Isolation and Characterization of Two Phytosterols from Strychnos Innocua (Delile) Root Bark, and In Silico Molecular Docking Studies as Antibacterial Agents

Phytosterols derived from medicinal plants are well-known for their therapeutic effects in the treatment of diabetes, cardiovascular disease, cancer, and microbial infections. Strychnos innocua (a Loganiaceae family member) grows in numerous African countries and is widely used for medicinal purposes. This plant s (root bark) ethyl acetate extract was subjected to chromatographic separation, resulting in the isolation of Campesterol (1) and β-Sitosterol (2). Their structures were verified using mass spectrometry, nuclear magnetic resonance (1D and 2D NMR), and in comparison to published data. This is a novel report of phytosterol compounds which were isolated from S. innocua root bark. The in silico investigation found that the binding affinities of Campesterol (1) with binding sites of Staphylococcus aureus pyruvate carboxylase (PDB: 3HO8) and Pseudomonas aeruginosa virulence factor regulator (PDB: 2OZ6) were -7.8 and -7.9 kcal/mol, respectively. Furthermore, the binding affinities of β-Sitosterol (2) with binding sites of S. aureus and P. aeruginosa are -7.6 and -7.7 kcal/mol, respectively, while ciprofloxacin (standard drugs) exhibited binding affinities of -6.6 and -8.7 kcal/mol. This study concluded that the S. innocua root bark has a rich presence of Campesterol and β-Sitosterol, while their molecular docking studies revealed that they have excellent interactions with S. aureus and P. aeruginosa.