Antimycobacterial Potential of Otok-otok Leaf (Flemingia strobilifera) Extract: An In Silico and In Vitro Study
DOI:
https://doi.org/10.54832/phj.v8i2.1518Keywords:
Flemingia strobilifera;, antimycobacterial activity, InhA, molecular docking, Mycobacterium smegmatisAbstract
Background: Tuberculosis (TB) remains a major global health challenge due to the emergence of drug-resistant strains and the limited availability of novel antitubercular agents. Natural products have gained increasing attention as potential sources of antimycobacterial compounds. Flemingia strobilifera is known to contain diverse bioactive metabolites that may exhibit inhibitory activity against mycobacterial targets.
Objective: This study aimed to evaluate the antimycobacterial potential of Otok-otok (Flemingia strobilifera) leaf extract through integrated in silico and in vitro approaches.
Methods: Five dominant metabolites of F. strobilifera, namely Octylimino dipropan-2-ol, 3,12-diketo-4,6-petromyzonene-24-sulfate, Kaempferol-3-O-rutinoside, Adenosine, and Flavonol 3-O-D-xylosylglucoside, were subjected to molecular docking against InhA (enoyl-acyl carrier protein reductase), a key enzyme involved in mycolic acid biosynthesis. Docking simulations were performed using AutoDock4 following validation through native ligand redocking. In vitro antimycobacterial activity was evaluated against Mycobacterium smegmatis using aqueous, ethanolic, and methanolic leaf extracts at concentrations ranging from 6.25 to 200 mg/mL, with activity assessed by measuring inhibition zone diameters.
Results: Molecular docking revealed that 3,12-diketo-4,6-petromyzonene-24-sulfate exhibited the strongest binding affinity toward InhA with a binding energy of –8.90 kcal/mol, followed by Flavonol 3-O-D-xylosylglucoside (–8.05 kcal/mol). The latter also formed multiple hydrogen bonds with key active-site residues, including Tyr158, Lys165, and Met199. In vitro evaluation demonstrated concentration-dependent antimycobacterial activity for all extracts. Methanolic extract showed the highest activity, producing inhibition zones ranging from 8.14 ± 0.42 mm to 23.08 ± 0.88 mm, followed by ethanolic extract (7.36 ± 0.38–20.54 ± 0.77 mm) and aqueous extract (5.24 ± 0.31–14.28 ± 0.74 mm). No inhibition was observed in the negative control, while streptomycin sulfate exhibited the highest inhibitory effect.
Conclusion: The findings indicate that Flemingia strobilifera possesses promising antimycobacterial potential. The strong affinity of selected metabolites toward InhA and the concentration-dependent inhibitory activity of leaf extracts against M. smegmatis suggest that this plant may serve as a potential source of antitubercular candidates. Further in vivo studies and mechanistic investigations are required to validate its therapeutic potential.
Downloads
References
Alcaraz, M. et al. (2022) ‘Designing quinoline-isoniazid hybrids as potent anti-tubercular agents inhibiting mycolic acid biosynthesis’, European Journal of Medicinal Chemistry, 239, p. 114531. Available at: https://doi.org/https://doi.org/10.1016/j.ejmech.2022.114531.
Denning, D.W. (2024) ‘Global incidence and mortality of severe fungal disease’, The Lancet Infectious Diseases, 24(7), pp. e428–e438. Available at: https://doi.org/10.1016/S1473-3099(23)00692-8.
Dyba, B. et al. (2025) ‘The effects of 3-hydroxyflavone complexes with transition metal ions on the physicochemical and microbial properties of bacterial cell membranes’, Scientific Reports, 15(1), p. 20743. Available at: https://doi.org/10.1038/s41598-025-07358-y.
Gulumbe, B.H. et al. (2025) ‘WHO report signals tuberculosis resurgence: Addressing systemic failures and revamping control strategies’, Decoding Infection and Transmission, 3, p. 100044. Available at: https://doi.org/https://doi.org/10.1016/j.dcit.2025.100044.
EL Haddoumi, G. et al. (2023) ‘Facing Antitubercular Resistance: Identification of Potential Direct Inhibitors Targeting InhA Enzyme and Generation of 3D-pharmacophore Model by in silico Approach’, Advances and Applications in Bioinformatics and Chemistry, 16(null), pp. 49–59. Available at: https://doi.org/10.2147/AABC.S394535.
Harrison, G.A. et al. (2024) ‘Inducing vulnerability to InhA inhibition restores isoniazid susceptibility in drug-resistant Mycobacterium tuberculosis’, mBio, 15(3), pp. e02968-23. Available at: https://doi.org/10.1128/mbio.02968-23.
Kim, S.K. et al. (2023) ‘Structure and dynamics of the essential endogenous mycobacterial polyketide synthase Pks13’, Nature Structural & Molecular Biology, 30(3), pp. 296–308. Available at: https://doi.org/10.1038/s41594-022-00918-0.
