Cinnamolides A-G, seven previously undescribed phytoconstituents from the peels of Cinnamomum chago and their anti-inflammatory activity.

Seven undescribed phytoconstituents (1-5, 9, and 10), cinnamolides A-G, along with three known compounds were isolated from the peels of Cinnamomum chago B. S. Sun & H. L. Zhao, a threatened plant resource. Structurally, cinnamolides A-E (1-5) possessed a typical butanolide skeleton. Their structures were confirmed by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculations. All compounds were evaluated for their anti-inflammatory activity in lipopolysaccharide (LPS)-induced RAW264.7 cells. Compound 1 exhibited the strongest inhibitory activity, with an IC50 value of 3.6 μM, which is more potent than the positive control, N-Monomethyl-l-arginine (L-NMMA, IC50 = 33.0 μM). Furthermore, compound 1 can reduce the levels of the pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β) and downregulate nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression.