| Plants are valuable sources of medicinal compounds and their use for healing is well known from ancient times. Natural drugs obtained from plants represent about 25% of the prescription drug market in the United States. Plants have a long history of use in the treatment of various cancer types. Currently, 60% of the anticancer agents available in the market are derived from natural sources. Since phytoconstituents play a vital role in the discovery of various anticancer drugs, they have been chosen as the area of focus for our research. In this proposed study, four medicinal plants with reported anticancer activity were selected (Hydrastis canadensis, Curcuma longa, Zingiber officinalis, and Alpinia officinarum). All these plants were extracted by percolation and tested for anti-proliferative activity against Dictyostelium cells. C. longa, Z. officinalis and A. officinarum organic extracts all showed significant anti-proliferative activity in this preliminary bioassay. Of the three active extracts, the turmeric extract was chosen for further investigation because of its great historical significance and the promising results of recent phase I clinical trials. Using flash chromatography, a total of nine fractions were obtained from the complex C. longa organic extract. Curcumin in these fractions was identified and quantified using high performance liquid chromatography - electrospray ionization mass spectrometry (HPLC-ESI-MS). Other active components (demethoxycurcumin, bisdemethoxycurcumin and ar-tumerone) were also characterized using the same system. All these fractions were then tested for in vitro anti-proliferative activity against MCF-7 cells using the XTT assay to determine whether activity correlates with the presence of curcumin in the fractions, or whether other (perhaps unidentified) compounds are involved. The results indicated that the major component curcumin was responsible for the majority of the anti-proliferative activity of the complex turmeric extract. Although no synergistic activity was seen for the various constituents present in the complex extract in this case, a novel approach for probing potential synergistic or additive effects was demonstrated. This approach could be applied to future investigations of synergistic or additive activity of medicinal plants. |
