Triple Effect of β‐Nitropropionic Acid on Hydrolases, Oxidases and Transferases

β‐Nitropropionic Acid (βNPA)has been found as a metabolite of higher plants fungi, it is identified as a product from streptomyces species. βNPA is chemically obtained from the reaction of β–propiolactone with sodium nitrite. It was found to be responsible for the toxic symptoms produced in dairy cattle. It is also fetal to adult rats at a dose of 100 mg/Kg body weight within one hour. The rats showed signs of tremors and difficulty in breathing 30 min post‐injection. The effect of βNPA on the activities of the hydrolase (cholinestrase) and the oxidative (monoamine oxidase) extracted from five different parts of rat brain tissues namely: basal ganglia, frontal cortex, medulla oblongata, pons and cerebellum was studied. Kinetic studies were done to determine the type of inhibition of AChE and MAO isozymes as well as the enzyme inhibitor‐ dissociation constant (Ki) by βNPA. The results indicate that the rate of inhibition of AChE extracted from frontal cortex and medulla oblongata was higher than that of the other parts by βNPA. The inhibition of these isozymes was dose dependent and of the competitive type. The values of Ki for βNPA‐ AChE isozymes varied from 3.8 to 10.8 mmole/L, for βNPA –MAO isozymes varied from 0.3 to 6.2 m mole/L and were of the same order of magnitude. The differences in the degree of inhibition of these extracts of these parts of the brain by βNPA could be attributed to the slight differences in the structures of the amino acids of these enzymes and to distinct gene loci. The inhibition of both AChE and MAO by βNPA may save ACh and some biogenic amines which are of great importance for patients suffering from Alzheimer and dementia. Moreover βNPA possessed an inhibitory effect on serum alanine and aspartate amino transferases and the inhibition was of the competitive type. The inhibition of all the above enzymes by βNPA recovered by dialysis (reversible inhibition).