The invention relates to a pharmaceutical composition with enhanced bioactivity and bioavailablity obtained from Ashwagandha, which on administration exhibit improved immunomodulatory activity, anti-inflammatory activity, anti stress activity, antidiabetic activity and sleep quality in human beings. It consists of withanolide glycoside in the range of 0.5 to 80%, saponins in the range of 0.1 to 15% alkaloids below 0.1, withanolideaglycones below 0.1%, and oligosaccharides below 0 to 0.1%. Method of preparation of the said composition from root, stems, leaves and whole plant of Ashwagandha also is disclosed. Further, the extract of Ashwagandha can be formulated with an enteric coating to protect the composition from acidic environment in the stomach and to release in a medium when pH is ranging from 6 to 9 for better absorption.
