Synthesis, Structural Characterization, and In Vitro and In Silico Antifungal Evaluation of Azo-Azomethine Pyrazoles (PhN2(PhOH)CHN(C3N2(CH3)3)PhR, R = H or NO2).

The azo-azomethine imines, R1-N=N-R2-CH=N-R3, are a class of active pharmacological ligands that have been prominent antifungal, antibacterial, and antitumor agents. In this study, four new azo-azomethines, R1 = Ph, R2 = phenol, and R3 = pyrazol-Ph-R' (R = H or NO2), have been synthesized, structurally characterized using X-ray, IR, NMR and UV-Vis techniques, and their antifungal activity evaluated against certified strains of Candida albicans and Cryptococcus neoformans. The antifungal tests revealed a high to moderate inhibitory activity towards both strains, which is regulated as a function of both the presence and the location of the nitro group in the aromatic ring of the series. These biological assays were further complemented with molecular docking studies against three different molecular targets from each fungus strain. Molecular dynamics simulations and binding free energy calculations were performed on the two best molecular docking results for each fungus strain. Better affinity for active sites for nitro compounds at the "meta" and "para" positions was found, making them promising building blocks for the development of new Schiff bases with high antifungal activity.

The antifungal activity and mechanisms of action of quantified extracts from berries, leaves and roots of Phytolacca tetramera.

BACKGROUND: Phytolacca tetramera is an endemic plant from Argentina that is currently at serious risk because its environment is subjected to a high anthropic impact. A previous study has shown that berry extracts obtained from this plant display antifungal activity against multiple human-pathogenic fungi when tested with a non-standardized method. Further evidences of the antifungal properties of other parts of the plant and studies of mechanism of antifungal action of the antifungal chemically characterized extracts are required. PURPOSE: This study aimed to gain further evidence of the antifungal activity of P. tetramera berry, leaf and root extracts in order to find the most active extract to be developed as an Herbal Medicinal Antifungal Product. The medicinal usefulness of P. tetramera extracts as antifungal agents will serve as an important support to create concience and carry out actions tending to the preservation of this threatened species and its environment. MATERIALS AND METHODS: Chemical analysis of all P. tetramera extracts, including quantitation of selected markers, was performed through UHPLC-ESI-MS/MS and UPLC-ESI-MS techniques according to the European Medicines Agency (EMA). The antifungal activity of the quantified extracts was tested with the standardized CLSI microbroth dilution method against Candida spp. Antifungal mechanisms of the most active extract were studied by examination of morphological changes by phase-contrast and fluorescence microscopies and both, cellular and enzymatic assays targeting either the fungal membrane or the cell wall. RESULTS: The antifungal activity of twelve P. tetramera extracts was tested against Candida albicans and Candida glabrata. The dichloromethane extract from berries (PtDEb) showed the best activity. Phytolaccagenin (PhytG) and phytolaccoside B (PhytB) were selected as the main active markers for the antifungal P. tetramera extracts. The quantitation of these active markers in all extracts showed that PtDEb possessed the highest amount of PhytG and PhytB. Finally, studies on the mechanism of antifungal action showed that the most active PtDEb extract produces morphological changes compatible with a damage of the cell wall and/or the plasma membrane. Cellular and enzymatic assays showed that PtDEb would not damage the fungal cell wall by itself, but would alter the plasma membrane. In agreement, PtDEb was found to bind to ergosterol, the main sterol of the fungal plasma membrane. CONCLUSION: Studies of the anti-Candida activity of P. tetramera extracts led to the selection of PtDEb as the most suitable extract, confirming the antifungal properties of the threatened species P. tetramera. The new data give a valuable reason for the definitive protection of this sp. and its natural environment thus allowing further studies for the future development of an Herbal Medicinal Antifungal Product.

Approaches to the mechanism of antifungal activity of Zuccagnia punctata-Larrea nitida bi-herbal combination.

BACKGROUND: In our previous study the synergism of four combinations of Zuccagnia punctata (ZpE) and Larrea nitida (LnE) exudates with the reliable statistical-based MixLow method was assessed, and the markers of the most anti-C. albicans synergistic ZpE-LnE bi-herbal combination were quantified according to European Medicines Agency (EMA). PURPOSE: To study the mechanisms of action as well as the cytotoxic properties of the ZpE-LnE most synergistic combination found in the previous work. MATERIALS AND METHODS: Minimum Fungicidal Concentration (MFC) and rate of killing of ZpE-LnE were assessed with the microbroth dilution and the time-kill assays respectively. Morphological alterations were observed with both confocal and fluorescence microscopy on the yeast Schizosaccharomyces pombe. The ergosterol exogenous assay, the quantification of ergosterol, the sorbitol as well as glucan synthase (GS) and chitin synthase (ChS) assays were used to detect the effects on the fungal membrane and cell wall respectively. The capacity of ZpE-LnE of inhibiting Candida virulence factors was assessed with previously reported methods. The effect of ZpE-LnE and of ZpE or LnE alone on cell viability was determined on human hepatoma cells line Huh7. RESULTS: ZpE-Ln E was fungicidal killing C. albicans in a shorter time than amphotericin B and produced malformations in S. pombe cells. ZpE-LnE showed to bind to ergosterol but not to inhibit any step of the ergosterol biosynthesis. ZpE-LnE showed a low or moderate capacity of inhibiting GS and ChS. Regarding inhibition of virulence factors, ZpE-LnE significantly decreased the capacity of adhesion to eukaryotic buccal epithelial cells (BECs), did not inhibit the germ tube formation and inhibited the secretion of phospholipases and proteinases but not of haemolysins. ZpE-LnE demonstrated very low toxicity on Huh7 cells, much lower than that each extract alone. CONCLUSION: The fungicidal properties of ZpE-LnE against C. albicans, its dual mechanism of action targeting the fungal membrane's ergosterol as well as the cell wall, its capacity of inhibiting several important virulence factors added to its low toxicity, make ZpE-LnE a good candidate for the development of a new antifungal bi-Herbal Medicinal Product.

Hybrid combinations containing natural products and antimicrobial drugs that interfere with bacterial and fungal biofilms.

BACKGROUND: Biofilms contribute to the pathogenesis of many chronic and difficult-to eradicate infections whose treatment is complicated due to the intrinsic resistance to conventional antibiotics. As a consequence, there is an urgent need for strategies that can be used for the prevention and treatment of biofilm-associated infections. The combination therapy comprising an antimicrobial drug with a low molecular weight (MW) natural product and an antimicrobial drug (antifungal or antibacterial) appeared as a good alternative to eradicate biofilms. PURPOSE: The aims of this review were to perform a literature search on the different natural products that have showed the ability of potentiating the antibiofilm capacity of antimicrobial drugs, to analyze which are the antimicrobial drugs most used in combination, and to have a look on the microbial species most used to prepare biofilms. RESULTS: Seventeen papers, nine on combinations against antifungal biofilms and eight against antibacterial biofilms were collected. Within the text, the following topics have been developed: breaf history of the discovery of biofilms; stages in the development of a biofilm; the most used methodologies to assess antibiofilm-activity; the natural products with capacity of eradicating biofilms when acting alone; the combinations of low MW natural products with antibiotics or antifungal drugs as a strategy for eradicating microbial biofilms and a list of the low MW natural products that potentiate the inhibition capacity of antifungal and antibacterial drugs against biofilms. CONCLUSIONS AND PERSPECTIVES: Regarding combinations against antifungal biofilms, eight over the nine collected works were carried out with in vitro studies while only one was performed with in vivo assays by using Caenorhabditis elegans nematode. All studies use biofilms of the Candida genus. A 67% of the potentiators were monoterpenes and sesquiterpenes and six over the nine works used FCZ as the antifungal drug. The activity of AmpB and Caspo was enhanced in one and two works respectively. Regarding combinations against bacterial biofilms, in vitro studies were performed in all works by using several different methods of higher variety than the used against fungal biofilms. Biofilms of both the gram (+) and gram (-) bacteria were prepared, although biofilm of Staphylococcus spp. were the most used in the collected works. Among the discovered potentiators of antibacterial drugs, 75% were terpenes, including mono, di- and triterpenes, and, among the atibacterial drugs, several structurally diverse types were used in the combinations: aminoglycosides, ß-lactams, glucopeptides and fluoroquinolones. The potentiating capacity of natural products, mainly terpenes, on the antibiofilm effect of antimicrobial drugs opens a wide range of possibilities for the combination antimicrobial therapy. More in vivo studies on combinations of natural products with antimicrobial drugs acting against biofilms are highly required to cope the difficult to treat biofilm-associated infections.

Plant phenolics and terpenoids as adjuvants of antibacterial and antifungal drugs.

BACKGROUND: The intensive use of antibacterial and antifungal drugs has dramatically increased the microbial resistance and has led to a higher number of difficult-to-eradicate infections. Combination therapy with two or more antimicrobial drugs has emerged some years ago to overcome the issue, but it has proven to be not completely effective. Natural secondary metabolites of MW ≤ 500 represent promising adjuvants for antimicrobials and have been the object of several researches that have increased in the last two decades. PURPOSE: The purpose of this Review is to do a literature search of the natural compounds that showed high enhancing capacity of antibacterials' and antifungals' effects against planktonic bacteria and fungi and to analyze which are the natural products most used in combination with a focus on polyphenols and terpenoids. RESULTS: One hundred of papers were collected for reviewing. Fifty six (56) of them deal with combinations of low MW natural products with antibacterial drugs against planktonic bacteria and forty four (44) on natural products with antifungal drugs against planktonic fungi. Of the antibacterial adjuvants, 41 (73%) were either polyphenols (27; 48%) or terpenes (14; 25%). The remaining 15 papers (27%), deal with different class of natural products. Since most natural potentiators belong to the terpene or phenolic structural types, a more detailed description of the works dealing with these type of compounds is provided here. Bacterial and fungal resistance mechanisms, the modes of action of the main classes of antibacterial and antifungal drugs and the methodologies most used to assess the type of interactions in the combinations were included in the Review too. CONCLUSIONS AND PERSPECTIVES: Several promising results on the potentiation effects of antifungals' and antibacterials' activities by low MW natural products mainly on polyphenols and terpenes were reported in the literature and, in spite of that most works included only in vitro assays, this knowledge opens a wide range of possibilities for the combination antimicrobial therapy. Further research including in vivo assays and clinical trials are required to determine the relevance of these antimicrobial enhancers in the clinical area and should be the focus of future studies in order to develop new antimicrobial combination agents that overpass the drawbacks of the existing antibiotics and antifungals in clinical use.

Synthesis and antifungal activity of bile acid-derived oxazoles.

Peracetylated bile acids (1a-g) were used as starting materials for the preparation of fourteen new derivatives bearing an oxazole moiety in their side chain (6a-g, 8a-g). The key step for the synthetic path was a Dakin-West reaction followed by a Robinson-Gabriel cyclodehydration. A simpler model oxazole (12) was also synthesized. The antifungal activity of the new compounds (6a-g) as well as their starting bile acids (1a-g) was tested against Candida albicans. Compounds 6e and 6g showed the highest percentages of inhibition (63.84% and 61.40% at 250 µg/mL respectively). Deacetylation of compounds 6a-g, led to compounds 8a-g which showed lower activities than the acetylated derivatives.

Antifungal drugs combinations: a patent review 2000-2015.

