Antioxidative and anti-inflammatory pyranoids and isochromenyl analogues from Corbiculid bivalve clam, Villorita cyprinoides

Abstract

Bivalve black clam, Villorita cyprinoides is traditional seafood in Southwestern coast of Arabian Sea. In this study, bioactivity - guided purification of ethyl acetate:methanol extract of black clam was carried out. Two irregular meroterpenoids [tetrahydro - 3 - methoxy - 5 - ((E) - 8,12 - dimethyloct - 8 - enyl) - pyran - 2 - one (1) and dihydro - 5 - (8 - (9,12 - dihydro - 8 - methyl - 11 - propyl - 2H - pyran - 8 - yl) - ethyl) - furan - 2(3H) - one (2)] and two hexahydro - isochromenyl - meroterpenoids (3–4) were identified. The structures were characterized by detailed spectroscopy and their antioxidant / anti - inflammatory potentials were evaluated. Compound 2 registered significantly greater 2,2 - diphenyl - 1 - picrylhydrazyl (DPPH) radical scavenging ability (IC50 < 0.65 mg / mL) than other analogues (IC50 ≥0.70 mg / mL). Ferrous ion (Fe2 + ) chelating ability was higher for 1–2 (IC50 ∼0.84 mg / mL) than α - tocopherol (IC50 0.89 mg / mL). The 5 - lipoxygenase inhibitory potential of furano - meroterpenoid analogue, 2 (IC50 0.76 mg / mL) was greater than other compounds (IC50 > 0.90 mg / mL). An optimum hydrophobic - hydrophilic balance of furano - meroterpenoid and lesser steric bulk manifested towards its greater bioactivities compared to other compounds. These anti - inflammatory and antioxidant leads could be used as potential functional food components.