In vivo antimutagenic effect of vitamins C and E against rifampicin-induced chromosome aberrations in mouse bone-marrow cells

The first-line antituberculosis drugs, and their fixed-dose combination induced abnormal sperm morphology and histological lesions in the testicular cells of male mice

Rifampicin (RIF), Isoniazid (INH), Ethambutol (EMB), Pyrazinamide (PZA), and/or their fixed-dose combination (FDC) are extensively prescribed in the cure of Tuberculosis (TB) globally. In spite of the beneficial effect, these drugs are capable of inducing cellular toxicity. Existing information on the genotoxic effects of the first-line anti-TB drugs is limited and contentious. Herein, we evaluated the reproductive genotoxicity of RIF, INH, EMB, PZA, and their FDC utilizing the mouse sperm morphology assay. Histological examination of the testes of exposed mice was also performed. Male Swiss albino mice (11-13 weeks old) were intraperitoneally exposed for 5 consecutive days to each of the anti-TB drugs at four different doses of 6.25, 12.5, 25, and 50 mg/kg bw of PZA; 2.5, 5.0, 10, and 20 mg/kg bw of RIF; 1.25, 2.5, 5.0 and 10 mg/kg bw of INH; 3.75, 7.5, 15 and 30 mg/kg bw of EMB; and 7, 14, 28 and 56 mg/kg bw of FDC corresponding respectively to ×0.25, ×0.5, ×1 and ×2.0 of the standard daily dose. In comparison with the negative control (normal saline), there was no significant difference in the testicular weight and organo-somatic index of exposed mice. There was an increase (p > 0.05) in the frequency of abnormal spermatozoa at most of the tested doses of each drug and a dose-dependent decrease with the FDC. Each of the anti-TB drugs except the FDC induced pathological lesions in the testes. These findings suggest that the individual first-line anti-TB drug unlike the FDC has the potential to provoke testicular anomalies in male mice.

Camels' biological fluids contained nanobodies: promising avenue in cancer therapy

Cancer is a major health concern and accounts for one of the main causes of death worldwide. Innovative strategies are needed to aid in the diagnosis and treatment of different types of cancers. Recently, there has been an evolving interest in utilizing nanobodies of camel origin as therapeutic tools against cancer. Nanotechnology uses nanobodies an emerging attractive field that provides promises to researchers in advancing different scientific sectors including medicine and oncology. Nanobodies are characteristically small-sized biologics featured with the ability for deep tissue penetration and dissemination and harbour high stability at high pH and temperatures. The current review highlights the potential use of nanobodies that are naturally secreted in camels’ biological fluids, both milk and urine, in the development of nanotechnology-based therapy for treating different typesQuery of cancers and other diseases. Moreover, the role of nano proteomics in the invention of novel therapeutic agents specifically used for cancer intervention is also illustrated.

What are the origins of growing microbial resistance? Both Lamarck and Darwin were right

INTRODUCTION

Microorganisms of clinical importance frequently develop resistance to drug therapy, now a growing problem. The experience with Mycobacterium tuberculosis is a representative example of increasing multi-drug resistance. To avoid reaching a crisis in which patients could be left without adequate treatment, a new strategy is needed. Anti-microbial therapy has historically targeted the mechanisms rather than origin of drug resistance, thus allowing microorganisms to adapt and survive.

AREAS COVERED

This contribution analyses the historical development (1943-2020) of the evolution of multi-drug resistance by M. tuberculosis strains in light of Darwin's and Lamarck's theories of evolution.

EXPERT OPINION

Regarding the molecular origin of microbial drug resistance, genetic mutations and epigenetic modifications are known to participate. The analysis of the history of drug resistance by M. tuberculosis evidences a gradual development of resistance to some antibiotics, undoubtedly due to random mutations together with natural selection based on environmental pressures (e.g., antibiotics), representing Darwin's idea. More rapid adaptation of M. tuberculosis to new antibiotic treatments has also occurred, probably because of heritable acquired characteristics, evidencing Lamarck's proposal. Therefore, microbial infections should be treated with an antibiotic producing null or low mutagenic activity along with a resistance inhibitor, preferably in a single medication.

DNA damage protective effect of honey-sweetened cashew apple nectar in Drosophila melanogaster

Fruits and derivatives, such as juices, are complex mixtures of chemicals, some of which may have mutagenic and/or carcinogenic potential, while others may have antimutagenic and/or anticancer activities. The modulating effects of honey-sweetened cashew apple nectar (HSCAN), on somatic mutation and recombination induced by ethyl methanesulfonate (EMS) and mitomycin C (MMC) were evaluated with the wing spot test in Drosophila melanogaster using co- and post-treatment protocols. Additionally, the antimutagenic activity of two HSCAN components, cashew apple pulp and honey, in MMC-induced DNA damage was also investigated. HSCAN reduced the mutagenic activity of both EMS and MMC in the co-treatment protocol, but had a co-mutagenic effect when post-administered. Similar results were also observed with honey on MMC mutagenic activity. Cashew apple pulp was effective in exerting protective or enhancing effects on the MMC mutagenicity, depending on the administration protocol and concentration used. Overall, these results indicate that HSCAN, cashew apple and honey seem capable of modulating not only the events that precede the induced DNA damages, but also the Drosophila DNA repair processes involved in the correction of EMS and MMC-induced damages.

