Antiplasmodial, Trypanocidal, and Genotoxicity In Vitro Assessment of New Hybrid α,α-Difluorophenylacetamide-statin Derivatives.

BACKGROUND: Statins present a plethora of pleiotropic effects including anti-inflammatory and antimicrobial responses. A,α-difluorophenylacetamides, analogs of diclofenac, are potent pre-clinical anti-inflammatory non-steroidal drugs. Molecular hybridization based on the combination of pharmacophoric moieties has emerged as a strategy for the development of new candidates aiming to obtain multitarget ligands. METHODS: Considering the anti-inflammatory activity of phenylacetamides and the potential microbicidal action of statins against obligate intracellular parasites, the objective of this work was to synthesize eight new hybrid compounds of α,α-difluorophenylacetamides with the moiety of statins and assess their phenotypic activity against in vitro models of Plasmodium falciparum and Trypanosoma cruzi infection besides exploring their genotoxicity safety profile. RESULTS: None of the sodium salt compounds presented antiparasitic activity and two acetated compounds displayed mild anti-P. falciparum effect. Against T. cruzi, the acetate halogenated hybrids showed moderate effect against both parasite forms relevant for human infection. Despite the considerable trypanosomicidal activity, the brominated compound revealed a genotoxic profile impairing future in vivo testing. CONCLUSIONS: However, the chlorinated derivative was the most promising compound with chemical and biological profitable characteristics, without presenting genotoxicity in vitro, being eligible for further in vivo experiments.

Toxicogenetic assessment of a pre-workout supplement: In vitro mutagenicity, cytotoxicity, genotoxicity and glutathione determination in liver cell lines and in silico ADMET approaches.

The benefits of practicing physical activity, such as weight loss and control, are commonly associated with caloric restriction diets and may be improved by the ingestion of thermogenic and ergogenic supplements. However, there is a lack of safety data on commonly marketed nutritional supplements. Therefore, this investigation aims to evaluate a pre-workout supplement for mutagenicity using the Ames test, hepatocytoxicity in HepG2 and F C3H cells after 24 h, 48 h and 72 h, genotoxicity using the CBMN assay, determination of gluthatione activity and computational prediction of the three major isolated compounds present in the supplement. The mutagenicity test showed a mutagenic response in TA98 His+ revertants of 5 mg/plate in the presence of metabolic activation, cytotoxicity in TA98 of 5 mg/plate in the absence of metabolic conditions, and in TA102 of 0.5 mg/plate both in the presence and absence of metabolic activation. In our in vitro eukaryotic cell viability, WST-1, LDH and alkaline phosphatase assays, the supplement showed hepatocytotoxicity both dose-dependently and time-dependently. In the cytokinesis blocking micronuclei assay, the supplement induced micronuclei, nuclear buds, nucleoplasmatic, bridge formation, and a decreased in nuclear division. In addition, the supplement decreased intra and extracellular GSH. Computational analysis showed that the three isolated compounds most present in the supplement have the potential to cause hepatotoxicity. In the present investigation, the pre-workout supplement induced mutagenic, genotoxic, and cytotoxic responses and GSH decrease. Thus, considering food safety and public health sanitary vigilance, the consumption of this pre-workout supplement may harm the health of its consumers.

Biochemical characterization and phytotoxic activity of protein extract from Euphorbia tirucalli L.

