In silico modelling and NMR Characterization of some steroids from Strychnos innocua (Delile) root bark as potential antifungal agents

Abstract

The root bark of Strychnos innocua has long been employed by traditional healers to treat a variety of ill health conditions including fungal infections. The objective of this study was to isolate, characterized and evaluate the antifungal potential (insilico approach) of some steroids from root bark of S. innocua. Conventional method of column chromatography was carried out on the ethyl acetate root bark extract of S. innocua, leading to the isolation of two steroids. On the basis of 1D NMR, 2D NMR, GC-ESI/MS analyses, and literature comparisons, the compounds were characterized as Stigmast-5-en-3β-ol (1) and Campest-5-en-3β-ol (2). This is the first time these compounds have been isolated from the plant. The results of the in silico modelling of the compounds 1, 2, and fluconazole (control drug) with the binding sites of SAP2 from Candida albicans (PDB: 1EAG) demonstrated that the binding energies were −8.3, −8.0, and −7.1 kcal/mol, respectively. However, the modelling with binding sites of a deglycating enzyme fructosamine oxidase from Aspergillus fumigatus (PDB: 3DJE) demonstrated that the binding energies were −5.9, −7.2, and −8.0 for Stigmast-5-en-3β-ol (1) and Campest-5-en-3β-ol (2), and fluconazole, respectively. In conclusion, the study found that Stigmast-5-en-3-ol and Campest-5-en-3-ol are both present in the root bark of S. innocua. The compounds exhibited promising interaction with the binding sites of the protein target (SAP2 from C. albicans) compare to fluconazole.