Fipronil-induced genotoxicity and DNA damage in vivo: Protective effect of vitamin E

Fipronil, an insecticide of the phenylpyrazole class has been classified as a carcinogen by United States Environmental Protection Agency, yet very limited information is available about its genotoxic effects. Adult male and female animals were gavaged with various doses of fipronil (2.5, 12.5, and 25 mg/kg body weight (bw)) to evaluate micronucleus test (mice), chromosome aberration (CA), and comet assay (rats), respectively. Cyclophosphamide (40 mg/kg bw; intraperitoneal) was used as positive control. Another group of animals were pretreated with vitamin E orally (400 mg/kg bw) for 5 days prior to administration of fipronil (12.5 mg/kg). Fipronil exposure in both male and female mice caused significant increase in the frequency of micronuclei (MN) in polychromatic erythrocytes. Similarly, structural CAs in bone marrow cells and DNA damage in the lymphocytes was found to be significantly higher in the male and female rats exposed to fipronil as compared to their respective controls. The average degree of protection (male and female animals combined together) shown by pretreatment of vitamin E against fipronil-induced genotoxicity was 63.28%: CAs; 47.91%: MN formation; and 74.70%: DNA damage. Findings of this study demonstrate genotoxic nature of fipronil regardless of gender effect and documents protective role of vitamin E.

In Vitro Protective Effect and Antioxidant Mechanism of Resveratrol Induced by Dapsone Hydroxylamine in Human Cells

Dapsone (DDS) hydroxylamine metabolites cause oxidative stress- linked adverse effects in patients, such as methemoglobin formation and DNA damage. This study evaluated the ameliorating effect of the antioxidant resveratrol (RSV) on DDS hydroxylamine (DDS-NHOH) mediated toxicity in vitro using human erythrocytes and lymphocytes. The antioxidant mechanism was also studied using in-silico methods. In addition, RSV provided intracellular protection by inhibiting DNA damage in human lymphocytes induced by DDS-NHOH. However, whilst pretreatment with RSV (10-1000 μM significantly attenuated DDS-NHOH-induced methemoglobinemia, but it was not only significantly less effective than methylene blue (MET), but also post-treatment with RSV did not reverse methemoglobin formation, contrarily to that observed with MET. DDS-NHOH inhibited catalase (CAT) activity and reactive oxygen species (ROS) generation, but did not alter superoxide dismutase (SOD) activity in erythrocytes. Pretreatment with RSV did not alter these antioxidant enzymes activities in erythrocytes treated with DDS-NHOH. Theoretical calculations using density functional theory methods showed that DDS-NHOH has a pro-oxidant effect, whereas RSV and MET have antioxidant effect on ROS. The effect on methemoglobinemia reversion for MET was significantly higher than that of RSV. These data suggest that the pretreatment with resveratrol may decrease heme-iron oxidation and DNA damage through reduction of ROS generated in cells during DDS therapy.

In vitro toxic action potential of anti tuberculosis drugs and their combinations

Tuberculosis (TB) is one of the leading infectious causes of death due to single infectious agent after HIV/AIDS. Rifampicin (RIF), Isoniazid (INH), Ethambutol (EMB), Pyrazinamide (PZA) and/or their combinations are extensively prescribed to treat TB. Despite several therapeutic implications, these drugs also produce several toxic effects at cellular level. MTT assay and Ames test were adopted in this study for the determination of cytotoxic and mutagenic potential of these anti-TB drugs. Among all tested drugs, cytotoxic potential of RIF was strongest with highly significant decline (p<0.001) in cell numbers at the concentration of 250μg/ml with LC50 at 325μg/ml, while significant decline (p<0.01) in cell count was observed in INH treated group at the concentration 500μg/ml with LC50 at 1000μg/ml. Moreover, combination RIPE demonstrated significant reduction (p<0.01) in cell number at the concentration of 25-500-500-500μg/ml with LC50 at 60-1200-1200-1200μg/ml. It is apparent from the data that almost all drugs represented identical mutagenic pattern i.e., more significant results were achieved in TA100 with metabolic activation (+S9). RIF proved to be highly mutagenic of all tested drugs with significant mutagenicity (p<0.01) at 0.0525μg/plate against TA98 strain with S9. The combination RIPE exhibited highly significant mutagenic activity (p<0.01) at concentration 0.125-3-3-3μg/plate without S9, while addition of S9 resulted in similar activity at lower doses, i.e., 0.0525-1-1-1μg/plate. It was concluded from the data that all anti-TB drugs possess significant cytotoxic and mutagenic potential, especially in combination, making TB patient more vulnerable to cytotoxic and mutagenic effects of anti-TB drugs, which could produce further health complications in TB patients.