INTRODUCTION: Combination therapy has emerged as an approach to improve the efficacy of antifungal drugs. Its main objective is to achieve synergistic interaction with higher antifungal properties and lower toxic effects than each substance alone. AREAS COVERED: Twenty-four patents disclosed in the period of 2000-2015 were covered in this review. Twenty of them were devoted to pharmacodynamic potentiation, while four were dedicated to pharmacokinetic actions. EXPERT OPINION: The common characteristic of most patents published in this area is that the main partner is a commercial antifungal drug. In the most innovative combinations the second component was either a modifier of proton homeostasis, an antibody, an inhibitor of the adhesion of epithelial or endothelial cells or a keratinolytic agent that improves the skin penetration. The evaluation of synergism is always made with simple in vitro methods, which constitutes a weakness of the disclosed patents, due to the lack of in vivo studies, since the in vitro tests cannot predict the in vivo behavior. Also, it is surprising that none of the patents analyze the toxicity of the new combinations, taking into account that one of the main objectives of the combinations is to reduce the toxicity of the existing antifungal drugs.

Synthesis and in vitro Evaluation of Antifungal Properties of Some 4-Aryl-3-Methyl-1,2,3,4-Tetrahydroquinolines Derivatives / Síntesis y evaluación in vitro de las propiedades antifungicas de algunos derivados de 4-aril-3-metil-1,2,3,4-tetrahidroquinolinas / Síntese e avaliação in vitro das propriedades antifungicas de alguns derivados de 4-Aryl-3-Methyl-1,2,3,4-Tetrahydroquinolines

Two series of 4-aryl-3-methyl-1,2,3,4-tetrahydroquinoline derivatives were efficiently synthesized according to a two-step synthesis and evaluated as potential antifungal agents. The key step was the formation of the corresponding N-benzyltetrahydroquinolines 5 via a three-component cationic imino Diels-Alder cycloaddition. The second step was a catalytic debenzylation to obtain the N-unprotected tetrahydroquinolines 6. The products were isolated and purified by column chromatography. Substances were characterized using nuclear magnetic resonance (NMR) mass spectrometry (MS) and infrared spectroscopy (IR). All compounds were tested in vitro against standardized, clinically important fungi, including yeasts, hialohyphomycetes, and dermatophytes. These studies showed that between the tetrahydroquinoline series tested, compounds 6f and 6g showed antifungal activity, specifically against dermatophytes. The compound 6-methoxy-4-(4-hydroxi-3-methoxyphenyl)-3-methyl-1,2,3,4-tetrahydroquinoline 6g exhibited the best in vitro activity (MIC 32-65 μg/mL). The results indicated that the elimination of benzyl group from the N-benzyltetrahydroquinolines derivatives, as well as the introduction of a hydroxyl group in the 4-aryl substituent caused a significant improvement in the antifungal activity. These results were supplemented by the in silico prediction; most of the tetrahydroquinolines evaluated showed high bioavailability, high drugs score and low potential risk.

Dos series de 4-aril-3-metil-1,2,3,4-tetrahidroquinolinas fueron sintetizadas de acuerdo con una metodología sintética de dos pasos y evaluadas como potenciales agentes antifúngicos. El paso clave involucró la formación de las correspondientes N-bencil tetrahidroquinolinas 5 vía una cicloadición imino Diels-Alder catiónica. El segundo paso consistió en obtener las tetrahidroquinolinas N-desprotegidas 6 vía una desbencilación catalítica. Los productos fueron aislados y purificados usando cromatografía en columna (CC). Las sustancias fueron identificadas usando resonancia magnética nuclear (RMN), espectrometría de masas (EM) y espectroscopia infrarroja (IR). Los compuestos fueron evaluados in vitro frente a cepas estandarizadas de hongos clínicamente relevantes, incluyendo levaduras, hialohifomicetes y dermatofitos. Estos estudios mostraron que, de las tetrahidroquinolinas ensayadas, los compuestos 6f y 6g mostraron actividad antifúngica, específicamente frente a dermatofitos. El compuesto 6-metoxi-4-(4-hidroxi-3-metoxifenil)-3-metil-1,2,3,4-tetrahidroquinolina 6g exhibió la mejor actividad (MIC 32-65 μg/mL). Los resultados indican que remover el grupo bencilo e introducir un grupo hidroxilo en el sustituyente arilo de las N-bencil tetrahidroquinolinas produce un mejoramiento de la actividad antifúngica. Predicciones in silico complementaron los resultados: la mayoría de las tetrahidroquinolinas ensayadas mostraron alta biodisponibilidad, altos "drug scores" y bajo riesgo potencial.

