Anti-inflammatory and cytotoxic diterpenes from formosan Polyalthia longifolia var. pendula

A new clerodane diterpenoid 16-hydroxycleroda-13-ene-15,16-olide-3-one (1) was isolated from the bark of Polyalthia longifolia var. pendula, along with 23 known compounds and phytosteroids. Among these compounds, 5-7, 10, and 24 were obtained for the first time from the family Annonaceae. The structures of the isolated compounds were determined by mass and spectroscopic analysis. The clerodane diterpenoids, 2-4, showed significant cytotoxicity towards Hep G2 and Hep 3B hepatoma cell lines. Furthermore, compound 5 exhibited potent anti-inflammatory activity towards formyl-L-methionyl-L-leucyl-L-phenylalanine/ cytochalasin B (fMLP/CB)-induced superoxide generation by neutrophils with IC₅₀ = 0.60 ± 0.09 μg/mL.