Inhibition of xanthine oxidase by an aqueous extract of banaba leaves (Lagerstroemia speciosa)

Abstract

The inhibitory effect of an aqueous extract of Lagerstroemia speciosa leaves, known as the name of banaba in the Philippines, on xanthine oxidase (XOD) was compared with that of green tea, rooibos tea and tochu tea. A spectroscopic technique to measure the increasing UV absorbance at 295 nm was used to estimate the formation of uric acid from xanthine. On the sample tested, banaba extract was shown to have the strongest potential in inhibiting XOD. The fractionation of the banaba extract with DIAION HP-20 resin resulted in enhancing the inhibitory effect on XOD. It was revealed that ellagic acid, main polyphenolic component in banaba extract, was one of the substance having the inhibitory effect on XOD.