Schisandrin B (Sch B), the most abundant and biologically active dibenzocyclooctadiene lignan present in Fructus Schisandrae (FS), is usually prepared and supplied in the form of a mixture of its stereoisomers, namely (±)γ-schisandrin and (–)Sch B. Recently, (–)Sch B has been shown to be more potent than (±)γ-schisandrin in protecting against oxidative injury, but less potent in producing cytotoxicity, in both cultured hepatocytes and cardiomyocytes. A high purity (–)Sch B preparation would therefore be of pharmacological interest. Our literature search revealed that the isolation of Sch B from FS usually required lengthy steps with a relatively low yield and no further enrichment of (–)Sch B. Thus, the objective of this study is to develop a process for the separation and purification...[ Read more ]

Schisandrin B (Sch B), the most abundant and biologically active dibenzocyclooctadiene lignan present in Fructus Schisandrae (FS), is usually prepared and supplied in the form of a mixture of its stereoisomers, namely (±)γ-schisandrin and (–)Sch B. Recently, (–)Sch B has been shown to be more potent than (±)γ-schisandrin in protecting against oxidative injury, but less potent in producing cytotoxicity, in both cultured hepatocytes and cardiomyocytes. A high purity (–)Sch B preparation would therefore be of pharmacological interest. Our literature search revealed that the isolation of Sch B from FS usually required lengthy steps with a relatively low yield and no further enrichment of (–)Sch B. Thus, the objective of this study is to develop a process for the separation and purification of (–)Sch B from FS.

A viable process for the isolation and purification of (–)Sch B from FS has been successfully developed. The first part involved the solid-liquid extraction of FS by petroleum ether to yield a Sch B-containing extract. The second part was the purification of the extract by removing the relatively non-polar substances, mostly fatty oils, by the adsorption-desorption step, which was followed by the chromatographic process to isolate the Sch B-enriched fraction that was then used to yield Sch B. The final part was to further purify (–)Sch B from Sch B. A solid-liquid equilibrium (SLE) phase diagram of the ternary system comprising (±)γ-schisandrin, (–)Sch B and ethanol (the selected solvent) was constructed, and a crystallization-based separation process flowsheet was then synthesized accordingly. High purity (–)Sch B product (~98.5 wt%) were obtained from bench-scale crystallization experiments.

Finally, the use of biological assay for the quality assurance of the purified Sch B products was also demonstrated. The antioxidant activity of the products was assessed by measuring the cellular glutathione (GSH) level. An increase in cellular GSH level induced by the high purity (–)Sch B product (32%) proved that the purified product possess antioxidant activity. Such an approach of using biological assay is important to the quality assurance of the isolated products in addition to chemical analysis.