[Importance of the polyamines: review of the literature]

The polyamines, putrescine, spermidine and spermine, are low-molecular weight substances, synthesized in eucariot cells from their immediate precursor, ornithine. These nitrogen compounds are essential for growth. The organism's endogenous supply is obtained through the diet or by synthesis in the intestinal flora. The polyamines are found in fruits and vegetables, foods of animal origin (milk, eggs, fish, and meat) and fermented food products (cheese, beer, and sauerkraut). Being nitrogenated compounds, they are considered as "minor" components of the diet. Ornithine decarboxylase, a short-half life enzyme, is the key to polyamine biosynthesis. Cellular polyamines are found in free or conjugated forms, the latter made possible, above all, by the presence of positive charges in their molecules. Their particular structure facilitates interaction with anions and binding to nuclear and membrane structures, particularly phospholipids, proteins and DNA. The organism's requirements for these substances are elevated during phases of intense growth or increased demand; thus, the nutritional supply can be crucial during the evolution of processes that involve a high degree of loss combined with deficits in endogenous biosynthesis. Increased tissue and organ polyamine concentrations correlate with diseases of neoplastic origin. It has been hypothesized that polyamine inhibition could be a therapeutic mechanism for such conditions. The supply of polyamines in artificial nutrition has not been measured and there are few data on the effects of artificial nutrition on circulating levels or the usual sites of storage in the body.