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 from 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. Using this methodology as the final isolation step, three new glycosylated polyketides, arthrinosides A-C, were isolated from fermentation extracts of an Arthrinium sp. The three compounds differ in the length and hydroxylation of the polyketide chain and were not easily separable using normal or reverse phase column chromatography. Mycoparasitic acids A and B, new natural products differing only in epoxidation of an endocyclic double bond, were separated directly from crude fungal culture extracts. This CCC method was applied to the purification of a new biotransformation product of sordarin resulting from hydroxylation at C-11. Several hundred milligrams of this new derivative were easily separated in a single chromatographic run.