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From the cultures of Streptomyces violaceoniger, strain Tü 96, two new lipophilic antibiotics, Lysolipin I and Lysolipin X were isolated. The latter one is chemically unstable and is easily transformed to Lysolipin I. The deeply yellow Lysolipin I has a molecular formula C29H24CINO11. It was characterized by the ir, uv, H-nmr and 13C-nmr spectra, which make a quinone structure very probable. Lysolipin I is active against Gram-positive and Gram-negative bacteria. However, enterobacteriae are only inhibited in high dilution, when the membrane permeation is damaged. Lysolipin I acts lytically against bacterial cells. Its activity is decreased by several lipids. The site of action is the biosynthesis of bacterial cell walls, an interaction with the carrier lipid for mureine intermediates being probable.

Candida lipolytica synthesizes the antibiotic tryptanthrin from 1 mole tryptophan and 1 mole anthranilic acid. When feeding tryptophan and substituted anthranilic acids, or substituted tryptophans and anthranilic acid, we could isolate and identify the expected derivatives of tryptanthrin. The enzymes of the biosynthesis of tryptanthrin, with the exception of bromotryptophan, had no specifity for these substrates. In addition to these experiments substituted tryptanthrines were chemically synthesized. We checked them for antibiotic action; the halogen compounds turned out to be especially effective.