The ability of some known antibiotics such as streptothricin, streptomycin, and clavacin to prevent bacteriophage action has been demonstrated (Jones, 1945). Schatz and Plager (1948), working with an actinomycete that demonstrated antiphage activity, extracted a material that was capable of weakly inhibiting a rodent-paralyzing virus (MM), but it appeared to be too toxic for further study. We have isolated a substance from Aspergillus sp. that was capable

Thin-layer and column chromatography show that the antifungal antibiotic filipin contains a minimum of eight filipin-like pentaenes. Three of the components, which seem to constitute 96% of the T A he isolation of the crystalline antifungal antibiotic filipin was described by Whitfield et al. (1955). Struc-ture studies have been reported by Berkoz and Djerassi (1959), Dhar et al. (1960, 1964), Djerassi et al. (1961), Ceder andRyhage (1964), and Golding et al. (1964).Recent advances particularly in thin-layer chromatography and partition chromatography have prompted us to investigate the homogeneity of the filipin used in these studies. Thin-layer chromatography on silica gel yielded the first evidence that filipin was a mixture, while subsequent partition chromatography revealed it was composed of at least eight components. Therefore, we will refer to the filipin described in the literature as the filipin complex. The chromatographic methods for isolating the three major components of the filipin complex as well as their characterization are the subjects of this paper. Materials and MethodsThin-Layer Chromatography. Thin-layer chromatography plates (10 X 20 cm) were prepared from 60 g of silica gel HF254 (E. Merck, AG-Darmstadt, Germany) suspended in 60 ml of 0.2 m KH2P04 and 60 ml of 0.2 m Na2HP04. They were air dried and then activated at 130°for 2 hr. The 0.3-mm thick plates were developed with normal saturation in methylene chloride-methanol (85:15). The filipins were visualized by their fluorescence under 366-m^i light and quantitated by densitometric measurement.Partition Chromatography. The solvent systems were prepared from dimethylformamide, water, ethyl acetate, and cyclohexane. The solvents were mixed and the two phases were separated. Proportions were as given in Table I. Siliceous earth, either Dicalite 436 or 4200 (Great Lakes Carbon Corp.), was slurried in upper phase and mixed with lower phase (0.4 ml/g). The mixture was poured into a glass tube and packed by gravity with flowing upper phase until the bed height was constant. The liquid was then drained to about 0.5 in. above the bed.

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