Fanyana Mtunzi
Vaal University of Technology, South Africa
Title: Evaluation of biological activities, isolation and identification of antimicrobial compound(s) from selected plants from Kwazulu-Natal South Africa
Biography
Biography: Fanyana Mtunzi
Abstract
Medicinal plants provides valuable alternative as sources of drugs and drug discovery since many have been used in traditional practices for centuries to manage or cure various forms of ailments. Plants in this research were selected on the basis of an ethno-botanical survey based on questionnaire responses and verbal interviews that was conducted in Mabandla village in KwaZulu-Natal, South Africa. Bioassay guided study involving anti-inflammatory studies measurements of LOX activity effected by a reaction medium containing 15-LOX, linoleic acid in buffer at pH 9 for 30 to 90 seconds after adding plant extract/fraction, free radical scavenging capacity against the ABTSâ—+ radical cation and DPPHâ— radicals; antimicrobial and bioautography assays against Staphylococcus aureus, ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 29212, Escherichia coli, ATCC25922, Candida albicans and A. fumigatus were carried out on the plants extracts, fractions and pure compounds. Isolation of compounds displaying biological activity was also carried out by use of open column chromatography and preparative TLC. The compounds were characterised by use of Nuclear Magnetic resonance, NMR, Mass Spectra, and Infra-red (IR) spectroscopy.
The DPPH sprayed TLC displayed that all the nine plants contain antioxidants most of which are contained in polar fractions of acetone and methanol. Results of the assays displayed a range of biological activities comparable to the positive controls used for each assay. DPPHâ— scavenging displayed EC50 values ranging between 1.008 and 467 mg/L. The highest activity is obtained from methanol fraction of Berkheya setifera with EC50 value of 1.008 mg/L within 0.5376 to 1.890 at 95 %confidence limit followed by crude fraction of Gunnera perpensa with EC50 value of 1.069 mg/L within 0.5222 to 2.188 at 95 % confidence limit. Carissa bispinosa hexane fraction displayed the lowest activity of 467.7 mg/L within 264.0 to 828.5 at 95 % confidence limit. Highest ABTSâ—+ radical scavenging was demonstrated by Pomaria sandersonii DCM, (1.273 mg/L at 0.9439 to 1.719 within 95% confidence limit) for the Ethyl acetate, (5.973 mg/L at 4.722 to 7.555 within 95% confidence limit while the lowest activity was displayed by hexane fraction from Eucomis autumnalis (929.4 mg/L at 557.5 to 1550 within 95% confidence limit)The activity of Pomaria sandersonii extracts and fractions demonstrated that the plant contains antioxidants that react with both DPPH and ABTS radicals although higher activities were shown by ABTS as displayed by the lower EC50 values. All of the crude fractions and extracts displayed high to moderate anti-bacterial activity (20 -625 µg/ml) and anti-fungal activity (20 -2500 µg /ml). P. sandersonii crude and fractions demonstrated highest antimicrobial activity compared to other plants. Some MIC values P. sandersonii DCM and ethyl acetate (80 µg /ml in each case) compared well with gentamycin (4 µg /ml) same value against S aureus, E. faecalis, E Coli and P aeruginosa. Anti-fungal activities of the DCM, acetone and methanol fractions were also highly active (20 µg /ml) for both C. a. and A. f. Inhibition of pathogen growth demonstrated by the polar fractions indicate that most of the active compounds would be soluble in water. P. Prunelloides, crude methanol extract produced 60% sucrose component and G. perpensa, 36% was glucose. Three compounds isolated from Alepidea amatymbica and three from Pomaria sandersonii which displayed high antimicrobial activities.