First report of anti-inflammatory chromenyl derivatives from the spineless cuttlefish Sepiella inermis

Abstract

The spineless cuttlefish Sepiella inermis encompasses a major share in the marine fisheries sector, and represents as a culinary delicacy in many cultures. Bioactivity-guided fractionation of methanol:ethyl acetate (MeOH:EtOAc, 1:1) extract of the edible parts of the species ensued in identification of two hexahydro chromenyl analogues namely, methyl 7-ethyl-hexahydro-8a-methyl-2H-chromene-4-carboxylate (1) and methyl 1-acetoxy-hexahydro-3-methyl-3-propyl-1H-isochromene-4-carboxylate (2). The isolated metabolites were checked for their radical scavenging and anti-inflammatory potentials by selective in vitro models. The isochromenyl derivative exhibited potential 2,2-diphenyl-1-picryl-hydrazil and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (IC50 < 0.45 mg mL−1) radical-scavenging capacities along with pro-inflammatory cyclooxygenase-2 (COX-2) (IC50 0.75 mg mL−1) and 5-lipoxygenase (5-LOX) (IC50 0.77 mg mL−1) inhibitory activities. The titled compounds displayed the selectivity indices (IC50 anti-COX-1/IC50 anti-COX-2) greater than 1.25, in comparison with synthetic anti-inflammatory drug ibuprofen (0.44), which attributed to their greater selectivity towards inducible pro-inflammatory enzyme COX-2.