NEW METHODS OF PREPARATION OF ALLOBETULIN 3-O-LACTATE AND ITS PHYSICOCHEMICAL PROPER-TIES

Abstract

In this work the new, one-step methods for the synthesis of allobetulin 3-O-lactate from betulin and birch bark were proposed. The composition of the obtained samples of allobetulin 3-O-lactate after recrystallization from ethanol and acetone was determined by elemental analysis, and its structure was confirmed by IR and NMR spectroscopy for the first time. The melting point of allobetulin 3-O-lactate is 225–226 °C. The one-step method for the preparation of allobetulin 3-O-lactate from betulin is based on the combination of the stages of isomerization of betulin in the presence of sulfuric acid and the formation of ester with lactic acid, that does not require an additional stage of allobetulin synthesis. The yield of allobetulin 3-O-lactate is 77 wt%. The one-stage method of obtaining allobetulin 3-O-lactate directly from birch bark is based on combining the stages of betulin extraction, its isomerization into allobetulin and esterification of allobetulin, it allowed to exclude the stages of betulin extraction and allobetulin synthesis. The yield of allobetulin 3-O-lactate is 12% of the mass of absolutely dry birch bark (~32%wt. of betulin contained in it). Taking into account that allobetulin and its derivatives have antibacterial, immunotropic, anti-ulcer and antiviral activity, and lactic acid derivatives show immunomodulatory, anti-inflammatory and antimicrobial activity, it can be expected that allobetulin 3-O-lactate will show improved pharmacological properties compared to the starting substances.