F-16438s, novel binding inhibitors of CD44 and hyaluronic acid. II. Producing organism, fermentation, isolation, physico-chemical properties and structural elucidation.

In the course of our screening for binding inhibitors of CD44 and hyaluronic acid, five active compounds, F-16438 A, B, E, F and G were found and isolated from the cultured broth of a fungal strain, Gloeoporus dichrous SANK 30502. The structures of these compounds except for F-16438 G were elucidated by physico-chemical and spectral data to be new compounds related to caloporoside; F-16438 G was identified to be the 6'-malonylated derivative of caloporoside.