Liu, Y. et al. (2025) ‘Flavonoids as Promising Natural Compounds for Combating Bacterial Infections’, International Journal of Molecular Sciences, 26(6), p. 2455. Available at: https://doi.org/10.3390/ijms26062455.
Luo, Jincan et al. (2025) ‘Latest research progress on anti-microbial effects, mechanisms of action, and product developments of dietary flavonoids: A systematic literature review’, Trends in Food Science & Technology, 156, p. 104839. Available at: https://doi.org/10.1016/j.tifs.2024.104839.
do Nascimento, J.B. and da Costa, J.G.M. (2025) ‘Flavonoids: A Review of Antibacterial Activity Against Gram‐Negative Bacteria’, International Journal of Microbiology. Edited by E. Saini, 2025(1). Available at: https://doi.org/10.1155/ijm/9961121.
Rabaan, A.A. et al. (2022) ‘Promising Antimycobacterial Activities of Flavonoids against Mycobacterium sp. Drug Targets: A Comprehensive Review.’, Molecules (Basel, Switzerland), 27(16). Available at: https://doi.org/10.3390/molecules27165335.
Rizet, J. et al. (2025) ‘Is Mycobacterial InhA a Suitable Target for Rational Drug Design?’, ChemMedChem, 20(13). Available at: https://doi.org/10.1002/cmdc.202500079.
Sahu, A. et al. (2025) ‘Flemingia Strobilifera– An Updated Review on its Pharmacognostic and Pharmacological Properties’, Current Nutrition & Food Science, 21(4), pp. 421–429. Available at: https://doi.org/10.2174/0115734013313350240918050329.
Singh, J. et al. (2025) ‘Targeting Mycobacterium tuberculosis InhA with Phytochemicals : Insights from Molecular Docking and Dynamics Simulations’, Journal of Pure and Applied Microbiology, 19(April), pp. 2305–2321. Available at: https://doi.org/10.22207/JPAM.19.3.56.
Sirikonda, A. et al. (2023) ‘Micropropagation of 2-methoxy-4-vinyl phenol rich Flemingia strobilifera and assessment of genetic and biochemical fidelity by SCoT and GC-MS analysis’, Plant Cell, Tissue and Organ Culture (PCTOC), 154(3), pp. 541–550. Available at: https://doi.org/10.1007/s11240-023-02526-2.
Sparks, I.L. et al. (2023) ‘Mycobacterium smegmatis : The Vanguard of Mycobacterial’, Journal of Bacteriology, 205(1), pp. 1–16.
Sun, H. et al. (2025) ‘Transcriptomic Analysis of Macrophages Infected with Mycobacterium smegmatis’, Microbiology Research, p. 146. Available at: https://doi.org/10.3390/microbiolres16070146.
Thakur, M. et al. (2026) ‘Molecular and pharmacological impacts of phytochemicals on the enoyl-acyl carrier protein reductase: potential therapeutic implications in tuberculosis’, Integrative Biology, 18, p. zyag007. Available at: https://doi.org/10.1093/intbio/zyag007.
Wahan, S.K. et al. (2024) ‘Unlocking InhA: Novel approaches to inhibit Mycobacterium tuberculosis’, Bioorganic Chemistry, 146, p. 107250. Available at: https://doi.org/https://doi.org/10.1016/j.bioorg.2024.107250.
Wang, H., Liu, D. and Zhou, X. (2024) ‘Effect of Mycolic Acids on Host Immunity and Lipid Metabolism’, International Journal of Molecular Sciences, 25(1). Available at: https://doi.org/10.3390/ijms25010396.
Wang, K. et al. (2023) ‘PatA Regulates Isoniazid Resistance by Mediating Mycolic Acid Synthesis and Controls Bio fi lm Formation by Affecting Lipid Synthesis in Mycobacteria’, microbiology spectrum, 11(3), pp. 1–12.
Yang, T. et al. (2026) ‘Barley Flavonoids: Molecular Insights into Disease Resistance and Stress Tolerance for Sustainable Agriculture’, Journal of Plant Growth Regulation, 45(3), pp. 1677–1696. Available at: https://doi.org/10.1007/s00344-025-11997-w.
Zhang, Z. et al. (2025) ‘Research Progress on the Antibacterial Activity of Natural Flavonoids’, Antibiotics. Available at: https://doi.org/10.3390/antibiotics14040334.
Zhou, Y. et al. (2025) ‘The Biosynthetic Pathway of Mycolic Acids: Dual-Function Targets for Tuberculosis Therapeutics and Green Steroid Drugs Biomanufacturing.’, Pharmaceutics, 18(1). Available at: https://doi.org/10.3390/pharmaceutics18010044.
