Antimicrobial and Phytochemical Screening of some Zimbabwean Medicinal Plants

Abstract

Twelve (12) medicinal plants endangered and commonly used by communities and traditional medical practitioners in 5 districts of Zimbabwe were selected. Twenty methanol freeze dried plant extracts were screened for phytochemistry using thin layer chromatography (TLC) with detection by UV and reagent sprays. Phytochemical group investigations indicated presence of tannins (80 %), saponins (70 %), flavonoids and cardiac glycosides (40 %), anthraquinone derivatives and coumarins (25 %) and alkaloid (15 %).Antibacterial and antifungal activity was tested by agar-well diffusion method using standard antimicrobial strains and expressed as average diameter of the zone of inhibition around the wells compared with reference standards. Most of the plant extracts were active against gram positive Staphylococcus aureus and Streptococcus Group A with Erythrina abyssinica, Ximenia caffra and Ziziphus mucronata being the most active. Extracts of Peltophorum africanum and Ximenia caffra were strongly active against gram-negative Escherichia coli and Pseudomonas aeruginosa. None of the extracts had pronounced activity against Candida albicans and Aspergillus niger. Dicoma anomala and Peltophorum africanum however, showed moderate activity against Candida albicans. Minimum inhibition concentrations (MICs) of active plant extracts ranged between 0.23 mg/ml to 5 mg/ml. The studies demonstrate the potential value of medicinal plants used by traditional medical practitioners and should be preserved, propagated and developed for the treatment of various ailments and for industrial expansion.

Toxicity and Antiviral Activities of Some Medicinal Plants Used by Traditional Medical Practitioners in Zimbabwe

“…In Zimbabwe, a study was set up with the help of GEF/UNDP/MET (Ministry of Environment and Tourism) to carry out scientific laboratory studies on 50 extracts from 26 medicinal plants commonly used by communities to assess their conservation status in five selected districts from two regions of the country and to raise awareness of their importance and promote their sustainable use. Subsequently, we reported the antioxidant properties of extracts from these plant species [6] [7] as well as their antimicrobial and phytochemical properties [8] [9]. The laboratory studies confirmed the rationale for their use in traditional medical practice in line with other studies elsewhere to evaluate TMs targeted at finding alternative safer drugs to treat modern illnesses and to overcome growing resistance to infective agents.…”

Dicoma Anomala Sond.: A Review of Its Botany, Ethnomedicine, Phytochemistry and Pharmacology

“…Becker et al [68] isolated a eudesmanolide-type sesquiterpene lactone, 3-oxoeudesma-1,4(15),11(13)-triene-12,6a-lide commonly called dehydrobrachylaenolide from the roots of D. anomala. Munodawafa et al [71] isolated saponins and tannins from D. anomala roots.…”

“…The following activities have been reported from D. anomala including anthelmintic [58,72], anticancer [66,70], antihyperglycemic [73,74], anti-inflammatory [47], antimicrobial [26,28,71,[75][76][77], antioxidant [26,71,74,78,79], antiplasmodial [66,80], hepatoprotective [56,79], toxicity, and cytotoxicity [68,71,74,80,81].…”

Biodiversity Studies in Key Species from the African Mopane and Miombo Woodlands

“…For example, the bark is used as a powerful astringent to treat diarrhea, heavy menstruation, nosebleeding, headache, stomachache, schistosomiasis, sores, and skin problems; the root is believed to cure malaria, blackwater fever and gonorrhea [6,24,28,35,36]. Research studies reveal promising results concerning their antibacterial [37][38][39], antifungal [38], anthelmintic [40,41], and HIV-1 reverse transcriptase inhibitory properties [38] ( Table 1). At the environmental level P. angolensis is able to establish nitrogen-ixing symbiosis with rhizobium bacteria and therefore relevant for soil fertilization.…”

“…Pterocarpus angolensis DC Antischistosomal [90] RAPD [79,80] Stem, stem bark, leaves: anthelmintic [40] Seeds: antibacterial [91] Stem bark: antibacterial and anti-inlammatory; lack of mutagenicity [92] Stem bark, leaves: anthelmintic, antibacterial, and cytotoxic [41] Antibacterial [93] Stem bark: antibacterial; epicatechin and derivatives identiied [37] Stem bark: antibacterial; leaves, stem bark: antifungal, HIV-1 reverse transcriptase inhibitory [38] Leaves, stem bark: anti-inlammatory [94] Stem bark, roots: antibacterial; tannins and saponins identiied [39] Colophospermum mopane (Benth. )…”