Vitamin C Modulation of Cisplatin-Induced Cytogenotoxicity in Bone Marrow, Spermatogonia and its Transmission in the Male Germline of Swiss Mice

Relative modulatory effects of three different doses of vitamin C (VC), 10, 20 and 40 mg/kg, on cytogenotoxicity induced by cisplatin (CP) 5 mg/kg were assessed from the comparison of chromosomal aberrations (CAs) and mitotic index in bone marrow cells, micronucleus test (MNT) in polychromatic erythrocytes from the somatic cell line and spermatogonial chromosome aberrations (SCAs), primary spermatocytic chromosome analysis and sperm morphology assay from the male germline of VC-pretreated and CP-alone treated mice. Each pretreatment dose of VC protected bone marrow cells from the CP-induced cytogenotoxicity by decreasing the aberrant metaphases, CAs and MN significantly, particularly the lower doses. The protection was inversely proportional to the pretreated dose of VC i.e., the higher the dose of VC the less protection was provided. The lower doses of VC also protected the spermatogonial cells by significantly decreasing the CP-induced aberrant metaphases and SCAs, whereas the highest dose potentiated such effects by increasing them significantly. Besides, transmission of CP-induced cytogenotoxicity in the male germline was enhanced significantly in all VC pretreated mice, resulting in an increase in the frequency of aberrant prima ry spermatocytes and abnormal sperm. Since the spermatogonial cells with gross effects were eliminated/died, the tolerable effects stabilized in some of them were transmitted through the male germline with the consequent increase in the manifestation of aberrant primary spermatocytes and abnormal sperm. However, VC failed to decrease in the transmission of such effects. Thus, the protective action of VC was dose dependent and tissue specific. Moreover, the time of VC treatment i.e., its pre- or post-treatment to the exposure of cells to cytogenotoxic substances is important in providing protection from or potentiation of the cytogenotoxic effects.

Studying the effect of antioxidants on cytogenetic manifestations of solvent exposure in the paint industry

OBJECTIVE

To investigate the antioxidant role in reversing cytogenetic changes caused by solvent exposure in paint industry.

SUBJECTS AND METHODS

A prospective controlled clinical trial was performed on 39 workers exposed to solvents and 39 workers not exposed to solvents by supplying a mixture of antioxidant vitamins (A, C, E and selenium) and the after effects of such regimen were analyzed. Environmental monitoring was carried out for air concentrations of different solvents at workplace. Exposed group was cytogenetically tested before and after giving the mixture of antioxidant vitamins for 1 month duration.

RESULTS

Frequency of chromosomal aberrations (CAs) and the mean of sister chromatid exchanges (SCEs) were statistically significantly higher among exposed workers than among controls. After the supplementation of antioxidants, there was a statistically significant decrease in the frequency of CAs, and 88% abnormal levels of SCEs were back to normal levels.

CONCLUSION

Antioxidant supplementation decreases the frequency of CAs and SCEs among exposed workers.

Investigation of cytotoxic and mutagenic effects of Malpighia glabra L. (barbados cherry) fruit pulp and vitamin C on plant and animal test systems

Fruits are important sources of nutrients in human diet, and Barbados Cherry (Malpighia glabra L.) is of particular interest due to its high content of antioxidants. Diets rich in fruits and vegetables protect individuals against diseases and cancer, but excessive intake of vitamins may act as pro-oxidant and generate changes in DNA. To evaluate the effect of different in natura (BAN) and frozen (BAF) Barbados Cherry pulp concentrations and synthetic vitamin C in liquid form (VC) on the chromosome level and the cell cycle division, root meristeme cells of Allium cepa L. and bone marrow cells of Wistar rats Rattus norvegicus, were used as test system. In Allium cepa L., BAN, at the highest concentration (0.4 mg.mL-1) and BAF, at the lowest concentration (0.2 mg.mL-1), inhibited cell division, and there was recovery of cell division after the recovery period in water only for BAN. In the Wistar rats, all treatments with Barbados Cherry, either acute or subchronic, were not cytotoxic or mutagenic; only the highest concentration of VC increased significantly the rate of chromosomal abnormalities. The data obtained are important to reinforce the use of Barbados Cherry fruit in the diet.

