Total syntheses of schizandriside, saracoside and ( ±)-isolariciresinol with antioxidant activities

AbstractLignans are widely distributed in plants and exhibit significant pharmacological effects, including anti-tumor and antioxidative activities. Here, we describe the total synthesis of schizandriside (1), a compound we previously isolated fromSaraca asoca by monitoring antioxidative activity using the 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. Starting from a tandem Michael-aldol reaction, the lignan skeleton was synthesized in 6 steps, including a cyclization step. To determine the stereochemistry of1, we synthesized the natural product ( ±)-isolariciresinol (18) from alcohol17. Comparison of the spectral data showed good agreement. Glycosylation was investigated using four different glycosyl donors. Only the Koenigs –Knorr condition using silver trifluoromethanesulfonate with 1,1,3,3-tetramethylurea provided the glycosylated product. Deprotection and purification using reverse-phase high-performance liquid chromatography gave schizandriside (1) and its diastereomer saracoside (2). Synthesized1,2 and18 showed antioxidant activity with IC50 = 34.4, 28.8, 53.0 μM, respectively.
Source: Journal of Natural Medicines - Category: Drugs & Pharmacology Source Type: research