Investigation of Antioxidant Activity of Cumin (Cuminum Cyminum L.) by Means of UV-Vis Spectroscopy, Proton Nuclear Magnetic Resonance and Iodometric Method

In this study cumin (Cuminum cyminum L.) seed extract was introduced as an efficient natural antioxidant on limitation of reactivity ...


Introduction
ROS is a phrase used to describe ROS and free radicals derived from molecular oxygen such as superoxide (O 2 -2), hydrogen peroxide (H 2 O 2 ), hydroxyl radical (OH⦁) and singlet oxygen ( 1 O 2 ) [1][2][3]. High levels of ROS can lead to cellular damage; oxidative stress and DNA damage [4]. Lipids due to the electrophilic inherent can be a target of ROS and converted to lipid hydroperoxides as primary product of fatty acid oxidation [5]. Antioxidants have important role to prevent oxidation biomolecular with inhabitation of Radical Chain Reaction (RCC). Recently, the interest in natural antioxidants has been increased since the application of the most widely used synthetic antioxidants such as Butylated Hydroxyanisole (BHA), Butylated Hydroxyl Toluene (BHT), Tert-Butyl Hydroquinone (TBHQ) and Propyl Gallate (PG) has been questioned because of possible toxic and carcinogenic components formed during their degradation [6]. Phenolic compounds are the main class of natural antioxidants [7]. Fruits, plants and vegetables and their processing by-products are one of the most essential sources of natural antioxidants due to the abundance of phenolic compounds such as flavonoids [8].
Cumin shown has bronchodilatory, hypotensive, antibacterial, antifungal, analgesic, anti-inflammatory, immuneopotentiating and antioxidant activities [9]. Each ROS as a result of different nature of the electrons has its own characteristics. Dioxygen in its ground state has two unpaired electron in terms of quantum ground state is its triplet [10].  [11][12][13][14]. The photosensitized production of singlet oxygen has significance in the areas of the photooxidation of organic compounds, DNA damage, and Photodynamic therapy [15,16].
Human skin is largest body organ and it constantly exposed to solar radiation which is capable of inducing the generation of ROS and UV exposure is thought to cause skin aging and skin cancer mainly by singlet oxygen [17]. UVB may produce O2⦁-, and UVA may produce 1 O 2 possibly through chromophores, such as porphyrin in skin [18].
There are few studies on the efficiency of natural antioxidant as O2 (1Δg) quenchers and their roles in the prevention of lipid oxidation in biological systems [19]. Cumin (Cuminum cyminum L.) is a small annual and herbaceous plant belonging to the Apiaceous family.
It is one of the popular spices regularly used as a flavoring agent.
It is cultivated in Iran, Arabia, India, China, and in the countries bordering the Mediterranean Sea [9]. This project was designed to characterize antioxidant potential of cumin in the oleic acid oxidation process by different ROS especially with singlet oxygen. Superoxide anion radical preparation for oleic acid oxidation: 2ml oleic acid and 0.44gr KO 2 added to 10ml DMSO in the presence of 3ml antioxidant (contains 6.9mg polyphenolic compounds).

Results and Discussion
In our previous studies, an efficient system for the porphyrinssensitized aerobic oxidation of fatty acids has been developed in the presence of visible light [21][22][23][24]. Herein, in continuation of our studies we report oxidative alterations of oleic acid as a result of oxidation with singlet oxygen, superoxide radical, hydrogen peroxide and radical hydroxyl in the presence and absence of cumin as a natural antioxidant. Our target of oxidation oleic acid by different ROS with focus on singlet oxygen (Figure 1), which has few studies on it [18].
Photooxygenation of oleic acid with H 2 TPP was investigated as a typical standard sample to evaluate singlet oxygen production and oleic acid oxidation monitored by 1H NMR and idometric method as a popular method [25]. It is important to note that 1H NMR and idometric method showed that the oxidation of oleic acid to peroxide product was stopped in the absence of porphyrin ( Figure   2 & Table 1 entry 1) or when the irradiation was interrupted (Table   1 entry 2). Accordingly, the presence of a porphyrin, light, and O 2 are essential for the conversion of oleic acid to corresponding products (Table 1 entry 3). Also, in the presence of N3-, which is a well-known singlet oxygen scavenger [25] oleic acid conversion was inhibited (Table 1, Table 1

Conflicts of Interest
The authors declare that they have no conflict of interest.