Number Of Indole Derivatives Research Articles

Synthesis of 1h-1,5,7-triaza- cyclopenta[c,d]phenalenes, a new heterocyclic system

In previous work [1-4], we have developed a number of methods for the peri annelation of six-membered rings to give perimidines. In light of the high biological activity of a significant number of indole derivatives, we propose a method for the peri annelation of the pyrrole ring to perimidines. The reaction of ketones 1a-c (1 mmol) and NaN3 (0.07 g, 1.08 mmol) in PPA* (2-3 g) at 70-80°C for 1 h and then at 150-160°C for 4 h monitored by thin-layer chromatography leads to 1H-1,5,7-triazacyclopenta[c,d]phenalenes 3a-c in 36-48% yield. The reaction involves intermediante formation of amides 2a-c, which cam be isolated, for example 2a. The H NMR spectra were taken on a Bruker WP-200 spectrometer at 200 MHz in DMSO-d6 with TMS as the internal standard. The reaction course and purity of the products obtained were monitored on Silufol UV-254 plates with 1:1 ethyl acetate–ethanol as the eluent.

Specificity of dopachrome tautomerase and inhibition by carboxylated indoles. Considerations on the enzyme active site

Dopachrome tautomerase (EC 5.3.2.3) catalyses the tautomerization of dopachrome to 5,6-dihydroxyindole-2-carboxylic acid (DHICA) within the melanin-formation pathway. We have analysed a series of substrate analogues and related compounds as possible substrates and inhibitors of tautomerization. The enzyme appears to be highly specific since D-dopachrome, alpha-methyldopachrome, dopaminochrome, adrenochrome methyl ether and deoxyadrenochrome are not substrates. Conversely, dopachrome tautomerase catalyses the tautomerization of dopachrome methyl ester, suggesting that a carboxy group, either free or as a methyl ester, is essential for enzyme recognition. No inhibition of dopachrome tautomerization was observed in the presence of either semiquinonic compounds, such as tropolone and L-mimosine, or pyrrole-2-carboxylic acid and unsubstituted indole. However, a number of indole derivatives, including DHICA, the product of dopachrome tautomerization, and the analogues 5-hydroxyindole-2-carboxylic and indole-2-carboxylic acid were able to inhibit the enzyme. Furthermore, indoles with a side chain at position 3 of the ring and containing a carboxylic group at the gamma-position of this chain, such as L-tryptophan or indole-3-propionic acid, are stronger inhibitors of the enzyme. Indole-3-carboxylic acid, indole-3-acetic acid and indole-3-butyric acid are very weak inhibitors, showing that the carboxylic group needs to be located at an optimal distance from the indole ring to mimic the carboxylic group at position 2 on the authentic substrate.

Isolation and characterization of wheat peroxidase isoenzyme B1

Abstract Two pure peroxidase isoenzymes B1 and D4 were isolated from the upper parts of 10-day-old wheat seedlings by means of gel and ion-exchange chromatography. Their MWs were 85000 and 24000 respectively. B1 was unstable and under various conditions it was converted to another isoenzyme, electrophoretically identical with D4. B1 contains about 40% of neutral sugars: 17.2% arabinose, 15.3% galactose, 5% glucose and traces of mannose. D4 is free of neutral sugars. None of the isoenzymes contained amino sugars. B1 oxidizes ferulic and p -coumaric acids. This oxidation has two pH optima of 4.4 and 5.4–5.6 and is inhibited by high concentrations of substrates, cyanide and azide. B1 oxidizes IAA in the presence of phenolic cofactor and Mn 2+ ions. IAA oxidation has two pH optima of 4.5 and 5.6 and is inhibited by high substrate concentration, cyanide and azide, and by a number of indole derivatives. The main products of IAA oxidation are 3-methyleneoxindole and indole-3-methanol. o - and p - diphenols induce a lag period prior to IAA oxidation. Ferulic acid is oxidized during this lag period, probably to a dimer. B1 is able to produce H 2 O 2 from oxygen. Mn 2+ ions, a phenolic cofactor and an electron donor (IAA or NADH) are needed. B1 oxidizes α-keto-γ- methylmercaptobutyric acid to ethylene. D4 has a low peroxidatic activity and is inactive as an IAA oxidase. Thus B1 is probably an active cell wall-bound peroxidase isoenzyme, whereas D4 is its decomposition product.

Reactivity of indoles in electrophilic substitution

The relative reactivities of a number of indole derivatives in the Vilsmeier–Haack formylation have been determined by a competitive procedure; the data are discussed in terms of possible substitution mechanisms.

ANALOGUES OF PSILOCIN AND LYSERGIC ACID DIETHYLAMIDE I. CHLORO, NITRO, AND AMINO DERIVATIVES OF 3-SUBSTITUTED INDOLES

A number of indole derivatives structurally related to either psilocin or lysergic acid diethylamide (LSD) were synthesized. The following structural analogues of psilocin are reported: 4-chloro-3-dimethylaminoethylindole, 4-nitro-3-dimethylaminoethylindole, 4-nitro-3-aminoethylindole, 4-amino-3-dimethylaminoethylindole, and 4-amino-3-aminoethylindole. Compounds structurally related to LSD that were synthesized are: 3-[β-carboxyethylaminoethyl]-4-nitroindole and 4-nitro-3-[N-methyl-N-(N′,N′-diethylcarboxamidoethy-aminoethyl]indole. Several 3,5- and 3,6-disubstituted indoles are also reported.