Three New Cycloartane Triterpenoids From the Caulis of Kadsura longipedunculata

Three unprecedented cycloartane triterpenoids (1-3) together with five known congeners (4-8) were isolated for the first time from the medicinal plant Kadsura longipedunculata. Their structural diversity was characterized by distinct skeletal modifications: compound 1 represents a rare 3,4-seco-cycloartane derivative featuring a 7-membered ester A-ring formed via Baeyer-Villiger oxidation, compound 2 is a schisanartane-type nortriterpenoid with unique 3,4:9,10-diseco structural motifs, while compound 3 exhibits an unprecedented 18,28-demethylated cycloartane skeleton. In addition, five known congeners (4-8) were cycloartane triterpenoids. Significantly, these structurally modified derivatives represent the first report of such skeletal variations within the K. longipedunculata genus. Structural elucidation and absolute configuration determination were achieved through comprehensive spectroscopic analysis (one-/two-dimensional nuclear magnetic resonance and high-resolution electrospray ionization-mass spectrometry) complemented by X-ray crystallographic verification and electronic circular dichroism calculation. These compounds were evaluated for their cytotoxicity and anti-inflammatory activity. Compounds 4 and 5 could inhibit nitric oxide production with 50% inhibitory concentration (IC₅₀) values of 36.45 and 28.38 µM. Compound 4 demonstrated concentration-dependent antiproliferative effects against HeLa cervical cancer cells, achieving 68.99% growth inhibition at 40 µM and an IC₅₀ value of 21.40 µM.