The present invention relates to a complex comprising acidic sophorolipid and curcumin ((SL(A)+Cur), wherein, curcumin is solubilized and nano-encapsulated in acidic sophorolipid to improve the water solubility, stability and bioavailability of curcumin in order to enhance its therapeutic activity. Further, the invention provides pharmaceutical compositions comprising the present complex and methods to treat cancer in a subject using the said composition.