ETHNOPHARMACOLOGICAL RELEVANCE: Euphorbia tirucalli L., a tropical and subtropical plant, also known by the popular name avelós, has been used in folk medicine against many diseases as rheumatism, asthma, toothache, and cancer. Studies have shown that natural compounds contained in this plant species may be associated with these functions. However, little is known about its potential toxicity. AIM OF THE STUDY: Several proteins conduct biological functions, in particular, proteinases, play a crucial role in many mechanisms of living beings, including plants, animals and microorganisms. However, when poorly regulated, they can generate consequences, such as the non-production of certain substances, or even the abnormal multiplication of cells, which leads to tumors. On the other hand, by regulating these enzymes, proteinase inhibitors act by reducing the activity of proteinases, thus preventing their malfunction. The objective of this work was to evaluate the toxicity of the protein extract of E. tirucalli and to purify a protease inhibitor that may be associated with the biological medicinal functions of the plant. MATERIALS AND METHODS: The cytotoxic and mutagenic properties of the protein extract produced from the stem of avelós was investigated using the Ames test. The protein extract was also submitted to a protease inhibitor purification process using the gel filtration chromatography technique and the purified protein was biochemically characterized. RESULTS: A protease inhibitor, called tirustatin, was isolated 1.84-fold by Biogel P100. The calculated molecular mass of the isolated protein is 25.97 kDa. The inhibitor was stable at pH 3-10, with pronounced activity at pH 6. Thermostability was observed even at elevated temperature (100 °C) with inhibitory activity increased by 1.14-fold compared to inhibitor activity at room temperature. Incubation at basic pH values for up to 60 min caused little reduction (0.25-fold) in the papain inhibitory activity of tirustatin. The stoichiometry of the papain-tirustatin interaction was 1.5: 1 and 28.8 pM of the inhibitor effected 50% inhibition. With an equilibrium dissociation constant of 8.74 x 10-8M for the papain enzyme, it is possible to evaluate the isolated protein as a non-competitive inhibitor. In addition, the protein extract of E. tirucalli even at the maximum concentration used (20 µg/mL), did not show a cytotoxic and mutagenic profile in a bacterial model. CONCLUSION: The results presented in this work provide data that reinforce the idea of the potential use of proteins produced in E. tirucalli as pharmacological and biotechnological agents that can be exploited for the development of efficient drugs.

Plinia cauliflora (Mart.) Kausel (Jaboticaba) leaf extract: In vitro anti-Trypanosoma cruzi activity, toxicity assessment and phenolic-targeted UPLC-MSE metabolomic analysis.

ETHNOPHARMACOLOGICAL RELEVANCE: Plinia cauliflora (Mart.) Kausel, known as Brazilian grape or jaboticaba, is widely used in Brazilian traditional medicine to treat infectious and inflammatory disorders. However, several aspects of its biological potential remain unclear, such as toxicity and effects on pathogenic protozoa. AIM OF THE STUDY: Investigate the phenolic composition, the in vitro and in silico toxicity profile, and the anti-Trypanosoma cruzi activity of the phenolics-enriched hydromethanolic extract of P. cauliflora leaf. MATERIAL AND METHODS: Phytochemical analysis was performed ultra-performance liquid chromatography-mass spectrometry (UPLC-MSE). Mutagenicity, genotoxicity and eukaryotic cytotoxicity was evaluated by Ames test, cytokinesis-block micronucleus and colorimetric assays, respectively, alongside with a computational prediction of the major compound's pharmacokinetics and toxicity. Anti-T. cruzi activity was investigated on T. cruzi bloodstream trypomastigotes. RESULTS: A total of 14 phenolic compounds were identified, including 11 flavonoids and 2 phenolic acids. No positive response regarding mutagenic potential was detected in Salmonella strains TA97, TA98, TA100, TA102, TA104, both in absence or presence of metabolic activation. The extract induced significant dose-response reduction on nuclear division indexes of HepG2 cells, suggesting cytostatic effects, with no micronuclei induction on cytokinesis-block micronucleus assay. Likewise, it also presented cytotoxic effects, inducing HepG2 and F C3H dose and time dependently cell death through cell membrane damage and more evidently by mitochondrial dysfunction. A dose-response curve of in vitro trypanocidal activity was observed against T. cruzi bloodstream trypomastigotes after 2 and 24 h of exposure. In silico predictions of most abundant compounds' structural alerts, pharmacokinetics and toxicity profile indicates a moderately feasible druglikeness profile and low toxicity for them, which is compatible with in vitro results. CONCLUSIONS: The present study demonstrated that P. cauliflora leaf extract is a potential source of antiparasitic bioactive compounds, however it presents cytotoxic effects in liver cell lines.

