Asymmetric synthesis and biological evaluation of Danshensu derivatives as anti-myocardial ischemia drug candidates.

The synthesis and bioactivities of Danshensu derivatives (R)-methyl 2-acetoxy-3-(3,4-diacetoxyphenyl)propanoate (1a), (R)-methyl 2-acetoxy-3-(3,4-methylenedioxyphenyl)propanoate (1b) and their racemates 7 and 10 were reported in this paper. These derivatives were designed to improve their chemical stability and liposolubility by protecting Danshensu's phenolic hydroxyl groups with acetyl or methylene which could be readily hydrolyzed to release bioactive Danshensu. The asymmetric synthesis of 1a and 1b were achieved by catalytic hydrogenation of (Z)-methyl 2-acetoxy-3-(3,4-diacetoxyphenyl)-2-propenoate (6a) and (Z)-methyl 2-acetoxy-3-(3,4-methylenedioxyphenyl)-2-propenoate (6b) in excellent enantiomeric excesses (92% ee and 98% ee, respectively) and good yields (>89%). An unexpected intermediate product, (Z)-2-acetoxy-3-(3,4-dihydroxyphenyl)acrylic acid (4c) was obtained with high chemoselectivity in 86% yield by keeping the reaction temperature at 60 degrees C and its structure was identified by X-ray single crystal diffraction analysis. 1a, 1b and their racemates 7, 10 as well as 4c exhibited potent protective activities against hypoxia-induced cellular damage. The in vitro test showed that all these compounds could increase cell viability, and inhibit lipid hyperoxidation. Furthermore, 1a and 4c could inhibit apoptosis by regulating the expression of apoptosis-related molecule in gene and protein levels, up-regulating the expression of bcl-2 and down-regulating bax and caspase-3. The in vivo test indicated that 4c exhibited anti-myocardial ischemic effects featured by reducing infarction size and increasing the level of the intracellular enzymes detectable in serum. Therefore, these Danshensu derivatives may be good drug candidates for anti-myocardial ischemia therapy and merit further investigation.