Phytochemical analysis and antibacterial properties of aqueous and ethanol extracts of brachylaena elliptica (thurb.) dc. and brachylaena ilicifolia (lam.) phill. & schweick.
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Date
2015
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University of Fort Hare
Abstract
Resistance of human pathogenic bacterial strains results in selective pressure against known
antibiotic. However, plant derived compounds that possess antibacterial potential are currently
being investigated for treatment of wound infections in diabetic patients as they are inexpensive
and non-toxic. Hence, this dissertation was designed to evaluate two medicinal plants
(Brachylaena elliptica and Brachylaena ilicifolia) traditionally used in the treatment of various
diseases such as diabetes, and its secondary complications in diabetic patients. The in vitro
antioxidant activity of both plants were evaluated using DPPH (1, 1-diphenylhydrazl), ferric
reducing power, ABTS (2, 2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid), NO (nitric
oxide) and H2O2 (hydrogen peroxide) techniques. The antibacterial test and Minimum inhibitory
concentration (MIC) was determined by agar dilution method against 5 bacteria strains
(Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogene, Proteus vulgaris and
Proteus mirabilis) infecting wounds in diabetic patients using amoxicillin and ciprofloxacin as
positive control. The phytochemical analyses were assessed using standard published methods.
Identification of bioactive components in essential oils of both plants were assessed using GCMS.
The aqueous and ethanol extracts of both plants were also evaluated to identify bioactive
components using LC-MS. The results of the phytochemical analysis revealed the presence of
phenols, tannins, flavanoids, flavanols, proanthocyanidins, saponins and alkaloids in both plants.
Both plants indicated strong antioxidant activities which might be due to the presence of bioactive
compounds. The aqueous and ethanol leaf extracts of both plants demonstrated
appreciable broad spectrum activities against these wound pathogens with MIC ranging between
5 and 0.3 mg/ml. The GC-MS analysis of the essential oils of both plants revealed the presence
of monoterpenes, oxygenated sesquiterpenes, phenolics and esters. The LC-MS analysis of the aqueous and ethanol leaf extracts of both plants showed that both plants are rich in alkaloids,
terpenes, terpenoids, monoterpernoids, and flavanoids. Conclusively, this study has partially
justified the ethnomedicinal use of B. elliptica and B. ilicifolia leaves for the treatment of various
diseases, including diabetes and wound infections caused by bacteria in diabetic patients. These
may be attributed to the presence of antioxidant compound such as phenols, flavanoids, saponins,
tannins, alkaloids and other phytochemical compounds.