Study On The Carboxymethyl Modification And Antitumor Activity Of Polysaccharide From Natural Portulaca Oleracea L.

With the rapid economic development and the acceleration of industrialization,the changes in lifestyles,environmental pollution and genetic factors,the incidence of cancer in our country is rapidly increasing,and it has become a disease that seriously endangers people's lives and health.Among non-communicable diseases,cancer is the second leading cause of death in humans.Worldwide,18.1 million people have been diagnosed with cancer,and 9.6 million people have died from cancer.China added 4.3million new cancer patients in 2018,and this number is expected to exceed 5 million or more in 2040.At present,the treatment methods for malignant tumors include early surgical treatment and advanced chemotherapy and other methods.Due to the limitations of surgical treatment and the toxic and side effects of radiotherapy and chemotherapy,it has caused irreparable damage to the physical and mental health of patients,and due to the high cost of some drugs,it has brought an economic burden on the patient and the country.Therefore,finding and developing new high-efficiency and cheap anti-tumor drugs from natural plant medicinal materials has become an important research direction in the field of medicine in recent years.Portulaca oleracea L.is also called five-element grass,long-lived vegetables,purslane,purslane,five-element vegetables..Purslane polysaccharide from Portulaca oleracea L.?POP?is one of its main active ingredients and has been proven to have anti-oxidant,hypoglycemic and anti-tumor effects.However,studies by scholars at home and abroad have found that natural polysaccharides are more difficult to dissolve in water,which limits the exertion of their biological activities.After structural modification such as sulfation,phosphorylation,acetylation,and carboxymethylation,the physical and chemical properties can be improved and the biological activity can be improved.Studies by Chen et al.showed that sulfated purslane polysaccharides had a significantly higher inhibition rate on Hep G2 cells and Hela cells than unmodified polysaccharides.However,no research has been reported on the carboxymethylation modification of Portulaca polysaccharide and its biological activity.For this reason,based on the preliminary isolation and extraction of purslane and purslane polysaccharides,this study carried out carboxymethyl modification,and compared the antioxidant and antitumor activities of purslane polysaccharides.The results of the research are as follows:1.Purification of purslane purslane polysaccharides.Modification of purslane purslane polysaccharides with isopropanol-chloroacetic acid reaction system.The modification of carboxymethyl purslane polysaccharides was optimized by single factor experiment and response surface methodology.The optimal modification conditions of carboxymethyl purslane polysaccharide CM-POP were:MCA 2.5 g,reaction time 3.7 h,reaction temperature 65.5?,and sodium hydroxide concentration 6.26 mol/L.2.Study on the antioxidant activity of polysaccharides from Portulaca oleracea and carboxymethyl Portulaca polysaccharide.Using vitamin C?Vc?as a reference,the scavenging rates of POP and CM-POP for DPPH,·OH,·O₂^-radicals were measured.The results showed that the purslane polysaccharides before and after carboxymethyl modification had certain antioxidant activity.As the concentration increased,the antioxidant activities of Vc and polysaccharides were enhanced,in the range of 0-5.0 mg/m L Vc has the strongest scavenging effect on three kinds of free radicals.Carboxymethyl modification did not improve the scavenging ability of purslane polysaccharide to DPPH free radicals,while the scavenging ability of·OH radicals and·O₂^-radicals had a significant effect on purslane polysaccharide CM-POP modified by carboxymethyl.Improvement,but compared to Vc,this improvement is limited.3.Study on the antitumor activity of polysaccharides from Portulaca oleracea and carboxymethyl Portulaca polysaccharides.Comparative study of the clearance rate of POP and CM-POP on Hep G2 and A549 cancer cells and their related mechanisms.The results showed that carboxymethyl purslane polysaccharide has a certain inhibitory effect on Hep G2 liver cancer cells,but has no significant inhibitory effect on the proliferation of A549 lung cancer cells.