Seladelicatulasine A-G, C27 steroidal glycosides with cholinesterase inhibitory activities from Selaginella delicatula.

Abstract Seven undescribed C27 steroidal glycosides, Seladelicatulasine A–G, including six cholestanol glycosides and one spirostanol glycoside, were isolated from Selaginella delicatula. Their structures were elucidated by 1D/2D NMR spectra and HRESIMS analyses. The absolute configurations of the sugars were determined by enzymatic hydrolysis and GC/MS analyses. These cholestanol glycosides were isolated from the family Selaginellaceae for the first time. Seladelicatulasine F is characterized as a rare B-5,6-secosteroid. In addition, all the compounds were evaluated for their inhibitory activities against cholinesterase (AChE/BChE) and monoamine oxidase (MAO-A/MAO-B). These steroidal glycosides displayed selective inhibition activities on cholinesterase. Seladelicatulasine A, B and E inhibited the AChE activity with IC50 values of 0.31, 0.09, and 0.04 μM, respectively. Seladelicatulasine A and F showed the strongest inhibition activity on BChE with IC50 values of 0.37 and 0.65 μM, respectively.