Synthesis and biological activity of N⁶-mannopyranosyladenines

Abstract

In this work, potentially bioactive condensation products of adenine with D-mannose and 6-deoxy-L-mannose (L-rhamnose) were synthesized in water and ethanol solutions. According to FTIR spectroscopy and elemental analysis, mono-N6-glycosylated adenines were isolated from water systems in satisfactory yields, while ethanol solutions contained mixtures of N6 and N9-products, as well as complexes of the latter with copper ions. A detailed analysis of the vibrational spectra of N6-glycosyladenines confirmed the structure of carbohydrate fragments in the form of pyranose rings, while some part of the product was obtained in the form of deoxyaminoketosis. N-rhamnosyladenine was formed with a more than double yield because of a higher stability of rhamnose with regard to side reactions. The reflection spectra of model solutions of glycosyladenines, recorded 4 days after preparation, showed no bands characteristic of free adenine in the range of 1250-1110 cm-1, which indicates a sufficient resistance of the synthesized products towards hydrolytic cleavage under experimental conditions. The conducted biotesting of the isolated products on wheat seeds (Triticum aestivum L.) showed an increase in the content of chlorophylls in seedlings for both mannosilade-nines compared to the control. A decrease in the concentration of synthesized products in germination solutions from 0.1 to 0.001% led to an increase in the accumulation of photosynthetic pigments, while this effect was more pronounced for rhamnosyladenine. The latter can be connected with the structural features of car-bohydrate fragments, in particular, the differences in the hydroxylation degree of glucoside fragments. Future research will investigate the mechanisms of transformation and action of N6-substituted adenines.