Broad-spectrum aminosterol antibiotic present in shark tissues; novel indication for steroid as vertebrate host-defense agent. Isoln from the stomach of the spiny dogfish shark, Squalus acanthias: M. Zasloff et al., US 5192756 (1993 to Children's Hospital of Penn.). Structural determn and antimicrobial activity: K. S. Moore et al., Proc. Natl. Acad. Sci. USA 90, 1354 (1993). NMR spectral studies: S. L. Wehrli et al., Steroids 58, 370 (1993). Synthesis of trihydrochloride: R. M. Moriarty et al., WO 9419366 (1994 to Magainin Pharm.).