Isolation and Identification of Components in the Dihydroquercetin-Rich Extract from Larch Wood (Larix olgensis Henry)

Background: The finding that antioxidant dihydroquercetin (DHQ) present in high content in the wood of Dahurian larch (Larix gmelinii Rupr.) which distributes mainly in Khingan Mountains led to the development and manufacture of a DHQ-rich extract, Lavitol (a trade name). Whether the composition of DHQ-rich extract from L. olgensis Henry, a great resource of Larch species distributed in Changbai Mountain in China, is same or similar with trade DHQ product becomes an interesting question.

Aims: To isolate and identify the components in the DHQ-rich extract from larch wood (L. olgensis).

Methodology: Compounds were isolated from a DHQ-rich extract (91% purity) of L. olgensis through polyamide and Sephadex LH-20 column chromatography, and their structures were elucidated based on 1H-NMR, 13C-NMR, MS and CD data analysis. Thin layer chromatography (TLC) was applied to quickly identify the components in the extract.

Results: Five compounds were isolated from the extract, the main one was (2R,3R)-dihydroquercetin (1), four minor components were identified as (2R,3R)-aromadendrin (2), quercetin (3), 3,5,7-trihydroxychromone (4) and (2R,3R)-3'-O-methyl-taxifolin (5). Polyamide and silica gel TLC were developed to identify these components in the extract, and the results indicated that three batches of DHQ-rich extracts contained the same components.

Conclusion: Except for the presence of trace impurities 4 and 5, DHQ-rich extracts from L. olgensis contained (2R,3R)-DHQ (1) and two minor impurities 2 and 3, which were similar with the composition of trade DHQ-rich extract from Dahurian larch (L. gmelinii). Further quantification of these impurities in DHQ-rich extract from L. olgensis by HPLC analysis need to be done in the future.