Metabolomic analysis of Cyrtopodium glutiniferum extract by UHPLC-MS/MS and in vitro antiproliferative and genotoxicity assessment.

ETHNOPHARMACOLOGICAL RELEVANCE: Extracts of orchids have been traditionally used as human phytotherapeutics. Cyrtopodium flavum, for example, due to the analgesic and anti-inflammatory properties, beside the capacity of heal skin lesions has been focus of research. Also Cyrtopodium glutiniferum, an orchid found in the Brazilian southeastern rainforest, is known to synthesize anti-inflammatory glucomannans in the pseudobulbs, as other potentially therapeutic compounds. AIM OF THE STUDY: We have reported the first metabolomic analysis focused on the phenols expression of the neotropical orchid Cyrtopodium glutiniferum Raddi, besides free radical scavenging, anti-inflammatory and antiproliferative activities, and the genotoxicity properties of the aqueous extract. MATERIAL AND METHODS: The metabolomics of C. glutiniferum aqueous extract was performed through UHPLC-MSn acquisition. We have detected the scavenging potential of the extract using DPPH assay. The genotoxic potential was performed by Ames Test (0-5000 µg mL-1) and micronucleous assay (0-5000 µg mL-1) in RAW264.7 cells. The cytotoxic potential of the extract against RAW264.7 was tested by WST-1 assay (0-500 µg mL-1). And after all, the RAW264.7 cells were treated with non-cytotoxic concentrations of C. glutiniferum (0-50 µg mL-1) to evaluate the antiproliferative and anti-inflammatory potential, besides the mitochondrial activity. RESULTS: From the 55 molecules identified, 45.5% belonged to the phenolic compounds database from Phenol Explorer, 29% to an in-house Orchidaceae molecules database, and 25.5% to both. Among the identified phenolic compounds, 18 subclasses were discriminated, being phenanthrenes the most abundant. Doses-dependent of C. glutiniferum extracts were able to induce DPPH free radicals scavenging and also to increase TA100 His+ revertants, in metabolic environment, showing mutagenicity just in the highest concentration, of 5 mg/plate. On Eukaryotic cell models, the extract also has induced dose-response and time-response cytotoxicity against RAW264.7 macrophages, mainly after 48 h and 72 h, even though the extract has not been able to induce the increase of micronucleated cells and mitotic index alteration on Micronucleus assay. The activation and proliferation of macrophages cultures were downregulated after 24 h and 48 h by the non-cytotoxic concentrations of the extract in a dose-dependent manner. CONCLUSIONS: The Cyrtopodium glutiniferum metabolomics, anti-inflammatory and anti-proliferative properties observed in this study suggest a therapeutic efficacy of the orchid extract applied in folk medicine.

New hydrazides derivatives of isoniazid against Mycobacterium tuberculosis: Higher potency and lower hepatocytotoxicity.

Tuberculosis (TB) is one of the leading causes of death worldwide. The emergence of multi-drug resistant strains of Mycobacterium tuberculosis (Mtb) and TB-HIV co-infection are major public health challenges. The anti-TB drugs of first choice were developed more than 4 decades ago and present several adverse effects, making the treatment of TB even more complicated and the development of new chemotherapeutics for this disease imperative. In this work, we synthesized two series of new acylhydrazides and evaluated their activity against different strains of Mtb. Derivatives of isoniazid (INH) showed important anti-Mtb activity, some being more potent than all anti-TB drugs of first choice. Moreover, three compounds proved to be more potent than INH against resistant Mtb. The Ames test showed favorable results for two of these substances compared to INH, one of which presented expressly lower toxicity to HepG2 cells than that of INH. This result shows that this compound has the potential to overcome one of the main adverse effects of this drug.

