Ashwagandha

Ashwagandha (Withania somnifera) is a perennial, adaptogenic herb native to the Indian subcontinent and parts of the Middle East.

• Its roots and berries contain a complex mixture of steroidal lactones (withanolides) and other phytochemicals.
• These compounds modulate stress-responsive pathways.
• Ashwagandha is a widely studied natural supplement for supporting physiological resilience and overall well-being.

• The principal active constituents are withanolides, a group of C-28 steroidal lactones.
• The prototypic compound, withaferin A, has the molecular formula C₂₈H₃₈O₆ and IUPAC name (5β,6β,7β,22R)-5,6-dihydro-22-hydroxy-2,3-dihydro-1-oxo-7,21-epoxy-5,6-dihydromeroterpenoid.
• Its structure features:
  • A C-28 ergostane skeleton with a lactone ring at C-22–C-26.
  • An epoxide bridge at C-5–C-6.
• Other withanolides (e.g., withanolide A, withanolide B) share a Δ²⁻³ double bond and a 7-acetyl group, conferring lipophilicity and membrane permeability.
• The molecules are moderately stable (pKa ≈ 4.5 for the hydroxyl group) and soluble in organic solvents (ethanol, methanol) but poorly water-soluble.
• This drives the use of carrier-based extracts (e.g., phosphatidylcholine complexes) to improve bioavailability.
• Their molecular weight (~450 Da) falls within the range for passive diffusion across the intestinal epithelium when formulated appropriately.

• Commercial Ashwagandra is primarily cultivated in India’s Rajasthan, Gujarat, and Madhya Pradesh regions.
• Soil and climate conditions favor high withanolide content.
• Sustainable cultivation uses organic farming practices to avoid pesticide residues that can affect extract purity.
• Extraction methods:
  • (i) ethanol-water (70 % ethanol) maceration, yielding a broad spectrum of withanolides
  • (ii) super-critical CO₂ extraction, which produces a more selective, high-purity extract with reduced solvent residues.
• Standardization to ≥5 % withanolides is mandated by major supplement bureaus (e.g., USP, NSF).
• Reliable supplements undergo third-party testing for:
  • Heavy metals (<10 ppb)
  • Microbial contamination (<10³ CFU/g)
  • Pesticide residues.
• When selecting a product, look for:
  • GMP-certified manufacturers
  • Clear labeling of extract strength
  • Independent certification (e.g., NSF-Certified for Sport).