Steroidal lactones from withania somnifera

Traditionally, ashwagandha has been prescribed as a nerve tonic and adaptogen—an agent which helps the body adapt to various emotional and physical stressors. It has classically been used in India for nearly 5,000 years for conditions such as failure to thrive in children, weakness and debility in old age, rheumatism, constipation, insomnia, nervous conditions, stress, goiter, joint inflammation, parasites, hormone balance, and more. A paste made from the root powder applied topically can treat boils, ulcers, and other skin irritations and infections.

Ayurveda is based on a system of Tridosha or Three Humours which classifies all individual constitutions of people, diseases, herbs and other non-herbal remedies and therapies according to whether they are Vata (air or nerve oriented), Kapha (water or mucoid type) or Pitta (fire type) [5] . Herbs that have pungent, sour and salty flavors stimulate fire; herbs that are astringent (drying) and bitter stimulate vata-air, or the nerve centeredhumour; herbs that are sweet, salty and sour stimulate or increase Kapha-water, or the mucoid humour. In contrast, herbs that are sweet, sour and salty flavored ameliorate Vata-air, which means that they have a particular affinity for the nervous system. Herbs that are astringent, sweet and bitter ameliorate Pitta-fire, meaning that they are soothing and anti-inflammatory. Finally herbs that are pungent, bitter and astringent ameliorate Kapha-water, which means they tend to increase digestive fire, expel and dry excessive fluid build up in the system, including clearing excessive fat from the body, and the accumulation ofcholesterol and other fatty deposits in the veins and arteries of the body.

AB - The fungus Corynespora cassiicola metabolises exogenous steroids in a unique and highly specific manner. Central to this, is the ability of this organism to functionalise substrates (androgens, progestogens) at the highly stereochemically hindered 8β-position of the steroid nucleus. A recent study has identified that 8β-hydroxylation occurs through inverted binding in a 9α-hydroxylase. In order to discern the metabolic fate of more symmetrical molecules, we have investigated the metabolism of a range of steroidal analogues functionalised with ring-D lactones, but differing in their functional group stereochemistry at carbon-3. Remarkably, the 3α-functionalised steroidal lactones underwent a mechanistically unique two step intramolecular cyclisation resulting in the generation of a ring-D spiro-carbolactone. This rapid rearrangement initiated with hydroxylation at carbon 14 followed by transesterification, resulting in ring contraction with formation of a butyrolactone at carbon-14. Remarkably this rearrangement was found to be highly dependent on the stereochemistry at carbon-3, with the β-analogues only undergoing 9α-hydroxylation. The implications of these findings and their mechanistic bases are discussed.

Steroidal lactones from withania somnifera

steroidal lactones from withania somnifera

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