowering stage (0.97%) and a minimum during the pre-flowering stage (0.13%). The composition showed different patterns at different phases of the vegetative cycle. Sesquiterpenes (α-cadinene, α-cadinol, T-muurolol, and epi-bicyclosesquiphellandrene) and monoterpenes (limonene, 1,8- cineole, and trans-β-ocimene) showed highest correlations with the age of the plant. An interesting stage is the post-flowering period, the essential oil being rich in α-cadinene, α- cadinol, T-muurolol, limonene, 1,8-cineole, with p-cymene presenting lower levels. The oils were extracted by hydrodistillation from fresh leaves, dry leaves, and fresh flowers yielding 0.06 %, 0.03 %, and 0.09 %, respectively. The analysis of oils by GCMS revealed a total of 30, 21, and 24 compounds from the fresh leaves, dry leaves, and the flowers, respectively, representing 91.7, 89.8, and 87.5% of the total oil composition. Sesquiterpenoids dominated in the fresh leaves (59.5 %) and flowers (26 %), while the monoterpenes dominated in the dry leaves (70.3 %). T-Muurolol (40.9 %) predominated in the fresh leaf oil, α-thujene (19.2 %) and δ-cadinene (11.8 %) were present in high quantities. In contrast, 1,8-cineole (29.4%), γ-terpenene (11.6 %), δ-cadinene (9.0 %), β- pinene (6.9 %), and α-thujene (6.3 %) were the major components in the dry leaf oil, while in the fresh flower oil, α-thujene (15.9 %), δ-cadinene (13.1 %) and γ-cadinene (10.9 %) were the major components. The significance of the effect of drying and age on essential oil composition is discussed.
Chemical transformations and phytochemical studies of bioactive components from extracts of rosmarinus officinalis L.
(University of Fort Hare, 2010) Okoh, Omobola Oluranti
Variations in the yield, chemical composition, antibacterial, and antioxidant properties of the essential oils of Rosmarinus officinalis L. cultivated in Alice, Eastern Cape of South Africa over a period of 12 months using the solvent-free microwave extraction and traditional hydrodistillation methods were evaluated. The GC-MS analyses of the essential oils revealed the presence of 33 compounds with 1,8-cineole, a-pinene, camphor, verbenone, bornyl acetate and camphene constituting about 80% of the oils throughout the period of investigation, with the solvent-free microwave extraction method generally yielding more of the major components than the hydrodistillation method. Each of the major components of the oils varied in quantity and quality of yield at different periods of the year. The method of extraction and time of harvest are of importance to the quantity and quality of essential oil of Rosmarinus officinalis. Higher amounts of oxygenated monoterpenes such as borneol, camphor, terpene- 4-ol, linalool, a-terpeneol were present in the oil of SFME in comparison with HD. However, HD oil contained more monoterpene hydrocarbons such as a-pinene, camphene, β-pinene, myrcene, a-phellanderene, 1,8-cineole, trans- β-ocimene, γ-teprinene, and cis-sabinene hydrate than SFME extracted oil. Accumulation of monoterpene alcohols and ketones was observed during maturation process of Rosmarinus leaves. Quantitative evaluation of antibacterial activity, minimum inhibitory concentration values were determined using a serial microplate dilution method. The essential oils obtained using both methods of extraction were active against all the bacteria tested at a concentration of 10 mg mL-1. The minimum inhibitory concentrations for the SFME extracted oils ranged between 0.23 and 1.88 mg mL-1, while those of the HD extracted oils varied between 0.94 and 7.5 mg mL-1, thus suggesting that the oil obtained by solvent free microwave extraction was more active against bacteria than the oil obtained through hydrodistillation. The antioxidant and free radical scavenging activity of the obtained oils were tested by means of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH+) assay and β- carotene bleaching test. In the DPPH+ assay, while the free radical scavenging activity of the oil obtained by SFME method showed percentage inhibitions of between 48.8 % and 67 %, the HD derived oil showed inhibitions of between 52.2 % and 65.30 % at concentrations of 0.33, 0.50 and 1.0 mg mL-1, respectively. In the β-carotene bleaching assay, the percentage inhibition increased with increasing concentration of both oils with a higher antioxidant activity of the oil obtained through the SFME than the HD method. Thin layer chromatography (TLC) was used to analyze the chemical composition of the extracts using three eluent solvent systems of varying polarities i. e. CEF, BEA and EMW and sprayed with vanillin-sulfuric acid. The chemical composition of the different extracts was similar with the exception of methanol and water extracts which had only one or two visible compounds after treating with vanillin-spray reagent. To evaluate the number of antibacterial compounds present in the fractions, bioautography was used against two most important nos ocomial microorganisms. S. aureus (Gram positive) and E. coli (Gram negative). Nearly all the crude serial extraction fractions contained compounds that inhibited the growth of E. coli. The hexane extract had the most lines of inhibition followed by ethyl acetate. Bioassay-guided fractionation against E. coli was used to isolate antibacterial compounds. The largest number of antibacterial compounds occurred in the hexane fraction. Furthermore we tried to complete the characterization by extracting and studying other biologically important plant metabolites such as phenolic compounds to evaluate the antioxidant capacity of Rosmarinus extracts.
