Fungicides are the most effective method to control fungal microorganisms which cause plant diseases. The benzimidazole group of fungicides acts by inhibiting microtubule formation. Benomyl and its metabolite carbendazim are the most commonly used benzimidazole group systemic agricultural fungus in developing countries. Benomyl is an important teratogenic agent, have toxic effects on male reproductive system and also on the nervous system due to the mechanisms that disrupt the microtubule organization are also frequently encountered. Carbendazim is also known aneugen fungucide. In our study, the cytotoxic effects of benomyl and its metabolite carbendazim were investigated by MTT and NRU tests on human neuroblastoma cell line (SH-SY5Y) and rat kidney epithelial cell line (NRK-52E) and their genotoxic effects were tested by Comet assay. According to the results of cytotoxicity in our study, the LC50 values in SH-SY5Y and NRK52E cell lines were 108.7μM and 25.7μM for benomyl, respectively; and 201.3μM and 1619.5μM for carbendazim, respectively. As a result of our cytotoxicity study, the doses to be used in the genotoxicity assessment were determined for benomyl and carbendazim in both cell lines. According to Comet assay results it has been observed that benomyl and carbendazim have genotoxic effects on SH-SY5Y and NRK52E cell lines.
Fungucides have been commonly used pesticides against fungal diseases in the aim of increase crop production. However adverse effects of fungucides on other species not yet clearly identified. It is important to understand mechanisms that play role under toxic effects for effective hazard identification and risk assessment, increase beneficities of fungucides and also protect non-target species [1]. Benzimidazole fungucides have systemic effects and selectively disrupt tubulin biosynthesis through inhibit α and β tubulin dimerisation that cause disruption in fungal spindle fibril structures. Benomyl and its metabolite carbendazim are widely used benzimidazole fungucides against to crop fungi and believed that these fungucides are nontoxic to other species except male reproductive system [2].
Benomyl is metabolized into functionally active carbendazim and this metabolite is commonly used fungucide from farmers. Benomyl and carbendazim show their toxic effects by inhibiting mitosis through binding β tubulin subunits of microtubules [3-5]. Benomyl binds mammalian neuronal tubulins with low affinity and prevent polymerization of tubulins [6]. Due to weak and slow catabolism of carbendazim, its mostly retained in the tissues [7]. In mammalians, benomyl rapidly absorbed and metabolized through hydroxylation and hydrolysis in the liver and excreted into urine and feces [8]. Carbendazim; absorbed as high as 80-85% after oral exposure and then metabolizes many molecules [7]. Benomyl and carbendazim have severel adverse effects as male reproductive system disruptions, teratogenicity, neurodegeneration, dermal sensitisation, tubular degeneration in kidney, liver toxicity, endocrine disruption and cancer [9-15]. There is only one studyabout benomyl’ toxic effect on SH-SY5Ycells in the literature and no data about carbendazim cytotoxic and genotoxic effect on SH-SY5Ycells [16], and therewithal there is no data on NRK52E cell line. In this study the aim was to investigate cytotoxic and genotoxic effects of benomyl and carbendazim commercial products on SH-SY5Y and NRK52 cell lines.
NRK-52E MTT Exposure Doses (µM) |
|
Benomyl |
10-100 |
Carbendazim |
50-1100 |
SH-SY5Y MTT Exposure Doses (µM) |
|
Benomyl |
6.25-250 |
Carbendazim |
25-350 |
NRK-52E NRU exposure doses (µM) |
|
Benomyl |
10-100 |
Carbendazim |
500-1100 |
SH-SY5Y NRU exposure doses (µM) |
|
Benomyl |
25-250 |
Carbendazim |
100-350 |
NRK-52E Cell Line Exposure Doses |
|||||
Benomyl |
10μM |
5μM |
2,5μΜ |
1,25μM |
Control |
Carbendazim |
900μΜ |
450μM |
225μM |
112,5μM |
Control |
SH-SY5Y Cell Line Exposure Doses |
|||||
Benomyl |
60μΜ |
30μM |
15μΜ |
7,5μM |
Control |
Carbendazim |
100μΜ |
50μM |
25μM |
12,5μM |
Control |
MTT and NRU tests results calculated and evaluated with Microsoft Office Excel Programme. Data were analyzed by one-way ANOVA Dunnett t-test and expressed as mean±SE. The level of statistical significance was set at p0.05, and all analyses were performed using the statistical package SPSS version 17.0 for Windows (SPSS Inc., Chicago, IL).
SH-SY5Y |
P Value |
NRK |
P Value |
||
Groups |
Mean ±SD |
|
Groups |
Mean ±SD |
|
Control |
3,774±0,632 |
|
Control |
4,184±0,377 |
|
7,5µM |
3,191±0,607 |
>0,05 |
1,25µM |
5,291±0,617 |
>0,05 |
15µM |
4,712±1,372 |
>0,05 |
2,5µM |
5,669±0,364 |
>0,05 |
30µM |
5,2349±0,522 |
<0,05* |
5µM |
4,959±0,950 |
>0,05 |
60µM |
6,306±0,344 |
<0,05* |
10µM |
3,514±0,238 |
>0,05 |
Table 3: Tail intensity values of Benomyl on SH-SY5Y and NRK cells.