Duas séries de 4-aril-3-metil-1,2,3,4-tetrahidroquinolina foram sintetizadas de acordo com um método de síntese em duas etapas e avaliadas como potenciais agentes antifúngicos. O passo chave envolveu a formação dos correspondentes N-bencil tetrahidroquinolinas 5 via uma cicloadição de imino Diels-Alder catiónica. O segundo passo foi obter as N-tetrahidroquinolinas 6 através de uma desbenzilação catalítica. Os produtos foram purificados utilizando cromatografia em coluna. As substancias foram identificadas por ressonancia magnética nuclear (RMN), espectrometria de massa (EM) e espectroscopia de infravermelho (IR). Todos o compostos foram testados in vitro contra as estirpes padrao e os fungos clinicamente importantes, incluindo as leveduras, hialohifomicetes e dermatófitos. Estes estudos mostraram que entre a série de tetrahidroquinolinas (THQ) os compostos 6f e 6g mostraram atividade antifúngica, particularmente contra dermatófitos. O composto 6-metoxi-4-(4-hidroxi-3-metoxifenil)-3-metil-1,2,3,4-tetrahidroquinila 6g mostrou melhor atividade (MIC 32-65 μg/mL). Os resultados indicam que a remoção do grupo benzilo e a introdujo de um grupo hidroxilo no substituinte arilo do N-benzil-tetrahidroquinolina, resultou num aumento significativo da atividade antifúngica. Os resultados foram suplementados por previsöes in silico, que mostraram alta biodisponibilidade e pouco risco potencial da maioria dos tetrahidroquinolinas avaliados.

Synergistic mutual potentiation of antifungal activity of Zuccagnia punctata Cav. and Larrea nitida Cav. extracts in clinical isolates of Candida albicans and Candida glabrata.

BACKGROUND: Zuccagnia punctata Cav. (Fabaceae) and Larrea nitida Cav. (Zygophyllaceae) are indistinctly or jointly used in traditional medicine for the treatment of fungal-related infections. Although their dichloromethane (DCM) extract have demonstrated moderate antifungal activities when tested on their own, antifungal properties of combinations of both plants have not been assessed previously. PURPOSE: The aim of this study was to establish with statistical rigor whether Z. punctata (ZpE) and L. nitida DCM extract (LnE) interact synergistically against the clinically important fungi Candida albicans and Candida glabrata and to characterize the most synergistic combinations. STUDY DESIGN: For synergism assessment, the statistical-based Boik's design was applied. Eight ZpE-LnE fixed-ratio mixtures were prepared from four different months of 1 year and tested against Candida strains. Lϕ (Loewe index) of each mixture at different fractions affected (ϕ) allowed for the finding of the most synergistic combinations, which were characterized by HPLC fingerprint and by the quantitation of the selected marker compounds. METHODS: Lϕ and confidence intervals were determined in vitro with the MixLow method, once the estimated parameters from the dose-response curves of independent extracts and mixtures, were obtained. Markers (four flavonoids for ZpE and three lignans for LnE) were quantified in each extract and their combinations, with a valid HPLC-UV method. The 3D-HPLC profiles of the most synergistic mixtures were obtained by HPLC-DAD. RESULTS: Three over four IC50ZpE/IC50LnE fixed-ratio mixtures displayed synergistic interactions at effect levels ϕ > 0.5 against C. albicans. The dosis of the most synergistic (Lϕ = 0.62) mixture was 65.96 µg/ml (ZpE = 28%; LnE = 72%) containing 8 and 36% of flavonoids and lignans respectively. On the other hand, one over four IC50ZpE/IC50LnE mixtures displays synergistic interactions at ϕ > 0.5 against C. glabrata. The dosis of the most synergistic (Lϕ = 0.67) mixture was 168.23 µg/ml (ZpE = 27%; LnE = 73%) with 9.7 and 31.6% of flavonoids and lignans respectively. CONCLUSIONS: Studies with the statistical-based MixLow method, allowed for the finding of the most ZpE-LnE synergistic mixtures, giving support to a proper joint use of both antifungal herbs in traditional medicine.

