Isolation, characterization, and docking studies of campesterol and β-sitosterol from Strychnos innocua (Delile) root bark

OBJECTIVES: Phytosterols obtained from medicinal plants are well known for their anti-diabetic, anti-cardiovascular, anti-cancer, and anti-microbial properties. Strychnos innocua (a member of the Loganiaceae family) grows in several African nations and is frequently used for medicinal purposes. METHODS: The chromatographic separation of S. innocua (root bark) ethyl acetate extract resulted in the isolation of campesterol (1) and β-sitosterol (2). RESULTS: The structures of 1 and 2 were confirmed by mass spectrometry, nuclear magnetic resonance (1D and 2D NMR), and literature data. This is a novel report of campesterol and β-sitosterol from S. innocua. Docking studies revealed that the binding affinities of 1 with the 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, 2 had binding affinities of −7.6 and −7.7 kcal/mol with binding sites of S. aureus and P. aeruginosa, respectively, whereas ciprofloxacin (a standard drug) had binding affinities of −6.6 and −8.7 kcal/mol. CONCLUSION: This study indicated that S. innocua root bark is rich in campesterol and β-sitosterol. In silico molecular docking demonstrated that the compounds interact well with the binding sites of S. aureus and P. aeruginosa.