15-Lipoxygenase inhibition of Commelina benghalensis, Tradescantia fluminensis, Tradescantia zebrina.

OBJECTIVE: To evaluate the 15-lipoxygenase inhibitory activity of the methanol leaf extracts of Commelina benghalensis, Tradescantia fluminensis (T. fluminensis) and Tradescantia zebrina. METHOD: The inhibitory activity was evaluated using a spectrophotometric assay by observing the increase in absorbance at 234 nm due to the formation of the product 13-hydroperoxyoctadecadienoic acid. The extracts were also tested for the presence of terpenoids, saponins, tannins, flavonoids, steroids, phenolic compounds, alkaloids and cardiac glycosides. RESULTS: All the extracts inhibited the action of 15-lipoxygenase at a concentration of 0.2 µg/mL. T. fluminensis and Tradescantia zebrina exhibited higher than 50% inhibition with T. fluminensis at 87.2%. T. fluminensis was partitioned with ethyl acetate and hexane and their IC50 values were determined at 8.72 µg/mL and 98.04 µg/mL, respectively. CONCLUSIONS: T. fluminensis is a potentially good source of 15-lipoxygenase inhibitors.