Isolation and characterization of sesquiterpenes from Arecophila saccharicola YMJ96022401 with NO production inhibitory activity

Abstract: Sesquiterpenes, arecoic acids A–F and arecolactone, were isolated from the ethyl acetate extracts of the fermented broth of Arecophila saccharicola YMJ96022401 along with two known analogues 1,7α,10α-trihydroxyeremophil-11(13)-en-12,8-olide and 1,10α,13-trihydroxyeremophil-7(11)-en-12,8-olide. Their structures were elucidated on the basis of spectroscopic data analyses. The inhibitory effects of all of these compounds on nitric oxide (NO) production in lipopolysaccharide (LPS, 200μg/mL)-activated murine macrophage RAW264.7cells were also evaluated. Among these compounds, 1,7α,10α-trihydroxyeremophil-11(13)-en-12,8-olide significantly inhibited NO production without any cytotoxicity, and its average maximum inhibition (E max) at 100μM and median inhibitory concentration (IC50) were 85.7%±0.8% and 16.5±1.0μM, respectively. Arecolactone was the most potent, with the E max at 12.5μM and IC50 being 94.7%±0.8% and 1.32±0.1μM, respectively, but displayed cytotoxicity at considerable higher concentrations than 25μM. Analyses of Western blotting indicated that arecolactone (0.8–12.5μM) inhibited induction of inducible NO synthase (iNOS) by LPS, which involved suppression of NF-κB activation and the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs) in activated RAW 264.7cells. In addition, arecolactone concentration-dependently prevented the vascular hyporeactivity to phenylephrine induced by LPS (300ng/mL) through iNOS pathway in isolated rat thoracic aortic rings. These results indicated that both of these naturally occurring iNOS inhibitors may provide a rationale for the potential anti-inflammatory effect of A. saccharicola YMJ96022401. [Copyright &y& Elsevier]