Development of a bench scale single batch biomass to liquid fuel facility
(2013) Zhang, Yusheng
The research described in this dissertation was motivated by the global demand for energy that is not dependent on coal, oil, natural gas and other non-renewable fossil fuels. The technology used in this project is related to the use of biomass to produce a viable alternative to conventional sources of fuel. A bench scale biomass to liquid (BTL) facility was built and tested. This produced results confirming the feasibility of the BTL process. The findings of the pilot study outlined in this dissertation justified the conclusion that the next step will be to expand the capacity and productivity of the BTL pilot plant to an industrial scale. Biomass comes from a variety of renewable sources that are readily available. In this case, the material used in the fixed bed biomass gasification facility to generate wood gas was agricultural and forestry waste, such as straw and woodchips. The gasifier had the capacity to produce up to 10 cubic metres/hr of gas with a carbon monoxide and hydrogen content of between 20–40% by volume, when it was operated at ambient pressure and with air as the oxidizer. The gas, produced at a temperature above700ºC, was cooled in a quench/water scrubber in order to remove most of the mechanical impurities (tars and water-soluble inorganic particles), condensed and dried with corn cobs before being compressed in cylinders at over 100 bar(g)for use in the Fischer-Tropsch Synthesis (FTS). The syngas was subjected further to a series of refining processes which included removal of sulphur and oxygen. The sulphur removal technology chose entailed applying modified activated carbon to adsorb H2S with the help of hydrolysis in order to convert organic sulphur impurities into H2Swhich reduced the sulphur content of the gas to less than 5ppbv. Supported cobalt catalyst (100 grams), were loaded into single-tube fixed bed FT reactor with an inner diameter of 50 mm. The reactor was fitted with a heating jacket through which, heated oil ran to cool the reactor during a normal reaction occurring at <250 ºC, while nitrogen was used in the heating jacket during reduction, which occurred at temperatures up ~350 ºC. The FTS reaction was carried out at different pressures and temperatures. Liquid and wax products were produced from the facility. The properties of the liquid and solid hydrocarbons produced were found to be the same as FT products from other feed stocks, such as natural gas and coal.
Biological Evaluation and Semi-synthesis of Isolated Compounds from (Syzygium aromaticum (L.) Merr. & Perry) Buds.
(University of Fort Hare, 2014) Rali, Sibusiso; Oyedeji, O.O.; Nkeh-Chungag, B.N.
Natural products play a fundamental role in modern drug discovery as they continue providing diverse bioactive lead compounds for new drug formulation. However, isolation of these valued compounds is problematic. On the other hand, the morbidity and mortality rates caused by non-communicable diseases are increasing with improved longevity. Thus, the study herein focused on the isolation of plant-derived compounds from Syzygium aromaticum and evaluated their biological properties. Syzygium aromaticum is a well-known plant which belongs to family Myrtaceae. Dried flower buds of S. aromaticum were subjected to sequential solvent extraction. The ethyl acetate extract (15.535 g) was subjected to column chromatography using a silica gel (0.063-0.200 mm) for isolation. This has led to the isolation of three distinct compounds that were identified as eugenol, maslinic acid (MA) and oleanolic acid (OA). The structural elucidation of these valued compounds was done using NMR, GC-MS, LC-MS, FT-IR and Mp. Further semi-synthesis of the oleanolic acid afforded acetate and ester OA-derived compounds with better solubility properties. All these compounds were evaluated for analgesic and anti-inflammatory properties. All tested compounds were administered at a dose of 40 mg/kg to both Wistar rats and Swiss mice. Significant (p<0.01) analgesic and anti-inflammatory properties are obtained for all compounds. The effects of eugenol in all experiment were better except in the thermal-induced pain or tail flick test. In the case of modified compounds, the formalin induced pain test disclosed that oleanane derived compounds confessed analgesic and anti-inflammatory effects better than OA, whereas, in tale flick test oleanolic acid proved superior analgesic effects compared to all its derivatives with the exception of the acetyl- derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation derivative. Acute anti-inflammatory test showed that acetyl-derivatives were more active than other compounds. In conclusion, chromatographic techniques and semi-synthesise of oleanolic acid have resulted to several plant-derived compounds with analgesic and anti-inflammatory properties. The semi-synthesized compounds may serve as alternative drug candidates for new analgesic and anti-inflammatory drug formulation.
Ethanol production from lignocellulosic sugarcane leaves and tops
(2014) Dodo, Charlie
Various methods for the production of bioethanol using different feedstocks have been researched on. In most work on bioethanol synthesis from sugar cane, tops and leaves have been regarded as waste and generally removed and thrown away. In this work, lignocellulosic sugarcane leaves and tops were not discarded but instead used as biomass to evaluate their hydrolyzate content. The leaves and tops were hydrolysed using different methods, namely concentrated acid, dilute acid pre-treatment with subsequent enzyme hydrolysis and compared with a combination of oxidative alkali pretreatment and enzyme hydrolysis. Subsequent fermentation of the hydrolyzates into bioethanol was done using the yeast saccharomyces cerevisae. Acid hydrolysis has the problem of producing inhibitors, which have to be removed and this was done using overliming with calcium hydroxide and compared to sodium hydroxide neutralization. Oxidative alkali pre-treatment with enzyme hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) peroxide pre-treated biomass than 36% (g/g) for 5% (v/v) with the least inhibitors. Concentrated and dilute acid hydrolysis each gave yields of25% (g/g) and 22% (g/g) yields respectively although for acid a neutralization step was necessary and resulted in dilution. Alkaline neutralization of acid hydrolyzates using sodium hydroxide resulted in less dilution and loss of fermentable sugars as compared to overliming. Higher yields of bioethanol, 13.7 (g/l) were obtained from enzyme hydrolyzates than 6.9 (g/l) bioethanol from dilute acid hydrolyzates. There was more bioethanol yield 13.7 (g/l) after 72h of fermentation with the yeast than 7.0 (g/l) bioethanol after 24h. However, the longer fermentation period diminishes the value of the increase in yield by lowering the efficiency of the process.
