Phytochemical Fractionation and Comparative In Vitro COX-1, COX-2, And 5-LOX Inhibitory Potential of Boswellia Serrata Resin

Abstract

Boswellia serrata gum resin is traditionally used for inflammatory disorders and contains triterpenoid constituents with potential effects on arachidonic-acid metabolism. The present study compared the in vitro cyclooxygenase and lipoxygenase inhibitory activities of a hydroethanolic extract of B. serrata resin and its polarity-based solvent fractions. The resin was extracted with 80% ethanol and sequentially fractionated into n-hexane, ethyl acetate, n-butanol, and residual aqueous fractions. Pharmacognostic parameters, preliminary phytochemical profile, total phenolic content, total triterpenoid content, and HPTLC fingerprints were evaluated. COX-1, COX-2, and human 5-lipoxygenase inhibitory activities were determined over a concentration range of 1–300 µg/mL, and IC50 values were calculated by nonlinear regression. The ethyl acetate fraction showed the highest total triterpenoid content (412.6 ± 10.4 mg UAE/g) and exhibited the strongest enzyme inhibition, with IC50 values of 54.8 µg/mL for COX-1, 31.6 µg/mL for COX-2, and 24.9 µg/mL for 5-LOX. The n-hexane fraction showed the second-highest activity, whereas the residual aqueous fraction was the least active. Enzyme-inhibitory potency correlated strongly with total triterpenoid content. These findings identify the ethyl acetate fraction as the most promising bioactive fraction for further phytochemical and mechanistic investigation.