Antivirulence activity and in vivo efficacy of a thiazole derivative against candidiasis.

Candida albicans is a pathogen equipped with a variety of commensal and virulence traits that help it colonize the microbiota and invade host tissue during infection. In this study, we investigated the potential anticandidal activity of 3-[2-(4-(4-methoxyphenyl)thiazol-2-yl)hydrazino)]butan-1-ol (MT), a thiazolylhydrazone compound synthesized by our group, and identified it as a promising antifungal agent. The activity of MT was evaluated in vitro and in vivo against C. albicans as well as its ability to inhibit virulence factors. For this, the ability of MT to inhibit the adhesion of C. albicans to human buccal epithelial cells and biofilm formation and filamentation was tested. In addition, the potential in vivo activity of MT was evaluated in murine models of oral candidiasis. Our results confirmed the antifungal activity of MT, with a minimal inhibitory concentration range of 0.5-2 µg/mL. Indeed, MT treatment in vitro decreased the expression of C. albicans genes involved in biofilm formation and morphogenesis and encoding hydrolytic enzymes, which was also confirmed through phenotypic observations. In addition, MT promoted a decrease in the colony forming units recovered from the tongues of mice with oral candidiasis. In this work, we present a potent antivirulence compound that shows potential for candidiasis therapy, especially for topical use.

In vitro and in silico studies of antioxidant activity of 2-thiazolylhydrazone derivatives.

The antioxidant potential of a series of thiazolylhydrazone derivatives was investigated using three different methods namely DPPH, ABTS and FRAP assays. In general, the tested compounds showed higher or comparable activity to that of curcumin, used as positive control. Chemometric analyses demonstrated that the presence of hydrazone moiety is required for the activity of this class of compounds. From these results, compound 4 was identified as the most promising molecule and was then selected for further studies. The antiproliferative effect of compound 4 was evaluated, being active in three (T47D, MDA-MB-231 and SKMEL) of the six cancer cell lines tested, with IC50 values ranging from 15.9 to 31.3 µM. Compound 4 exhibited no detectable cytotoxic effect on peripheral blood mononuclear cells (PBMC) when tested at a concentration of 100 µM, demonstrating good selectivity. From these results, it is possible to infer that there is a correlation between antioxidant capacity and anticancer effects.

Assessment of anti-diabetic activity of a novel hydrazine-thiazole derivative: in vitro and in vivo method

Diabetes mellitus is a chronic disease resulting in oxidative stress that promotes tissue damage. The appearance of this disease is highly related to lifestyle and food of the population, being of great interest to search for a dietary supplement that can also act by reducing oxidative alterations. Based on the broad range of biological activity of thiazole derivatives, this work aimed to evaluate the in vitro antioxidant activity of a novel hydrazine-thiazole derivative and studies in vivo. In in vivo experiments, the liver extracts of healthy and diabetic Wistar rats were used, with analysis to determine the enzymatic activity of SOD, CAT, GPx, and GR, and determination of lipid peroxidation. Finally, in the blood of these animals, biochemical parameters were evaluated. Statistical evidence of changes caused in liver enzymes and liquid peroxidation was not detected; however, these parameters were also not changed between control groups with and without diabetes. On the other hand, concerning biochemical parameters, significant differences were detected in uric acid, alkaline phosphatase, ALT, and urea, indicating a possible antioxidant protective role of such substances in the liver and kidney of diabetic animals that could be acting by means other than that commonly reported in the literature.

Anti-Candida albicans Activity of Thiazolylhydrazone Derivatives in Invertebrate and Murine Models.

Candidiasis is an opportunistic fungal infection with Candida albicans being the most frequently isolated species. Treatment of these infections is challenging due to resistance that can develop during therapy, and the limited number of available antifungal compounds. Given this situation, the aim of this study was to evaluate the antifungal activity of four thiazolylhydrazone compounds against C. albicans. Thiazolylhydrazone compounds 1, 2, 3, and 4 were found to exert antifungal activity, with MICs of 0.125⁻16.0 µg/mL against C. albicans. The toxicity of the compounds was evaluated using human erythrocytes and yielded LC50 > 64 µg/mL. The compounds were further evaluated using the greater wax moth Galleria mellonella as an in vivo model. The compounds prolonged larval survival when tested between 5 and 15 mg/kg, performing as well as fluconazole. Compound 2 was evaluated in murine models of oral and systemic candidiasis. In the oral model, compound 2 reduced the fungal load on the mouse tongue; and in the systemic model it reduced the fungal burden found in the kidney when tested at 10 mg/kg. These results show that thiazolylhydrazones are an antifungal towards C. albicans with in vivo efficacy.

In vivo and in vitro activity of a bis-arylidenecyclo-alkanone against fluconazole-susceptible and -resistant isolates of Candida albicans.

