Untitled Document
Withania somnifera, commonly known as Ashwagandha (winter cherry), is an important medicinal plant that has been used in Ayurvedic and indigenous medicine for more than 3,000 years. Some herbalists refer to Ashwagandha as Indian ginseng. The plant extract has many bioactive compounds and thereby exerts antioxidant, anti-inflammatory, and immunomodulatory activities. The plant extract and its bioactive compounds are used in the prevention and treatment of many diseases, such as arthritis, impotence, amnesia, anxiety, cancer, neurodegenerative and cardiovascular diseases, and others.
The pharmacological effects of the roots of W. somnifera are attributed to the presence of withanolides, a group of steroidal lactones. This plant is commonly used in formulations for its wide range of health benefits. In Ayurveda, Withania is widely claimed to be a potent aphrodisiac, sedative, and rejuvenative, and to have life-prolonging properties. It is also used as a general energy-enhancing tonic known as Medharasayana, which means that “it promotes learning and a good memory”.
Laboratory analysis has revealed more than 35 chemical constituents contained in the roots of W. somnifera (Rastogi and Mehrotra, 1998). The biologically active chemical constituents are alkaloids (isopellertierine, anferine), steroidal lactones (withanolides, withaferins), saponins containing an additional acyl group (sitoindoside VII and VIII), and withanoloides with a glucose at carbon 27 (sitonidoside XI and X). W. somnifera is also rich in iron. The roots of W. somnifera consist primarily of withanolides, which are believed to account for its extraordinary medicinal properties. Withanolides are steroidal and bear a resemblance, both in their action and appearance, to the active constituents ginsenosides present in Asian ginseng (Panax ginseng). Ashwagandha’s withanolides have been researched in a variety of animal studies examining their effect on numerous conditions, including immune function and even cancer (Grandhi et al., 1994). Chemical analysis of Ashwagandha shows its main constituents to be alkaloids and steroidal lactones. Among the various alkaloids, withanine is the main constituent. The other alkaloids are somniferine, somnine, somniferinine, withananine, pseudo-withanine, tropine, pseudo-tropine, 3-a-gloyloxytropine, choline, cuscohygrine, isopelletierine, anaferine, and anahydrine. The withanolides within the leaves have C28 steroidal nucleus with C9 side chain and a six-member lactone ring. Twelve alkaloids, 35 withanolides, and several sitoindosides from W. somnifera have been isolated and studied. A sitoindoside is a withanolide containing a glucose molecule at carbon 27. Much of Ashwagandha’s pharmacological activity has been attributed to two main withanolides, withaferin A and withanolide D. Further chemical analysis has shown the presence of the following:
Alkaloids: Anaferine, Anahygrine, Cuscohygrine, Scopoletin, Withanine, Withaninine, Somniferine, Tropeltigloate, Somniferinine, Somninine, Nicotine, Visamine, Withasomine, and Pseudotropine.
Salts: Cuscohygrine, Anahygrine, Tropine, Pseudotropine, and Anaferine.
Steroidal Lactones: Withaferin-A, Withanone, WS-1, Withanolide E, Withanolide F, Withanolide G, Withanolide H, Withanolide I, Withanolide J, Withanolide K, Withanolide L, and Withanolide M.
Nitrogen containing compounds: Withanol, Somnisol, and Somnitol.
Steroids: Cholesterol, β-sitosterol, Stigmasterol, Diosgenin, Stigmastadien, Sitoinosides VII, Sitoinosides VIII, Sitoinosides IX, and Sitoinosides X.
Flavonoids: Kaempferol and Quercetin.
The plant contains carbohydrate-D-glucose, maltose, rhamnose, sucrose, and starch. It contains proteins, amino acids, and the alkaloid shankhpushpine (C17H25NO2), with a melting point of 162–164°C. The most notable constituents are tropine alkaloids. Only convolamine has been identified, but other alkaloids (convoline, convolidine, convolvine, confoline, convosine, etc.) found in other species from this family are most likely present as well (Prasad et al., 1974; Lounasmaa, 1988; Singh and Bhandari, 2000). The fresh plant contains volatile oils, fatty acids, fatty alcohols>, and hydrocarbons, such as myristic acid (30.9%), palmitic acid (66.8%), linoleic acid (2.3%), and straight chain hydrocarbon hextriacontane (Deshpande and Srivastava, 1975). A study was performed for a chemical examination of the whole plant (C. pluricaulis) and reported the presence of scopoletin, β-sitosterol, and ceryl alcohol. The chloroform fraction of this plant extract contains 20-oxodotriacontanol, tetratriacontanoic acid, and 29-oxodotriacontanol. The flavonoid kaempferol and steroids phytosterol and β-sitosterol were also found in significant amounts (Singh and Bhandari, 2000). An estimation of scopoletin (Nahata and Dixit, 2008) content was determined by spectrofluorimetry and HPTLC.
Ashwagandha roots contain alkaloids, starch, reducing sugar, hentriacontane, glycosides, dulcital, withaniol acid, and a neutral compound. Wide variation (0.13–0.31%) is observed in alkaloid content. Majumdar (1955) isolated eight amorphous bases (withanine, somniferine, somniferinine, somnine, withananine, withananinine, pseudowithanine, and withasomnine). Other alkaloids reported are nicotine, tropine, pseudotropine, 3,a-tigloyloxytropine, choline, cuscudohygrine, anaferine, anahygrine, and others. Free amino acids in the roots include aspartic acid, glycine, tyrosine, alanine, proline, tryptophan, glutamic acid, and cystine. The leaves contain 12 withanolides, alkaloids, glycosides, glucose, and free amino acids. The berries contain a milk-coagulating enzyme, two esterases, free amino acids, fatty oil, essential oils, and alkaloids. Methods for the analysis of alkaloid in Asgandh roots have also been reported.