In vitro antibacterial, antioxidant activities, molecular docking, and ADMET analysis of phytochemicals from roots of Hydnora johannis

Hydnora johannis is a medicinal plant traditionally used to treat various ailments. Chemical investigation of the dichloromethane (DCM)/methanol (MeOH) (1:1) roots extract of Hydnora johannis afforded three compounds (1-3), reported herein for the first time from the species. The structures of the isolated compounds 1-3 were elucidated using 1D and 2D NMR spectroscopic analysis and comparison with literature data. The highest zone of inhibition value was measured for DCM/MeOH extract (10.75 +/- 0.25 mm) against Staphylococcus aureus at concentration of 0.25 mg/mL, promising in comparison to the standard amoxicillin (16.0 +/- 0.0 mm, 0.25 mg/mL). At concentration of 0.25 mg/mL, the largest mean inhibition zone of 12.0 +/- 0.0 mm was measured for compound 2 against Pseudomonas aeruginosa, comparable to the standard drug amoxicillin (16.0 +/- 0.0 mm, 0.25 mg/mL). Compound 2 displayed better binding affinity with minimum binding energy of - 8.7 kcal/mol (PqsA), - 7.6 kcal/mol (DNA gyrase), and - 7.4 kcal/mol ( S aureus PK) than amoxicillin (- 7.3, - 6.1, and - 7.0 kcal/mol, respectively). This suggests that compound 2 may act as potential inhibitor of the tested bacterial proteins. Compound 1 satisfies the Lipinski's rule of five with zero violations. Compound 2 obey the MW (452.4 g/mol) and iLogP (< 5) rules, and compound 3 obey the NHD (4) and NHA (6) rules. Compounds 2 recorded iLogP value less enough than five (1.55), implying its optimal lipophilicity. Compounds 1 and 3 satisfy the veber's rule (NRB < 12, and TPSA < 140 unit). Compound 2 and 3 exhibited negligible acute toxicity (LD50 > 5000, Toxicity class > 5. Compound 2 demonstrated maximum scavenging activity (67.87%) with IC50 value of 0.190 mu g/mL, compared to ascorbic acid (78.21%) with IC50 value of 0.014 mu g/mL at concentration of 12.5 mu g/mL. Overall, the in vitro antibacterial activity of the extracts and compounds, molecular docking analysis and radical scavenging activity results of the isolated compounds suggest DCM/MeOH crude extract and compound 2 are promising antibacterial agents whereas compound 2 and 3 are promising antioxidants which corroborates with the traditional uses of the roots of H. johannis.