Study On Chemical Constituents,Antioxidant And Hypoglycemic Activities Of Flavonoids From Flos Dolichoris Lablab L.

As an herbaceous perennial grown in many countries,Flos.Dolichoris Lablab L.is the flower of Dolichos Lablab L.belonging to the family Leguminosae(Fabaceae).As a medicinal and edible plant,phytochemical analysis showed that Dolichos Lablab L.is rich in flavonoids,proanthocyanidins,saponins,proteins,and dietary fiber.Preliminary pharmacological studies revealed that Dolichos Lablab L.possessed antioxidant,antidiabetic,antiinflammatory,insecticidal,hepatoprotective,and antispasmodic effects and was also used to treat iron-deficiency anemia.These findings are closely associated with abundant phytochemical activity in Flo.Dolichos lablab L.,especially the flavonoids.However,few studies have been conducted on the phytochemical composition,antioxidant activity and anti-diabetic activity of the Flo.Dolichos lablab L..Therefore,this paper starts with the research on the flavonoids and their antioxidant and anti-diabetic activities to further understand the nutritional value of Flo.Dolichos lablab L.and the utilization value of raw materials,and the related research is as follows:(1)An effective method was established by AB-8 and SPHPLC to isolate and prepare the main flavonoids from the Flo.Dolichos lablab L..The results showed that the main flavonoids in Flo.Dolichos lablab L.were quercetin flavonoid glycosides and kaempferol flavonoid glycosides.The results of this study are helpful to supply the chemical constituents and related liquid phase analysis of Flo.Dolichos lablab L..(2)The seven major flavonoids isolated are kaempferol-3-O-sophoroside(1),quercetin 3-rutin(2),quercetin 3-glucoside(3),kaempferol-3-O-robinobioside(4),kaempferol-3-O-rutinoside(5),isorhamnetin 3-O-neohesperidoside(6),and kaempferol-3-O-galactoside(7).In addition,as far as we know,all flavonoids have been isolated from the Lablab genus for the first time.(3)The antioxidant activity of the isolated flavonoids was investigated in vitro quickly and accurately by DPPH,ABTS+,PTIO' and total reducing power methods.The structure-activity relationship between flavonoids and flavonoids was studied by analyzing the IC50.The results showed that the presence of 3',4'dihydroxyl on the B ring and the 5,7-dihydroxyl sites arranged in the A ring of flavonoids enhanced the antioxidant capacity,but the effect of the antioxidant capacity was far less than that of the B ring.(4)Using the experimental methods of DPPH,ABTS+,PTIO·and total reducing power to quickly and accurately investigate the antioxidant capacity of the isolated flavonoids in vitro.The clearance rates of the compounds kaempferol3-O-sophoroside,quercetin 3-glucoside,kaempferol-3-O-rutinoside and kaempferol-3-O-galactoside are at relatively high concentrations(>100 ?g/mL)showed excellent oxidation resistance,while at lower concentrations(<30?g/mL),the oxidation resistance was weak.(5)This study also investigates the antioxidant effect relationship between different flavonoids compounds,including structural activity effect,synergistic or antagonistic effect.The results showed that the scavenging activity of flavonoids was affected by the combination of flavonoids,and it were relatively complex.(6)The inhibitory effect of flavonoids on ?-glucosidase was determined by pNPG method.The results showed that kaempferol-3-O-galactoside,kaempferol3-O-sophoroside and kaempferol-3-O-rutinoside had the best inhibitory effect.(7)The inhibition types of the interaction between three flavonoids and ?glucosidase were explored through enzyme inhibition kinetics,and the mechanism was studied through varieties spectral methods and molecular docking.The results provided a scientific basis for the development of natural hypoglycemic drugs extracted from the flower of Flo.Dolichos lablab L.for treated ? type diabetes mellitus.