Computational studies, synthesis and characterization of Ruthenium(ii) anticancer complexes.
(University of Fort Hare, 2014) Adeniyi, Adebayo Azeez
As demand for water grows in South Africa, alternative sources are actively being sought to augment conventional water supply. While domestic rainwater harvesting has been put forward as one such an alternative water supply, little information is available on whether harvested rainwater is safe for human use or even how local communities feel about using the water from such an alternative source. The SU team tested the chemical and microbial quality of rainwater collected from the rainwater tanks of 29 houses over six months. In addition, 68 households were interviewed to investigate the acceptance and perception on the use of the domestic rainwater harvesting tanks. The results obtained for the chemical analysis indicated that the rainwater quality was within potable, chemical standards. Metals, cations and anions that were analysed for in the harvested rainwater samples were all below the recommended drinking water guidelines. However, the microbial analysis showed that the presence of the following group of indicator organisms exceeded the recommended drinking water guidelines: total coliforms, Eneterocci, faecal coliforms, and heterotrophic bacteria. The presence of several opportunistic pathogens, including E.coli, Cryptosporidium and Salmonella, were also detected. In short, the water from the rainwater harvesting tanks in Kleinmond is not fit for human consumption, and prior treatment is required before the water source can be used for drinking purposes. The main causes of contamination are dirt and faeces (from birds and small animals) on the roof surface, which fall into the tank. Other sources of rainwater contamination include leaf debris and organic material washed into the tank, animals or birds that fall into uncovered tanks as well as breeding mosquitoes. It was found that many of the households placed their garbage bags on top of the tanks to protect them from being ripped open by stray dogs. These garbage bags could easily contaminate the rainwater, especially if the tanks are leaking or broken and/or the lid is absent. This general lack of awareness of contamination hazards highlights the importance of training users in the proper use and maintenance of the technology. It has been recommended that some form of pre-treatment be installed to make the rainwater safe for drinking. As a follow up to this part of the project, the SU team is now investigating the use of solar water pasteurisation and filtration systems for the treatment of harvested rainwater. Interestingly, the SU user survey indicated that the majority of community members of the Kleinmond Housing Scheme instinctively steered clear of using the water from their rainwater harvesting tanks for drinking purposes. About two-thirds of the respondents do not use the water in the tank for drinking, while by far the majority of those who use it for drinking do so only sometimes (24%). The majority of respondents who do drink the water pre-treat it first. One mother reported that her baby developed a rash after rainwater was used to bath him, while others said that drinking the water was ‘bad for your stomach’. The majority of respondents indicated that they use the harvested rainwater for household chores instead, such as laundry, cleaning, and gardening. One respondent was even applying his rainwater to help run his small car wash business. This thesis is centred on the application of Ru-based complexes as a promising alternative to cis-platin in cancer chemotherapy. Cis-platin is known to be the most prescribed chemotherapy which has more than 70% application in cancer cases especially the testicular cancer. An insight is provided in Chapter One and Two into the literatures reports on the application of Ru(II)-based complexes in cancer chemotherapy. In order to address some of the pressing challenges in rational design of Ru-based anticancer complexes, section 3.3 and 3.4 deal with efforts to elucidate the complication of their chemistry and instability while in section 3.5 efforts are made to find solution to the lack of proper knowledge of their targets using different theoretical approaches as presented in Chapter Three. In addition to the theoretical study, this thesis also comprises of the synthesis of the bis-pyrazole derivatives type of ligands and the derivatives of their Ru(II)-based complexes as provided in Chapter Four and Five respectively. Also the computational methods were used to elucidate the structural and spectroscopic properties of the synthesised ligands and their Ru(II)-based complexes. The geometrical and electronic properties are studied in relation to the stability and the reported anticancer activities of Ru(II)-based complexes in section 3.3. In subsection 3.3.1, several quantum properties including the natural energy decomposition analysis (NEDA) and quantum theory of atoms in a molecule (QTAIM) are computed on three models of RAPTA-C complexes using DFT with hybrid functional and basis set with ECP and without ECP. The higher stability of Carbo-RAPTA-C and Oxalo-RAPTA-C over RAPTA-C comes from the lower exchange repulsion and higher polarization contributions to their stability which gives insight into experimental observation. A similar study was carried out in subsection 3.3.2 on half-sandwich Ru(II)-based anticancer complexes with 6-toluene and 6-trifluorotoluene. The trifluorotoluene and the hydrated models are characterised with higher charge transfer, polarizability, synergistic effect of ligand fragments, stronger and higher HB interactions that support their reported experimental anticancer activities and the mechanism of their activation by hydrolysis. Also in the subsection 3.3.3, the factors that determine the stability and the effects of non-covalent interaction on the two models of these half-sandwich 6-arene ruthenium anticancer complexes and their respective hydrated forms were investigated using DFT method. Lastly in section 3.3, the subsection 3.3.4 deals with the intramolecular properties of five sets of ruthenium based anticancer complexes using DFT method. The spectroscopic and the non-linear optical properties of selected Ru(II) anticancer complexes are shown in Section 3.4. In subsection 3.2.1, DFT method was applied to study the thermodynamic and spectroscopic properties of three Ru-based complexes in order to give possible reasons for the reported experimental stability of complexes 1 and 2 with bidentate chelating ligands than complex 3. A further study was carried out in Subsection 3.4.2 where computational method was used to gain insight into the correlation between the chemistry of the hydrolysis and the anticancer activities of selected Ru(II)-based complexes. Lastly in this section, subsection 3.2.3 deals with application of