Synthesis and antifungal activities of 5/6-arylamino-4,7-dioxobenzothiazoles

Highly Active Small Aminated Quinolinequinones against Drug-Resistant Staphylococcus aureus and Candida albicans

Two subseries of aminated quinolinequinones (AQQs, AQQ1-16) containing electron-withdrawing group (EWG) or electron-donating group (EDG) in aryl amine moiety were successfully synthesized. Antimicrobial activity assessment indicates that some of the AQQs (AQQ8-10 and AQQ12-14) with an EDG in aryl amine exhibited strong antibacterial activity against Gram-positive bacterial strains, including Staphylococcus aureus (ATCC^® 29213) and Enterococcus faecalis (ATCC^® 29212). In contrast, AQQ4 with an EWG in aryl amine displayed excellent antifungal activity against fungi Candida albicans (ATCC^® 10231) with a MIC value of 1.22 μg/mL. To explore the mode of action, the selected AQQs (AQQ4 and AQQ9) were further evaluated in vitro to determine their antimicrobial activity against each of 20 clinically obtained resistant strains of Gram-positive bacteria by performing antibiofilm activity assay and time-kill curve assay. In addition, in silico studies were carried out to determine the possible mechanism of action observed in vitro. The data obtained from these experiments suggests that these molecules could be used to target pathogens in different modes of growth, such as planktonic and biofilm.

Synthesis and antiproliferative evaluation of some 1,4-naphthoquinone derivatives against human cervical cancer cells

In the course of biological properties of quinone derivatives, the N(H)-, S- and S,S-substituted-1,4-naphthoquinones were synthesized by reactions of 2,3-dichloro-1,4-naphthoquinone with different amines (2-morpholinoaniline, tert-butyl 4-aminobenzoate, 4-tert-butylbenzylamine, N-(3-aminopropyl)-2-pipecoline, 2-amino-5,6-dimethylbenzothiazole, N,N'-diphenyl-p-phenylenediamine) and thiolat (sodium 2-methyl-2-propanethiolate). All new products were characterized by MS-ESI, UV-Vis, FT-IR, 1H NMR, 13C NMR. The antiproliferative activities of these compounds on human cervical cancer (HeLa) cells were evaluated by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. Although all derivatives inhibited cell growth, the most active compound was 2-(tert-butylthio)-3-chloronaphthalene-1,4-dione 5 (IC50=10.16 μM) against the HeLa cells.

Natural Products: An Alternative to Conventional Therapy for Dermatophytosis?

The increased incidence of fungal infections, associated with the widespread use of antifungal drugs, has resulted in the development of resistance, making it necessary to discover new therapeutic alternatives. Among fungal infections, dermatophytoses constitute a serious public health problem, affecting 20-25 % of the world population. Medicinal plants represent an endless source of bioactive molecules, and their volatile and non-volatile extracts are clearly recognized for being the historical basis of therapeutic health care. Because of this, the research on natural products with antifungal activity against dermatophytes has considerably increased in recent years. However, despite the recognized anti-dermatophytic potential of natural products, often advantageous face to commercial drugs, there is still a long way to go until their use in therapeutics. This review attempts to summarize the current status of anti-dermatophytic natural products, focusing on their mechanism of action, the developed pharmaceutical formulations and their effectiveness in human and animal models of infection.

QuBiLs-MAS method in early drug discovery and rational drug identification of antifungal agents

The QuBiLs-MAS approach is used for the in silico modelling of the antifungal activity of organic molecules. To this effect, non-stochastic (NS) and simple-stochastic (SS) atom-based quadratic indices are used to codify chemical information for a comprehensive dataset of 2478 compounds having a great structural variability, with 1087 of them being antifungal agents, covering the broadest antifungal mechanisms of action known so far. The NS and SS index-based antifungal activity classification models obtained using linear discriminant analysis (LDA) yield correct classification percentages of 90.73% and 92.47%, respectively, for the training set. Additionally, these models are able to correctly classify 92.16% and 87.56% of 706 compounds in an external test set. A comparison of the statistical parameters of the QuBiLs-MAS LDA-based models with those for models reported in the literature reveals comparable to superior performance, although the latter were built over much smaller and less diverse datasets, representing fewer mechanisms of action. It may therefore be inferred that the QuBiLs-MAS method constitutes a valuable tool useful in the design and/or selection of new and broad spectrum agents against life-threatening fungal infections.

