Cucurbitane Glycosides and Their Potential Anti-Inflammatory Activities from Hemsleya chinensis Tubers

Hemsleya chinensis tubers, abundantly produced in southwestern China, are commonly used as a folk medicine that excel in anti-inflammation to treat enteritis, bronchitis, and tonsillitis. In this study, three previously undescribed cucurbitane glycosides, hemchinins G-H (1-3), that were characterized by the presence of four glucose substitutions, as well as eleven ones with one to three β-glucoses, were isolated from the tubers of H. chinensis. The structures were confirmed using comprehensive UV, IR, HR-ESI-MS, and NMR analyses, and absolute configurations were determined through a comparison of calculated and experimental ECD after acid hydrolysis. Compounds 1-3 showed NO inhibition effects on LPS-induced RAW 264.7 cells. Finally, molecular docking analyses were conducted to obtain the affinities of the isolated cucurbitane glycosides and our previously reported 19 cucurbitane triterpenes, focusing on targets involved in anti-inflammatory effects. The results indicated that they showed high docking scores of affinities with the proteins in the NF-κB, AMPK, and Nrf2 signaling pathways. Among them, cucurbitane triterpenes with sugar moiety substitution at C-3 and C-26/27 showed better affinity ability. The findings can provide insights into the anti-inflammatory mechanisms of this species and facilitate the development of novel therapeutic agents.