Metabolite profiling of polyphenols in a Terminalia chebula Retzius extract and evaluation of cancer preventive activities

Medicinal plants have been employed for several centuries as the main source of biologically active compounds for pharmaceutical and health purposes. A valuable research strategy for the discovery of active compounds from plants is represented by the validation of ethnopharmacological data by means of a scientific and rational approach. Following this concept, a decoction of Terminalia chebula Retzius, obtained from the pericarp of ripe fruits (called in Bengali language Haritaki), was selected in this study to evaluate its polyphenol profile and its cancer preventive properties. This herbal drug is used alone or as an ingredient of preparations like Triphala, an esteemed Ayurvedic rasayana formulation whose usual intake through the diet is reputed as a way to restore normal function, also under the perspective of a reduced risk of cancer, metabolic and cardiovascular diseases. Besides that, traditional use of T. chebula decoction encompasses purgative, mild laxative, digestive, tonic, hepatoprotective, antipyretic, spasmolytic, astringent, expectorant, antiasthmatic, antiviral and hypoglycemic purposes. The T. chebula fruit extract can be obtained with different methods, with the consequence of a considerable variability in the chemical composition. In any case, the traditional extraction method is represented by the decoction of the powdered fruits. Many polyphenols have recently been identified in this plant, but no reports are available on the phytochemical profile of the traditional drug, which is the pharmaceutical form actually employed in the ayurvedic medicine. In this study, a metabolite profiling of the polyphenol compounds of a T. chebula decoction was performed using HPLC-UV/DAD, HPLC-ESI-MS and MS2 with an ion trap mass analyzer. The analysis were carried out on a C18 column (250 × 4.6 mm, 5 µm), with a mobile phase consisting of H2O and acetonitrile, both containing 0.1% HCOOH. The most relevant constituents were isolated by means of preparative chromatographic techniques from the aqueous and organic fractions obtained from the crude extract; the isolated compounds were characterized by relevant MS and MS2 data. In particular, chebulic acid, chebulanin, punicalagin, 1,6-di-O-galloyl-beta-D-glucose and corilagin were isolated from the aqueous phase; gallic acid, 3,4,6-tri-O-galloyl-beta-D-glucose, chebulagic acid, chebulinic acid, 1,2,3,4,6-penta-O-galloyl-beta-D-glucose were isolated from the organic phase. The crude decoction, enriched fractions and purified compounds were then tested for their antimutagenic properties against direct and indirect mutagens and for their ability to modulate the EphA2-ephrinA1 system.