different density functional methods (DFT) to optimize and study the chemistry of five potential anticancer complexes in terms of their electronic, conductive and spectroscopic properties. The carboxylic and pyrazole units are found to significantly enhance the polarizabilities and hyperpolarizabilities of the complexes while the chloride only improves the polarity of the complexes. The possible targets of Ru(II)-based anticancer complexes are predicted using docking methods as presented in section 3.5 of this thesis. In subsection 3.5.1, the interactions of selected Ru(II)-based complexes with different cancer receptors are carried out using computational docking. The study focuses more on finding alternative protein targets other DNA for some Ru(II)-based complexes using computational docking. A further study on addressing the problem of the improper knowledge of of the targets of Ru-based anticancer complexes was carried out in subsection 3.5.2. Some promising anticancer complexes of Ru(II) such as RAPTA based complexes formulated as [Ru(η6-p-cymene)L2(pta)] and those with unusual ligands are docked against receptors using Autodock, Glide and Gold. Lastly in section 3.5, docking packages Molegro and Autodock were applied in subsection 3.5.3 to predict the anticancer activities of selected Ru(II) complexes against twelve anticancer targets. Introducing the quantum calculated atomic charges of the optimized geometries is found to significantly improve the docking predictions of these anticancer metallocompounds. In section 4.3-4.6, the spectroscopic and the geometric properties of ligands with pyrazole, methylpyrazole, bipyridine and phenanthroline derivatives were studied at both experimental and computational levels. The computational results are perfectly in agreement with the experimental results especially in terms of the spectroscopic properties. The spectroscopic analyses as well as the computed properties were used to establish the successful synthesis of the ligands. Many of the functional groups in these ligands are found to be Raman active which also help in their spectroscopic elucidation. Lastly in chapter five, the method used for the synthesis of forty Ru(II)-based complexes were presented with their experimental spectroscopic features being elucidated using theoretical methods. A very high correlation was observed between experimental and theoretical characterisation of the complexes which is an indication of successful synthesis of the complexes.
Investigation into the characteristics and possible applications of biomass gasification by-products from a downdraft gasifier system.
(University of Fort Hare, 2014) Melapi, Aviwe;
Biomass gasification has attracted the interest of researchers because it produces zero carbon to the atmosphere. This technology does not only produce syngas but also the by-products which can be used for various applications depending on quality. The study conducted at Melani village in Alice in the Eastern Cape of South Africa was aimed at investigating the possible applications of the gasification by-products instead of being thrown away. Pine wood was employed as the parent feedstock material for the gasifier. Biomass gasification by-products were then collected for further analysis. The studied by-products included tar (condensate), char, soot and resin. These materials were also blended to produce strong materials. The essence of the blending was to generate ideal material that is strong but light at the same time. The elemental analysis of the samples performed by CHNS analyser revealed that carbon element is in large quantities in all samples. The FTIR spectra showed almost similar results for all the studied samples, since the samples are end products of lignocellulose gasification. The major functional groups observed in all the samples under FTIR included C=C, O-H, C-H, C-O, C-C. Samples under XRD showed amorphous structure as they mostly absorbed within the range of 10°-35°. SEM gave the sticky images of resin as well as porous char structures. Char showed a higher heating value of 35.37MJ/Kg when compared to other by-products samples.
Copper dithiocarbamate complexes and copper sulfide nanoparticles : synthesis, characterization and antifungal studies
(University of Fort Hare, 2015) Botha, Nandipha Loveness
Six dithiocarbamate ligands were synthesized from anisidine, aniline, ethyl aniline, butyl amine, morpholine and piperidine and used to synthesize homoleptic copper(II) dithiocarbamate complexes. The ligands and their corresponding complexes were characterized by conductivity measurement, FTIR and UV-Vis spectroscopy. The ligands were further characterized using NMR spectroscopy. The electronic spectra of the complexes showed that the coordination geometries around the Cu2+ ion is four coordinate square planar. FTIR spectroscopic studies indicated that the dithiocarbamate ligands are bidentately coordinated to the copper ion through the sulfur atoms with the C-S stretching frequencies changing from two peaks in the ligands to single sharp peaks in the corresponding metal complexes. The complexes were used as single source precursors to synthesize copper sulfide nanoparticles. All the six complexes were thermolysed at 180 oC to prepare copper sulfide nanoparticles and three of them were further thermolysed at 120 oC to study the effects of temperature on size and shape of the nanoparticles. All the nanoparticles were characterized with UV-Vis, PL, XRD, TEM, SEM and EDX. The optical properties of the as-prepared CuS nanoparticles showed that they are quantum confined with absorption band edges that are blue shifted compared to bulk CuS and all the as-prepared CuS nanoparticles showed narrow emission curves. The XRD diffraction patterns were indexed to the hexagonal covellite CuS crystalline phase with estimated particle sizes of 15.8-23.24 nm. These sizes are significantly different from the values, 3.02-98.94 nm obtained from TEM studies. The TEM images also showed nanoparticles with varied shapes with some agglomerations. SEM micrographs showed that the morphologies of the nanoparticles are mostly smooth surfaces and EDX spectra analyses confirmed the formation of the nanoparticles. Thermolysis of three of the complexes at 120 oC confirmed that temperature do affect the optical and structural properties of the CuS nanoparticles. Only three complexes soluble in DMSO were screened for their antimicrobial activity. Three complexes C1, C4 and C5 were screened against four fungi organisms, namely: Candida rugosa, Candida neoformans, Candida albicans and Trychophyton mucoides. All the compounds were promising as shown by the minimum inhibitory concentrations determined. C5 was the most active compound against all the organisms. They were also screened against four bacteria organisms and they were all active but not as they were against fungi organisms.
