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Though pyrrolnitrin is surpassed by clotrimazole in in vitro antitrichophyton activity against Trichophyton sp., the therapeutic effect of pyrrolnitrin against experimental trichophytosis in guinea pigs was more potent than that of clotrimazole. The detection of antifungal activity from topically treated guinea pigs suggests that pyrrolnitrin obtains higher concentrations than clotrimazole in dermal tissue.
Bacterial strain B37w (= NRRL B-14858), an isolate noteworthy because it inhibits the growth of the bioherbicide fungus Colletotrichum truncatum, was selected for further studies of bacterial antifungal properties. This isolate was identified as a Pseudomonas cepacia strain by performing carbohydrate utilization and fatty acid profile analyses, as well as other biochemical and physiological tests. Petri plate assays revealed that strain B37w exhibited antifungal activity against the potato dry rot fungus Fusarium sambucinum. Using bioautography, we correlated antifungal activity with production of a specific compound. Isolation from strain B37w and identification of the antifungal antibiotic pyrrolnitrin are described. A whole-potato assay revealed B37w's ability to colonize potato wounds. Wounded potatoes were inoculated with B37w, and pyrrolnitrin was detected in these potatoes by thin-layer chromatography-bioautography at a concentration on the order of nanograms per wound. We performed an assay in which we examined efficacy against F. sambucinum-incited potato dry rot and found that B37w inhibited disease development. This is the first report of P. cepacia or pyrrolnitrin activity against the economically important potato pathogen F. sambucinum.
During development of nitroheterocycles with potential antimycobacterial activities we have tested against Mycobacterium tuberculosis a number of pyrroles strictly related to pyrrolnitrin, an antifungal antibiotic isolated from Streptomyces pyrrocinia. Some of the tested arylpyrrole derivatives and pyrrolnitrin have shown appreciable inhibiting activity against M. tuberculosis and M. avium. SAR studies well correlate antimycobacterial potency with the presence of halogens in the phenyl ring and a nitro group at position 3 of pyrrole.
Studies on the metabolism of tryptophan in Pseudomonas aureofaciens ATCC 15926 revealed different metabolic routes for the L- and D-isomer besides the biosynthetic pathway for pyrrolnitrin synthesis. L-Tryptophan catabolism follows the aromatic route via anthranilic acid. Tryptophan 2,3-dioxygenase were induced by L-tryptophan. Kynureninase and anthranilate 1,2-dioxygenase were induced by L-tryptophan, L-kynurenine and anthranilic acid. Anthranilate 1,2-dioxygenase was absent from a mutant strain of P. aureofaciens ATCC 19526 which produced about 30-fold increased amounts of pyrrolnitrin. The Km values of tryptophan 2,3-dioxygenase and kynureninase did not differ substantially between the two strains. Kynurenine 3-monooxygenase, 3-hydroxyanthranilate 3,4-dioxygenase, tryptophanase and indolyl-3-alkane alpha-hydroxylase activities were not detected. D- and L-tryptophan were converted to indole-3-acetic acid. This additional catabolic pathway was well as tryptophan racemase activity was constitutive and present in both strains.
Pyrrolnitrin is the active ingredient of drugs for the treatment of superficial fungal infections and was used as a lead structure for the development of fludioxonil. It is an effective agent for plant diseases caused by the fungal pathogen Rhizoctonia solani. Pyrrolnitrin is made in four steps, the second of which, catalyzed by PrnB, is a novel chemical rearrangement of 7-chlorotryptophan. PrnB was overproduced in Pseudomonas fluorescens (BL915) and well diffracting crystals were obtained of a triple cysteine-to-serine mutant by sitting-drop vapour diffusion. Crystals grown in the presence of L-7-chlorotryptophan, D-tryptophan and L-tryptophan are reported. Data sets for each are reported with high-resolution limits of 2.0, 1.75 and 1.75 A, respectively. Two crystals (PrnB in the presence of D-tryptophan and L-7-chlorotryptophan) belong to space group C2 with similar unit-cell parameters (a = 68.6, b = 79.5, c = 92.7 A, alpha = gamma = 90.0, beta = 103.8 degrees). Crystals grown in the presence of L-tryptophan belong to space group C222(1) and have unit-cell parameters a = 67.7, b = 80.1, c = 129.5 A. All crystals contain a monomer in the asymmetric unit.
Two cases are described of acute contact dermatitis from an antifungal cream, containing pyrrolnitrin, employed for the treatment of tinea cruris. Positive reactions to pyrrolnitrin and to a chemically related substance, 1-chlor-2,4dinitrobenzene, were put into evidence.
The author has analyzed the pyrrolnitrine activity on eighty strains of Candida albicans isolated from hospital patients. On these various strains the M.I.C., the enzymatic activity, the pathogenicity on rabbits, the ability to form clamydospores were determined. Also cytochemical tests, tests on chorioallantoic membrane, absorption tests and morphological analysis at the scanning microscope were performed on these strains. The various findings obtained have shown a strong activity of pyrrolnitrine on the different biological activities of Candida albicans strains used in the present work.
