ANTIOXIDANT ACTIVITY AND PHYTOCHEMICAL PROPERTIES OF METHANOL, ETHANOL AND HEXANE SOME EXTRACTS OF Alstoniaboonei LEAVES

Thesis Abstract

In traditional setting, Alstoniaboonei is used for the treatment of different ailments, this has been attributed to its rich phytochemical and antioxidant properties.The objective of the study was to evaluate the phytochemical properties and antioxidant activity of the methanol, ethanol and hexane extracts of Alstoniaboonei leaves. Qualitative analysis of phytochemical constituents such as tannins, saponins, cardiac glycosides flavonoids and phenols were carried out. Quantitative analysis of total phenolics, saponins and flavonoids was performed by well-known test protocol. Antioxidant activity reveals the presence of reactive oxygen species which helps to scavenge free radicals that are present in the body. The in vitro antioxidant activity was studied by diphenyl-2-picryl-hydrazyl (DPPH), ferric reducing antioxidant power (FRAP), reducing power (RP) and ferrous ion metal chelating. Results obtained for phytochemical studies revealed that flavonoids were highest in ethanol extract(101.6±1.35) while hexane extract (56.6±1.510) had the lowest content. Also phenol was highest in methanol extract (262±4.93) and lowest in ethanol extract (172.7±1.66). Result for total tannins (271±6) and proanthocyanidin (200.7±2.19) indicates that methanol and ethanol extract had the highest amount while hexane extract had and the lowest amount. IC5o values obtained by DPPH for ethanol extracts of Alstoniaboonei (2.362µg/ml), when compared with other extracts, and was significantly (P>0.05) lower than that of the standard vitamin C (12.81µg/ml). Also, the ethanol extract(0.026µg/ml) showed low IC50 value for ferrous ion metal chelating ability when compared with other extract, but this value was non significantly (P>0.05) lower than the standard(4.11µg/ml). Therefore, Alstoniaboonei has a great potential for use as a natural source of antioxidant and also help in the treatment of various ailments, or against free radical damage.