First report of dual cyclooxygenase-2 and 5-lipoxygenase inhibitory halogen derivatives from the thallus of intertidal seaweed Kappaphycus alvarezii

Two halogen derivatives, characterized as 2-butyl-7-4-(chloromethyl) cyclooct-1-enyl) hept-5-en-1-ol (compound 1) and 4- (2-chloroethyl)-5-7-(methoxymethyl) undec-3-enyl) cyclooct-4-enone (compound 2) were isolated from the ethyl acetatemethanol extract of the intertidal red seaweed Kappaphycus alvarezii. The studied compounds were evaluated for their inhibitory effects towards pro-inflammatory 5-lipoxygenase along with cyclooxygenases, and also were determined the free radical scavenging potential. The halogenated cyclooctenone (compound 2) displayed greater 5-lipoxygenase (IC50 0.90 mg mL−1) inhibitory activity when compared to the non steroidal anti-inflammatory drug ibuprofen (IC50 0.93 mg mL−1). Similarly selectivity indices of the studied compounds were higher (anti-cyclooxygense-1 IC50/anti-cyclooxygense-2 IC50 ~1.06–1.07) when compared to those displayed by ibuprofen (0.44) and aspirin (0.02). The antioxidative activities of the halogen derivatives were found to be greater (IC50 < 0.30 mg mL−1) in comparison with that exhibited by α-tocopherol (IC50 > 0.50 mg mL−1). This is the first report on structural characterization of unusual halogen analogues from K. alvarezii with dual cyclooxygenase-2 and 5-lipoxygenase inhibitory activities