In vitro and in vivo studies of the antiparasitic activity of sterol 14α-demethylase (CYP51) inhibitor VNI against drug-resistant strains of Trypanosoma cruzi.

Chagas disease affects more than 10 million people worldwide, and yet, as it has historically been known as a disease of the poor, it remains highly neglected. Two currently available drugs exhibit severe toxicity and low effectiveness, especially in the chronic phase, while new drug discovery has been halted for years as a result of a lack of interest from pharmaceutical companies. Although attempts to repurpose the antifungal drugs posaconazole and ravuconazole (inhibitors of fungal sterol 14α-demethylase [CYP51]) are finally in progress, development of cheaper and more efficient, preferably Trypanosoma cruzi-specific, chemotherapies would be highly advantageous. We have recently reported that the experimental T. cruzi CYP51 inhibitor VNI cures with 100% survival and 100% parasitological clearance both acute and chronic murine infections with the Tulahuen strain of T. cruzi. In this work, we further explored the potential of VNI by assaying nitro-derivative-resistant T. cruzi strains, Y and Colombiana, in highly stringent protocols of acute infection. The data show high antiparasitic efficacy of VNI and its derivative (VNI/VNF) against both forms of T. cruzi that are relevant for mammalian host infection (bloodstream and amastigotes), with the in vivo potency, at 25 mg/kg twice a day (b.i.d.), similar to that of benznidazole (100 mg/kg/day). Transmission electron microscopy and reverse mutation tests were performed to explore cellular ultrastructural and mutagenic aspects of VNI, respectively. No mutagenic potential could be seen by the Ames test at up to 3.5 µM, and the main ultrastructural damage induced by VNI in T. cruzi was related to Golgi apparatus and endoplasmic reticulum organization, with membrane blebs presenting an autophagic phenotype. Thus, these preliminary studies confirm VNI as a very promising trypanocidal drug candidate for Chagas disease therapy.

DNA-repair genes and vitamin E in the prevention of N-nitrosodiethylamine mutagenicity.

Nitrosamines are stable compounds, biologically and chemically inert unless activated. In biological systems, N-nitrosodiethylamine (NDEA) can be activated by a variety of enzymes, leading to aldehydes and/or intermediates which are themselves alkylating agents. Additionally, it has been shown that NDEA causes reactive oxygen species (ROS) production and induces mutagenicity. The cell defense seeks to neutralize ROS that escape the primary defense mechanisms (antioxidants) by DNA-repair mechanisms. NDEA is present at low concentrations in major dietary sources, like cured meats, salami, millet flour, and dried cuttlefish, where NDEA mutagenicity has been detected. These facts lead us to evaluate vitamin E as a ROS scavenger, in Escherichia coli mutants system, against genotoxicity induced by NDEA at low concentrations under exogenous metabolic activation. Statistical analysis were performed in order to compare the effects of NDEA-induced genotoxicity (a) between the mutants and the wild-type strains, at the same metabolic activation conditions and, (b) between the same strains in the presence or in the absence of vitamin E (150 muM). The indirect evaluation of ROS production by NDEA metabolizing shows that vitamin E protects E. coli cells proficient or deficient in the DNA-repair genes from cytotoxic effects. Our results underscore the role of scavenger molecules such as vitamin E in the diet, avoiding lesions induced by NDEA at low concentrations, via ROS, that could be repaired by nucleotide excision repair and base excision repair proteins.

Evaluation of nitroreductase and acetyltransferase participation in N-nitrosodiethylamine genotoxicity.

