An anti-inflammatory salmachroman from the sea urchinSalmacis bicolor: a prospective duel inhibitor of cyclooxygenase-2 and 5-lipoxygenase

An isochroman derived polyketide, salmachroman characterized as methyl 15(3)(11-(10-hydroxy-12-oxo-6-pent-6(3)-en-6(1)-yl)isochroman-10-yl)-13-oxotetrahydrofuran-15-yl was isolated from the organic extract of the Echinodermata sea urchinSalmacis bicolor(family Temnopleuridae) through chromatographic fractionation. The structure of the compound was identified by detailed spectroscopic techniques. Salmachroman demonstrated significant duel inhibition potential against pro-inflammatory enzymes, cyclooxygense-2 (IC(50)1.29 mM) and 5-lipoxygenase (IC(50)1.39 mM). The compound exhibited significantly greater anti-inflammatory selectivity index (1.03) than that displayed by the anti-inflammatory agent ibuprofen (0.43). The isochroman analogue exhibited greater antioxidant activities against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (IC(50)1.19 mM) and 2,2-diphenyl-1-picrylhydrazyl (IC(50)1.24 mM) than the standard antioxidative agent alpha-tocopherol (IC50> 1.50 mM). The binding properties of the compound with the active site of cyclooxygense-2 and 5-lipoxygenase enzymes, combined with its higher electronic parameters as attributed by the structure-activity relationship accounted for its significant anti-inflammatory properties.