Koji Tsubono

Convenient synthesis of magnoshinin, an anti-inflammatory neolignan

Magnoshinin (1) was conveniently synthesized from E-asarone (5) under photochemical conditions. Photochemical conversion of cyclobutane type dimers was also described.

Biotransformation of shikonin by human intestinal bacteria

Abstract The bacterial transformation of shikonin (1) in culture media has been investigated using human intestinal bacteria. Of 24 anaerobes tested, Bacteroides fragilis subsp. thetaotus showed an ability to transform 1 extensively to ten metabolites, five monomers; anhydroalkannin (2), deoxyshikonin (3), cycloshikonin (4), metaboshikonin I (5) and II (6), and five dimers; shikometabolins A (7), B (8), C (9), D (10) and E (11), after anaerobic incubation for 3 days. The structures of these metabolites were determined mainly by 2D-NMR including the INADEQUATE experiment.

Shikometabolins A, B, C and D, novel dimeric naphthoquinone metabolites obtained from shikonin by human intestinal bacteria

Shikometabolins A (2), B (3), C (4) and D (5), four novel naphthoquinone dimers, have been isolated after anaerobic incubation of shikonin (1) with Bacteroides fragillis subsp. thetaotus, and their structures have been determined by means of 2-D NMR spectroscopy including INADEQUATE experiments.