Three-liquid-phase extraction and re-partition as an integrated process for simultaneous extraction and separation of lithospermic acid B and tanshinone IIA

Abstract

Lithospermic acid B (LAB) and tanshinone IIA (Tan IIA) are main bioactive components in Salvia miltiorrhiza Bunge which is a traditional Chinese herb. Three-liquid-phase extraction and re-partition as an integrated process was designed for simultaneous extraction and fractionation of LAB and Tan IIA from Salvia miltiorrhiza Bunge. In extraction with three-liquid-phase system (TLPS, n-hexane-ethanol-NaH2PO4-H2O), effect of pH, TLPS compositions, time and temperature were investigated; and partition coefficients in TLPS were evaluated. The extraction was optimized with response surface methodology to achieve two sets of optimal conditions for respective LAB and Tan IIA yields. Then, two sets of optimal conditions were unified. Using TLPS with aqueous NaH2PO4 solution (pH 2.55, 3.75 mol/L):ethanol:n-hexane 384:376:240 (v:v:v) for simultaneous extraction at 47 °C for 6.65 h, extraction efficiency was 83.7 ± 6.2% and 87.8 ± 2.1% for LAB and Tan IIA, respectively. LAB and Tan IIA were further fractionated by partitioning into different phases via addition of water and n-hexane to the top two phases. Partitions of LAB and Tan IIA into their respective phases were spontaneous, irreversible and endothermic. Compared with single-phase extraction, LAB and Tan IIA yields were improved by 116% and 35.5%, respectively. Simultaneous extraction and fractionation of LAB and Tan IIA were successfully accomplished with TLPS extraction combined with two-phase partition.