Studies on the anti-tumour activity of aliphatic aldehydes. IV. Radiosensitizing properties of L-erythro-alpha, beta-dihydroxybutyraldehyde on E. coli B and Ehrlich ascites tumour cells

The aim of the present paper was to see if L-erythro-α, β-dihydroxybutyraldehyde (DHBA) which interacts with intracellular cysteine, may act as a radiosensitizing compound on bacteria and tumour cells. A test of radiosensitivity carried out with conventional procedures on E.coli B indicated that DHBA enhances the effect of radiation both in non-toxic and toxic conditions, giving respectively a DMF of 1·3 and 1·7. In vitro/in vivo experiments, carried out with the adenocarcinoma Ehrlich ascites cells, have shown that DHBA displays a marked radiosensitizing action at non-toxic doses (1 or 5 mM), when the irradiation is carried out in air as well as in nitrogen. The combined action of DHBA and X-rays leads to a slow-down of tumour growth with increased survival of the animals and, in convenient X-rays doses, brings about a dramatic decrease in the number of the tumour cells from the ascitic fluid with their total disappearance confirmed by the lack of tumour growth in all animals. DHBA must be present during the radiation. The addition of aldehyde to irradiated cells appeared to be without effect on the cytokynetics of tumour growth. Immunological processes play a negligible role under our experimental conditions. The results are discussed.