NAD(P)H quinone oxidoreductase 1 (NQO1)-bioactivated pronqodine A regulates prostaglandin release from human synovial sarcoma cells

Natural products have contributed to the elucidation of biological mechanisms as well as drug discovery research. Even now, the expectation for natural products is undiminished. We screened prostaglandin release inhibitors that had no effect on in vitro cyclooxygenase activity derived from natural product sources and discovered pronqodine A. Using spectral analysis and total synthesis, the structure of pronqodine A was shown to be a benzo[d]isothiazole-4,7-dione analogue. Evaluation of the biological activity of pronqodine A revealed that the NAD(P)H dehydrogenase quinone 1 (NQO1) converted pronqodine A into a two-electron reductive form. The reductive form underwent autoxidation and reversed to its native form immediately with the generation of reactive oxygen species. Further investigations proved that pronqodine A inhibited cyclooxygenase enzyme activity only in the presence of NQO1. Pronqodine A acts as a potential bioreductive compound, inhibiting prostaglandin release in selectively activated NQO1-expressing cells.

'On water' assisted synthesis and biological evaluation of nitrogen and sulfur containing hetero-1,4-naphthoquinones as potent antifungal and antibacterial agents

2-chloro-3-(4-methylpiperazin-1-yl)naphthalene-1,4-dione (3a), 2-chloro-3-(pyrrolidin-1-yl)naphthalene-1,4-dione (3b), 2-chloro-3-(piperidin-1-yl)naphthalene-1,4-dione (3c), 2-chloro-3-morpholinonaphthalene-1,4-dione (3d), 2-chloro-3-(2-phenylhydrazinyl)naphthalene-1,4-dione (3e), 2-(allylamino)-3-chloronaphthalene-1,4-dione (3f), 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)acetic acid (3g), 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)succinic acid (3h), methyl 2-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-ylthio)acetate (3i), 2-chloro-3-(2-mercaptoethylthio)naphthalene-1,4-dione (3j), 3-hydroxy-4-methyl-4H-naphtho[2,3-b][1,4]thiazine-5,10-dione (3k) and compounds 3l-q have been synthesized by a green methodology approach using water as solvent and evaluated for their antifungal and antibacterial activity. The antifungal profile of 3a-n indicated that compounds 3a-d, 3j, 3e and 3k have potent antifungal activity. Amongst the most promising antifungal compounds, 3a-g, 3j, 3k showed better antifungal activity than clinically prevalent antifungal drugs Fluconazole and Amphotericin-B against Trichophyton mentagraphytes and compounds 3j and 3k have been found to be lead antifungal bicyclic and tricyclic 1,4-naphthoquinones. Compound 3k also exhibited pronounced antibacterial activity.

Synthesis and antifungal activity of benzo[d]oxazole-4,7-diones

Benzo[d]oxazole-4,7-diones were synthesized and tested for in vitro antifungal activity against fungi. Among them tested, many compounds showed good antifungal activity. The results suggest that benzo[d]oxazole-4,7-diones would be potent antifungal agents.

Discovery of novel indazole-linked triazoles as antifungal agents

The in vitro and in vivo activities of a series of (2R,3R)-2-(2,4-difluorophenyl)-3-(substituted indazol-1-yl)-1-(1H-1,2,4-triazol-1-yl)butan-2-ol as potential antifungal agents are described. In particular, the analog 12j having 5-bromo substitution on the indazole ring exhibited significant antifungal activity against a variety of fungal cultures (Candida spp. and Aspergillus spp.). In addition, oral administration of 12j showed its excellent efficacy against Candida albicans in a murine infection model and the significantly improved survival rates of the infected mice.

