Phytochemical and biological studies on rare and endangered plants endemic to China. Part XLIX. Terpenoids and phenylpropanoid-substituted flavan-3-ols from the leaves of Camellia petelotii (golden-flower tea) and their bioactivities.

Camellia petelotii (Merr.) Sealy, commonly known as golden-flower tea, is an endangered yellow-flowering species of the genus Camellia (Theaceae). As a medicine and food homology (MFH) plant, it possesses significant medicinal and edible value. However, because the chemical constituents of C. petelotii have rarely been investigated, its potential medicinal and nutritional benefits remain poorly understood, hindering its further utilization. In this study, a comprehensive phytochemical investigation was conducted on the EtOAc-soluble fraction of a 90% MeOH extract derived from the leaves of C. petelotii, resulting in the isolation and characterization of five previously undescribed (1-5) and 19 known (6-24) compounds. Among these compounds, campetelolides A (1) and B (2) are identified as guaianolides bearing a 2-methyl-2-butenoxyl moiety. Campetelols A (3), B (4), and C (5) are classified as phenylpropanoid-substituted flavan-3-ols. The chemical structures and absolute configurations of these metabolites were elucidated through spectroscopic techniques, supported by calculated NMR data, combined with DP4+ analysis, as well as by comparison of calculated and experimental electronic circular dichroism (ECD) spectra. Compounds 1, 2, and eupachinilide I (6) exhibited anti-inflammatory activity in lipopolysaccharide (LPS)-induced RAW 264.7 cells by suppressing nitric oxide (NO) production, with IC50 values of 5.8, 4.8, and 4.8 μM, respectively. In addition, compound 2 and 3β,11α,12,21β-tetrahydroxy-22-oxours-12-en-24-oic acid methyl ester (7) inhibited ATP-citrate lyase (ACL), exhibiting IC50 values of 11.2 and 9.3 μM, respectively. The findings highlight the therapeutic potential of the endangered plant C. petelotii, offering prospects for the discovery of novel bioactive agents while simultaneously emphasizing the importance of its conservation and sustainable utilization.