Antiestrogenic activity of flavonoids from cirsium tenoreanum petrak

The present research is a part of a main project focused on endemic plats from Southern Italy. Cirsium tenoreanum Petrak is a lacking studied member of Compositae(1), which only use described has been as treatment for varicose vein. An ethylacetate extract (AcOEt) was obtained from dried aerial parts (600g) previously extracted with MeOH and dissolved in a MeOH/H2O (9:1) mixture and partitioned. This portion (1.55g) was subjected to silica gel CC and eluted with an increasingly polar gradient of CHCl3/MeOH. Fractions were assayed and combined to yield two fractions A and B. Fraction A, submitted to silica gel preparative TLC and eluted with CH2Cl2/MeOH (9:1) resulted in apigenin. Fraction B was subjected to silica gel CC and eluted with CH2Cl2/MeOH (8:2) instead, giving quercetin-3-O-galactoside and kaempferol-3-O-ramnoside. The structures of the isolated compounds were determined by GC-MS, H1 and C13NMR analysis (2). The antiestrogenic activity was analysed using human breast cancer MCF7-wt cells. Cells were cultured in two different growth conditions: DMEM with red phenol (DMEMRP) and without (DMEM) (3) and monitored using the Trypan blue dye exclusion assay (4).Treated cells were exposed to a range from 5 to 100g/ml of AcOEt extract at 24,48 and 72h. The flavonoids from both fractions, displayed cytotoxic activity on MCF7-wt in a dose-dependent and time manner. IC50 values at 48h were slightly lower for cells cultured in DMEM (74.98g/ml) than in DMEMRP (90.59g/ml). These findings suggested that the antiproliferative activity observed in C. tenoreanum Petrak, follows the same pathway independently of the presence of the stimulating factor red phenol. The flavonoids have antiestrogenic activity which inhibit the aromatase and 17--hydroxysteroid DH enzymes. The structural analysis of apigenin showed a hydroxylic group at position 7, this could be consider significant as antiestrogenic activity when compared with other compounds containing the same group (5), therefore providing a possible mechanism of action for this AcOEt extract of Cirsium tenoreanum Petrak . References: 1.Bernardo, L. (1995) Fiori e Piante del Pollino. Edizioni Prometeo. Castrovillari (CS). 2.Agrawal, PK. (1989) Carbon-13 NMR of flavonoids. Elsevier.3. Berthois, Y.et al. (1986) Proc.Natl.Acad. USA 83:2496-99.4.Moldens, P.et al.(1978) Methods in enzymology. Academic Press .New York.5.Le Bail, JC. Et al.( 1998) Cancer Lett. Nov 13,133,1:101-6.