Study On The Chemoenzymatic Synthesis Of Danshensu

Danshensu is a highly water-soluble and active compound of Danshen(Salvia miltiorrhiza) root extract. However, Salvia miltiorrhiza relatively scarce resources,Danshen contains only 0.5% Danshensu, the purification of the active compound is difficult, Only from natural herbs extraction was increased medical cost is higher, and the extracts directly extracted from Salvia are mostly water-soluble mixture of lower purity, the therapeutic effect of the drug are seriously affected. When chiral drugs into the body, the pharmacological effects of different configurations of the drug molecules may be different. Since left danshensu pharmacological activity has not yet been thoroughly studied in clinical, racemic danshensu exists clinic risks. A single chiral natural danshensu need to be obtained by splitting danshensu racemate, which was chemically synthesized. Therefore, setting up a synthesis route of single enantiomer of Danshensu with simple operations, mild conditions and high yield is an important method to solve drug resources, improve the quality of medicinal products,which has important implications for the development and use of drugs Danshensu.In this paper, chemical-enzymatic synthesis of a natural right-handed danshensu,3,4-hydroxybenzaldehyde, a cheap petroleum chemical produets, and acetyl glycine as raw materials, through the Erlenmeyer condensation preparation of 2-methyl-4-(3,4-diacetoxy-benzylidene) oxazolone, intermediate ring opening reaction in ice water gave α-acetamino-β-(3,4-diacetoxylphenyl)acrylic acid. Then,β-(3,4-dihydroxyphenyl) pyruvate was obtained by hydrolysis ofα-acetamino-β-(3,4-diacetoxylphenyl)acrylic acid with 1 mol/L of aqueous hydrochloric acid. On the one hand, Danshensu racemate was prepared by NaBH4-MeOH reduced of β-(3,4-dihydroxyphenyl) pyruvate, and provide raw materials for the chiral separation experiments; On the other hand, Screening of suitable species, Danshensu was prepared by bio-catalytic reduced ofβ-(3,4-dihydroxyphenyl) pyruvate with the use of microbial cells, finally found that resting cells of pediococcus acidilactici ATCC 1.2696 can effectively catalyze the asymmetric reduction of carbonyl preparing natural right-handed Danshensu.The optimum conditions was found by optimizing the reaction conditionsthrough single factor and orthogonal optimization. The structure of all intermediates and final products were characterized by means of IR, NMR, melting point apparatus,mass spectrometry, optical rotation, HPLC and so on. Under optimum conditions,α-acetamino-β-(3,4-diacetoxylphenyl)acrylic acid, β-(3,4-dihydroxyphenyl) pyruvate,Danshensu racemate and natural right-handed Danshensu yield by resting cells transformation was 84.8%, 89.0%, 83.97% and 92.0%. Calculated on the basis of3,4-hydroxybenzaldehyde, the overall yield of Danshensu racemate was 63.37%, and the overall yield of natural right-handed Danshensu was up to 69.4%, and the optical purity of Danshensu was 97.5%ee.