Studies On The C₂₁ Steroidal Glycosides Constituents Of Cynanchum Stauntonii ?Decne.? Schltr.ex Lévl And Their Bioactive In Anti-inflammatory

Cynanchum stauntonii?Decne.? Schltr.ex Lévl., a plant from the family of Asclepiadaceae, is widely distributed in the south region of China and was recorded in the Chinese Pharmacopoieia?ChP? as an antitussives and expectorants herb medicine.Various chromatographic methods including Silica gel, Sephadex LH-20, ODS column chromatographies, and preparative HPLC were applied to separation and purification of the chemical constituents of Cynanchum stauntonii, which led to obtain 11 C₂₁ steroidal glycosides-type compounds?1¹1?, including five new compounds?1, 2, 5⁷?. Their chemical structures were determined by various spectroscopic techniques including IR, MS and NMR in combination with chemical derivatization. Among them, compounds 1⁴ were 14, 15-secopregnane-type C₂₁ steroidal glycosides containing hirundigenin aglycone, which was easy to isomerization due to the presence of 14-hemiketal hydroxyl group. Here, in order to explore the reason of isomerization, compounds 1 and 3 were selected to permethylate and led to obtain two pair of epimers?1a/1b and 3a/3b?. In adiition, mild acidic hydrolysis of compounds 1 and 3 led to isolation of eight anhydrohirundigosides and anhydrohirundigenin in order to discuss their structure-activity relationship of anti-inflammatory bioactivity.All the compounds mentioned above were subjected to evaluate their anti-inflammatory bioactivity by using a LPS-stimulated RAW264.7 cell model. Results revealed that all the compounds could obviously inhibit LPS-induced iNOS protein expression compared to single LPS stimulation?blank control? in RAW264.7 cells. Meanwhile, results showed that all tested compounds couldn't remarkably suppress COX-2 protein expression. On the contrary, compound 3e obviously increased COX-2 protein expression compared to single LPS stimulation. Structure-activity relationship?SAR? analysis revealed that anhydrohirundigenin-type C₂₁ glycosides exhibited stronger inhibitory effects on the LPS-induced iNOS protein expression compared to that of hirundigenin-type C₂₁ glycosides.