Synthesis and antifungal activity of 1H-indole-4,7-diones

1H-Indole-4,7-diones were synthesized and tested for in vitro antifungal activity against fungi. The synthesized 1H-indole-4,7-diones generally showed good antifungal activity against Candida krusei, Cryptococcus neoformans, and Aspergillus niger. The results suggest that 1H-indole-4,7-diones would be potent antifungal agents.

Synthesis and cytotoxicity evaluation of substituted pyridazino[4,5-b]phenazine-5,12-diones and tri/tetra-azabenzofluorene-5,6-diones

The substituted pyridazino[4,5-b]phenazine-5,12-diones and tri/tetra-azabenzo[a]fluorene-5,6-diones were synthesized from 6,7-dichlorophthalazine-5,8-dione and 6,7-dichloroquinoline-5,8-dione, respectively. The cytotoxic activities of the prepared compounds were evaluated by an SRB (Sulforhodamine B) assay against the following human cancer cell lines: A549 (lung), SK-OV-3 (ovarian), SK-MEL-2 (melanoma), XF 498 (CNS), and HCT 15 (colon). Almost all synthesized pyridazino[4,5-b]phenazine-5,12-diones (7a-j) presented higher cytotoxicity than that of doxorubicin (IC(50)=0.097-0.225 microM) against the cancer cell lines. In particular, the cytotoxicity of compounds 7f (R(1)=Et) and 7h (R(1), R(2)=Me) against all human cancer cell lines examined was about 10 times higher than that of doxorubicin. However, the cytotoxicities of several synthesized azabenzo[a]fluorene-5,6-diones (12a, 12c, 12d, 12e, and 12g) against the cancer cell lines in vitro were comparable to those of doxorubicin.

Design, synthesis, and biological evaluation of 1,2,3-trisubstituted-1,4-dihydrobenzo[g]quinoxaline-5,10-diones and related compounds as antifungal and antibacterial agents

A series of (S)-N-(3-chloro-1,4-naphthoquinon-2-yl)-alpha-amino acid ethyl esters 3 and 1,2,3-trisubstituted-1,4-dihydrobenzo[g]quinoxaline-5,10-diones 6-23 were synthesized and evaluated for antifungal and antibacterial activities. The structure-activity relationship of these compounds was studied and the results show that the compounds 3a and 3b exhibited in vitro antifungal activity against Candida albicans, Cryptococcus neoformans, and Sporothrix schenckii whereas compounds 12 and 22 showed in vitro antibacterial activity against Klebsiella pneumoniae and Escherichia coli.

Synthesis and evaluation of antifungal activity of naphthoquinone derivatives

3-Arylamino-2-phenylsulfinylnaphthoquinones, 2,3-diarylthio-naphthoquinones and 2-phenylsulfinyl-3-arylthio-1,4-dihydronaphtalenes are synthesized and tested against five fungi. The activities of these products were better than amphotericine B against all the strains except for Candida albicans.

The development of 3D-QSAR study and recursive partitioning of heterocyclic quinone derivatives with antifungal activity

It was reported that some 1,4-quinone derivatives such as 6-(N-arylamino)-7-chloro/6,7-bis[S-(aryl)thio]-5,8-quinolinedione and 6-arylthio-/5,6-arylamino-4,7-dioxobenzothiazoles have antifungal effects. To understand the structural basis for antifungal activity and guide in the design of more potent agents, we performed three-dimensional quantitative structure-activity relationship studies for a series of compounds using comparative molecular field analysis (CoMFA). The MIC values of 1,4-quinone derivatives on Aspergillus niger exhibited a strong correlation with steric and electrostatic factors of the 3D structure of molecules. The statistical results of the training set, cross-validated q(2) (0.683) and conventional r(2) (0.877) values, gave reliability to the prediction of inhibitory activity of a series of compounds. We also performed recursive partitioning (RP) analysis, used for the classification of molecules with activity using CART methods. Physicochemical, structural, and topological connectivity indices and E-state key descriptors were used for obtaining the decision tree models. The decision tree could classify the inhibitory activity of 1,4-quinone derivatives and its essential descriptors were S_aaN, Hbond donor, and Kappa-3.

