QUERCETIN EXERTS A PREFERENTIAL CYTOTOXIC EFFECT ON ACTIVE DIVIDING COLON-CARCINOMA HT29 AND CACO-2 CELLS

The effect of the naturally occurring flavonol, quercetin, was investi gated on cell growth and metabolism of two human carcinoma cell lines, HT29 and Caco-2 cells, both during the exponentially growing phase an d after confluence. Our results show clearly that, after a 48-h period of treatment, quercetin (in the range of concentration from 15 mu M t o 120 mu M) exerted a preferential cytotoxic effect on active prolifer ating cells. This effect was dose dependent and was accompanied by a s imultaneous inhibition of lactate release and a dramatic decrease of t otal cellular ATP content. In contrast, in confluent cells, quercetin failed to affect cell viability or lactate release, but led neverthele ss to a depletion of cellular ATP level. In conclusion, the cytotoxici ty of quercetin is markedly higher in actively growing cells in compar ison with confluent cells.