Phytochemical screening, antioxidant and antimicrobial activities of Berkheya bergiana leaves
The use of medicinal plants in the world and especially in South Africa, contributes significantly to Primary Health Care . The genus Berkheya belongs to the family Astereceae . The plant material collected from Zululand within KwaZulu-Natal province in South Africa, was air-dried, powdered and extracted with methanol. Fractions were obtained by successive extraction with n-Hexane (Hex), Chloroform (CHCl3), Ethyl acetate (EtOAc), and n-Butanol (BuOH). Antioxidant activity was investigated by DPPH radical scavenging effect, reducing power and metal chelating effect on ferrous ion. Antimicrobial test was carried out by disc-diffusion method on some selected bacterials. Phytochemical screening  carried out on B. bergiana revealed the presence of carbohydrate, flavonoids, terpenoids, saponins and tannins but absence of anthraquinones and alkaloids. The result demonstrated that methanolic extract of B. bergiana have excellent antioxidant activities and also shows that crude and fractions found to have different levels of antioxidant activity in all the system tested. Results revealed that BuOH fraction exhibited the best performance in DPPH and Metal chelating assay, 93.7% and 63.0% respectively. Total phenolic and flavonoid contents in the crude and fractions were also determined in which EtOAc fraction (12.29±0.11) has the highest total phenolic content. Strong correlation was recorded between DPPH/GAE (R2=0.85). Antimicrobial activity was highest on gram E. coli, P. aeruginosa, E. cloacae, K. pneumonia, B. cereus and S. aureus. The results of this study suggested that the antioxidant potential of B. bergiana leaf extract could be due to its strong proton donating ability and thus justified its use for the treatment of bacterial infections in ethnomedicine.
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