Chemical Constituents and Biological Studies of Tagetes minuta L. and Rauvolfia caffra Sond.
(University of Fort Hare, 2015) Mlala, Sithenkosi; Oyedeji, O.O.; Nkeh-Chungag, B.N.
Green plants synthesize and store a variety of biochemical compounds some of which are extractable as raw material and can be used for various scientific investigations. Different plant parts have different effects as they often contain different active chemical components. Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03%), caryophyllene oxide (18.04%), alloocimene (25.35 %), isopropyl tetradecanoate (17.02 %), cis-ocimene (38.14%) and trans-β-ocimene (37.03%) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
Isolation, Characterisation, and biological activity evaluation of essential Oils of Cymbopogon validus (Stapf) Stapf ex Burtt Davy and Hyparrhenia hirta (L.) Stapf.
(University of Fort Hare, 2015) Rungqu, Pamela; Oyedeji, A.O.
strong anti-inflammatory properties when compared to control group. However, the H. hirta essential oil was more effective than that of C. validus. Linalool, α-terpineol, and northujane extracted from C. validus and H. hirta essential oils might have contributed to the anti-inflammatory effects observed in Wistar rats. This study, confirms the anti-inflammatory properties of C. validus and H. hirta suggesting that they may be used in diseases related to anti-inflammation.
Synthesis and characterization of Ru(II) phenyl-3-indenylidene olefin metathesis type complexes
(2015) Yalezo, Ntsikelelo
In this study, a series of Ru(II) phenyl-3-indenylidene complexes with general formula of [RuCl2(NHC)(Ind)(L)] (where L= triphenylphosphine, pyridine and NHC = five different types of N-heterocyclic carbene ligands), have been synthesized and characterized using FT-IR, UV-Vis, elementally analysis and melting/decomposition point. The N,N’-diarylimidazolinium chlorides have been used as N-heterocyclic carbene precursors and were synthesized from their corresponding N,N’-diarylformamidines and further characterized using 1H-NMR, 13C-NMR, FTIR and melting point determination. The infrared spectra of the N,N’-diarylimidazolinium chlorides show a quaternary nature (R2N=C+) with broad vibration band in region 3300-3400 cm-1. The disappearance of this vibration band in the infrared spectra of the ruthenium(II) complexes was used to confirm the coordination of the ligand to the ruthenium ions. The percentage analysis of carbon, hydrogen and nitrogen obtained corresponded with the calculated percentages of these atoms in the complexes with the slight difference of less than 1%. The electronic spectra of the complexes show three distinct absorption bands. The two bands are due to intraligand charge transfers transition assigned to π→π*, n→π* and third band is due to d-d transition, signifying the presence of the metal ion. The synthesized Ru(II) complexes did not show any of melting, however a change in colour was observed signifying the decomposition of the complexes.
Isolation, characterisation of Terpenoids and Biosynthesis of silver Nanoparticles of Acacia Mearnsii de Wild and Acacia Karroo Hayne and their Bioassays
(University of Fort Hare, 2015) Nudewhenu, Avoseh Opeyemi
Great wealth of traditional knowledge about the use of plants had been transferred from generation to generations leading to the present day drug discovery and invention of new scientific methods of isolation, purification and identification. With the discovery of new diseases and drug-resistant organisms, there is no other source or deposit of lead compounds or drugs than the plant kingdom. As a result of this, about 25% of the current drug administered owe their origin to plant sources with the view to reduce the carcinogenic effect of synthetic drugs. Volatile terpenoids among other broad spectrum of natural product had been implicated to show high therapeutic properly. In the present study, selected locally-used medicinal plants were exploited for the presence of potent bioactive compounds and ability to form nanoparticles with distinctive property for use as chemoprotective agent against inflammation, tumors, cancer and other chronic diseases. Acacia mearnsii De Wild and Acacia karroo Hayne studied in this report are known to be invasive species with no proper regulation to conserve and preserve them. However, ethnopharmacology report of these plant species in the Southern Africa region reveals that they are good antiseptic, anti-diarrhea, anti-inflammation and a forage for livestock. These plants were subjected to volatile extraction protocol of some parts of the plants (stem and leaves) followed by examination of the anti-inflammation capacity of the extracts using an animal model. In addition, the bye-product (hydrosol) from the stem bark of each species possess a high reducing and stabilizing property leading to synthesis of silver nanoparticles, followed by investigation of the anti-inflammation potential of the synthesized silver nanoparticles using animal model. The volatile oils of the leaves and stem bark of Acacia mearnsii De Wild obtained by hydro-distillation were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). Twenty, Thirty-Eight, Twenty-nine and Thirty-Eight components accounting for 93.8%, 92.1%, 78.5% and 90.9% of the total oils of the fresh, dry leaves and fresh, dry stem bark respectively. The major components of the oil were octadecyl alcohol (25.5%) and phytol (10.5%); cis-verbenol (29.5%); phytol (10.1%) and