Two new <i>β</i> -dihydroagarofuran sesquiterpene polyesters from the seeds of <i>Celastrus angulatus</i> Maxim and their nitric oxide inhibitory activity

Two new <i>β</i>-dihydroagarofuran sesquiterpene polyesters, angu-latinpip I (1<i>β</i>,15-biacetoxy-8<i>α</i>-butanoyloxy-9<i>β</i>-benzoyloxy-<i>β</i>-dihy-dro---agarofu-ran) (<b>1</b>) and angulatinpip II (1<i>β</i>,9<i>α</i>,15-triacetoxy-8<i>α</i>-benzoyloxy-<i>β</i>-dihydroagarofuran) (<b>2</b>), together with two known compounds 1<i>β</i>,6<i>α</i>-biacetoxy-9<i>α</i>-benzoyloxy-<i>β</i>-dihydroagarofuran (<b>3</b>) and angulatueoid F (<b>4</b>), were isolated from the seeds of <i>Celastrus angulatus</i> Maxim. The structures of the new compounds were elucidated by means of extensive spectrometric analyses (IR, HRESI MS, 1D and 2D NMR). The anti-inflammatory activity of all compounds was evaluated by measuring nitric oxide production in RAW264.7 macrophages. Compounds <b>1-4</b> all exhibited a certain degree of inhibitory effect on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. Compounds <b>2</b> and <b>3</b> demonstrated inhibitory activities, with their half-maximal inhibitory concentration (IC₅₀) values determined to be 8.93 μM and 42.52 μM, respectively. Moreover, their inhibitory effects showed a dose-dependent relationship.