HPLCbioautography of the directed biosynthesis of Zalerion arboricola led to the discovery of pneumocandin Bo (L-688,786), a new antifungal and anti-Pneumocystis carinii lipopeptide. Isolation techniques were developed to separate this componentfrom pneumocandinAo(L-67 1 ,329) in fermentations of a mutant of Zalerion arboricola. Anumberof related compounds were also isolated, which differ from pneumocandinsAoand Bo in the hydroxylation patterns on the ornithine, homotyrosine, and proline. Aculeacin1 '2) and echinocandin B3'4) are representatives of a large class of naturally-occuring antifungal lipopeptides which are characterized by potent fungicidal activity against Candida sp. A semi-synthetic derivative ofechinocandin B, cilofungin, has been shown to protect animals with systemic fungal infections. 5) Another representative, pneumocandin Ao (L-671,329),6~8) is active against Pneumocystis carinii6~9) an important opportunistic organism which causes pneumonia in AIDS patients. The commonmechanism of action against these two pathogens is presumed to be inhibition of l,3-/?-glucan synthesis.9) This paper describes the discovery, production, and isolation of pneumocandin Bo and related lipopeptides, which have biological activity against both Candida sp. and P. carinii. Materials and Methods Identification of the Producing Strain The strain of Zalerion arboricola Buczacki (ATCC20868) was recovered from filtrates of water and sediments from a farm pond in the Valle del Rio Lozoya, near Madrid, Spain. This unusual isolate was sent to the Centraalbureau voor Schimmelcultures, Baarn, The Netherlands, where Dr. G. S. DeHoog made the original identification. The characteristics of this strain coincide well with the original descriptions of Buczacki10) and with the comparative treatment of the original strain by Goos.n) In the description of the organism presented in the "Results and Discussion" section, capitalized color namesare from Ridgway.12) Analytical and Preparative HPLCSystems HPLCanalysis of pneumocandin Bo was performed on a system consisting of a Spectra-Physics 8700 pump, a Spectra-Physics 8780 autoinjector, a DuPont Zorbax ODS4.6mm i.d. x 25 cm column, an LKB 2151 variable wavelength UVdetector equipped with a 10 mmpathlength cell and a Spectra-Physics 4200 integrator. Column temperature was maintained constant at 40°C via jacketing and a constant temperature bath. The isocratic solvent system was CH3CN-H2O(45 : 55), the flow rate was 1.0ml/minute, and the UVabsorbance of the effluent was monitored at 210nm. Under these conditions the retention times of