phytol (23.4%) for the fresh leaves, dried leaves, and fresh stem, dry stem bark respectively. Oral administration of essential oils at the dose of 2% showed significant (p<0.05) anti-inflammatory properties in the albumin induced vi test model in rats. Oils from the fresh leaves and dry stems inhibited inflammation beyond 4 h post treatment. Furthermore, the chemical composition of the essential oils obtained by hydro-distillation from the leaves and stem bark (dry and fresh) of Acacia karroo Hayne, analysed by GC-MS, shows that hexanal (10.67%) and ß-ionone (9.74%) were dominant in the dried leaves, β-pinene (14.30%), and (Z)-2-Hexen-1-ol (10.21%) in the fresh leaves while Octacosane (10.59%) and phytol (23.38%) were dominant in the dry and fresh stem respectively. The anti-inflammation ability of these oils after an albumin-induced inflammation on wistar rats, shows a significant effect at the 1st h of treatment with a significance of P< 0.01 for all part plants, while the fresh leaves shows further inhibitory activities at the 2nd h of analysis. Silver nanoparticles (AgNPs) were successfully synthesized from AgNO3 through a green route using the aqueous extract (hydrosols) of Acacia mearnsii De Wild and Acacia karroo Hayne as reducing agent and as well as capping agent. The Acacia-mediated AgNPs were characterized with the use of UV-vis absorption spectroscopy, Fourier Transform Spectroscopy (FT-IR), Transmission electron microscope (TEM), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDX), and X-ray Diffractometry (XRD). A spherical, 10-40 nm diameter silver nanoparticles were synthesized with very low level of stability for the AMDS and the AKDS-AgNPs. In addition, nociceptive activity with a mice rat reveals higher inhibition at the neurogenic phase for the AKDS-AgNPs, while AMDS-AgNPs exhibited a high inhibition at the inflammatory phase. The potent anti-inflammatory activity of essential oils of A. mearnsii De Wild and A. karroo Hayne hereby confirmed its traditional use in treating various inflammatory diseases, while the inflammatory studies on the synthesized AgNPs reveals a very active compound which can be used as a potent opioid or non-steroidal anti-inflammatory drug (NSAID).
Ni(II) and Pb(II) dithiocarbamate complexes as precursors for the synthesis of HDA-capped NiS and PbS nanoparticles
(University of Fort Hare, 2015) Chintso, Thobani
Ni(II) and Pb(II) dithiocarbamate complexes were synthesized and characterized by elemental analysis, UV-Vis, FTIR and TGA and some of the Ni(II) complexes and one Pb(II) were further analyzed by 1H-NMR and 13C-NMR spectroscopy. Generally all the dithiocarbamate ligands are soluble in water while the complexes were soluble mostly in solvents such as chloroform, toluene, DMSO and DCM. Based on the elemental analysis, the dithiocarbamate complexes are formulated as four coordinate (tetrahedral or square planar) compounds. However, the FTIR showed that each of the dithiocarbamate ligands acted as bidentate ligand through two sulfur atoms. The TGA of the most complexes showed one major decomposition step to give respective metal sulfide above 200 oC. In this research project, dithiocarbamate complexes were used as single source precursor for the synthesis of metal sulfide nanoparticles. We studied the optical and structural properties of metal sulfide nanoparticles using UV-Vis, photoluminescence (PL), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorption spectra of the metal sulfide nanoparticles are blue shifted in respect to bulk material and they also showed broad emission. The XRD of the NiS nanoparticles were indexed to the cubic and rhombohedral phase, with crystallite sizes of 15 - 18 nm. The XRD of PbS nanoparticles were indexed to the face centered cubic and cubic rock salts, with the crystallite sizes 12 - 18 nm. The TEM images of the metal sulfide nanoparticles showed particles with spherical and rectangular shapes with crystallite sizes 4 - 35 nm.
Synthesis, characterization and evaluation of ruthenium(II) polypyridyl complexes as sensitizer for dye sensitized solar cells
(University of Fort Hare, 2015) Mkhohlakali, Andile Cyril; Ajibade, P. A.
Dye sensitized solar cell is the device that is made up of metal oxide semiconductor, electrolyte and ruthenium complexes as sensitizer. This device harvest sun light and convert it to electricity, the first ruthenium complex dye used was N3. In this study, ruthenium(II) polypyridyl complexes formulated as [(RuLXLY)(NCS)2], where Lx and Ly are different types of ligands comprising bpy or phen as ancillary ligands were synthesized and characterized by FT-IR and 1H-NMR spectroscopy. The complexes were further characterized with UV-Vis, and photoluminescence (PL) spectroscopy. These dyes showed good photophysical properties, with absorption spectra dominated by metal to ligand charge transfer (MLCT) transitions in the visible region and part of the near IR (NIR) region of the electromagnetic spectrum. The solar cell fabrication with these complexes was done, using doctor blade technique, and these cells were further characterized for current- voltages (J-V) curve and solar cell efficiency test. The solar cells based on these ruthenium complexes using TiO2 as semiconductor gave good (J-V) curve, with overall efficiency (  ) between 0,2%- 1.02 %, with JSC = 0. 776-3.44 mA cm-2, VOC = +/-0.59 V and FF = 0.5-0.6 under global air mass (1.5AM) illumination using potassium iodide in acetonitrile as electrolyte.
