THE ABILITY OF THE RAT TO METABOLIZE MYRISTOYL-METHIONINE - AN ACYLAMINO ACID WITH POTENTIALLY USEFUL ANTIBACTERIAL PROPERTIES

Two experiments with Sprague-Dawley rats tested their ability to hydro lyse myristoyl-methionine ((M-M) into myristic acid and L-methionine ( M). In the first experiment, lasting for 3 days, male rats were orally administered [9,10-H-3]myristoyl-L-[S-35]methionine. The recovery of radioactivity was approximately 90% for both isotopes; 19% of the admi nistered H-3 was recovered in the urine and 16% in the faeces, while t he recovered S-35 activity was 13 and 12%, respectively. The balance o f the radioactivity was found among the tissues, organs and blood. In the second experiment, male and female rats received soybean-based die ts which were supplemented with either 0.305% M-M or 0.2% M (both diet s contained equal amounts of M) for periods up to 3 weeks. The growth rate of the rats receiving the 0.305% M-M diets was slightly slower th an that for the rats on the 0.2% M diet, but the difference was not st atistically significant (P > 0.05). The M-M rats had a transitory decr ease in feed consumption, suggesting that palatability may have contri buted to the growth difference and that a somewhat greater amount of M -M was necessary for the rat to attain the same growth rate as that pr oduced by 0.2% M. When the amount of dietary M-M was increased to 3.05 % M-M, a greater reduction in feed consumption and body weight gain wa s observed. This latter diet was an initial attempt to study the poten tial toxicity of M-M. None of the haematological, clinical chemistry o r organ weight data suggested that M-M was overtly toxic pe, se, but l onger-term feeding Studies are needed to evaluate the potential toxici ty of M-M more fully. (C) 1998 Elsevier Science Lid. All rights reserv ed.