Previously undescribed benzoxepins with bioactivities against inducible pro-inflammatory cyclooxygenase and lipoxygenase from Rhizophora annamalayana Kathir.
الكلمات الدالة
نبذة مختصرة
Two unprecedented benzoxepins were obtained from the ethyl acetate fraction of the leaves of Rhizophora annamalayana Kathir, and characterized as 4-(11-(hydroxymethyl)-10-methylpentan-2-yl)-4, 5-dihydrobenzo[c]oxepin-1(3H)-one (1) and (E)-methyl-14-hydroxy-4-(11-(5-hydroxy-1-oxo-3,4,5-tetrahydrobenzo[c]oxepin-4-yl)ethyl)-10-methylhept-11-enoate (2). The benzoxepin 2 exhibited greater 1, 1-diphenyl-2-picrylhydrazyl and 2, 2'-azino-bis-3 ethylbenzothiozoline-6-sulfonic acid diammonium radical scavenging assays (IC50 0.68 and 0.84 mg/mL, respectively) than those recorded with 1 (IC50 0.70 and 0.89 mg/mL, respectively). The tetrahydrobenzo[c]oxepin analogue (2) exhibited significantly great cyclooxygenase-2 and 5-lipoxygenase inhibitory properties (IC50 0.87 and 0.94 mg/mL, respectively), while compared with its dihydrobenzo[c]oxepin-1(3H)-one isoform (1) (IC50 1.16 and 1.64 mg/mL, respectively). The dihydrobenzo[c]oxepin-1(3H)-one isoform (2) exhibited significantly greater selectivity index (~2) than synthetic ibuprofen (0.44) (p < 0.05), which attributed the higher anti-inflammatory selectivity of the former against inducible pro-inflammatory cyclooxygenase-2 than its constitutive isoform (cyclooxygenase-1). No significant difference in 5-lipoxygenase (5-LOX) inhibitory activities were apparent between compound 2 (IC50 0.94 mg/mL) and synthetic ibuprofen (IC50 0.93 mg/mL).