Major Alkaloid in Ashwagandha is

The major Alkaloid in Ashwagandha is Withanine.
The biologically active chemical constituents of Withania somnifera (WS) include alkaloids (isopelletierine, anaferine, cuseohygrine, anahygrine, etc.), steroidal lactones and saponins.
Withanine, a group of alkaloids isolated from the roots of the plant, forms 38% of the total weight of alkaloids. The principal withanolides extracted from W. somnifera in India were withanolide D and withaferin A which exhibited antitumor and cytotoxic properties.