Acrocalyenes A and B, Two New Diterpenoids from Sinomenium acutum Associated Fungus Acrocalymma sp.

We identified two new diterpenoidal acrocalyenes A (1) and B (2) through chemical investigation on Acrocalymma sp., a plant-associated fungus from the tender stem isolates of Sinomenium acutum collected from the Qinling Mountains, along with seven already-recognized compounds (3-9). The HR-ESI-TOF-MS and 1D/2D NMR data were utilized for structural elucidation of these compounds, and the single-crystal X-ray diffraction was employed for absolute configuration clarification of the novel acrocalyenes 1 and 2. Bioassays revealed that the cytotoxicities of compounds 2, 4, 6, 7, and 8 against three human carcinoma cells (RKO, HeLa and HCC-1806) were moderate to strong, with IC50 between 6.70-38.82 µM. These isolates were also evaluated for their fungal resistant potentials against Botrytis cinerea, Fusarium culmorum and Fusarium solani, in which 3 displayed significant inhibitory effects on all three phytopathogenic fungi, showing respective MIC of 50, 25 and 25 µM.