Chemical constituents and biological studies of Tagetes minuta L. and Rauvolfia caffra sond
(University of Fort Hare, 2015) Mlala, Sithenkosi
Green plants synthesize and store a variety of biochemical compounds some of which are extractable as raw material and can be used for various scientific investigations. Different plant parts have different effects as they often contain different active chemical components. Consequently, specific parts or the whole plant can be used for various treatments. The aim of this study was to extract, isolate and characterize the biologically active volatile and non-volatile compounds from Tagetes minuta and Rauvolfia caffra respectively. Tagetes minuta plant was considered for extraction of essential oils using hydrodistillation method. Cis-β-ocimene (38.03 percent), caryophyllene oxide (18.04 percent), alloocimene (25.35 percent), isopropyl tetradecanoate (17.02 percent), cis-ocimene (38.14 percent) and trans-β-ocimene (37.03 percent) were the major components of essential oil analyzed from fresh stem, dried stem, fresh leaf, dried leaf, fresh flower and dried flower respectively. The volatile compounds were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography (GC). Essential oil of dried stem leaf and flower parts of T. minuta exhibit antioxidant activity as demonstrated by the DPPH and FRAP bioassays. Crude extracts were extracted from R. caffra stem bark using sequence of solvents namely n-hexane, dichloromethane, ethyl acetate, methanol and ethanol. A white powder, a β-sitosterol (non-volatile compound) was isolated by column chromatography from ethyl acetate fractions of R. caffra stem bark and identified on various spectroscopic techniques such as FTIR and (1D and 2D) NMR. Melting point was also determined to be a sharp 129-130 ºC. DCM, EA, MetOH and EtOH fractions as well as β-Sitosterol (compound SM/01), showed antioxidant activity when tested on DPPH, FRAP, total phenolic and flavonoid bioassays. This antioxidant activity might be due to the presence of hydroxyl groups in the compound and crude fractions. On the other hand, T. minuta’s essential oil showed high antioxidant activity when evaluated on the DPPH and FRAP bioassays, which can be attributed to the presence of oxygenated monoterpenes and sesquiterpenes known to act as free radical scavenging and reducing agents. The use of R. caffra stem bark extracts against hypertension and other diseases by traditional healers could be attributed to the presence of phytochemicals (polyphenols and flavonoids) with known health benefits. Thus, it is recommended that the plant should be exploited further using modern techniques involving separation and purification of compounds that can be used for drug formulation. This study supports the use of T. minuta and R. caffra as the potential natural antioxidant source to manage various diseases including hypertension.
Synthesis, characterisation and evaluation of functionalized lignocelluloses-clay nanocomposites for organic pollutant removal from water
(2015) Mafukidze, Donovan M
PMPSgLig-NaMMT nanocomposites were prepared from methacryloxypropyltrimethoxysilane (MPS), lignocellulose and montmorillonite clay. The potential enhancement of organic pollutant adsorption capabilities of PMPSgLig-NaMMT nanocomposite from water through functionalization was investigated. PMPSgLig-NaMMT was functionalized by esterification and etherification using different methods so as to increase the surface hydrophobicity of the material and hence improve its compatibility with the target pollutants. Specific chemical routes specially tailored for PMPSgLig-NaMMT were established for functionalization mostly based on the common esterification (Fischer esterification) and etherification (Williamson‟s etherification) reactions. In the functionalization methods, factors such as pH environment, nanocomposite composition, nature of functionalization moiety, and use of or absence of solvents and their variations were studied. FT-IR, XRD, SEM and TGA were used to characterize the synthesized and functionalized nanoadsorbents. The techniques showed successful functionalization via esterification and etherification methods albeit to different extents, with clear retention of the material‟s original structure though there were signs of degradation with some methods. Characterization was supported by adsorption studies to validate implications and draw conclusions. The use of 1,10-phenathroline as a model organic pollutant in water in the adsorption studies showed that adsorbents conformed to monolayer adsorption following pseudo-second order kinetics for adsorption of organic pollutants accurately represented. Most importantly the studies revealed the significant impact of the nanocomposite composition on the overall absorbent performance. Adsorption studies also showed that functionalization via esterification methods gave rise to better adsorbents.
Synthesis, characterization & application of visible light responsive nitrogen doped tio2 and copolymer-grafted asymmetric membranes with ozonolysis for water treatment
(University of Fort Hare, 2015) Mungondori, Henry H.
