Withametelin: a biologically active withanolide in cancer, inflammation, pain and depression

Withanolides are natural medicinal agents whose safety and therapeutic profiles make them valuable to mankind. Among multiple withanolides, withametelin is underexplored. The present study was aimed to create a general biological profile of isolated withametelin from Datura innoxia Mill. targeting different biological models. In-silico studies include drug-likeliness, pharmacokinetics, toxicity, molecular targets and cytotoxicity to cancer cell lines predictions. In silico directed preliminary in-vitro evaluation comprised of cancer/normal cell cytotoxicity, DPPH and protein kinase inhibition assays while in-vivo bioactivities include antiinflammatory, analgesic, antidepressant and anticoagulant assays. Pharmacological findings were strengthened by molecular docking studies to check interactions with various proteins and to propose the future path of studies. Results indicated compliance with Lipinski drug-likeliness rule (score -0.55). ADMET prediction showed strong plasma protein binding, GI absorption (Caco-2 cells permeability = 46.74 nm/s), blood brain barrier penetration (Cbrain/Cblood = 0.31), efflux by P-glycoprotein, metabolism by CYP1A2, CYP2C19 and CYP3A4, medium hERG inhibition and non-carcinogenicity in rodents. Predicted molecular targets included mainly receptors (glucocorticoid, kappa opioid, delta opioid, adrenergic and dopamine), oxidoreductase (arachidonate 5-lipoxygenase and cyclooxygenase-2), enzymes (HMG-CoA reductase) and kinase (NFκb). Withametelin was more cytotoxic to cancer cells (DU145 IC₅₀ 7.67 ± 0.54 µM) than normal lymphocytes (IC₅₀ 33.55 ± 1.31 µM). It also showed good antioxidant and protein kinase inhibition potentials. Furthermore, withametelin (20 mg/kg) significantly reduced inflammatory paw edema (68.94 ± 5.55%), heat-induced pain (78.94 ± 6.87%) and immobility time (50%) in animals. Molecular docking showed hydrogen bonding interactions (binding energies: -11.3 to -7.8 kcal/mol) with arachidonate 5 lipoxygenase, NFκb and glucocorticoid receptor. Withametelin has potential for advance investigations for its cytotoxic, anti-inflammatory, analgesic and antidepressant activities.