Sesquiterpenoids and Diarylheptanoids from Nidus Vespae and Their Inhibitory Effects on Nitric Oxide Production

Abstract Two coriamyrtin‐type sesquiterpenes, fengfangin A ( 1 ) and tutin ( 2 ), and six diarylheptanoids, namely alnusone ( 3 ), centrolobol ( 4 ), muricarpone B ( 5 ), 1‐(3,4‐dihydroxyphenyl)‐7‐(4‐hydroxyphenyl)heptan‐3‐one ( 6 ), (3 S )‐1‐(3,4‐dihydroxyphenyl)‐7‐(4‐hydroxyphenyl)heptan‐3‐ol ( 7 ), and (3 S )‐1‐(4‐hydroxyphenyl)‐7‐(3,4‐dihydroxyphenyl)heptan‐3‐ol ( 8 ), were isolated from the 95% EtOH extract of nidus vespae , the nest of Polistes species. Their structures were identified by spectroscopic methods. Compounds 1 and 8 are new products. The absolute configuration of 1 was determined by single‐crystal X‐ray diffraction analysis using Flack parameter. The biological tests showed that compounds 5, 6 , and 8 could inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)‐stimulated RAW 264.7 cells with IC 50 values in the range of 13–17 μ M , whereas the sesquiterpenes were inactive in this assay (>25 μ M ). In addition, the ecological significance of the presence of neurotoxic sesquiterpene lactones in nidus vespae is briefly discussed.