Isolation, characterization, and biological evaluation of flavonols and 1,2-diphenylethanes from Bauhinia vahlii

Abstract

In this study, three known flavonols, namely kaempferol (1), ombuin (2), and quercetin (3), and three known 1,2-diphenylethanes, namely 5-(2-hydroxyphenethyl)-3-methoxy-2-methylphenol (4), 2-(3,5-dimethoxyphenethyl) phenol (5) and 2-(2-hydroxyphenethyl)-4,6-dimethoxyphenol (6) from the methanolic extract (ME) of Bauhinia vahlii were identified and sucessfully isolated. They were also evaluated for in vitro antioxidant, anti-inflammatory, anti-gout and anticancer effects. Compound 3 (26.00±2.17 µg/mL) showed an almost equivalent IC₅₀ value of standard drug (25.55±2.80 µg/mL) against superoxide free radicals. Moreover, compound 3 showed significant inhibition of COXs and 5-LOX enzymes, while compounds 1, 2, 4 and 5 exhibited good inhibition of XO enzymes. Except for compound 5, all compounds showed a significant reduction of cell growth lysis of MCF-7, DLD-1, HeLa, and A549. Besides, all the metabolites and ME showed a very weak degree of specificity against NHME, indicates less toxicity to normal cells. The results suggest that B. vahlii can be a favourable natural source for the treatment of oxidative stress, inflammation, gout and cancer, and these actions are linked to the natural active compounds 1, 3, 4 and 6.