EFFECT OF NEOMYCIN ON THE HYDROLYSIS AND TOXICITY OF VICINE AND CONVICINE IN RATS

This study in the rat established the effects that a broad-spectrum an d poorly absorbed antibiotic, neomycin sulfate, had on the in vitro an d in vivo hydrolysis of vicine and convicine by the intestinal microfl ora, and on vicine- and convicine-induced depletion of blood glutathio ne and the resulting toxicity. The in vitro studies demonstrated that digesta from the caecum and large intestine were highly effective in h ydrolysing vicine and convicine, whereas digesta from the same section s of the gastro-intestinal tract of neomycin-treated rats were much le ss effective (P < 0.0001). The in vivo studies showed that the total a mount of vicine and convicine excreted in the urine and faeces was muc h greater in neomycin-treated rats compared with controls (P < 0.05), indicating the ability of neomycin to increase the amount of glycoside s, particularly that of vicine, excreted in the faeces. The ability of glycosides to decrease the concentration of glutathione in blood (P < 0.05) and to increase rat mortality was greatly reduced in rats that were treated with neomycin, particularly in those treated ip with the toxin. Thus, the results demonstrated that neomycin reduced the rate a t which vicine and convicine were hydrolysed in the lower section of t he gastro-intestinal tract, and that neomycin treatment was associated with a reduced toxicity of the glycosides.