Cancer-specific chemoprevention and anti-metastatic potentials of Rheum emodi rhizome ethyl acetate extracts and identification of active principles through HPLC and GC-MS analysis.

Rheum emodi Wall. ex Meissn. (Polygonaceae) is a Himalayan perennial herb which has been cultivated over 5000 years for its medicinal properties by rural and tribal people of Kashmir, and has great significance for its traditional use in Ayurvedic, Unani and folk systems of medicine for cancer treatments. However, there is lack of reports pertaining to specific-chemopreventive properties of R. emodi rhizome. The present study investigates R. emodi rhizome hot and cold ethyl acetate extracts (EHR and ECR) for specific-chemopreventive properties. The extracts were found to be effective antioxidant sources, and showed significant (P<0.05) cancer-specific cytotoxicity towards MDA-MB-231 cells (when compared to WRL-68 [non-tumoral cells]) with IC(50) values of 56.59±1.29 μg/ml (EHR) and 152.38±1.45 μg/ml (ECR) respectively, and induced apoptosis significantly (P<0.05) high in MDA-MB-231 cells (estrogen receptor-(ER)-negative) when compared to MCF-7 cells (ER-positive). Extracts also demonstrated evident anti-metastatic activity. Further, the extracts were chemically characterized through HPLC analysis which revealed major polyphenolics and the GC-MS analysis of the effective extract EHR unveiled (Methyl 6,7-dideoxy-6-C-methyl-2,3-di-O-methyl-à-D-gluco-oct-6-eno-1,5-pyranosid)urono-8,4-lactone,Chrysophanol, derivatives of cyclopropanes and a quinazoline derivative. Overall, EHR exhibited significantly better results on par with ECR, and thus could be considered for their use in designing cancer-specific chemopreventive agents against ER-negative breast cancer.