OBJECTIVES: Candida albicans is a commensal organism and opportunistic pathogen associated both with superficial (mucosal and cutaneous) and systemic infections. Extensive use of antifungal agents has led to reduced susceptibility to the few existing drugs, which has encouraged the search for novel antifungal agents. Therefore, the present study investigated the antifungal activity of 2,6-bis[(E)-(4-pyridyl)methylidene]cyclohexanone (PMC) against C. albicans. METHODS: The in vitro activity of PMC was evaluated against C. albicans. Additionally, an invertebrate infection model in Caenorhabditis elegans as well as two infected murine models of oral and systemic candidiasis were used to determine the antifungal efficacy of PMC in vivo. RESULTS: Minimum inhibitory concentrations (MICs) of PMC ranged from 4-32µg/mL against nine clinical and two reference C. albicans isolates. Interestingly, PMC inhibited filamentation in vitro at subinhibitory concentrations similar to fluconazole. PMC also showed low toxicity against murine macrophages and human erythrocytes. In the invertebrate infection model, PMC was efficient in prolonging survival of C. elegans infected with C. albicans SC5314. Treatment with PMC was efficient both in murine models of systemic and oral candidiasis and was similar to that observed with conventional drug treatments (nystatin and fluconazole). CONCLUSIONS: The results of this study indicate the therapeutic potential of PMC as it was able to inhibit filamentation of C. albicans in vitro. These alterations to the fungi by PMC resulted in a reduction of oral and systemic infection in mice. In conclusion, we present promising evidence of the anticandidal activity of PMC in vitro and in vivo.

Synthesis, molecular modeling studies and evaluation of antifungal activity of a novel series of thiazole derivatives.

In the search for new antifungal agents, a novel series of fifteen hydrazine-thiazole derivatives was synthesized and assayed in vitro against six clinically important Candida and Cryptococcus species and Paracoccidioides brasiliensis. Eight compounds showed promising antifungal activity with minimum inhibitory concentration (MIC) values ranging from 0.45 to 31.2 µM, some of them being equally or more active than the drug fluconazole and amphotericin B. Active compounds were additionally tested for toxicity against human embryonic kidney (HEK-293) cells and none of them exhibited significant cytotoxicity, indicating high selectivity. Molecular modeling studies results corroborated experimental SAR results, suggesting their use in the design of new antifungal agents.

Heterocycle Thiazole Compounds Exhibit Antifungal Activity through Increase in the Production of Reactive Oxygen Species in the Cryptococcus neoformans-Cryptococcus gattii Species Complex.

Human cryptococcosis can occur as a primary or opportunistic infection and develops as an acute, subacute, or chronic systemic infection involving different organs of the host. Given the limited therapeutic options and the occasional resistance to fluconazole, there is a need to develop novel drugs for the treatment of cryptococcosis. In this report, we describe promising thiazole compounds 1, 2, 3, and 4 and explore their possible modes of action against Cryptococcus To this end, we show evidence of interference in the Cryptococcus antioxidant system. The tested compounds exhibited MICs ranging from 0.25 to 2 µg/ml against Cryptococcus neoformans strains H99 and KN99α. Interestingly, the knockout strains for Cu oxidase and sarcosine oxidase were resistant to thiazoles. MIC values of thiazole compounds 1, 2, and 4 against these mutants were higher than for the parental strain. After the treatment of C. neoformans ATCC 24067 (or C. deneoformans) and C. gattii strain L27/01 (or C. deuterogattii) with thiazoles, we verified an increase in intracellular reactive oxygen species (ROS). Also, we verified the synergistic interactions among thiazoles and menadione, which generates superoxides, with fractional inhibitory concentrations (FICs) equal to 0.1874, 0.3024, 0.25, and 0.25 for the thiazole compounds 1, 2, 3, and 4, respectively. In addition, thiazoles exhibited antagonistic interactions with parasulphonatephenyl porphyrinato ferrate III (FeTPPS). Thus, in this work, we showed that the action of these thiazoles is related to an interference with the antioxidant system. These findings suggest that oxidative stress may be primarily related to the accumulation of superoxide radicals.

Thiazole compounds with activity against Cryptococcus gattii and Cryptococcus neoformans in vitro.

Human cryptococcosis can occur as a primary or opportunistic infection and develop as an acute, subacute, or chronic, systemic infection involving different host organs. We evaluated the antifungal activity of thirteen compounds against Cryptococcus gattii and Cryptococcus neoformans in vitro, by assessing the toxicity of the compounds showing the greatest antifungal activity in VERO cells and murine macrophages. From these results, four compounds were considered promising for further studies because they displayed low cytotoxicity and significant antifungal activity. The heterocyclic compounds 1b, 1c, 1d, and 1m have antifungal activity levels between that of amphotericin B and fluconazole in vitro. The death curve of Cryptococcus spp. treated with these four compounds was similar to the curve obtained for amphotericin B, in that we observed a significant reduction in cell viability within the first 24 h of treatment. Additionally, we found that there was no effect when these compounds were combined with amphotericin and fluconazole, except for 1c, which antagonized the effect of amphotericin B against C. gattii, also reflected in the reduction of the post-antifungal effect (PAFE); however, this interaction did not alter the ergosterol content. The results shown in this paper reveal the discovery of novel thiazole compounds, which are easy to synthesize, and with potentially exhibit antifungal activity, and display low cytotoxicity in normal mammalian cells. These compounds can be used as prototypes for the design of new antifungal drugs against C. gattii and C. neoformans.