A gas-liquid chromatographic technique was applied to the separation of pyrrolnitrin and its derivatives. The simultaneous use of a flame detector and an electron capture detector made possible the distinction between the nitro derivatives of pyrrolnitrin and the other metabolites. The metabolites could be readily quantitated with the electron capture detector, offering a much more sensitive assay than the flame detector.
Pyrrolnitrin, at low concentrations, uncouples oxidative phosphorylation in Neurospora mitochondria. At higher concentrations, pyrrolnitrin inhibits electron transport both in the flavine region and through cytochrome oxidase.
The UV irradiation of pyrrolnitrin (1a), which is an antibiotic clinically useful against dermatophytosis and possesses a unique 2-(pyrrol-3-yl)nitrobenzene moiety in the molecule, in an anhydrous aprotic solvent resulted in the exclusive formation of transient 7,4'-dichlorospiro[1,3-dihydrobenzo(c)isoxazole-3,3'-pyrrolin-2'-one] (2a) via the intramolecular oxidation of the juxtaposed pyrrole ring by the triplet-excited nitro group. The irradiation in an aqueous aprotic solvent, however, allowed the concurrent occurrence of intramolecular cyclization by the singlet-excited nitro group in 1a and the hydroxylation at the 2-position of the pyrrole ring by water to afford 3,7-dichloro-8-hydroxy-8,8a-dihydropyrrolo[2,3-b]indol-2-one (3a), accompanied by the formation of 2a. Elongation of the irradiation time in these photoreactions caused a rapid consumption of the products, 2a and 3a, to give undetermined polar polymeric products. The present results indicate that the photodegradation of 1a is significantly influenced by the presence of water in the reaction media and by the nature of its excited state. Thus, the loss of the antifungal activities by the photosensitive antibiotic 1a was chemically proved.
A mutant having a 30-fold increased ability to synthesize pyrrolnitrin was isolated from Pseudomonas aureofaciens ATCC 15926 after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. The mutant strain also differed from the parent strain in pigmentation and in its inability to catabolize anthranilic acid and the benzene moiety of tryptophan and kynurenine.
The therapeutic efficacy of a topical antifungal solution containing a mixture of 0.2% pyrrolnitrin and 0.4% clotrimazole (Pyroace W) was tested in a guinea pig model of tinea pedis using a 1% newly solution formulated preparation of miconazole (Dermalin-L) as a reference drug. Infected animals were treated once or twice daily with the testing drug and once daily with the reference drug for 4 weeks. Therapeutic efficacy was evaluated on the basis of the extent of the yield of fungal cultures from the infected skin tissues (infection intensity) and the relative number of culture-negative animals at the end of the treatment period. In an animal group treated once daily with the testing drug, the infection intensity was significantly lower than that for untreated or vehicle-treated control group (p < 0.0001) although there was no culture-negative animal. A similar extent of therapeutic efficacy was obtained with a once daily treatment with the reference drug, yielding one of ten culture-negative animal. A better efficacy was seen in animals treated twice daily with the testing drug; the infection intensity was further decreased to a significant level and eight of ten animals became culture-negative. These results demonstrated that twice daily treatment with the testing drug was highly effective in guinea pig model of tinea pedis, 80% of infected animals being mycologically cured. It confirms the clinical usefulness of this regimen in the treatment of patients with tinea pedis or other types of dermatophytosis.
The synthesis and microbiological activities of new 1,4- and 1,5-diarylpyrroles is reported. Antimicrobial data in comparison with fungal antibiotic pyrrolnitrin confirm an interesting antimicotic activity of 1,4-diarylpyrroles. On the contrary 1,5-diarylpyrroles show antibacterial activity and an unexpected antimicotic activity. The position of the 4-nitrophenyl group at C4 or C5 of the pyrrole ring influences antibacterial activity.
The reaction between N-(4-nitrophenacyl)-3,5-dimethylaniline and ethyl acetoacetate in boiling ethanol afforded 3-carbethoxy-5-(1-carbethoxyacetonyl)-4,5-dihydro-1-(3,5-dimethylphenyl)-4-hydroxy-2-methyl-4-(4-nitrophenyl)pyrrole and in low yield 3-carbethoxy-1-(3,5-dimethylphenyl)-2-methyl-4-(4-nitrophenyl)pyrrole. Chemical transformation of the former compound into 5-acetonyl-1-(3,5-dimethylphenyl)-2-methyl-4-(4-nitrophenyl)pyrrole is described. The structure of 3-carbethoxy-5-(1-carbethoxyacetonyl)-4,5-dihydro-1-(3,5-dimethylphenyl)-4-hydroxy-2-methyl-4-(4-nitrophenyl)pyrrole has been established by the aid of N.M.R. spectral data. The above reaction, when carried out in boiling ethanol in the presence of a catalytic amount of 3,5-dimethylaniline hydrobromide, led to the formation of 3-carbethoxy-1-(3,5-dimethylphenyl)-2-methyl-4-(4-nitrophenyl)pyrrole and 4,6-dimethyl-2-(4-nitrophenyl)indole, the former formed in a very good yield. Some pyrrolnitrin analogues have been prepared starting from 3-carbethoxy-1-(3,5-dimethylphenyl)-2-methyl-4-(4-nitrophenyl)pyrrole.
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