ABSTRACT
The plant Hydnora johannis has been utilized in folk medicine. Analyzing phytochemical composition of dichloromethane/methanol (1 : 1) root part of Hydnora johannis gave oleic acid (1), caffeic acid-2-hydroxynonylester (2), catechin (3), and a pregnane derivative (4). NMR spectroscopy was used to characterize compounds 1-3, while compound 4 was identified through GC-MS analysis and literature comparison. The cytotoxicity of extracts from roots of H. johannis was conducted against MCF-7 cell lines (human breast cancer) by MTT assay. According to the cytotoxicity study, n-hexane extract exhibited a high level of toxicity with 28.9 ± 5.6% cell viability. Antibacterial activity was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogen. The highest bacterial growth mean inhibition zone was measured for catechin (3) (13.72 ± 0.05 mm)) against P. aeruginosa at 0.25 mg/mL and acceptable related to standard. Antioxidant activity was studied by the DPPH assay. Based on the data from the antioxidant study, DCM/MeOH extract (70.32%) and catechin (3) showed good antioxidant activity (65.61%) (IC50 0.25 µg/mL) relative to that of the positive control (78.21%, IC50 0.014 µg/mL) at 12.5 µg/mL. In each docking pose, catechin (3) scored higher binding affinity of -7.9, -7.2, and -6.4 kcal/mol towards PqsA, DNA gyraseB, and S. aureus PK, respectively, compared to amoxicillin (-8.1, -6.1, and -6.4 kcal/mol). All five Lipinski rules were obeyed by compounds 1-3, which showed an acceptable drug resemblance. The lipophilicity was computed as less than five (1.47-4.01) indicating a lipophilic property. Catechin (3) obeys Veber's rule implying its good oral bioavailability. Binding affinity scores of catechin (3)-protein interactions are in line with those from in vitro tests, indicating its potential antibacterial effect. The obtained cytotoxicity and antibacterial activity results support the utilization of H. johannis in folk medicine.
ABSTRACT
Background: Cyphostemma cyphopetalum is a medicinal plant traditionally used to treat various ailments. Limited studies on C. cyphopetalum inspired us to investigate the chemical nature and therapeutic potential of the plant. Methods: Silica gel column chromatographic separation was used for isolation. 1D and 2D NMR spectroscopic analysis and literature data were used for structural elucidation. Agar well diffusion assay was used for evaluation of antibacterial activity against E. coli, P. aeruginosa, and S. aureus. DPPH assay was used to evaluate radical scavenging activities. Molecular docking was done by AutoDock Vina 4.2 open-source program. DFT calculations were performed using the Gaussian 16 program package. Results: Dichloromethane/methanol (1:1) roots extract afforded a new hydroxyl-spongiane diterpenoid lactone derivative, 3-hydroxyisoagatholactone (1), along with ß-sitosterol (2) and ε-viniferin (3) whereas methanol extract afforded trans-resveratrol (4), gnetin H (5), tricuspidatol A (6), ε-viniferin-diol (7) and parthenostilbenin B (8). At 50 µg/mL, compound 3 recorded the highest inhibition against E. coli (8.55 ± 0.45 mm) and S. aureus (9.30 ±1.39 mm). Against P. aeruginosa, compound 5 consistently outperformed chloramphenicol (11.76 ± 0.77 mm, at 30 g/mL). Maximum binding affinity were observed by compound 3 against DNA gyrase B (-7.6 kcal/mol) where as compound 5 displayed maximum binding against PqsA (-8.8 kcal/mol) and S. aureus PK (-5.8 kcal/mol). Compounds 1, 3 and 4 satisfy Lipinski's rule of five. Trans-resveratrol (4) demonstrated strong DPPH scavenging activity at 12.5 g/mL, with IC50 values of 0.052 µg/mL, compared to ascorbic acid (IC50 value of 0.0012 µg/mL). Conclusion: In this work, eight compounds were identified from the roots extracts of C. cyphopetalum including a new hydroxyl-spongiane diterpenoid lactone, 3-hydroxyisoagatholactone (1). Compounds 3 and 5 exhibited good antibacterial activity and binding affinities. The docking result is in agreement with the in vitro antibacterial study. Overall, the study result suggests that the isolated compounds have the potential to be used as therapeutic agents, which supports the traditional uses of C. cyphpetalum roots.
