Purification, Molecular Docking and Cytotoxicity Evaluation of Bioactive Pentacyclic Polyhydroxylated Triterpenoids from Salvia urmiensis

Abstract

Triterpenoids, as one of the largest classes of naturally occurring secondary metabolites in higher plants, are of interest due to their high structural diversity and wide range of biological activities. In addition of several promising pharmacological activities such as antimicrobial, antiviral, antioxidant, anti-inflammatory and hepatoprotective effects, a large number of triterpenoids has revealed high potential for cancer therapy through their strong cytotoxicity on cancer cell lines and also low toxicity in normal cells. So, this study was aimed to discover novel and potentially bioactive triterpenoids from Salvia urmiensis species. For this, an ethyl acetate fraction of the acetone extract of the aerial parts of plant was chromatographed to yield five novel polyhydroxylated triterpenoids (1-5). Their structure was elucidated by extensive spectroscopic methods including 1D (1H, 13C, DEPT-Q) and 2D NMR (COSY, HSQC, HMBC, NOESY) experiments as well as HRESIMS analysis. Cytotoxic activity of the purified compounds was also investigated by the MTT assay against MCF-7 cancer cell line. Furthermore, a molecular docking analysis was applied to evaluate the inhibition potential of the ligands against the Nuclear Factor Kappa B (NF-κB) protein which promotes tumor metastasis or affects gene expression in cancer disease. 1β,11β,22α-Trihydroxy-olean-12-ene-3-one (compound 4) indicated the best activity in both in vitro and in silico assays, with an IC50 value of 32 µM and a docking score value of -3.976 kcal/mol, respectively.