Pumpkin Vitro Antioxidant Activity Of Extracts

Pumpkin is an annual vine herbaceous plant,which belongs to the genus Cucurbita (Cucurbitaceae).It is one of the main worldwide vegetables.At present,there are 129 edible vegetables in the world.The integrated nutritions of pumpkin in these vegetables are at the top of the list.It is rich in variety of amino acids,polysaccharides,carotenoids,vitamins and mineral salts,with various physiological activities,such as anti-hyperglycemic activity,antihypertensive,antitumor, and antioxidant.Therefore,pumpkin is a very important food as well as a medicinal therapeutic with great potential for development and application.Now,more researches of the pumpkin focus on the hypoglycemic effect.The reports about its antioxidant activity are few,and only limited to the in vitro antioxidant assay of pumpkin polysaccharides,while the study on the contents of other effective components,total antioxidant capacity and particularly on the protection of DNA and mitochondrial have never been reported.To exploit the pumpkin's health value and medicinal value,we took Cucurbita moschata Duch.as material and investigated its extraction process,the contents of effective compositions.We used various in vitro chemical simulation methods to analyze the antioxidant potential,the effect of DNA damage protecting activity and the antioxidant effect on mitochondria of Cucurbita moschata Duch. extract(CE).The research was divided into three parts as follows:PartⅠ:Extraction and determination the content of the effective components,including the polyphenols,reducing sugars,total flavonoids and carotenoids.PartⅡ:The in vitro antioxidant experiments of CE,including the scavenging activities of free radicals,reducing power assay system,the total antioxidant activity,inhibition effect of lipid peroxidation of polyunsaturated fatty acid.PartⅢ:The experiment of using CE to protect plasmid pUC18 DNA and mitochondria from the oxidative damage.We have investigated the effects of CE on damaged DNA and rat liver mitochondria induced by free radical.Malondialdehyde(MDA),mitochondrial swelling,protein carbonyl content and ATPase activity along with superoxide anion generation were measured.The main results were as follows:1.Comparing the results of in vitro antioxidant of pumpkin ethanol extract(PEE) done before, we found that adding a step of liquid-liquid extraction using with petroleum ether and ethyl acetate after refluxing with 90%ethanol can get rid of most fats,proteins and water-soluble impurities.The main active ingredients of CE were polyphenols,reducing sugar,followed by the total flavonoids and also contained few quantities of carotenoids.Contents of polyphenols,reducing sugar,total flavonoids and carotenoids are 22.46%,20.72%,10.24%and 2.50%respectively.The active ingredients were more than 50%.It can be anticipated that the antioxidant activity of CE would be better than PEE.2.CE had strong scavenging free radical capacity and the radical-scavenging effects were in a dose-dependent manner,which can effectively remove DPPH·,·O₂^- and·OH,and the IC₅₀ were 1.47mg/mL,4.51 mg/mL and 0.14mg/mL respectively.The damaging action of the hydroxyl radical is the strongest among free radicals.It is known that hydroxyl radical is a powerful oxidant that can react with all biological molecules.CE can significantly remove·OH,so it has a great development prospects for antioxidant.3.CE has reducing power and its capacity was in a dose-dependent manner.The total antioxidant activity was significant,which was better than positive control Vc,and closer to BHT of CE(1 mg/mL).Moreover,CE could inhibit lipid peroxidation,but its effect was not obvious,and the largest inhibition rate of 45.81%.4.0.85mg/mL of CE protected pUC18 plasmid DNA against damaged by hydroxyl radicals significantly.5.CE could inhibit the rat liver mitochondrial swelling and the protein oxidation to ensure that the mitochondrial membrane osmotic pressure.It also protected mitochondrial membranes by scavenging superoxide anions and scavenging lipid free radicals as well as maintaining ATPase activity obviously.CE can protect mitochondria well.In conclusion,CE has significant antioxidant activity,effective protection the activity of DNA and mitochondria.CE has great potential as health food or antioxidant functional food ingredients.