## Introduction
### Chemical constituents
#### Molecules 2009  
Withaferin A (48,27-dihydroxy-1-oxo-58,68-epoxywitha-2-24-dienolide, Figure 3) was the first member of this group of compounds to be isolated from the well-known South-Asian medicinal plant, _W. sominfera_. The structural novelty and interesting biological activities elicited by this compound led to a thorough chemical investigation of the plant and numerous compounds with similar structural features were isolated [28, 30, 36].  
[PERSON]'s group [44] elucidated the structure of withaferin A in leaves of this plant, which is mainly valued for its anti-cancerous properties. The yields of withaferin A from intact plants of _Withania_ spp. (Israel Chemotype) are 0.2-0.3% of DW of leaves [45]. [PERSON] _et al_. [46] have performed a quantitative analysis of Indian chemotypes of _W. sominfera_ by TLC densitometry and observed that withaferin A is totally absent in roots, stems, seeds and persistent calyx of fruits of intact plants but present in leaves (1.6%). Today over 130 withanolides from Solanaceae genera are known, mostly occurring in free form, but in a few cases also as glycosides [28], some of which are shown in Figure 4.  
Figure 4: Different structures of withanolides.  
Figure 3: Structure of withaferin A.  
**Other compounds**  
Examination of _W. somifera_ roots has resulted in the isolation of a new dimeric thiowithanolide, named ashwagandhanolide (Figure 5) [47]. A bioassay-guided purification of the methanolic extract of _W. somifera_ fruits yielded withnamides A-I (Figure 6). The structure of these compounds was determined by using serotonin, glucose and long-chain hydroxyl fatty acid moieties [48].  
In their quantitative analysis of Indian chemotypes of _W. somifera_ by TLC densitometry, [PERSON] _et al_. [46] detected alkaloids in all the abovementioned plant parts, with the highest content found in leaves. This is in contrast to the general belief that tropane alkaloids are restricted to the roots of _Withania_ spp. Extraction with 45% alcohol yields the highest percentage of alkaloids. The isolation of nicotine, somiferine, somniferine, withanine, withananine, pseudowithanine, troponin, pseudotropine, 3\(\alpha\)-tigloyloxytropane, choline, cusochygrine, _dl_-isopelletierine and new alkaloids anaferine and anhygrine has been described [14,49]. The reported total alkaloid content in the roots of Indian _W. somifera_ varies between 0.13 and 0.31%, though much higher yields (up to 4.3%) have been recorded in plants of other regions/countries. In addition to the alkaloids, the roots are reported to contain starch, reducing sugars, hentriacontane, glycosides, dulcitol, withanicil, an acid and a neutral compound. The leaves are reported to contain five unidentified alkaloids (yield 0.09%), chlorogenic acid, calystegines (nitrogen-containing polyhydroxylated heterocyclic compounds) withanone, condensed tannin and flavonoids. The berries have amino acids. Four types of peroxididases have been purified and characterized from _W. somifera_ roots [14,50].  
Figure 4: Cont.  
**Figure 5.** Ashwagandhanolide, a new compound isolated from _W. somnifera_.  
**Figure 6.** Different withanamides (A-I) isolated from _W. somnifera_ fruits.