Microwave-Assisted Synthesis of Novel Pyrazolo[3,4-g][1,8]naphthyridin-5-amine with Potential Antifungal and Antitumor Activity.

The microwave assisted reaction between heterocyclic o-aminonitriles 1 and cyclic ketones 2 catalyzed by zinc chloride led to new series of pyrazolo[3,4-b] [1,8]naphthyridin-5-amines 3 in good yields. This procedure provides several advantages such as being environmentally friendly, high yields, simple work-up procedure, broad scope of applicability and the protocol provides an alternative for the synthesis of pyrazolonaphthyridines. The whole series showed antifungal activities against Candida albicans and Cryptococcus neoformans standardized strains, being compounds with a 4-p-tolyl substituent of the naphthyridin scheleton (3a, 3d and 3g), the most active ones mainly against C. albicans, which appear to be related to their comparative hydrophobicity. Among them, 3d, containing a cyclohexyl fused ring, showed the best activity. The anti-Candida activity was corroborated by testing the three most active compounds against clinical isolates of albicans and non-albicans Candida strains. These compounds were also screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines. Compounds 3a and 3e showed remarkable antitumor activity against cancer cell lines, with the most important GI50 values ranging from 0.62 to 2.18 µM.

Efficient production of the flavoring agent zingerone and of both (R)- and (S)-zingerols via green fungal biocatalysis. Comparative antifungal activities between enantiomers.

Zingerone (1) and both chiral forms of zingerol (2) were obtained from dehydrozingerone (3) by biotransformation with filamentous fungi. The bioconversion of 3 with A. fumigatus, G. candidum or R. oryzae allowed the production of 1 as the sole product at 8 h and in 81%-90% at 72 h. In turn, A. flavus, A. niger, C. echinulata, M. circinelloides and P. citrinum produced 1 at 8 h, but at 72 h alcohol 2 was obtained as the major product (74%-99%). Among them, A. niger and M. circinelloides led to the anti-Prelog zingerol (R)-2 in only one step with high conversion rates and ee. Instead, C. echinulata and P. citrinum allowed to obtain (S)-2 in only one step, with high conversion rates and ee. Both chiral forms of 2 were tested for antifungal properties against a panel of clinically important fungi, showing that (R)-, but not (S)-2 possessed antifungal activity.

Antifungal terpenoids from Hyalis argentea var. latisquama.

A detailed chemical study of the aerial parts and rhizomes of Hyalis argentea var. latisquama yielded a variety of sesqui- and diterpenes. In total, 26 compounds were isolated and identified, of which four are new, namely, two ent-kaurenes (1 and 2), a diterpene lactone (3), and a lindenanolide (4). The previously reported compounds included a series of lindenanolides, guaianolides, elemanolides, and additional diterpenes. The antifungal activity of the isolated compounds was tested against Cryptococcus neoformans and Candida albicans. Among the isolated compounds, the lindenanolides were the only structural class that showed strong antifungal activity, and onoseriolide acetate (5) was the most active. On the other hand, the isolated guaianolides were only moderately active, while the diterpenes did not show significant antifungal activity.

Efficient synthesis of novel 3-aryl-5-(4-chloro-2-morpholinothiazol-5-yl)-4,5-dihydro-1H-pyrazoles and their antifungal activity alone and in combination with commercial antifungal agents.

