Vol. 4, Issue 6 (2015)

Author(s):
MS Hifnawy, SF AbouZid, Zeinab Y Ali, MM Fouda

Abstract:
Three flavonoids were isolated and identified using different spectroscopic procedures from the fruits of Tribulus terrestris L. viz. Querctin-3-O-α-L-rhamnopyranosyl (1```-6``)–O-β-D-glucopyranosoide, Quercetin and Isorhamentin-3-O-α-L-rhamnopyranosyl (1```-6``)–O-β-D- glucopyranosoide. The last compound is reported for the first time in the fruits under investigation. Qualitative and quantitative determination of flavonoids and phenolic acids of the total alcoholic extract, different solvent extractives and isolated compounds in addition to their antioxidant activity adopting the DPPH method are presented. The results revealed that the total alcoholic, n –butanol and ethyl acetate fractions as well as rutin and quercetin have potent free radical scavenging activity (IC50 = 64.0 ± 2.45, 240.4 ± 5.61, 280.9 ± 4.28, 12.1± 1.13 and 11.2 ± 0.81 µg/ml respectively). Moreover, the antimicrobial and antifungal activities of the total alcoholic extract, its subfractions and isolated compounds showed that they possessed non-significant antifungal activity. However, the butanol and ethyl acetate fractions in addition to the quercetin exerted potent antimicrobial activity against all investigated strains.