Spectroscopic studies of cutaneous photosensitizing agents. XVIII. Indomethacin

The photochemistry, photophysics, and photosensitization (Type I and II) of indomethacin (IN) (N-[p-chlorobenzoyl]-5-methoxy-2-methylindole-3-acetic acid) has been studied in a variety of solvents using NMR, high performance liquid chromatography-mass spectroscopy, transient spectroscopy, electron paramagnetic resonance in conjunction with the spin trapping technique, and the direct detection of singlet molecular oxygen (1O2) luminescence. Photodecomposition of IN (lambda ex > 330 nm) in degassed or air-saturated benzene proceeds rapidly to yield a major (2; N-[p-chlorobenzyl]-5-methoxy-2-methyl-3-methylene-indoline) and a minor (3; N-[p-chlorobenzoyl]-5-methoxy-2,3-dimethyl-indole) decarboxylated product and a minor indoline (5; 1-en-5-methoxy-2-methyl-3- methylene-indoline), which is formed by loss of the p-chlorobenzoyl moiety. In air-saturated solvents two minor oxidized products 4 (N-[p-chlorobenzoyl]-5-methoxy-2-methyl-indole-3-aldehyde) and 6 (5-methoxy-2-methyl-indole-3-aldehyde) are also formed. When photolysis was carried out in 18O2-saturated benzene, the oxidized products 4 and 6 contained 18O, indicating that oxidation was mediated by dissolved oxygen in the solvent. In more polar solvents such as acetonitrile or ethanol, photodecomposition is extremely slow and inefficient. Phosphorescence of IN at 77 K shows strong solvent dependence and its emission is greatly reduced as polarity of solvent is increased. Flash excitation of In in degassed ethanol or acetonitrile products no transients. A weak transient is observed at 375 nm in degassed benzene, which is not quenched by oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

AT2433-A1, AT2433-A2, AT2433-B1 and AT2433-B2 novel antitumor compounds produced by Actinomadura melliaura. II. Structure determination

The chemical structures of AT2433-A1 (2), AT2433-A2 (3), AT2433-B1 (4) and AT2433-B2 (5) were elucidated by degradation and spectroscopic studies. Compounds 2-5 are disaccharides closely related to rebeccamycin. The aglycone in 2 and 3 was determined to be 6-N-methyl-11-chloro-5H-indolo[2,3-a]pyrolo[3,4-c]carbazole and in 4 and 5 it was determined to be 6-N-methyl-5H-indolo[2,3-a]pyrolo[3,4-c]carbazole. Compounds 2 and 4 are 4-N"-methyl analogs of 3 and 5.

Integrated biological-physicochemical system for the identification of antitumor compounds in fermentation broths

A rapid, integrated biological-physicochemical system for the identification of six major classes of antitumor compounds in fermentation broths is described. The system relies upon preliminary fractionation of the fermentation broth by liquid-solid extraction, gradient high-performance liquid chromatography with diode-array spectrophotometric detection of the compounds and automated bioassay. The previously stored UV-VIS spectra of the biologically active peaks are used for identification. Confirmation of compound identity is by thermospray liquid chromatography-mass spectrometry. The method has been applied to representatives of the bleomycin, streptonigrin, echinomycin, chromomycin, actinomycin and anthracycline groups.