The callus on this medium was whitish green in nature. As NAA at 100mg/l showed maximum induction of andrographolide in leaves, the same concentration of NAA was used to treat the callus of A. paniculata. HPLC analysis of calli treated with NAA showed a peak at 223 nm with the retention time of 4.99 indicating the induction of andrographolide in these samples (Fig.2b). Calli that served as control did not show the peak that represents andrographolide (Fig.2a). This study clearly indicates that andrographolide can be produced under in vitro conditions by treating the callus with NAA.