Efficient purification of the diarylheptanoid oregonin from red alder (Alnus rubra) leaves and bark combining aqueous extraction, spray drying and flash-chromatography.

Carmen S Lea, Chakravarthi Simhadri, Stephen G Bradbury, Jeremy E Wulff, C Peter Constabel

Phytochemical analysis : PCA 2021 Jul

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The diarylheptanoid xyloside oregonin ((5S)-1,7-bis(3,4-dihydroxyphenyl)-5-(β-d-xylopyranosyloxy)-heptan-3-one) has significant medicinal potential and is found at high concentration in leaves and bark of red alder (Alnus rubra). To establish inexpensive and easily scaled methods for the extraction and purification of oregonin from timber by-products. We developed a method combining aqueous extraction with spray drying of red alder extract into a powder, thus reducing the need for organic solvents used in traditional Soxhlet extraction or in solvent partitioning. Flash chromatography was utilised to purify oregonin from crude spray-dried alder extract. Crude spray-dried alder extract was comprised of an average of 9% of the diarylheptanoid compound oregonin. Less than 10% thermal degradation of oregonin was observed using extraction temperatures between 25°C and 50°C, followed by spray drying. The structure of purified oregonin was validated using high-performance liquid chromatography (HPLC), mass spectrometry (MS), ultraviolet spectroscopy (UV), and nuclear magnetic resonance (NMR). The developed method was robust, repeatable, and yielded purified oregonin of greater than > 95% purity (average of 95.8%). Our analysis represents the most complete NMR characterisation of oregonin reported to date. © 2020 John Wiley & Sons, Ltd.

Citation

Carmen S Lea, Chakravarthi Simhadri, Stephen G Bradbury, Jeremy E Wulff, C Peter Constabel. Efficient purification of the diarylheptanoid oregonin from red alder (Alnus rubra) leaves and bark combining aqueous extraction, spray drying and flash-chromatography. Phytochemical analysis : PCA. 2021 Jul;32(4):554-561