Application of pH-zone-refining CCC to the isolation of antifungal fermentation products

The application of pH-zone-refining countercurrent chromatography (CCC) to the purification and bioassay guided isolation of novel antifungal agents f rom fungal fermentation extracts is demonstrated with separations of three families of acidic natural products. The separations were carried out using two types of commercially available multilayer coil planet centrifuges. Us ing this methodology as the final isolation step, three new glycosylated po lyketides, arthrinosides A-C, were isolated from fermentation extracts of a n Arthrinium sp. The three compounds differ in the length and hydroxylation of the polyketide chain and were not easily separable using normal or reve rse phase column chromatography. Mycoparasitic acids A and B, new natural p roducts differing only in epoxidation of an endocyclic double bond, were se parated directly from crude fungal culture extracts. This CCC method was ap plied to the purification of a new biotransformation product of sordarin re sulting from hydroxylation at C-11. Several hundred milligrams of this new derivative were easily separated in a single chromatographic run.