Induction of heme oxygenase-1 mediates the anti-inflammatory effects of the ethanol extract of Rubus coreanus in murine macrophages

Foods of plant origin, especially fruits and vegetables, draw increased attention because of their potential benefits to human health. The aim of the present study was to determine in vitro anti-inflammatory activity of four different extracts obtained from the fruits of Rubus coreanus (aqueous and ethanol extracts of unripe and ripe fruits). Among the four extracts, the ethanol extract of unripe fruits of R. coreanus (URCE) suppressed nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production in lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophages. We also demonstrated that URCE by itself is a potent inducer of heme oxygenase-1 (HO-1). Inhibition of HO-1 activity by tin protoporphyrin, a specific HO-1 inhibitor, suppressed the URCE-induced reductions in the production of NO and PGE(2) as well as the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2). Our data suggest that URCE exerts anti-inflammatory effects in macrophages via activation of the HO-1 pathway and helps to elucidate the mechanism underlying the potential therapeutic value of R. coreanus extracts.