Dose-dependent effect of resveratrol on proliferation and apoptosis in endothelial and tumor cell cultures.

Experimental data suggest that Resveratrol, a compound found in grapes and other fruits may influence cell proliferation and apoptosis. The aim of our experiments was to study the effect of Resveratrol on tumor cell cultures and an endothelial cell culture in order to examine the effect of various doses of this compound on active cell death and cell proliferation. Human tumor (HT-29, SW-620, HT-1080) and endothelial (HUV-EC-C) cells were treated with various doses of (0.1 to 100.0 microg/ml) Resveratrol in vitro. Cell number, apoptotic and mitotic index was measured 24, 48 and 72 h after treatment. Low doses (0.1-1.0 microg/ml) of Resveratrol enhance cell proliferation, higher doses (10.0-100.0 microg/ml) induce apoptosis and decrease mitotic activity, which is reflected in changes of cell number. Resveratrol influences dose dependently the proliferative and apoptotic activity of human tumor and endothelial cells. The possible role of formaldehyde in the mechanism of action of Resveratrol is discussed.

Formaldehyde cycle and the natural formaldehyde generators and capturers.

S-adenosyl-L-methionine serves as a methyl donor in virtually all of the vast number of enzymatic transmethylation reactions including DNA methylation. On the basis of our former experiences we questioned the formation of a methyl cation or methyl radical in the enzymatic transmethylation reactions. The formation of formaldehyde from the methyl moiety of S-adenosyl-L-methionine has been demonstrated. It became increasingly evident that there is a formaldehyde cycle in biological systems in which the formation of the methyl group of L-methionine takes place through formaldehyde and the formation of formaldehyde from S-adenosyl-L-methionine is linked to different enzymatic transmethylation reactions. It is also known that during demethylation processes both formaldehyde and demethylated compound can be formed. The abnormalities of the originally controlled formaldehyde cycle and the uncontrolled enzymatic production of formaldehyde from endogenous and/or exogenous substrates may be potential risk factors in pathogenesis of different disorders. The formaldehyde generator and capturer molecules may potentially normalise these abnormal processes. Trans-resveratrol (trans-3,5,4'-trihydroxystilbene), which is as phytoalexin, occurs naturally in grapes and a variety of medicinal plants. According to our present observations it is a natural concentration-dependent formaldehyde capture molecule. It would seem that elimination of the uncontrolled formaldehyde with resveratrol may exert a double effect in biological systems. The elimination of formaldehyde with resveratrol (first step) may cause a cardioprotective effect and the reaction products between resveratrol and formaldehyde (second step) may act as a chemopreventive factor against cancer.

Identification and measurement of resveratrol and formaldehyde in parts of white and blue grape berries.

The phytoalexin resveratrol (3,5,4'-trihydroxy-trans-stilbene) and formaldehyde (as its dimedone adduct, formaldemethone) have been identified and measured in the extracts of parts of white and blue grapes as well as in white and red wines by overpressured layer chromatography (OPLC), high performance liquid chromatography (HPLC) and from matrix assisted laser desorption/ionization mass spectrometric data. It has been established that the level of resveratrol was very high in skin and in some cases in the stem. Blue grape varieties and red wines always contained a considerably higher amount of resveratrol than white grapes and wines. The measurable level of formaldehyde as well as the resveratrol content was always parallelly high in the same parts of the berries, however, the formaldehyde level was higher in white grapes than in blue ones. The simultaneous occurrence of resveratrol and formaldehyde gives a possibility for interaction between these two special molecules, consequently, hydroxymethyl derivatives of resveratrol can be formed. These resveratrol derivatives may be responsible for special biological activities of resveratrol in grapes and dietetically (cardioprotective effect and chemopreventive effect against cancer) in the human organism.

Formaldehyde generators and capturers as influencing factors of mitotic and apoptotic processes.

There is a growing amount of evidence pointing to the fact that several endogenous and exogenous methylated compounds are potential formaldehyde generators in their biological reactions. N(G)-methylated lysines, N(G)-methylated as well as hydroxymethylated arginines, and 1'-methyl-ascorbigen have been examined in this respect. The apoptosis-inducing effect of formaldehyde molecules formed from methyl groups was earlier first published by our group. Dimedone, an artificial capturer molecule for formaldehyde, has been found to prevent the apoptosis-inducing effect of 1'-methyl-ascorbigen as well as N(G)-hydroxymethylated arginines. More recently resveratrol, present in grapes and wines, has been shown to have cardioprotective and cancer chemopreventive effect. Our group has been successful in demonstrating that this natural formaldehyde capturer molecule can also influence cell proliferation and apoptosis. The apoptosis-inducing or -preventing effect of formaldehyde generators and capturers seems to be dose-dependent and may be utilized in various disturbances of cell proliferation and active cell death.