Cytotoxic and genotoxic profiles of the pyrethroid insecticide lambda-cyhalothrin and its microformulation Karate® in CHO-K1 cells

Lambda-cyhalothrin (LCT) and its microformulation Karate® (25 % a.i.) were analysed for its genotoxicity and cytotoxicity on Chinese hamster ovary (CHO-K1) cells. Cytokinesis-block micronucleus cytome (CBMN-cyt) and alkaline single-cell gel electrophoresis (SCGE) bioassays were selected to test genotoxicity. Neutral red uptake (NRU), succinic dehydrogenase activity (MTT) and apoptogenic induction were employed for estimating cytotoxicity. Both compounds were analysed within a concentration range of 0.1-100 µg/mL. Only LCT produced a significant augment in the frequency of micronuclei (MNs) when the cultures were exposed to highest concentrations of 10 and 100 µg LCT/mL. A noticeable decrease in NDI was observed for cultures treated with LCT at 10 and 100 µg/mL. Karate® induced the inhibition of both the proportion of viable cells and succinic dehydrogenase activity and triggered apoptosis 24 h of exposition. Whilst an increased GDI in CHO-K1 cells was observed in the treatments with 1-100 µg Karate®/mL, the GDI was not modified in the treatments employing LCT at equivalent doses. SCGE showed that Karate® was more prone to induce genotoxic effects than LCT. Only 50 µg/mL of Karate® was able to increase apoptosis. Our results demonstrate the genomic instability and cytotoxic effects induced by this pyrethroid insecticide, confirming that LCT exposure can result in a severe drawback for the ecological equilibrium of the environment.

Cytotoxic and genotoxic assessments of 2,4-dichlorophenoxyacetic acid (2,4-D) in in vitro mammalian cells

A combined approach employing alkaline single cell gel electrophoresis (SCGE) and cytokinesis-blocked micronucleus (MNs) cytome bioassays was adopted to assess the deleterious properties of the auxinic 2,4-dichlorophenoxyacetic acid (2,4-D) and its microparticulated low volatility product Dedalo Elite (30% a.i.) on Chinese hamster ovary (CHO-K1) cells. Cytotoxicity was estimated by neutral red uptake (NRU), succinic dehydrogenase activity (MTT) and apoptosis assessment. Both compounds were assayed at 0.1-10 μg/ml concentration range. Whereas exposed CHO-K1 cells revealed a statistically significant enhancement of MNs when 10 μg 2,4-D/ml was assayed, MNs were only achieved in cells treated with 2 μg Dedalo Elite/ml. A diminution in the nuclear division index was only achieved after exposure to Dedalo Elite within the 1-10 μg/ml concentration range. Whereas increased genetic damage index was achieved when 6 and 10 μg 2,4-D/ml were assayed, GDI induction was observed in treatments employing 4 μg Dedalo Elite/ml. Both compounds induced cytotoxicity by inhibition of both lysosomal and MTT activities by enhancing the frequencies of early and late apoptotic cells. Our results not only indicate the genotoxic and cytotoxic potential of 2,4-D and its microparticulated marketplace formulation, but also highlight the risk of these agrochemicals present towards the biota and human health.

Folic acid enhances the apoptotic and genotoxic activity of carboplatin in HeLa cell line

In human tumor cells, experimental and clinical evidence indicates that some factors involved in signal transduction and cell growth can also modulate the response to chemotherapeutic treatment. The aim of the present study was to investigate the role of folic acid (FA) as a modulator of carboplatin (CBDCA) activity. Genotoxicity and cytotoxicity induced by CBDCA alone and in combination with FA were assessed in cultured HeLa cells. We used comet assay, mitotic index analysis, MTT and NR assays, cytokinesis-block micronucleus cytome assay and annexin V-IP as different cytotoxicity and genotoxicity approaches for human cervical carcinoma cell line studies. The results showed that addition of 900nM FA together with 40.4mM CBDCA enhanced the activity of the platinum compound, increasing its effect on cell death by nearly 20%, as evidenced by the MTT and NR assays. Moreover, not only higher levels of DNA and chromosomal damage were reached but also the number of necrotic and apoptotic cells were significantly increased when cell cultures were treated with the combined procedure. This situation opens the possibility to explore the use of FA in platinum-based chemotherapy protocols to reduce the platinum doses for patient treatment and decrease the chance of developing the known side effects without losing biological activity.

Carbamates: A study on genotoxic, cytotoxic, and apoptotic effects induced in Chinese hamster ovary (CHO-K1) cells

In vitro effects of the carbamates pirimicarb and zineb and their formulations Aficida® (50% pirimicarb) and Azzurro® (70% zineb), respectively, were evaluated in Chinese hamster ovary (CHO-K1) cells. Whereas the cytokinesis-blocked micronucleus cytome assay was employed to test for genotoxicity, MTT, neutral red (NR), and apoptosis evaluation were used as tests for estimating cell viability and succinic dehydrogenase activity, respectively. Concentrations tested were 10-300 μg/ml for pirimicarb and Aficida®, and 1-50 μg/ml for zineb and Azzurro®. All compounds were able to increase the frequency of micronuclei. A marked reduction in the nuclear division index was observed after treatment with 5 μg/ml of zineb and Azzurro® and 10 μg/ml of Azzurro®. Alterations in the cellular morphology not allowing the recognition of binucleated cells exposed to 300 μg/ml pirimicarb and Aficida® as well as 10-50 μg/ml zineb and Azzurro®. All four compounds induced inhibition of both cell viability and succinic dehydrogenase activity and trigger apoptosis in CHO-K1 cells, at least when exposed for 24 h. The data herein demonstrate the genotoxic and cytotoxic effects exerted by these carbamates and reveal the potential risk factor of these pesticides, still extensively used worldwide, for both human health and the environment.

Comparative evaluation in vitro of the herbicide flurochloridone by cytokinesis-block micronucleus cytome and comet assays

The in-vitro effects of flurochloridone and its formulations Twin Pack Gold® (25% a.i.) and Rainbow® (25% a.i.) were evaluated in Chinese Hamster Ovary K1 (CHO-K1) cells. The cytokinesis-block micronucleus cytome (CBMN-cyt) and single-cell gel electrophoresis (SCGE) assays were used. The activities were tested within the range of final concentrations of 0.25-15 μg flurochloridone/mL. The results demonstrated that both the flurochloridone and Rainbow® were not able to induce micronuclei (MN). On the other hand, Twin Pack Gold® only increased the frequency of MN at 5 μg/mL. Furthermore, 10 and 15 μg/mL of both formulations resulted in a cellular cytotoxicity demonstrated by alterations in the nuclear division index and cellular death. SCGE assay appeared to be a more sensitive bioassay for detecting primary DNA strand breaks at lower concentrations of flurochloridone than MN did. A marked increase in the genetic damage index was observed when 5 and 15 μg/mL of both flurochloridone and Rainbow® but only when 15 μg/mL of Twin Pack Gold® were used. This is the first report demonstrating that flurochloridone and its two commercial formulations are able to induce single-strand DNA breaks in vitro on mammalian cells.