Ultrasound-enzyme Assisted Extraction, Physicochemical Properties And Antioxidant Activities Of Polysaccharides From Oxalis Corniculata L.

Oxalis corniculata L.belongs to the family Oxalidaceae,which has the functions of clearing heat,promoting diuresis,detoxification and detumescence.It is often used for cold,fever,enteritis,hematuria,urinary tract infection,urinary calculus,neurasthenia,jaundice,hepatitis,etc.And it is also used to treat bruises,snake bites,swollen sores,tinea pedis,eczema,burn and scald through external use.O.corniculata is a traditional medicinal herb and has a wide range of medical uses in folk traditional Chinese medicine.Therefore,the researching of extraction,physicochemical properties and biological activities of O.corniculata polysaccharides has great practical significance for Chinese herbal medicine researching and comprehensive utilization.In this research,polysaccharides were extracted from O.corniculata,their physicochemical properties were determined,and their antioxidant activities were evaluated in vitro and in vivo.The main results are as follows:1.Ultrasound-enzyme assisted extraction was used to extract O.corniculata polysaccharides.Based on the single factor experiment,the optimal process conditions were obtained by RSM:extraction temperature 50°C,ultrasonic power 270 W,ultrasonic time 25 min,and liquid-solid ratio 30:1 mL/g.Under this condition,the yield of O.corniculata polysaccharides was 9.45%,which was very close to the predicted yield?9.57%?.This result indicated that the optimal process for ultrasonic-enzyme assisted extraction from O.corniculata was reliable and practical.2.The O.corniculata polysaccharides was separated with DEAE-52 cellulose column,and four subfractions were separated with 0.1,0.2,0.3 and 0.4 mol/L NaCl,respectively.OCP-3 fraction was further purified with Sephadex G-100 column and a single symmetric peak was obtained,indicating that OCP-3 was homogeneous polysaccharide.3.Purified component OCP-3 was acidic polysaccharide,and its relative molecular weight was 108.26 kDa.The total sugar content of OCP-3 was 71.66%,glucuronic acid content was 15.13%,and protein content was 1.66%.OCP-3 was composed of arabinose,xylose,mannose and galactose,and the molar ratio was 1.00:6.49:1.05:1.43.The FT-IR spectrum showed that OCP-3 had the characteristic of polysaccharides functional group.Its thermodynamic curve of endothermic peak temperature was 181.77°C and the exothermic peak temperature was 248.94°C,proved that OCP-3 was thermal stability.OCP-3 had a single helix structure,and consisted of 1?6?19%?and 1?3?73%?glycoside bonds.It also presented 1?4 bond types,and may contain 1?2 bond types,accounting for 8%of the total.4.In vitro antioxidant analysis indicated that OCP-3 had strong scavenging ability against DPPH,·OH and ABTS·⁺radicals,with IC₅₀ values of 2.95,0.57,and 2.09mg/mL,respectively.The oil anti-oxidation activity of OCP-3 was better than ascorbic acid,with IC₅₀ values of 3.71 mg/mL.OCP-3 had a protective effect on the oxidative damage of plasmid DNA at 50⁴00?g/mL.5.Cell experiments demonstrated that OCP-3 promoted the proliferation of HEK293 cells.OCP-3 could alleviate the oxidative damage,reduced the content of malondialdehyde?MDA?and protein carbonyl?PC?in H₂O₂-induced cells.Meanwhile,it also improved the antioxidant enzyme activity of superoxide dismutase?SOD?,catalase?CAT?and glutathione peroxidase?GSH-PX?.6.OCP-3 could obviously prolong the Caenorhabditis elegans survival rate under the heat stress at 37°C.The maximum survival time was 22 h when OCP-3 concentration was 4 and 8 mg/mL.OCP-3 inhibited the generation of MDA and PC in cells induced by heat stress.At the same time,it could also enhance the antioxidant enzyme activity of SOD,CAT and GSH-PX.