Hyrtioscalaranes A and B, two new scalarane-type sesterterpenes from Hyrtios erectus with anti-inflammatory and antioxidant effects

Abstract

Two new scalarane-type sesterterpenes, hyrtioscalaranes A and B, were isolated from the organic extract of the Demosponge Hyrtios erectus through extensive chromatographic purification. Hyrtioscalarane A exhibited significantly greater attenuation property against cyclooxygense-2 (IC50 0.83 mM) than that displayed by hyrtioscalarane B (IC50 0.98 mM). The greater selectivity index of hyrtioscalaranes (> 1) than that exhibited by the commercial anti-inflammatory agent ibuprofen (0.43) further supported the higher selectivity of the former towards pro-inflammatory cyclooxygenase-2. Hyrtioscalarane A exhibited greater antioxidant activities as determined by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (IC50 0.77 mM) and 2,2-diphenyl-1-picrylhydrazyl (IC50 0.81 mM) free radical quenching properties than those displayed by hyrtioscalarane B (IC50 > 0.83 mM) and the antioxidative agent α-tocopherol (IC50 1.51 mM). The greater binding energy (–14.32 kcal/mol) and docking score (15.22 kcal/mol) of hyrtioscalarane A at the active site of cyclooxygenase-2 along with the higher electronic parameters and balanced hydrophobicity could attribute its potential anti-inflammatory activity.