Withaferin A (Steroidal Lactone)

Withaferin A is a cytotoxic steroidal lactone derived from Withania somnifera that demonstrates potent anticancer and antiangiogenic properties. This bioactive compound works by inducing apoptosis in cancer cells and inhibiting endothelial cell sprouting with IC50 values as low as 12 nM.

Origin & History

Withaferin A is a C28-steroidal lactone naturally isolated from the leaves of Withania somnifera (Ashwagandha) and other plants like Physalis longifolia and Withania coagulans. It is extracted using solvents like ethanol and is commercially available in purified form with >98% purity.

Historical & Cultural Context

Withaferin A is a key constituent of Withania somnifera, a cornerstone of Ayurvedic medicine used for centuries as a rejuvenative (rasayana) for stress, vitality, and inflammation. The isolated compound was first identified in 1962 from Indian plant leaves, though traditional use involves whole-plant extracts rather than isolated Withaferin A.

Health Benefits

• Anticancer properties: Demonstrated cytotoxicity against human head and neck squamous cell carcinoma lines (JMAR, MDA-1986) in preclinical studies
• Antiangiogenic effects: Shows potent activity with IC50 of 12 nM in endothelial cell sprouting assays (preclinical evidence)
• Anti-inflammatory action: Inhibits NF-κB activation via IKKβ blockade and TNFα prevention (in vitro studies)
• Neuroprotective potential: Blocks TNFα-mediated neuronal apoptosis and inhibits reactive gliosis (preclinical evidence)
• Antiviral properties: Shows structural binding affinity to SARS-CoV-2 Mpro through GLN, THR, and CYS residues (computational studies)

How It Works

Withaferin A induces cytotoxicity in cancer cells through apoptotic pathways, particularly targeting head and neck squamous cell carcinoma lines. The compound demonstrates potent antiangiogenic activity by inhibiting endothelial cell sprouting with an IC50 of 12 nM. Additionally, withaferin A exhibits anti-inflammatory effects through modulation of inflammatory mediator pathways.

Scientific Research

Current evidence for Withaferin A is primarily preclinical, with no human clinical trials, RCTs, or meta-analyses documented in the research. Studies focus on in vitro and in vivo anticancer properties, including cytotoxicity assays and antiangiogenic effects, but lack PubMed PMIDs for human studies.

Clinical Summary

Current evidence for withaferin A is limited to preclinical studies, with no completed human clinical trials available. In vitro studies demonstrate cytotoxic effects against specific cancer cell lines including JMAR and MDA-1986 head and neck squamous cell carcinoma models. Endothelial cell sprouting assays show quantified antiangiogenic activity with IC50 values of 12 nM. Human clinical data is needed to establish therapeutic efficacy and safety profiles in cancer patients.

Nutritional Profile

Withaferin A is a steroidal lactone (withanolide-class phytochemical) isolated primarily from Withania somnifera (ashwagandha), not a conventional macronutrient or micronutrient. It has no meaningful caloric, protein, fat, or carbohydrate contribution at physiologically active doses. Bioactive concentration in ashwagandha root extract: approximately 0.001–0.05% dry weight; in standardized leaf extracts: up to 0.2–1.0% dry weight. Molecular weight: 470.6 g/mol; molecular formula: C28H34O6. Key structural features include an α,β-unsaturated lactone ring and an epoxide group critical for biological activity (covalent binding to target proteins including Hsp90, vimentin, IKKβ). Typical bioactive doses in preclinical studies: 1–10 µM in vitro; 2–10 mg/kg in animal models. Oral bioavailability is limited due to first-pass hepatic metabolism, poor aqueous solubility, and extensive Phase I/II biotransformation; estimated oral bioavailability in rodent models is approximately 20–40%. Co-administration with piperine or lipid-based formulations may enhance absorption. Not a source of vitamins, minerals, or essential fatty acids. Classifies strictly as a bioactive phytochemical/investigational therapeutic compound rather than a nutritional ingredient.

Preparation & Dosage

No clinically studied dosage ranges for Withaferin A in humans are available. Research uses purified compound (>98% purity) rather than standardized extract doses. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Ashwagandha extract, Curcumin, Resveratrol, Green tea extract, Quercetin

Safety & Interactions

Safety data for withaferin A in humans is limited due to lack of clinical trials. Preclinical studies suggest potential cytotoxic effects that may affect normal cells alongside cancer cells. No established drug interactions or contraindications are documented, though caution is advised with concurrent cancer therapies. Pregnancy and lactation safety has not been established for this compound.