Research On Extraction Of Betulin And Synthesis Of Betulinic Acid

Betulin and betulinic acid are pentacyclic triterpene compounds with activities of antitumor, antihiv, antiseptic and antiphlogosis which exist in many kinds of plants. They are widely used in food, medicine and cosmetics fields. In the field of food, both of them can be used as additive to play a role in antioxidant and preservation.White birch is widely distributed in China and betulin has a high content in birch bark which can be easily obtained by extraction method. While the content of betulinic acid in birch bark is low and it is difficult to extract it from birch bark. The main way to obtain betulinic acid is synthesis it from betulin. But the industrial application method has an issue of low effect at present. Aiming at this situation, the paper carried out research on extraction of betulin and betulinic acid synthesis technology with the birch bark of Changbai mountain as raw material, in order to develop the production technology that can be popularized and applied.1. Research on extraction and purity technology of betulin. The birch bark was extracted by soxhlet extractor to obtain betulin after procedures of cleaning, drying and crushing. Effective extraction condition was: ethyl acetate as extraction solvent, solid-liquid ratio 1:20, time 6 hours. Betulin purity can reach 83.43% and the yield can reach 22.80%.Condition of recrystallization was: isopropyl alcohol as solvent, solid-liquid ratio 1:35,crystallization temperature 4℃, and the purity can be 97.3%.2. Research on synthesis and purity technology of betulonic acid. The optimum condition for synthesis of betulonic acid was: acetone as solvent, mole ratio of betulin and Jones was 1:15, reaction temperature was 0℃, the comprehensive yield was 68.96%; The purification of intermediate betulonic acid was discussed and the acidification method was determined as the most suitable method finally. 15% KOH solution was used to convert betulonic acid to salt, then acidified with dilute hydrochloric acid solution. The purity can be 80.63% and the yield can reach 38.06%.3. Research on synthesis and purity technology of betulinic acid. The optimum condition for betulonic acid reduction to betulinic acid was: tetrahydrofuran as solvent,sodium borohydride as reductant, quality ratio 1:0.227, reaction temperature 0℃, reaction time 8 hours, and the purity can be 85.2%; Through the purification of column chromatography and recrystallization method, the purity of betulinic acid can over 94%.