Determination of antioxidant activities of three different cucurbita species

There is a natural defense mechanism in the body against free radicals formed as a result of certain metabolic reactions. The molecules that play crucial role in the defense mechanism are called "antioxidants". Antioxidants are molecules that keep free radical species stable and minimize the damage they can cause in metabolism without damaging the cells. The main effect of antioxidants on living life is through the mechanisms of scavenging free radicals and breaking chains. Molecular structures with one or an unpaired electron in their final orbital are usually unstable and highly reactive. These are called free radicals. Free radicals can contain oxygen and nitrogen. Since oxygen radicals in this group easily pass through cell membranes, they have the ability to cause changes in the structure of lipids, proteins and nucleic acids in cells and have an effective harmful effect on cells. These radicals are called "reactive oxygen species (ROS)". Antioxidants act as hydrogen atom donors by converting these harmful ROS, especially chain-forming radicals, into slightly reactive forms. The resulting antioxidant radical is stabilized by replacing the oxygen atom in the aromatic ring with an unpaired electron. For this reason, antioxidant molecules generally perform phenolic functions in their structures. The role of antioxidants in human health has recently been better understood. Research shows that antioxidants; It has been shown to play a more effective role in preventing cataracts, cancer, cardiovascular disease or many other diseases caused by oxidative stress. Antimutagenic, antitumor and anti-aging effects are due to substances with antioxidant properties found in living organisms. Oxygen or nitrogen groups that are reactive in the absence of antioxidants can cause cancer, diabetes, arthritis, Parkinson's disease, AIDS, brain or heart disease, etc. cause various diseases. Antioxidants play important roles in the defense system of living cells as enzymatic and non-enzymatic. While there are enzymes such as Superoxide dismutase (SOD), Catalase (CAT), Ascorbate Peroxidase (APX), Glutathione peroxidase (GPx) and Glutathione reductase (GR) as enzymatic antioxidants in living systems, non-enzymatic antioxidants include melatonin, glutathione, bilirubin, uric acid, albumin, selenium, coenzyme Q10, α-lipoic acid and transferrin. Antioxidants are also used in many industrial areas. Antioxidants, which are widely used in the food industry, are artificially produced antioxidants. Among the artificial antioxidant group used for this purpose, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tertiary butylhydroquinone (TBHQ) and ethoxygin are the common ones. These antioxidants are very stable, effective and inexpensive. The use of antioxidants in this group has become more widespread due to the fact that they are cheaper than the other antioxidant class, their durability and effectiveness are higher. This is the chemical that works against rancidity and food spoilage. Antioxidants are produced by body cells and can also be obtained from food. The main natural antioxidants found in foods and trying to protect the human body from the useless effects of radicals are primarily called vitamin groups (vitamins A, C, E), flavonoids, carotenoids and polyphenols. While examining the enzyme activities of antioxidants, the enzymes Polyphenol oxidase (PPO), peroxidase (POD), ascorbate peroxidase (APX) and catalase (CAT) were selected. Polyphenol oxidase (PPO) is the name of a particular group of enzymes that creates a brownish color from oxidation products on the surface of cut fruits and vegetables. They are mainly found in bacteria, fungi, plants and animals. PPO enzyme is an oxidoreductase class enzyme (EC 1.14.18.1) and catalyzes the hydroxylation of monophenolic compounds to o-diphenols (cresolase activity) and oxidation of o-diphenols to o-quinones (catecholase activity) in the presence of oxygen. While the PPO enzyme causes darkening in fruits and vegetables, it also takes part in the co-creation of dark pigments in the body, the biosynthesis of melanin pigments, and the initiation and protection of polyphenol groups. Peroxidase (POD) enzyme (EC:1.11.1.7) is an oxidaoreductase class antioxidant enzyme that uses hydrogen peroxide (H2O2) as an oxidizer, reducing it in the presence of a second substrate and forming water while catalyzing the oxidation of the other substrate. Peroxidases can be divided into two active groups. These; they can be grouped as animal peroxidases and plant, fungal and bacterial peroxidases. Ascorbate peroxidase (APX) reduces H2O2 to water and uses acid (AsA) as an electron donor. APX (ascorbate peroxidases) have an important role in the antioxidant defense mechanisms of plants. Catalase (CAT) enzyme (E.C.1.11.1.6) is an oxidreductase class enzyme found in aerobic animals, plants and microorganisms that catalyzes the conversion of hydrogen peroxide (H2O2) to water and oxygen. If the hydrogen peroxide produced by the metabolic processes inside the cell is not hydrolyzed by the enzyme catalase, a very harmful and toxic radical is produced in the cells that causes permanent damage to the body. In this study, the antioxidant activities of the skin and inner parts of three different zucchini species (pumpkin, spaghetti squash, gum zucchini) grown in Sakarya were investigated. Antioxidant activities were determined using three different antioxidant analysis methods. The methods used for this purpose; Iron (II) Ions Chelating Activity, DPPH Free Radical Removal Activity and Reducing Capacity. At the same time, the antioxidant enzyme (Polyphenoloxidase, Peroxidase, Catalase and Ascorbate peroxidase) activities of the skin and inner parts of three different pumpkin species were investigated. In the analysis results; The results obtained from the peel and inner parts of the squash analyzed were the highest DPPH activity, % 94.93 (±0.12) in the skin of the pumpkin in ethyl acetate, and the highest DPPH removal activity in methanol was % 94.40 in the skin of the spaghetti squash. (±0.18). The highest reducing capacity was observed in pumpkin cultivars studied in ethyl acetate extracts. In the Chelating of Iron (II) Ions method, it was determined the most in the shell of the pumpkin in ethyl acetate extracts, and the most in the inner part of the pumpkin in methanol extracts. While determining the antioxidant enzyme activities of pumpkin, activities were determined for four enzymes. These enzymes are polyphenol oxidase, peroxidase, catalase and ascorbate peroxidase. When polyphenol oxidase enzyme values were analyzed in pumpkins, the highest enzyme activity was found in the skin of the spaghetti squash, while the lowest enzyme activity was found in the skin of the pumpkin. When the peroxidase enzyme activity was examined, the highest enzyme activity was found in the peel of the pumpkin, while the lowest enzyme activity was determined in the inner part of the gum squash. When catalase enzyme activity is examined, for 100 µL; While the highest value was found in the shell part of the pumpkin, the lowest value was found in the shell part of the pumpkin. When catalase enzyme activity was also tested in a volume of 500 µL, the maximum activity value was observed in the skin of the spaghetti squash, while the lowest enzyme activity value was observed in the inner part of the gum squash. The highest enzyme activity value for ascorbate peroxidase was found in the skin of the pumpkin, while the lowest enzyme activity value was found in the inner part of the spaghetti squash. In the light of all the data obtained, when the enzymatic and non-enzymatic antioxidant activities in different parts of three different pumpkins grown in Sakarya were evaluated, it was determined that the highest antioxidant activity was in the skin part of the pumpkin.