Alcohol-precipitation mechanism of Danshen Injection based on molecular state quantitative calculation model

Abstract

Objective To explore the transfer rules of phenolic acids in the alcohol precipitation process of Danshen Injection (DI) based on molecular state quantitative calculation model. Methods In the experiment, sodium danshensu, protocatechuic aldehyde, rosmarinic acid and salvianolic acid B were selected as indexes for exploring the alcohol-precipitation mechanism. Based on the mathematical model of nanofiltration mass transfer, membrane flux and rejection were collected to calculate the solute mass transfer coefficients, and the quantitative calculation model of molecular state was established with molecular monomer components as reference of DI. Furthermore, the correlation among the transfer rate, molecular state and molecular weight was analyzed with the densities of 1.05, 1.15, 1.25 g/mL of concentrated solution under the alcohol precipitation of 75% and 85%. Results The power function equation of molecular state quantitative calculation was set up successfully with the regression coefficients (R2 > 0.99), as the density of intermediate in DI was 1.05—1.25 g/mL, the molecular proportions of sodium danshensu, protocatechuic aldehyde, rosmarinic acid and salvianolic acid B were 1.14%—5.25%, 66.70%—80.25%, 10.51%—19.11% and 1.13%—11.44%, respectively. The correlation analysis of “density- molecular state ratio- alcohol precipitation transfer rate” showed that alcohol precipitation concentration increased from 75% to 85%, and the decreasing rate of transfer rate was in the order of sodium danshensu > salvianolic acid B > rosmarinic acid > protocatechualdehyde. Therefore, the molecular state of phenolic acids was the main factor which affected the transfer rate of alcohol precipitation, and the relative molecular weight was correlated with the transfer rate. Conclusion The quantitative calculation method of molecular state was established for phenolic acids in the intermediate of DI, and the refining mechanism of alcohol precipitation was preliminarily expounded which was helpful for standardized control of preparation alcohol precipitation process.