Two 9,10-syn-pimarane diterpenes from the roots of Lonicera macranthoides

Abstract Two previously undescribed 9,10- syn -pimarane diterpenes, lonimacranthoidins A-B ( 1 - 2 ), were isolated from the roots of Lonicera macranthoides . Their structures were characterized by the interpretation of spectroscopic data. X-ray crystallographic analysis was applied to determine the absolute configuration of lonimacranthoidin A ( 1 ). Bioassay results suggested that lonimacranthoidin A ( 1 ) possessed moderate antifungal activities against two strains of plant-pathogenic fungi, Rhizoctonia solani and Fusarium graminearum , with EC 50 values of 20.07 ± 4.90 and 62.86 ± 23.51 μg mL −1 , respectively. Liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis showed that lonimacranthoidin A ( 1 ) only occurred in the roots of L. macranthoides .