Further Investigations of the Effect of Riboflavine Photolysates on the Intestinal Absorption of Certain Drugs in Rats and Their Mechanism of Action

Abstract

Studies of the influence of riboflavine (RF) and flavine mononucleotide (FMN) photolysates on the intestinal membrane and its constituents have been pursued. The absorption experiments were carried out using in situ recirculation technique. It was found that the uptake of bromphenol blue (BPB) by the isolated intestinal epithelial cells was increased. Pretreatment experiments showed that, a period of 15 min was required for the hyperabsorptive state of the intestine to return back to its normal function. Histological studies of small intestinal mucosa could not demonstrate any detectable change. D-glucose absorption was not affected by the photolysates of riboflavine. NMR studies and liposome experiments revealed an interaction between the intermediate products of photolysis and egg phosphatidylcholine (PC). TLC and thiobarbituric acid test disclosed formation of lipid peroxides. A decrease in the surface tension was also occurred. From these data it was assumed that the intermediate products of photolyses attacked the double bonds of the unsaturated fatty acid side chain of PC molecules followed by cleavage and splitting of short chain fatty acids, consequently, change in permeability of the intestinal membrane due to disorganization of phospholipid moecules could be expected.