Synthesis and cytotoxicity of new aminoterpenylquinones

Several 6(7)-alkyl-1,4-naphthoquinones (NQ) have been prepared by cycloaddition reactions between the monoterpene alpha-myrcene and p-benzoquinones and halogen and nitrogen-containing functional groups have been introduced at the C-2 position of the naphthoquinone ring via nucleophilic addition or substitution reactions. These substituents at positions 2/3 of the NQ clearly influence the cytotoxic potency of this type of compound. Of particular interest is substitution by arylamino, specifically p-oxyarylamino, groups, which considerably enhance their bioactivity and selectivity.

Synthesis and antifungal activity of 5-arylamino-4,7-dioxobenzo[b]thiophenes

5-Arylamino-4,7-dioxobenzo[b]thiophenes 3-6 were synthesized and tested for in vitro antifungal activity against Candida and Aspergillus species. 5-Arylamino-6-chloro-2-(methoxycarbonyl)-4,7-dioxobenzo[b]thiophenes 5 showed, in general, more potent antifungal activity against Candida species than the other 4,7-dioxobenzo[b]thiophenes 3, 4 and 6. The results suggest that 5-arylamino-4,7-dioxobenzo[b]thiophenes would be potent antifungal agents.

Synthesis and antifungal activity of noble 5-arylamino- and 6-arylthio-4,7-dioxobenzoselenazoles

5-Arylamino- and 6-arylthio-4,7-dioxobenzoselenazoles 4 and 5 were synthesized and tested for in vitro antifungal activity against Candida and Aspergillus species. 5-Arylamino-4,7-dioxobenzoselenazoles 4 showed, in general, more potent antifungal activity than 6-arylthio-4,7-dioxobenzoselenazoles 5. The results suggest that 5-arylamino-4,7-dioxobenzoselenazoles 4 would be potent antifungal agents.

Synthesis and antifungal activity of 6-arylthio-/6-arylamino-4,7-dioxobenzothiazoles

6-Arylthio-/6-arylamino-4,7-dioxobenzothiazoles were synthesized and tested for in vitro antifungal activity against Candida species and Aspergillus niger. 6-Arylamino-4,7-dioxobenzothiazoles 5 and 6 showed, in general, more potent antifungal activity than 6-arylthio-4,7-dioxobenzothiazoles 3 and 4. The 6-arylamino-substituted compounds 5 and 6 exhibited the greatest activity. In contrast, 6-arylthio-, 2-/5-methyl- or 5-methoxy-moieties of compounds 3-4 did not improve their antifungal activity significantly. The results of this study suggest that 6-arylamino-4,7-dioxobenzothiazoles would be potent antifungal agents.

Synthesis and antifungal activity of 2,5-disubstituted-6-arylamino-4,7-benzimidazolediones

2,5-Disubstituted-6-arylamino-4,7-benzimidazolediones were synthesized and tested for in vitro antifungal activity against pathogenic fungi. Among them, 6-arylamino-5-chloro-2-(2-pyridyl)-4,7-benzimidazolediones exhibited potent antifungal activity against Candida species and Aspergillus niger.

Synthesis and antifungal activity of 6,7-bis-[S-(aryl)thio]-5,8-quinolinediones

6,7-Bis-[S-(aryl)thio]-5,8-quinolinediones 4 and 5 were synthesized by the substitution of 6,7-dichloro-5,8-quinolinediones with appropriate arylthiols. Their antifungal activity were tested in vitro for their growth inhibitory activities against pathogenic fungi in comparison with flucytosine. The antifungal activities were significantly improved by S-(aryl)thio moieties of the compounds 4 and 5. The all tested compounds 4 and 5 showed generally good activities against C. albicans and A. niger ranging from 0.8 to 25 microg/ml. Among them, compounds 4d-4h and 5a-5c exhibited also good activities against C. krusei and C. tropicalis. The activities of compounds 4j and 4l were comparable to those of flucytosine against all tested fungi.