Anti-inflammatory ent-cleistanthane-type diterpenoids from Phyllanthus rheophyticus

A bioactivity-guided isolation from the aerial parts of Phyllanthus rheophyticus obtained 17 undescribed ent-cleistanthane-type diterpenoids, namely phyllarheophols A−Q, as well as 12 known analogs. Their structures were characterized by a combination of spectroscopic data interpretation, single-crystal X-ray diffraction and ECD analysis. The anti-inflammatory activities of these compounds were evaluated by measuring their inhibitory effects on NO production in LPS-stimulated RAW264.7 macrophages, and their preliminary structure-activity relationships were also discussed. Further study showed that promising compounds phyllarheophol D and phyacioid B significantly suppressed the expressions of cytokines and nitric oxide synthase through the NF-κB signaling pathway. 29 ent-cleistanthane-type diterpenoids were isolated from the aerial parts of Phyllanthus rheophyticus, and their anti-inflammatory activities were evaluated. [Display omitted] •The phytochemical components of Phyllanthus rheophyticus were first reported.•17 undescribed ent-cleistanthane-type diterpenoids and 12 known ones were isolated.•Six compounds exhibited significant NO inhibitory activities (8.58< IC50