Phytochemical analyses, synthesis of silver nanoparticles from Filipendula ulmaria (L.) Maxin and Agathosma betulina (Berg.) Pillans and their bioassays.

Abstract

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.