4.1. Antioxidant in irradiated plant leaves
The irradiation treatment can increase the content of some phytochemicals and the plant's antioxidant activity, thereby increased biological value (Zevallos-Concha et al., 2016; Pereira et al., 2018). The results indicated that the extract of irradiated basil showed a highly significant increase in total antioxidants as a comparison to raw basil. Similar observations were reported in previous studies on basil and some other plants (Khawory et al., 2020; Osman, Ghazwani and Balamash, 2020; Rady et al., 2020).
Basil contains phenolic compounds and flavonoids (Bahcesular et al., 2020), that are considered as natural antioxidants. These biomolecules exhibit their activity through various mechanisms, including inhibiting enzymes that inducing free radical produce, increasing endogenous antioxidants, removing free radicals, and inducing the expression of the numerous genes responsible for enzyme synthesis that inhibit oxidative stress (Primiano, Sutter and Kensler, 1997). Ghazwani, Osman and Balamash (2020) reported that the Fourier-transform infrared (FTIR) analysis indicated to increase the content of phenolic acids and flavonoids in basil leaves after treated with 10 kGy of gamma-ray. Moreover, Maraei, Khaled and Elsawy (2017) reported that the gamma irradiation-induced the biosynthesis of certain phenolic compounds. Also, it seems that gamma irradiation with 10 kGy might stimulate some chemical reactions in basil, which perhaps increase in phenolic content by the breakdown of covalence bonds among phenolic components and, free phenolic components with low molecular weight are increasing (Jamshidi, Barzegar and Sahari, 2014).
4.2. Complete blood count (CBC)
A complete blood count test is a blood test used to assess general health and detect a range of disorders in hematological parameters. A complete blood count test measures many blood components and features, including red blood cells that carry oxygen, white blood cells that fight infection, hemoglobin that oxygen-carrying protein in red blood cells, hematocrit that indicate to the ratio of red blood cells to the liquid or plasma component of the blood and platelets that help blood clot, and that any change whether an abnormal rise or decrease in the census, indicate the incidence of diseases or disorders requiring medical procedures (Clinic, 2018).
In our study, it has been observed that the levels of HB, RBC, PLT, NEU, and LYM are decreased significantly with a marked increase in the HCT, WBC, MON and reticulocyte count in rats exposed to arsenic compared to the control group. The results are consistent with some studies (Kajiguchi et al., 2005; Bhattacharya and Haldar, 2012; Sumedha and Miltonprabu, 2013; Lemaire et al., 2015; Ghosh et al., 2017; Su et al., 2018). This effect of Arsenic exposure on the hematopoietic system may be attributed to the mechanisms of arsenic toxicity which may induce hemolysis and erythrophagocytosis through increased oxidation of sulfhydryl groups in hemoglobin and decreased oxygen intake by cells as a result of decreased intracellular glutathione, which decreases the lifespan of erythrocytes (Abdul et al., 2015). Moreover, arsenic exposure can also cause a range of changes, such as increasing ceramide formation, membrane disintegration, cytosolic calcium levels, besides decreasing in adenosine triphosphate (ATP) levels, cell membrane integrity affecting erythrocyte lifespan (Abdul et al., 2015).
Regarded the change in platelet count, this confirmed that arsenic inhibited platelet differentiation within the hematopoietic system of bone marrow, leading to reduced platelet production (Wu et al., 2014).
The white blood cell level was decreased in arsenic feed groups. It might be due to the impact of arsenic which induced apoptotic effect on plasma cells as noted by Rousselot et al. (2004). WBC may generally be divided into five classes, based on their function, morphology and origin: LYM, MON and NEU (Villa et al., 2003). The changes in the LYM and NEU populations present in this study may be due to arsenic caused immune inhibition in rats (Taheri et al., 2016).
Our findings demonstrated that extracts of basil caused improved the disorders that occur in CBC. This is in agreement with the results of previous researches (Ofem, Ani and Eno, 2012; Zangeneh et al., 2019). This effect may due to basil which contains a proportion of iron (Nworgu, Yekini and Oduola, 2013), that contributes to improving the level of HB in the blood and has the ability to stimulate production and increase of RBC to treat deficiency caused by arsenic. Furthermore, in normal, the lack of oxygen in the local tissue appears to lead to the production of glycoprotein known as erythropoietin, which induces increased erythrocyte output (Bowman and Rand, 1980). Basil leaves extract is very likely to contain erythropoietin-like agents that are responsible for increased erythrocyte production (Ofem, Ani and Eno, 2012). Saha et al. (2012) reported that secondary metabolites of basil, consisting of important elements include essential oil geraniol, a monoterpene and citral, play a role as the modulator in hematological abnormalities (Ofem, Ani and Eno, 2012). Moreover, in results about the increased lymphocyte count after basil administration, it has been reported that Ocimum basilicum modulates the cell-mediated as well as a humoral immune response that could be due to the presence of flavonoids and terpenoids (Mediratta, Sharma and Singh, 2002).
Antibodies also are known as immunoglobulins, are substances made by the body's immune system in response to foreign substances. Antibodies bind to these foreign substances and they can be killed by the immune system. IgG, IgM and IgA from the major types of antibodies. If reduced levels of antibodies produced by the immune system, it leads to more likely to develop repeated infections (Staff, 2019).
