Winter-cherry

The most studied withanolide, a highly oxygenated C28 steroidal lactone. In preclinical models it shows pro-apoptotic, anti-angiogenic and anti-inflammatory activity (NF-κB and STAT3 inhibition) and is the compound most associated with the herb's experimental anticancer effects. It is also more cytotoxic than root-predominant withanolides.

A root-predominant withanolide investigated for neuritogenic and neuroprotective effects in cell and animal models, including promotion of dendrite/axon outgrowth and reduction of amyloid-beta associated toxicity. Frequently used as a chemical marker for standardising root extracts.

A cytotoxic withanolide reported to induce apoptosis in leukaemia and other tumour cell lines through ceramide-mediated and caspase pathways in vitro.

Glycosylated withanolides credited with much of the adaptogenic and anti-stress activity of aqueous root preparations; studied for antioxidant and neurite-promoting effects in experimental models.

A group including withanine, somniferine, anaferine, isopelletierine and tropine derivatives, historically associated with mild sedative and hypotensive actions attributed to the root.

The withanolide fraction as a whole is the standardisation target for most clinical-grade extracts and is linked to the herb's anti-stress, immunomodulatory and antioxidant activity.

Dried root is powdered (churna) and taken, classically 3–6 g daily, often boiled in milk or water with honey or ghee as an evening rasayana tonic. Milk decoction (ksheerapaka) is a traditional vehicle believed to enhance the restorative action.

Commercial extracts are standardised to withanolide content (commonly 1.5–5%). Typical clinical trial doses are 300 mg twice daily. Best avoided in pregnancy (traditionally regarded as abortifacient), and cautioned in hyperthyroidism, active autoimmune disease and with sedatives. Rare idiosyncratic liver injury has been reported with some supplements, so discontinue if jaundice or abdominal pain occurs.

Root tincture (typically 1:2–1:5) is used at around 2–4 mL up to three times daily in Western herbal practice as an adaptogen. As a nightshade-family plant, source and dosing should be controlled.

Sixty-four adults with chronic stress took 300 mg of standardised ashwagandha root extract or placebo twice daily for 60 days. The ashwagandha group showed significantly greater reductions in perceived-stress and anxiety scores and in serum cortisol, with adverse events comparable to placebo.

Sixty patients received 300 mg ashwagandha root extract or placebo twice daily for 10 weeks. Actigraphy showed significant improvements in sleep onset latency, total sleep time and sleep efficiency and reduced anxiety versus placebo, with good tolerability.

In healthy men undergoing resistance training, 300 mg ashwagandha root extract twice daily for 8 weeks produced significantly greater gains in muscle strength and size, greater reductions in exercise-induced muscle damage, and increased serum testosterone compared with placebo.