The use of titanium dioxide for the photo-catalytic removal of organic, inorganic, and microbial pollutants from natural water and wastewater has been considered a very promising technique. The aim of this study was to prepare nitrogen doped titanium dioxide, immobilize it on asymmetric polymeric membranes of poly (methacrylic acid) grafted onto poly (vinylidene difluoride) (PVDF) blended with poly (acrylonitrile) (PAN), and evaluate the photo-catalytic, antimicrobial, and antifouling properties of the membranes. Nitrogen doped titanium dioxide (N-TiO2) nano-particles were prepared by a low temperature sol gel synthesis technique. The modification of TiO2 with nitrogen allows photo-sensitization of the photo-catalyst towards visible light utilization. The N-TiO2 nano-particles were characterized by fourier transform infrared spectroscopy (FT-IR), scanning x-ray photoelectron spectroscopy (SXPS), X-ray diffraction analysis (XRD), diffuse reflectance spectroscopy (DRS), Brunauer Emmett Teller (BET) surface area analysis, and transmission electron microscopy (TEM). The characterizations revealed the presence of the expected functional groups and confirmed successful doping and that the product was visible light responsive. Novel poly (methacrylic acid) grafted onto poly (vinylidene difluoride)/ poly (acrylonitrile) (PMAA-g-PVDF/ PAN) asymmetric membranes were prepared by the dry-wet phase inversion technique. The poly (methacrylic acid) (PMAA) side chains where grafted onto an activated PVDF backbone by reversible addition fragmentation chain transfer (RAFT) polymerization. The photo-catalytic membranes were generated by blending N-TiO2 with the polymer solution before casting the membranes. The membranes were characterized by FT-IR, nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM), and thermo-gravimetric analysis (TGA). FT-IR and NMR analyses confirmed successful grafting of MAA chains onto PVDF while SEM confirmed the successful preparation of membranes with asymmetric structure. The efficacy of the photo-catalytic asymmetric membranes was evaluated on the removal of herbicides from synthetic water. Bentazon was easily degraded while atrazine and paraquat were recalcitrant and proved difficult to degrade. The best results were observed with 3 % N-TiO2-PMAA-g-PVDF/ PAN asymmetric membranes on the photo-degradation of bentazon, atrazine and paraquat in water. Significant enhancement in the photo-degradation of the three herbicides was observed when photo-catalytic degradation was coupled with ozonation. Liquid chromatography-mass spectrometry (LC-MS) analysis confirmed the presence of a degradation by-product during the photo-catalytic degradation of bentazon. The photo-catalytic membranes were also evaluated on the photo-catalytic reduction of heavy metals Pb2+ and Fe3+ in water, and the best results were obtained using 1 % N-TiO2-PMAA-g-PVDF/ PAN and 1 % N-TiO2-PAN asymmetric membranes. All prepared photo-catalytic membranes where capable of completely inactivating E. coli ATCC 8739 within 120 minutes of exposure and inactivation rate increased with increasing N-TiO2 photo-catalyst loading. However, there was an indication from the results obtained that N-TiO2 supported on PMAA-g-PVDF/ PAN showed a higher inactivation rate of E. coli ATCC 8739 compared to N-TiO2-PAN and N-TiO2-PVDF membranes. The 1 % N-TiO2-PMAA-g-PVDF/ PAN membranes gave the highest pure water flux (421.83 L/m2h). This increase (PVDF = 30.50 L/m2h, PAN = 73.85 L/m2h) in pure water flux is owed to PMAA grafting as well as addition of N-TiO2. These modifications resulted in an increased membrane surface hydrophilicity, which promoted permeation of pure water through the membrane structure. A high bovine serum albumin (BSA) rejection (76.5 %) was noted and can be attributed to steric hindrance brought about by PMAA side chains which prevented the bulky BSA molecules from attaching to the membrane surface for PMAA-g-PVDF/ PAN membranes. However, the supporting porous sub-layer of an asymmetric membrane seemed to play a very important role in the overall permeability of a membrane. PVDF membranes are highly hydrophobic hence they gave a very low pure water flux.
Phytochemical analyses, synthesis of silver nanoparticles from Filipendula ulmaria (L.) Maxin and Agathosma betulina (Berg.) Pillans and their bioassays.
(University of Fort Hare, 2015) Chiguvare, Herbert
Agathosma betulina (Buchu) and Filipendula ulmaria (Meadowsweet) are popular herbal plants used in South Africa. These plants have been used as herbal medicines for the treatment of several diseases for years but without scientific analysis to validate their claims as herbal remedies. Hydrodistillation was carried out for the two plants and 2.3 g were obtained from buchu representing a yield of 0.8 % while 0.73 g was obtained from A. betulina representing a yield of 0.73 %. The two oils were analysed using GC/MS and 41 oil components were obtained from F. ulmaria and 11 oil components were obtained from A. betulina. The major oil components of F. ulmaria oil were found to be Methyl salicylate (17.2 %), salicaldehyde (10.6 %), menthol (8.6 %), Anisaldehyde (8.2 %), menthone (8.1 %) Isomenthone (6.3 %) and A. betulina oil comprised majorly of Isomenthone (26.1 %), Diosphenol (17.9 %), Menthone (12.1 %), p-Diosphenol (12.8 %) and pulegone (10.5 %). Diosphenol with its two isomers constitute the biggest component of 30.7 % of A betulina oil. The ethanolic crude extract of F. ulmaria was subjected to isolation through chromatographic methods. One isolate was obtained and fully elucidated by 2D NMR analysis to be Lupeol. The two plants were further used as agents in plant mediated silver nanoparticle synthesis. Use of medicinal plants for the synthesis of silver nanoparticles is a green synthesis approach because of the use of non hazardous reacting materials, less aggressive reaction conditions such as very low energy requirements, harmless solvents systems among others. F. ulmaria mediated Ag-NPs synthesis was not successful and thus yielded inconclusive results. A. betulina plant mediated biosynthesis of silver nanoparticles using the chemical reduction of silver nitrate method was completed in 24 hours at 40⁰C, 60⁰C and 75⁰C. UV-Vis spectroscopy, FTIR spectroscopy and TEM were used to confirm the reduction of silver ions and formation of silver nanoparticles. F. ulmaria mediated synthesis of silver nanoparticles yielded inconclusive results. Polydispersed spherical, oblong and irregularly shaped silver nanoparticles ranging from 5-60 nm were produced from the A. betulina extract at synthesised at 60⁰C. This is the first report on the synthesis of silver nanoparticles using A. betulina and F. ulmaria. The Formalin assay, a chemical model for stimulation of pain and the egg albumin paw oedema model were used for testing analgesic and anti-inflammatory activity respectively. The oils, ethanolic crude extracts and the silver nano particles were tested against standard drugs. The oils, ethanolic crude extracts and the silver nano particles were found to have significant ability to inhibit pain and inflammation. Results obtained gave scientific validation for the uses of A. betulina and F.ulmaria extracts in the management of pain and inflammation in traditional medicine.

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