Triplinones I-O: arylalkenyl α,β-unsaturated-δ-lactones isolated from the leaves of Australian rainforest plant Cryptocarya triplinervis (Lauraceae) displaying anti-inflammatory activity

Seven new arylalkenyl α,β-unsaturated-δ-lactones, triplinones I-O (1-7), were isolated from the leaves of the Australian rainforest plant Cryptocarya triplinervis B. Hyland (Lauraceae). The chemical structures of these compounds were established by NMR spectroscopic data analysis, while their relative and absolute configurations were established using a combination of Mosher ester analysis utilizing both Riguera's and Kishi's methods and CD experiments. Compounds 2 and 4 were identified as epimers, where the relative stereochemistry of the 1,3-diol moiety in both structures was first confirmed by Kishi's method, followed by their absolute configuration determination using Riguera's method. Compounds 1-7 exhibited good inhibitory activities toward nitric oxide (NO) production in lipopolysaccharide (LPS) and interferon (IFN)-γ-induced RAW 264.7 macrophages, in particular compounds 6, 2, and 4, with IC50 values of 2.1 ± 1.4, 8.5 ± 0.6, and 8.5 ± 0.7 μM, respectively.