N-Nitroso compounds, such as N-nitrosodiethylamine (NDEA), are a versatile group of chemical carcinogens, being suspected to be involved in gastrointestinal tumors in humans. The intestinal microflora can modify a wide range of environmental chemicals either directly or in the course of enterohepatic circulation. Nitroreductases from bacteria seem to have a wide spectrum of substrates, as observed by the reduction of several nitroaromatic compounds, but their capacity to metabolize N-nitroso compounds has not been described. To elucidate the participation of nitroreductase or acetyltransferase enzymes in the mutagenic activity of NDEA, the bacterial (reverse) mutation test was carried out with the strains YG1021 (nitroreductase overexpression), YG1024 (acetyltransferase overexpression), TA98NR (nitroreductase deficient), and TA98DNP6 (acetyltrasferase deficient), and YG1041, which overexpresses both enzymes. The presence of high levels of acetyltransferase may generate toxic compounds that must be eliminated by cellular processes or can lead to cell death, and consequently decrease the mutagenic effect, as can be observed by the comparison of strain TA98DNP6 with the strains TA98 and YG1024. The slope curves for TA98 strain were 0.66 rev/microM (R(2) = 0.51) and 52.8 rev/microM (R(2) = 0.88), in the absence and presence of S9 mix, respectively. For YG1024 strain, the slope curve, in the presence of S9 mix was 6897 rev/microM (R(2) = 0.78). Our data suggest that N-nitroso compounds need to be initially metabolized by enzymes such as cytochromes P450 to induce mutagenicity. Nitroreductase stimulates toxicity, while acetyltransferase stimulates mutagenicity, and nitroreductase can neutralize the mechanism of mutagenicity generating innoccuos compounds, probably by acting on the product generated after NDEA activation.

Participation of BER and NER pathways in the repair of DNA lesions induced at low N-nitrosodiethylamine concentrations.

In the present work, we evaluated (p < 0.05) the participation of base excision repair (BER) and nucleotide excision repair (NER) mechanisms in repairing DNA lesions induced by N-nitrosodiethylamine (NDEA) at 1.5 ng/mL-36.5 microg/mL, through cell survival, in different single and double Escherichia coli DNA repair mutants (uvrA, uvrB, uvrC, fpg, nth, xthA, fpg/nth, uvrA/fpg, fpg/xthA, mutY, and fpg/mutY), using pre-incubation periods of 90 min. Mutant strains BH20 (fpg) and AB1886 (uvrA) showed microsomal enzyme (S9 mix) independent NDEA cytotoxicity. Cytotoxicity was also detected at lowest NDEA concentrations, in the presence of S9 mix, with strains BH980 (mutY) and BH990 (fpg/mutY). NDEA cytotoxicity, without S9 mix, was detected for mutant strains AB1884 (uvrC) and AB1885 (uvrB). Through SOS chromotest with 90 min of pre-incubation for uvrA and nth strains, only NER was shown to be required for repairing NDEA-induced lesions with or without metabolic activation. PQ37 and PQ66 strains, both uvrA mutants, showed different levels of NDEA sensitivity. The findings suggest that, under the used conditions, and at low concentrations, NDEA-induced lesions require both repair pathways.

Standardization of conditions for the metabolic activation of N-nitrosodiethylamine in mutagenicity tests.

Like all nitrosamines, N-nitrosodiethylamine (NDEA) requires metabolic activation in order to exert its carcinogenic effects. This activation involves cytochrome P450s (CYP), which generates unstable metabolites that react with the DNA of cells in the immediate vicinity of metabolite formation. Although NDEA is carcinogenic, it has been considered a weak mutagen in classic genotoxicity assays. We used optimized Salmonella/mammalian microsome genotoxicity assays to assess the mutagenicity and toxicity of low concentrations of NDEA. Using a fixed concentration of NDEA (36.5 mg/ml), we varied the length of preincubation in the presence of different concentrations of an S9 metabolic activation mixture. Salmonella typhimurium strains TA97 and TA102 were resistant to NDEA-induced mutagenesis, even after a preincubation of up to 120 min and the use of different concentrations of the S9 mix. Strain TA98 was susceptible to mutagenesis by NDEA in the absence of the S9 mix and after preincubation with NDEA for 90 min. When bacteria of this strain were preincubated with NDEA for 60 min, mutagenesis was detected at an S9 mix concentration >9.55 mg/ml. NDEA also induced mutagenesis in strain TA100 after preincubation for 90 or 120 min, and this effect was dependent on the S9 concentration. E. coli strain BH990 also showed a concentration-dependent response, with only 60% of the cells surviving after a 120-min preincubation with NDEA in the presence of 19.1 mg S9 mix/ml.

