Melatonin scavenges phenylglyoxylic ketyl radicals.
The antioxidant properties of melatonin were tested in this work by EPR technique. It was found that melatonin scavenges phenylglyoxylic ketyl radicals. Its effectiveness was 10-times lower than that of vitamin C. A new method of generation of phenylglyoxylic ketyl radicals by spontaneous decomposition of D,L-2,3-diphenyltartaric acid in propan-2-ol was used.
Sono-photolysis of phenylglyoxylic acid and stability studies of d,l-2,3-diphenyltartaric acid
Abstract Photodecarboxylation and photoreduction of phenylglyoxylic acid as well as the influence of ultrasound on these reactions were studied. Ultrasound considerably enhanced photodecarboxylation of phenylglyoxylic acid in acetonitrile with low content of water (CH 3 CN–H 2 O, 0.5%, v/v). No ultrasound effect was observed at higher content of water. Photoreduction of phenylglyoxylic acid resulted in formation of isomers of 2,3-diphenyltartaric acid. We found out that photosonication had no influence on the rate of formation of 2,3-diphenyltartaric acids but affected only the ratio of d , l and meso isomers of this acid. The thermal instability of 2,3-diphenyltartaric acids can affect the course of photoreduction of phenylglyoxylic acid. Phenylglyoxylic and benzoic acids were the main products after the thermal decomposition of d , l -2,3-diphenyltartaric acid in 2-propanol. The rate of decomposition of d , l -2,3-diphenyltartaric acid was very sensitive to its concentration, temperature and a presence of oxygen as well as water in the reaction mixture. Sonication caused a large decrease of the rate of decomposition of d , l -2,3-diphenyltartaric acid.
Effect of pretreatment with antibiotics on the hydrolysis of salicyluric acid in rabbit intestinal microorganisms.
The effect of pretreatment with antibiotics on the hydrolysis of salicyluric acid in rabbit intestinal microorganisms was investigated. Latamoxef sodium (LMOX, 25 mg/kg/d, intravenously) and cephalexin (CEX, 16.7 mg/kg/d, orally) were administered for 1 or 3 d. The blood concentration of salicyluric acid and salicylic acid following oral, intracecal and rectal administration of salicyluric acid was determined. By the pretreatment with LMOX for 1 or 3 d, the blood concentration of salicylic acid following oral administration of salicyluric acid was slightly decreased. In rabbits pretreated with CEX for 3 d, the blood concentration of salicylic acid was detected at low concentration. By the pretreatment with LMOX and CEX, however, the decrease in the blood concentration of salicylic acid following rectal administration of salicyluric acid was not observed. Although the examination of population of intestinal microorganisms induced by the pretreatment with antibiotics was not performed, the metabolic activity of intestinal microorganisms may be changed.