Total extract of Beta vulgaris var. cicla seeds versus its purified phenolic components: antioxidant activities and antiproliferative effects against colon cancer cells.

Introduction – Beta vulgaris var. cicla (BV) leaves contain chemopreventive compounds that have been investigated for new drug discovery. These compounds belong to the family of the apigenin-glycosides. Since the leaves are seasonal products containing high percentages of water, they are easily degradable during storage in fresh conditions. To be stored they require a drying process, consuming time and a large amount of energy. The extraction of apigenin-glycosides may also be conveniently performed from BV seeds, which represent a stable and year-long available biomass. Objectives – The present reportwas undertaken to find a strategy of purification of bioactive flavonoids fromBV seeds and test their ability to inhibit proliferation both on human colon cancer (RKO) cells and normal human fibroblasts (HF). Materials and methods – The ethyl-acetate extract of BV seedswas fractionated on a Sephadex LH 20 column. A fraction of this extract, labeled as P4, exploited amarked antiproliferative activity on RKOcells.The components of P4were purified on an RP18 column chromatography and identified by HPLC-ESI-MS as 2,4,5-trihydroxybenzaldehyde, 2,5-dihydroxybenzaldehyde, vanillic acid, xylosylvitexin, glucopyranosyl-glucopyrasyl-rhamnetin and glucopyranosyl-xylosyl-rhamnetin. All of them were tested for cytostatic and cytotoxic activity on RKO and HF cells. Results – Xylosylvitexin exhibited the strongest antiproliferative activity on RKO cells, together with an enhancement of the apoptosis, an increase of cells in the G1 phase and a reduction of cells in the S phase; on the contrary, the proliferation of HFwas significantly stimulated. Conclusion – Xylosylvitexin is the main and more efficient chemopreventive compound in BV seeds, but the natural cocktail of molecules, represented by P4 fraction, showed a better compromise between the antiproliferative activity on RKOcells and the enhancement of HF proliferation.