The α,ß-unsaturated carbonyl compounds 5a-f were prepared by reaction between 2-chloro-4-morpholinothiazol-5-carbaldehyde 3 and substituted acetophenones 4a-f. Treatment of compounds 5a-f with hydrazine hydrate employing mild reaction conditions led to the formation of 4,5-dihydro-1H-pyrazoles 6a-f. Then the treatment with acetic anhydride or formic acid afforded the expected 4,5-dihydro-1H-pyrazoles 7a-f and 8a-f. The antifungal activity of each series of synthesized compounds was determined against the clinically important fungi Candida albicans and Cryptococcus neoformans. In addition, the most active compounds 7e and 7f were tested in combination with the commercial antifungal agents: fluconazole, itraconazole, and amphotericin B. Compound 7e showed a synergistic effect with fluconazole against C. albicans while 7f showed synergistic activities with all tested antifungal drugs against the same yeast.

Novel antifungal agents: a patent review (2011 - present).

INTRODUCTION: Invasive fungal infections (IFI) have increased significantly over the past decades. The mortality rate of IFI is alarming, and early and accurate diagnosis is difficult. Most used antifungal drugs are not completely effective due to the development of increasing resistance and undesirable side effects which limit their use. In this scenario, new effective broad spectrum and safer antifungal drugs are urgently needed. AREAS COVERED: This review summarizes the latest advances in the discovery of new antifungal compounds through the patents granted from 2011 to August 2013. In the 26 patents reviewed here, either derivatives of existing antifungal drugs or novel structures are included. New imidazoles, fluconazole analogs and adducts of azoles with 2,6-di-tert-butyl-4-methylphenol are described. The review also includes chitinases, ß-1,3-D-glucan and chitin synthases inhibitors and novel structures. EXPERT OPINION: In the patents reviewed here, progress has been made to accomplish at least one of the necessary requirements for the development of novel antifungal agents, such as broad spectrum of activity, more favorable pharmacokinetic profile, good bioavailability and low adverse effects. However, in vivo activity, mechanisms of action, drug-drug interactions and other aspects that make a compound a good antifungal agent need further development.

Detection of synergistic combinations of Baccharis extracts with terbinafine against Trichophyton rubrum with high throughput screening synergy assay (HTSS) followed by 3D graphs. Behavior of some of their components.

Forty four extracts from nine Baccharis spp. from the Caulopterae section were tested in combination with terbinafine against Trichophyton rubrum with the HTSS assay at six different ratios with the aim of detecting those mixtures that produced a ≥50% statistically significant enhancement of growth inhibition. Since an enhanced effect of a combination respective of its components, does not necessarily indicate synergism, three-dimensional (3D) dose-response surfaces were constructed for each selected pair of extract/antifungal drug with the aid of CombiTool software. Ten extracts showed synergistic or additive combinations which constitutes a 22% hit rate of the extracts submitted to evaluation. Four flavonoids and three ent-clerodanes were detected in the active Baccharis extracts with HPLC/UV/ESI-MS methodology, all of which were tested in combination with terbinafine. Results showed that ent-clerodanes but not flavonoids showed synergistic or additive effects. Among them, bacchotricuneatin A followed by bacrispine showed synergistic effects while hawtriwaic acid showed additive effects.

Synthesis, antifungal and antitumor activity of novel (Z)-5-hetarylmethylidene-1,3-thiazol-4-ones and (z)-5-ethylidene-1,3-thiazol-4-ones.

New hetaryl- and alkylidenerhodanine derivatives 3a-d, 3e, and 4a-d were prepared from heterocyclic aldehydes 1a-d or acetaldehyde 1e. The treatment of several rhodanine derivatives 3a-d and 3e with piperidine or morpholine in THF under reflux, afforded (Z)-5-(hetarylmethylidene)-2-(piperidin-1-yl)thiazol-4(5H)-ones and 2-morpholinothiazol-4(5H)-ones 5a-d, 6a-d, and (Z)-5-ethylidene-2-morpholinothiazol-4(5H)-one (5e), respectively, in good yields. Structures of all compounds were determined by IR, 1D and 2D NMR and mass spectrometry. Several of these compounds were screened by the U.S. National Cancer Institute (NCI) to assess their antitumor activity against 60 different human tumor cell lines. Compound 3c showed high activity against HOP-92 (Non-Small Cell Lung Cancer), which was the most sensitive cell line, with GI50 = 0.62 µM and LC50 > 100 µM from the in vitro assays. In vitro antifungal activity of these compounds was also determined against 10 fungal strains. Compound 3e showed activity against all fungal strains tested, but showed high activity against Saccharomyces cerevisiae (MIC 3.9 µg/mL).

