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Tryptanthrins have potential therapeutic activity against a wide variety of pathogenic organisms, although little is known about their mechanism. Activity against Escherichia coli, however, has not been examined. The effects of tryptanthrin (indolo[2,1-b]quinazolin-6,12-dione) and nine derivatives on growth, survival, and mutagenesis in E. coli were examined. Analogues with a nitrogen atom at the 4-position of tryptanthrin stopped log phase growth of E. coli cultures at concentrations as low as 5 microM. Tryptanthrins decreased viability during incubation with cells in buffer by factors of 10(-2) to <10(-6) at 0.2-40 microM. Derivatives with an oxime group at the 6-position exhibited the greatest bactericidal activity. Most tryptanthrins were not mutagenic in several independent assays, although the 4-aza and 4 aza-8-fluoro derivatives increased frameshift mutations about 22- and 4-fold, respectively. Given the structure of trypanthrins, binding to DNA may occur by intercalation. From analysis using a sensitive linking number assay, several tryptanthrins, especially the 4-aza and 6-oximo derivatives, intercalate into DNA.

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Hepta-lf6-dienes disubstituted at C -4 with certain carbonyl-containing groups cyclise, in good yield, to the corresponding 4,4-disubstituted 1,2-dirnethylcyclopent-2-enes when treated with a catalytic amount of palladium acetate in chloroform containing hydrogen chloride. Changing the catalyst precursor to chlorotris(triphenylphosphine)rhodium( I ) led to the formation of the corresponding 1 -methyl-2-methylenecyclopentanes which, in turn, isomerised to 1,2-dimethylcyclopent-I -enes in ethanolic hydrogen chloride containing the rhodium complex. The effect of terminal substitution of the dienes with methyl groups was examined. 1,7-and 1,8-Dienes give rise to mixtures of five-membered ring products. Possible mechanisms for the catalytic processes are discussed. The X-ray crystal structure ana I ysis of d ic h loro (4,4d iacetyl hepta -1 6d iene) platinum ( I I ) is reported.