The protective role of ascorbic acid on imazalil-induced genetic damage assessed by the cytogenetic tests

Ascorbic acid (AA), known as vitamin C, has important antioxidant and metabolic functions, making its incorporation into the human diet essential. On the other hand, imazalil (IMA), a commonly used fungicide in both agricultural and clinical domains is suspected to produce very serious toxic effects in vertebrates. In this study, the antigenotoxic effects of AA were studied against the genotoxic damage induced by IMA on cultured human lymphocytes using chromosomal aberration (CA) and sister chromatid exchange (SCE) as genetic end points. Human peripheral lymphocytes were treated in vitro with varying concentrations of AA (25, 50, 100, 200, and 400 μg/ml), tested in combination with IMA (336 mg/L). AA alone was not genotoxic and when combined with IMA treatment, reduced the frequencies of CAs and SCEs. A clear dose-dependent decrease in the genotoxic damage of IMA was observed, suggesting a genoprotective role of AA. In conclusion, the preventive role of AA in alleviating IMA-induced DNA damage was indicated for the first time in the present study.

Antigenotoxic and anticytotoxic effect of camel milk in mice treated with cisplatin

Camel milk (CM) has good nutritive value, in addition to its antigenotoxic and anticytotoxic effects. Therefore the aim of this investigation was to evaluate the capacity of CM to inhibit the micronucleated polychromatic erythrocytes (MnPCEs) in the bone marrow and improve the mitotic activity produced by cisplatin. Cisplatin is one of the most widely used antineoplastic drugs in the treatment of cancer. The 70 adult male Swiss albino mice were divided into seven groups:Gr. I: treated with distilled water and considered as a control group.Gr. II: treated with camel milk (33 ml/kg, b.w).Gr. III: treated previously with cisplatin (0.5 mg/kg, b.w).Gr. IV: treated with camel milk and followed after 2 h. with cisplatin (33 ml/kg → 0.5 mg/kg, b.w).Gr. V: treated with camel milk and cisplatin at the same time (33 ml/kg + 0.5 mg/kg, b.w).Gr. VI: treated with an acute single dose of cisplatin (2.5 mg/kg, b.w).Gr. VII: treated with camel milk prior and followed with an acute single dose of cisplatin (33 ml/kg → 2.5 mg /kg, b.w). The animals were sacrificed 24 h after cisplatin injection. The pretreatment with CM dose caused a significant decrease (P < 0.001) in the frequency of MnPCEs and increase (P < 0.001) in the mitotic index (MI) induced by cisplatin when compared with the groups treated with cisplatin alone. The possible explanation for the antigenotoxic and anticytotoxic effects observed in the pretreatment with CM is ascribed to its contents. In conclusion, from the findings we suggest that this milk has some antioxidant effect, and the antigenotoxic mechanism of this milk needs to be explored further before their use during cisplatin chemotherapy.

Antimutagenic effect of neem leaves extract in freshwater fish, Channa punctatus evaluated by cytogenetic tests

Neem (Azadirachta indica), an indigenous plant commonly grown in India and its sub-continent is a multipurpose plant well known for its insecticidal and biomedical properties, however, its antimutagenic effects in vertebrate organisms are lacking. The present work is therefore, focused on possible antimutagenic potential of ethanolic extract of neem leaves evaluated on the clastogenicity induced by Pentachlorophenol (PCP) and 2, 4-dichlorophenoxyacetic acid (2,4-D) in freshwater fish, Channa punctatus used as a vertebrate model, by cytogenetic endpoints: chromosome aberration (CA) and micronucleus (MN) test. In the first set of experiment, fish were exposed by medium treatment to a single treatment of each chemical (PCP, 0.6 ppm; 2,4-D, 75 ppm; neem extract, 3 ppm) along with the controls. The chromosome preparations were made after processing kidney cells and micronucleus slides were prepared from peripheral blood at multiple duration (48, 72 and 96 h). PCP and 2,4-D when used alone, induced significant CA and MN in a time dependent manner. Neem extract did not show genotoxic potential in both assays. The maximum frequency of CA were recorded as 18.58% and 15.17%, while frequency of MN reached to 8.08% and 4.62% by PCP and 2,4-D respectively, after 96 h exposure. In the second set of experiment, three concentrations of neem extract (1, 2 and 3 ppm) were run simultaneously with the same concentration of PCP (0.6 ppm) and 2,4-D (75 ppm) for antimutagenicity estimates. In mixed treatment, neem extract significantly reduced the frequency of CA and MN. The reduction in the frequency of CA ranged from 40-75% and 45.4-83.3% and similar values for MN were 40.2-75.3% and 44.1-65.8% for PCP and 2,4-D respectively. Although the reductions were significant but not dependent on concentration and time intervals employed. Results suggested that under present experimental conditions, neem extract exhibit strong antimutagenic activity in this fish model, which could further contribute to study its benefit in humans.