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Synthesis of gentianine N-oxide by enzymatic hydrolysis of swertiamarin in the presence of hydroxylamine and reaction pathway to gentianine and gentianol
- Fujii, Mikio, Kuramochi, Taiki, Nakakuki, Yuhi, Hatazawa, Rina, Konno, Kiju, Munakata, Tatsuo, Hirai, Yasuaki
- Tetrahedron letters 2019 v.60 no.10 pp. 721-725
- Swertia, antihypertensive effect, chemical structure, enzymatic hydrolysis, glycemic effect, hydrolysis, hydroxylamine, metabolites, organic compounds
- Gentianine is a metabolite of gentiopicroside and swertiamarin. Several biological activities have been reported for gentianine, such as antiinflammatory and antidiabetic activity, and hypotensive effect. Gentiopicroside is found in 0.9–9.8% content in Gentian root or Gentian scabra root, and Swertiamarin is contained in Swertia herb in 2–10%. These natural products can be potential starting materials for the synthesis of gentianine. This study describes the β-glucosidase-catalyzed hydrolysis of gentiopicroside and swertiamarin in the presence of hydroxylamine to afford gentianine N-oxide, which can be a synthetic precursor of gentianine derivatives. Enzymatic hydrolysis of swertiamarin selectively afforded gentianine N-oxide in 81% yield, whereas gentiopicroside afforded gentianine N-oxide and gentianol N-oxide. Plausible reaction pathways leading to gentianine, gentianol, and their N-oxides were also investigated.