Development of bioactive functions in Hydrangeae Dulcis Folium. VI. Syntheses of thunberginols A and F and their 3'-deoxy-derivatives using regiospecific lactonization of stilbene carboxylic acid: Structures and inhibitory activity on histamine release of hydramacrophyllols A and B

Article abstract of DOI:10.1248/cpb.44.1890

Lactonization reaction of 2-carboxystilbene mediated by copper(II) chloride proceeded regiospecifically to give the five-membered lactone, while the bromolactonizations using N-bromosuccinimide and anodic oxidation were found to furnish the six-membered lactone. Using these regiospecific lactonization reactions as a key step, antiallergic and antimicrobial isocoumarins and the benzylidenephthalides thunberginols A and F and their 3'-deoxyanalogs were synthesized from phyllodulcin and hydrangenol. Two phthalides called hydramacrophyllols A and B were isolated from Hydrangeae Dulcis Folium and their stereostructures were determined on the basis of physicochemical and chemical evidence, which included the syntheses of hydramacrophyllols A and B from hydrangenol by the application of the lactonization method using copper(II) chloride. In addition, hydramacrophyllols A and B were found to exhibit an inhibitory effect on the histamine release from rat peritoneal exudate cells induced by antigen- antibody reaction.

Full text of DOI:10.1248/cpb.44.1890

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