Standardization of conditions for the metabolic activation of N-nitrosodiethylamine in mutagenicity tests

Like all nitrosamines, N-nitrosodiethylamine (NDEA) requires metabolic activation in order to exert its carcinogenic effects. This activation involves cytochrome P450s (CYP), which generates unstable metabolites that react with the DNA of cells in the immediate vicinity of metabolite formation. Although NDEA is carcinogenic, it has been considered a weak mutagen in classic genotoxicity assays. We used optimized Salmonella/mammalian microsome genotoxicity assays to assess the mutagenicity and toxicity of low concentrations of NDEA. Using a fixed concentration of NDEA (36.5 mg/ml), we varied the length of preincubation in the presence of different concentrations of an S9 metabolic activation mixture. Salmonella typhimurium strains TA97 and TA102 were resistant to NDEA-induced mutagenesis, even after a preincubation of up to 120 min and the use of different concentrations of the S9 mix. Strain TA98 was susceptible to mutagenesis by NDEA in the absence of the S9 mix and after preincubation with NDEA for 90 min. When bacteria of this strain were preincubated with NDEA for 60 min, mutagenesis was detected at an S9 mix concentration >9.55 mg/ml. NDEA also induced mutagenesis in strain TA100 after preincubation for 90 or 120 min, and this effect was dependent on the S9 concentration. E. coli strain BH990 also showed a concentration-dependent response, with only 60% of the cells surviving after a 120-min preincubation with NDEA in the presence of 19.1 mg S9 mix/ml.

N-Nitrosodiethylamine mutagenicity at low concentrations.

N-Nitrosodiethylamine (NDEA) requires metabolic activation by cytochrome P450 enzymes, leading to electrophile species that react in DNA. Although, carcinogenicity is not an end point in genotoxicity assays, NDEA has been considered a weak carcinogen. In this study, we carried out an analysis of the mutagenicity at low concentrations of NDEA. Using SOS chromotest in the presence of metabolic activation, we detected positive mutagenicity response for NDEA doses between 0.75 and 36.46 microg/ml. In Ames test, using more sensitive strains in the presence of S9 metabolic activation mixture (S9 mix), positive results were also detected for NDEA doses between 1.01 x 10(-3) and 50.64 x 10(-3 microg per plate. Our results indicate that NDEA mutagenicity can be detected at low concentrations when more sensitive conditions are used.

Genotoxic evaluation of the organophosphorous pesticide temephos.

The chemical compound temephos (0,0,0',0'-tetrametyl-0,0'-thiodi-p-phenylene phosphorothioate) is an organophosphorous pesticide that has been used in Brazil since 1967 in control campaigns against the mosquito Aedes aegypti, the vector of dengue and yellow fever. We used single cell gel electrophoresis (SCGE), SOS/umu and Ames/Salmonella assays to test the toxicity and mutagenicity of temephos. Temephos was genotoxic in the SCGE assay, inducing severe DNA lesions (type IV lesions) at doses above 1.34 micro M. It was mutagenic, but not toxic, in the SOS/umu assay to Escherichia coli strain PQ37, but not to PQ35, at concentrations above 1.33 micro M, particularly when the S9 mixture was not used in the assay. Temephos was not mutagenic in the Ames assay with S. typhimurium strains TA97, TA98, TA100 and TA102, both with and without metabolic activation. However, temephos at concentrations above 3.33 micro M was mutagenic to TA98NR, YG7104 and YG7108, both with and without metabolic activation. In conclusion, temephos was genotoxic and mutagenic in all the three tests used, and in two of them at concentrations similar to those routinely used to combat Aedes aegypti.