Antioxidant Activity of a New Indole Alkaloid from Cassia alata L.

摘要

Free radicals have significant effects on the structure and general function of the cell. They play a role in the body's defense against infection by microorganisms. At the same time, they cause a number of diseases by inducing damage to DNA and otherimportant biomolecules. Hence, the search for additional free radical scavengers or antioxidants, especially from plant sources, is of prime importance. Leaf extracts from Cassia alata L. (locally known as 'akapulko'), traditionally used for the treatment of a variety of diseases, were evaluated as free radical scavengers using the diphenyl picryl hydrazyl hydrochloride (DPPH) assay. The ethyl acetate (EtOAc) fraction showed scavenging activity of 100%, comparable to gallic acid, a widely used antioxidant. Repeated column fractionation of the EtOAc fraction yielded a new indole alkaloid, 1-(4'-hydroxyphenyl)-2,4,6-trihydroxy-indole-3-carboxylic acid, which demonstrated a dose-dependent scavenging activity against DPPH with an IC_(50) of 0.0311 mu M +-0.002, indicating strong antioxidant potential.