Note: *significantly increased compared to control group.
SH-SY5Y |
P Value |
NRK |
P Value |
||
Groups |
Mean±SD |
|
Groups |
Mean±SD |
|
Control |
3,774±0,632 |
|
Control |
6,467±0,336 |
|
12,5µM |
4,235±1,393 |
>0,05 |
112,5µM |
8,926±1,230 |
<0,05* |
25µM |
3,869±0,772 |
>0,05 |
225µM |
9,787±0,604 |
<0,05* |
50µM |
5,224±0,683 |
>0,05 |
450µM |
12,45±0,932 |
<0,05* |
100µM |
5,260±1,453 |
>0,05 |
900µM |
12,19±0,219 |
<0,05* |
Table 4: Tail intensity values of Carbendazim on SH-SY5Y and NRK cells.
Note: *significantly increased compared to control group.
The benzimidazole pesticides benomyl and its main metabolite carbendazim, are fungicides that target to microtubules and inhibit microtubule asssembly and perturbing microtubule formation so this resulted with chromosomal assemble disruptions. It has been reported that carbendazim inhibit mitosis by disrupting the polymerization of mammalian tubulin into microtubules and arrest the cell cycle at the G2/M phase in turn induce apoptosis. Benomyl and carbendazim are worldwide used antifungal pesticides. It has been shown in different studies that benomyl and carbendazim cytotoxic effects on pancreas, prostate, colon and breast tissues. And also carbendazim have role on immun system deregulation [18-20].
In our study we found that the IC50 values of benomyl on NRK52E and SH-SY5Y cells were 25,78μM and 108,7μM and carbendazim were 1619,47μM and 201,27μM. DNA damage increased dose dependent with benomyl and carbendazim in NRK cells and in SH-SY5Y cells DNA damage increased in 30 and 60µM groups compared to control.There are different studies in the literature about cytotoxic and genotoxic effects of benomyl and carbendazim on different cells. Chang et al. [20], showed cell proliferation inhibition in human endometrial cells of benomyl and carbendazim with dose dependent . Laryae et al. [18], showed that benomyl have more potent cytotoxic effect than carbendazim on T-cell leukomia, multiple myeloma, small cell lung cancer, renal adenocarcinoma, cervical adenocarcinoma, normal retinal epithelial cells and LNCaP cells. In LNCaP cells IC50 values of benomyl and carbendazim were reported as 15±5.7 and 50±9.0 mmol/l.In another study in cultured rat hepatocytes 35ug/ml benomyl decreased 49% cell viability [21]. Dierickx [22], reported benomyl and carbendazim’s IC50 values in HepG2 cells are 203uM and >1750uM and in Fa32 cell 205uM and >1750uM neutral red uptake inhibition assay. In this study Dierickx classified benomyl more toxic chemical compared to carbendazim, quinalphos, carbaryl, piperonyl butoxide and 1-Aminobenzotriazole.
In another study with benomyl effects on 16HBE14o-(16HBE) human bronchial epithelial cells results indiated that IC50 values of benomyl administration for 24 or 48h are 44.2 and 7.2μM [23]. In human placental trophoblast cell line (HTR-8), compared to control group 2.5 and 5μM benomyl doses reduced cell viability by 5.79% and 6.49% and 5μM carbendazim dose decreased viability by 5.17% [24].
Benomyl and carbendazim classified as IARC group 2B possible human carcinogens. Benomyl is an aneugenic pesticide that disrupt microtubule formation. Benomyl caus micronuclei formation dyring cell division mechanism. It has been reported that 3.2-4.1mM benomyl concentrations associaed with chromosomal abormalities [25]. Lebailly et al. [26], reported that, benomyl administration in human peripheral blood lymphocytes up to 500uM did not increase DNA damage with Comet Assay. 1000mg/kg benomyl induces DNA damage in Japanese quails [27]. It has been demonstrated in several different studies that carbendazim induce DNA damage in different species asDaphnia magna, Eisenia foetida earthworms, Donax faba,mice, rat, in human lymphocytes. In D.magna species it has been demonstrated with comet assay that, carbendazim induce DNA damage cumulative and were seen in all the generations with multigenerational study. In another study, carbendazim induce DNA damage with duration dependent in Eisenia foetida earthworms [26-32].
In conclusion, our in-vitro study results in accordance with different studies about benomyl and carbendazim’s cytotoxic and genotoxic effects. While benomyl and carbendazim usage restricted in many countries, their usage stil continue in many developing countires. Thus deailed studies on these fungusides about its usage currency, accumulation in the environment, detailed mechanistic studies on their toxic effects should be clarified with further studies.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Citation: Kara M, Jannuzzi AT, Yön ? (2019) In-Vitro Investigation of the Cytotoxic and Genotoxic Effects of Benzimidazole Group Pesticides Benomyl and Carbendazim. J Toxicol Cur Res 3: 007.
Copyright: © 2019 Mehtap Kara, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.