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

Abstract 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 IC 50 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.