Inducible nitric oxide synthase and cyclooxygenase-2 participate in anti-inflammatory and analgesic effects of the natural marine compound lemnalol from Formosan soft coral Lemnalia cervicorni

Lemnalol (8-isopropyl-5-methyl-4-methylene-decahydro-1,5-cyclo-naphthalen-3-ol) is a natural compound isolated from the marine soft coral Lemnalia cervicorni. In the present study, the anti-inflammatory and anti-nociceptive properties of lemnalol were investigated in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and carrageenan-injected rats, respectively. Our results demonstrate that lemnalol significantly inhibited the expression of the pro-inflammatory proteins, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in LPS-stimulated RAW 264.7 cells. An in vivo inflammation model was induced by intraplantar injection of carrageenan into rat hind paws. An intramuscular injection of lemnalol (15 mg/kg) 10 min before carrageenan injection resulted in significant inhibition of carrageenan-induced rat paw edema and thermal hyperalgesia behavior. Western blot experiments revealed that the carrageenan-induced expression of iNOS and COX-2 in paw tissue was significantly down-regulated by lemnalol. Moreover, post-intrathecal injection of lemnalol produced a dose-dependent anti-nociceptive effect in carrageenan-injected rats (1 and 5 μg). The present results indicate that the marine-derived compound lemnalol had anti-inflammatory and analgesic effects in LPS-stimulated RAW 264.7 cells and carrageenan-injected rats, respectively. In addition, inhibition of elevated iNOS and COX-2 protein expression as well as neurophil infiltration of carrageenan-injected paws may be involved in the beneficial effects of lemnalol.