The results of our study showed that in the arsenic group of rats (10 mg/kg BW) a highly significant reduction was observed in IgG, IgA and IgM levels compared to the control group. The results are consistent with some studies (Institoris et al., 2001; Sankar et al., 2013). The effect on immunoglobulin levels associated with arsenic exposure can attribute to the arsenic disrupts glucocorticoid regulation, responsible for immune function (Kaltreider et al., 2001). Furthermore, the apoptosis caused by arsenic may result in decreased immune responses (Harrison and McCoy, 2001).
The administration of water extract from raw or irradiated basil extract demonstrated a protective effect against arsenic toxicity in rats, by increasing antibodies that decreased as a result of arsenic poisoning. These results are in line with the findings of Mohammed, Kadhim and Taher (2017) and Jahejo et al. (2019). Jeba, Vaidyanathan and Rameshkumar (2011) showed that aqueous extract of basil stimulated the antibody production in rats. The flavonoids present in the basil leaves are mainly responsible for the immunomodulatory effect (Ravindran, 2017).
4.4 Inflammatory markers
Inflammation is a biological response of the immune system which can be induced by damaged cells, toxic compounds or pathogens (Medzhitov, 2010). It is part of the body's defense mechanism. one of the major aims of inflammation is to bring immune cells to the area of concern as well as to inactivate or destroy any injurious stimuli and to also begin the repair (Ferrero-Miliani et al., 2007; Medzhitov, 2010). The inflammation response is caused by specific immune factors released from the damaged cells. Where, the damaged cells release cytokines, including interleukins, such as IL-6, IL-8, and tumor necrosis factor-α, that are responsible for communication between white blood cells. Interleukins also stimulate the production and release of CRP from the liver; an important component of the innate immune system (Sinclair, Wang and Tetrick, 2012).
Usually, molecular and cellular activities and interactions efficiently alleviate inevitable infection or damage, during acute inflammatory responses. This effect helps restore homeostasis in the tissue and overcome the acute inflammation. Uncontrolled acute inflammation can become chronic, however, and can lead to a number of chronic inflammatory diseases (Zhou, Hong and Huang, 2016). The elevated levels of inflammatory markers are expected to be associated with toxic metals exposure.
Results of this study showed that serum IL-6, TNF-α and CRP level in rats exposed to arsenic was highly significantly elevated. Our findings agree with the results of the previous study on the association between arsenic and ability to cause chronic inflammation by demonstrating the increased pro-inflammatory mediators like TNF-α, IL-6 and CRP in the arsenic exposed group in comparison to the control group (Prasad and Sinha, 2017). Inflammation considered to be one of the main arsenic toxicity mechanisms that can be correlated with increasing cellular damages ,oxidative stress and lipid peroxidation (Bhadauria and Flora, 2007).
In this work also, it was demonstrated that oral treatment with basil extracts diminished inflammations in rats exposed to arsenic. These results in agreement with Aye et al. (2019) and Takeuchi et al. (2020) who found that basil has anti-inflammatory effects. Rodrigues et al. (2016) reported that the basil essential oil was effective in reducing inflammations (acute or chronic) by induced inhibiting of the inflammatory mediator receptors and the migration of cells to stimulus locations. This may be attributed to the contains of basil of rosmarinic acid (Kwon et al., 2019), where this compound has been related to anti-inflammatory activities (Luo et al., 2020).
4.5 Antioxidants and oxidative damage
Antioxidants are considered the enzymes of the body's protection, are able to stabilize free radicals before attacking components of the cell. They work to diminishing free radicals through reducing their energy or donate electrons to them, thus making it stable (Krishnamurthy and Wadhwani, 2012). While, "oxidative stress, defined as a disturbance in the balance between the production of reactive oxygen species (free radicals) and antioxidant defenses" (Betteridge, 2000).
In the present study, observed a very highly significant decrease in GSH, SOD and CAT accompanied by increased MDA of the rat's brain in the arsenic group as compared to the normal control group. This result is similar to the study of Sun et al. (2018) that reported that arsenic caused significantly decreased GSH, SOD and CAT with increased MDA content in the brain tissues of chickens. This may be attributed to the toxic effect of arsenic that may induce oxidative stress by interacting with antioxidants, resulting in the accumulation of free radicals in cells (Bonetto, Villaamil Lepori and Puntarulo, 2014).
In contrast, basil giving a positive effect on the brain by improving the levels of antioxidant antioxidants, and fat oxidation (MDA). These results were in line with recent studies showed that the water extract of gamma-irradiated basil contributes to improving the oxidative stress induced by arsenic exposure in rats (Ghazwani, Osman and Balamash, 2020; Osman, Ghazwani and Balamash, 2020). Also agree with the results of Khodabakhshi et al. (2017), who proved that the increased level of MDA in the mice brain tissue following seizures was prevented by basil extract. Moreover, Khaki (2016) demonstrated that the basil extract protects brain cells from the harmful effects by regulating the antioxidant enzymes in the serum. This saves the neurons from irreversible cell injury. The antioxidant effect is due primarily to phenolic elements, such as, phenolic acids and flavonoids, which have redox properties and ability to neutralize free radicals (Shahidi, Janitha and Wanasundara, 1992).