Antioxidant activity of Cynodon dactylonmediated selenium nanoparticles

The nanoparticles are known to reduce toxicity, enhance bioactivity and improve targeting cells. Themetal andmetal oxide nanoparticles such as gold, silver, zinc oxide, zirconium oxide, copper oxide, copper sul ide, selenium, hydroxyl apatite, and titanium oxide were used in several biomedical applications especially diagnosis of cancer, etc. The selenium nanoparticles (SeNPs) are explored due toits unique characteristics and various known therapeutic bene its such as anti bacterial, anti fungal and anti cancer activities. The selenium nanoparticles actively involved in the free radical scavenging activity and anti in lammatory activity. The antioxidant activities and reducing risk of cancer.In this present study, Cynodondactylon or Bermuda grass mediated synthesis of selenium nanoparticles and it was characterized using UVvis spectrophotometer. And its antioxidant effect was analysed using DPPH assay. The plant extract of Cynodondactylon was prepared using distilled water and mixed with the sodium selenite solution. The solution was kept in a magnetic stirrer at 100 RPM for constant stirring while being observed for any colour change. The results showed that there was a signi icant antioxidant activity and peak con irm the selenium nanoparticles formation. Finally we conclude that the selenium nanoparticles can be used in various drug designing aspects in future.


INTRODUCTION
Cynodon dactylon is a warm-season perennial grass that can be grown on almost all soil types.Cynodon dactylon has been shown to possess various medic-inal properties. The aqueous extract of the plant is used as antioxidant, anti-in lammatory, diuretic, antiemetic, antidiabetic and blood-purifying agent (Harlan and Wet, 1969). Recent studies have also shown promising effects on kidney stone disease and can be used as a value-added agent for managing diabetes as well as oxidative stress associated with it (Zhao et al., 2011).
Among the different nanoparticles such as silver nanoparticles and gold nanoparticles from inorganic metals, nanoparticles from selenium (Se) have been explored. Selenium is an essential non-metal that is colourless and has zero oxidation state which makes it a biologically inert material . Selenium has lesser therapeutic factors and delicate toxicity margins whereas the nanoparticles of selenium possess reduced toxicity and potential therapeutic bene its such as being an antioxidant, reducing risk of certain cancers, protection against heart diseases, etc. The maximum safe dosage is dose in 300µg/day (Rajeshkumar and Bharath, 2017;Agarwal et al., 2018). Selenium nanoparticles have also been studied in various in lammation mediated disorders such as arthritis, cancer, diabetes and nephropathy (Gao et al., 2014). As an example of selenium nanoparticle's function as a treatment bene icial to human health, some studies have shown that selenium nanoparticles can show promising effects on kidney stone disease (Estevez et al., 2014). Hence, functionalized selenium nanoparticles have become the leading innovation in controlling Se dosage for such human health bene its. Studies have shown that selenium nanoparticles containing a variety of polysaccharides have a size range of 20-200 nm hence demonstrating the importance of using higher order saccharides to synthesise biologically therapeutic selenium nanoparticles. Using plants for NP synthesis can be advantageous over other biological processes because it eliminates the extensive process of cell culture maintenance and can also provide large scale NP synthesis (Zhang et al., 2004;Jia et al., 2015). This research aims to provide conjunction between the antioxidant activity of Cynodon dactylon and selenium nanoparticles materials in order to prove the antioxidant activity of Cynodon dactylon mediated with selenium nanoparticles.

Plant extracts preparation
1g of arrow root powder was measured and taken. The measured amount of plant powder was then mixed with 100ml of distilled water and boiled for 5-10 mins. The contents were iltered using a ilter paper, funnel and measuring cylinder as shown in Figure 1.

Synthesis of Cynodon dactylon selenium nanoparticles
0.519g of sodium selenite was mixed with 60ml of distilled water (Figure 2). To this solution, 40ml of plant extract was mixed. Then the Cynodon dactylon selenium solution was kept in the hot plate with magnetic stirrer for nanoparticle synthesis. The spectroscopy reading based on colour change was observed (Figure 2).
In this assay, 1ml of 0.1mM DPPH in methanol solution was mixed in different concentra-tions of Cynodon dactylon selenium solution of 10µL,20µL,30µL,40µL,50µL respectively. After 15 minutes of dark room incubation the reduction in the number of DPPH free radicals was measured by reading absorption at 517nm (Figure 3 (a) and (b)). Standard used was ascorbic acid (vitamin C). Antioxidant activity was analysed.

Formation of Cynodon dactylon selenium nanoparticles
In the performed selenium nanoparticles formulation process, sodium selenite solution was mixed with arrow root and no chemical reaction was observed. Slight brownish colour change is observed gradually in an interval of 24 h. Graph 1 shows the UV-vis spectroscopic readings of Cynodon dactylon selenium nanoparticles showed an absorbance value of 517 nm (Johnson et al., 1999;Yang et al., 2008).
The characteristic absorption does not originate from any synthetic precursors because the solution was subjected to iltration to remove any impurities. The strongest absorption intensity hails from when Cynodon dactylon selenium NPs concentration increases (Xiao et al., 2017). The antioxidant activity of SeNPs was studied using Free radical scavenging (DPPH) assay (Graph 2). The graphs obtained showed a peak at different intervals indicating synthesis of nanoparticles.

In vitro antioxidant activity of Cynodon dactylon selenium nanoparticles
Although oxygen is essential for life, the production of free radicals in our body provokes uncontrolled reactions. This may lead to the development of degenerative diseases such as diabetic complications, liver cirrhosis, nephrotoxicity, cancer etc. Reactive oxygen species such as super oxide anions, hydroxyl radicals and nitric oxide inactivate certain enzymes and causes damage to important cellular components causing tissue injury (Re et al., 1999).
Antioxidants offers resistance against the oxidative stress by scavenging the free radicals and inhibiting lipid peroxidation (Gillman et al., 1997). Antioxidants present in plant materials such as Cynodon dactylon act as radical scavengers, and helps in converting the radicals to less reactive species. The Cynodon dactylon selenium nanoparticles possessed signi icant antioxidant activity in increasing concentrations when compared to the standard ascorbic acid values, which was capable of reducing DPPH radical hence the change in colour depends on the number of electrons (Menon et al., 2020). Results were positive when compared to the standard used i.e. ascorbic acid (vitamin C) and were calculated using the following formula, %Inhibition : Ac − As Ac × 100 Where Ac is the absorbance of control and As is absorbance of sample.

CONCLUSIONS
This proves that there are antioxidant mechanisms adopted by the selenium nanoparticles. They show protection against oxidative stress initiated by excess reactive oxygen species (ROS) and reactive nitrogen species (NOS). In future these nanoparticles can be used for new drug designing and targeting and offer treatment for various oxidative stress related disorders with minimal side effects. Also these Cynodon dactylon stabilized nanoparticle formulations were demonstrated to have biocompatibility, as well as strong potential for application in the ields of medicine and food.