Browsing by Author "Nethengwe, Mulalo Flexy"

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    Antiplasmodial/Antipyretic activity of some Zulu medicinal plants
    (University of Zululand, 2011) Nethengwe, Mulalo Flexy; Opoku, A.R.; Shonhai, A.; Oyedeji, O.A.
    Malaria is one of the major diseases that have partially paralysed the world‘s health presently. There is, therefore, an urgent need to identify new antimalarial drugs as the plasmodium species continues to gain resistance to presently used drugs. In developing communities where malaria is prevalent, people depend strongly on traditional medicine as a source of inexpensive treatment for this disease. Gardenia thunbergia T.A Sprague, Siphonochilus aethiopicus (Schweif.) B.L Burtt, Schotia brachypetala Sond., Acorus calamus L., Withania somnifera (L) Dunal in DC., Elaeodendron transvalense (Burtt Davy) R.H. Archer, Hypoxis hemerocallidea Fisch., C.A. Mey.&Ave-Lall., Vernonia adoensis Sch. Bip. Ex Walp. and Acanthospermum australe (Loefl.) Kuntze) are some of the medicinal plants commonly used by Zulu traditional healers in South Africa to treat malaria. Aim The study aims to determine the phytochemicals present in the plants, larvicidal, antioxidant, in vivo antipyretic and in vitro antiplasmodial activities as well as the cytotoxicity of the nine plants. The study also aims to isolate and purify the active compound in the most active plant extract. Material and methods Plants obtained from the muti market were botanically identified and were screened for phytochemicals; the appropriate portions of each plant were separately extracted v into dichloromethane, methanol and water solvents. Larvicidal activity against Culex quinquefascitus larvae was determined by incubating the larvae with the plant extracts for 24 hours, where after percentage mortality was calculated. The antioxidant activity of the methanol extracts of the plants was determined by measuring the decrease in the colour of an oxidative system in the presence of the plants extracts. The various antioxidant activities investigated included the free radical (DPPH, ABTS, super oxide, nitric oxide and hydroxyl) scavenging activity, Fe2+ chelating, reducing power, and total antioxidant capacity. Antipyretic activity was determined by treating different groups of pyretic rats with different concentrations of the plants extracts (100 mg/kg, 500 mg/kg and 1000 mg/kg). The pyretic condition was induced by subcutaneous injection of 12% brewer‘s yeast. Temperatures before and after treatment were also compared. The antimalarial activity of the plants extracts were also screened against the chloroquine sensitive plasmodium falciparum D10 strain. Tests were done in triplicate for three concentrations (20 μg/ml, 10 μg/ml and 5 μg/ml). The active extracts were screened for cytotoxicity using the MTT assay. The most active in vitro antiplasmodial extract was subjected to isolation, purification and characterization using chromatographic and spectrometric techniques-IR, GC-MS, 1H-NMR, and 13C-NMR. Results Phytochemical screening revealed the presence of saponins, terpernoids, flavonoids, anthroquenones, cardiac glycosides; alkaloids (the major active constituents of most antimalarial drugs) were also observed in A. australe which, amongst others, exhibited the most in vitro antiplasmodial activity. The plant extracts either killed or reduced spontaneous movement in Culex quinquefascitus larvae after 24 hours following treatment. Methanol extracts exhibited antioxidant (DPPH, ABTS scavenging, Fe2+ chelating) activity, albeit to varying degree of efficiency. The dichloromethane and methanol extracts significantly (p≤ 0.05) reduced pyrexia with activity increasing in a concentration dependent manner. The antiplasmodial activity against chloroquine sensitive strain of Plasmodium falciparum (D10) showed that the methanol extracts of G. thunbergia, V. adoensis and the dichloromethane extracts of E. transvalense, and W. somnifera were active (IC50 of 1.04-5.07μg/ml). Although A. australe exhibited high in vitro antiplasmodial activity, the major compounds (Sitosterol and Stigmasterol) present in the extract did not exhibit any observable antiplasmodial activity. Conclusion The results support the use of some of these plants in folk medicine and suggest that these plants contained constituents that could be developed as potent antimalarial drugs (mosquito larvicide, anti-fever and anti-plasmodial).