In Vitro Antibacterial Activity, In-Silico Molecular Docking and Pharmacokinetic Profile of a Phytosterol Isolated from The Leaves of Carissa Bispinosa

Carissa bispinosa (L.) Desf. Ex-Brenan is a medicinal plant widely used in South Africa. The study reports on the isolation of a phytosterol from C. bispinosa along with molecular docking and pharmacokinetic studies. The phytochemicals were extracted with hexane, dichloromethane, acetone and methanol. The compound was isolated following a bioactivity-guided isolation protocol using column-chromatography and thin-layer chromatography. Nuclear magnetic resonance (NMR) was used for compound characterisation. The antimicrobial activity was assessed using bioautography and micro-broth dilution assays. AutoDock vina, SwissADME and ADMET lab were used for molecular docking, pharmacokinetic and toxicological properties, respectively. Drug-likeness was evaluated based on Lipinski's rule of five (Ro5). The isolated compound was identified as β-sitosterol. It had an anti-S. aureus activity of (0.31 mg/mL). It revealed binding scores of -7.2 and -6.4 kcal/mol against penicillin-binding protein and DNA gyrase, respectively. It violated one of Ro5 (MLOGP > 4.15). It has no inhibitory effects against isoforms of cytochrome P450. Moreover, it demonstrated no adverse effect on skin, non-carcinogenic and non-hepatotoxic effects. Based on the results, β-sitosterol can be considered as potential anti-S. aureus drug. Further studies may focus on ascertaining the mechanism of action in-vitro and investigating the synergistic effects of the compound with conventional drugs.