Chiang Mai Journal of Science

Indirubin is a naturally occurring pigment and widely used as natural dye for local handicraft and industrial application. Although there are many extraction and purification methods of indirubin, the complex and several methods were used and the purified indirubin still contained impurity. In this study, we purposed to improve the extraction and purification methods of indirubin and study its anticancer property. A methanol extract of Indigofera tinctoria Linn. (Thai name - ‘kram’) powder was purified by two steps of silica gel 60 column chromatography and reverse phase high performance liquid chromatography (RP-HPLC) using C18 column. The purified indirubin has the high purity with exactly molecular mass of 263 Da. In addition, the inhibitory effect of indirubin on MCF-7 human breast cancer cells showed that 30 mM indirubin strongly inhibited the cell growth of MCF-7 cells about 42% within 24 h. A longer time of treatment and a higher concentration of indirubin could reduce the cell growth inhibition of MCF-7 cells, in which it may be caused by degradation and crystallization of indirubin. Thus, we suggest that the incubation time of treatment and indirubin concentration are the essential factors of the inhibition of indirubin on MCF-7 cell growth.