Structural requirements for the antifungal activities of natural drimane sesquiterpenes and analogues, supported by conformational and electronic studies.

Seventeen drimanes including polygodial (1), isopolygodial (2), drimenol (3) and confertifolin (4) obtained from natural sources and the semi-synthetic derivatives 5-17 obtained from 1-3, were evaluated in vitro for antifungal properties against a unique panel of fungi with standardized procedures by using two end-points, MIC(100) and MIC(50). A SAR analysis of the whole series, supported by conformational and electronic studies, allowed us to show that the Δ7,8 -double bond would be one of the key structural features related to the antifungal activity. The MEPs obtained for active compounds exhibit a clear negative minimum value (deep red zone) in the vicinity of the Δ7,8 -double bond, which is not present in the inactive ones. Apart of this negative zone, a positive region (deep blue) appears in 1, which is not observed either in its epimer 2 nor in the rest of the active compounds. The LogP of active compounds varies between 2.33 and 3.84, but differences in MICs are not correlated with concomitant variations in LogP values.

Cytotoxic and Antifungal Activities of Diverse α-Naphthylamine Derivatives.

Diverse α-naphthylamine derivatives were easily prepared from corresponding aldimines derived from commercially available α-naphthaldehyde and anilines or isomeric pyridinecarboxyaldehydes and α-naphthylamine. The secondary amines obtained were tested as possible antifungal and cytotoxic agents. The diverse N-aryl-N-[1-(1-naphthyl)but-3-enyl]amines obtained were active (IC(50) < 10 µg/mL) against breast (MCF-7), non-small cell lung (H-460), and central nervous system (SF-268) human cancer cell lines, while N-(pyridinylmethyl)-naphthalen-1-amines resulted in activity against (MIC 25-32 µg/mL) some human opportunistic pathogenic fungi including yeasts, hialohyphomycetes, and dermatophytes.

Synthesis and antifungal activity of diverse C-2 pyridinyl and pyridinylvinyl substituted quinolines.

Diverse 2-pyridinyl quinolines 6-12 and 2-pyridinilvinyl quinolines 13-17 were prepared using a straightforward synthesis based on the BiCl(3)-catalyzed multicomponent imino Diels-Alder (imino DA) reaction or a novel tandem imino DA/catalytic tetrahydroquinoline ring oxidation/Perkin condensation sequential process. All members of the series showed activities against dermatophytes and some of them possessed a broad spectrum of action. 2-(Pyridin-4-yl)quinoline 9 and 2-(2-pyridin-4-yl)vinyl)quinoline 16 showed the best MIC(80) and MIC(50) against the clinically important fungi Candida albicans and non-albicans Candida species. In turn, 6-ethyl-2-(pyridin-2-yl)quinoline 6 showed the best properties against standardized as well as clinical strains of Cryptococcus neoformans.

Synthesis of steroidal quinones and hydroquinones from bile acids by Barton radical decarboxylation and benzoquinone addition. Studies on their cytotoxic and antifungal activities.

Twelve new hydroquinones and quinones (4a-c to 7a-c) derived from free or peracetylated bile acids were prepared by a Barton decarboxylation reaction, with subsequent trapping of the resulting free radical by benzoquinone. All new compounds were completely characterized by 2D NMR techniques and screened for antifungal and cytotoxic activity. One of the new hydroquinones (7b) showed promising results against the human pancreatic ductal carcinoma cell line PANC1, with similar cytotoxic activity as the commercial chemotherapy drug doxorubicin.