Dihydrochalcones and Diterpenoids from Pteris ensiformis and Their Bioactivities

Two new dihydrochalcone enantiomers (+)-1 and (-)-1, along with eight known compounds 3-10, were obtained from Pteris ensiformis. The planar structures were determined on the basis of extensive 1D and 2DNMR and HRESIMS. The resolution of (+)-1 and (-)-1 was achieved by chiral HPLC analysis. The absolute configurations of (+)-1 and (-)-1 were established by the bulkiness rule using Rh₂(O₂CCF₃)₄-induced circular dichroism (ICD) method. Compounds (+)-1, (-)-1, 8, 9 and 10 exhibited the inhibitory assay of NO production in mouse macrophages stimulated by LPS, with IC₅₀ values of 2.0, 2.5, 8.0, 9.5 and 5.6 μM, respectively. Otherwise, compound 10 showed moderate cytotoxic activity against HCT-116, HepG-2 and BGC-823 cell lines with IC₅₀ values of 3.0, 10.5 and 6.3 μM, respectively.