Study On Analysis, Identification And Hypoglycemic Activity Of Flavonoids From Lotus Plumule

Lotus pumule is the young leaves and radicle in mature seeds of plant lotus (Nelumbo nucifera Gaertn), which belongs to the Nymphaeaceae family. As an important Chinese herbal medicine, lotus plumule has broad pharmacological applications and is of high research value. JianNing (Fuzhou, China) enjoys the reputation of "hometown of jian-lotusis" and is one of the main areas for lotus plumule production. In this paper, we extracted and purified the lotus pumule, and determined its hypoglycemic activity. This study established a foundation for further investigation on the structure-activity relationship of the hypoglycemic activity of total flavonoids from Lotus Plumule. Our study offered important theoretical basis and technological support for developing deep-processing products of total flavonoids from Lotus Plumule.(1)We determined the content of flavonoids in lotus plumule with the method of aluminum nitrate chromogenic combing ultraviolet-visible spectrophotometer. The results were compared with those of Rutin. This method was shown to be intuitive, rapid, simple and feasible with good accuracy and stability.(2) We investigated the microwave-ultrasound-assisted extraction of total flavonoids from lotus plumule and optimized the parameters. The optimal parameters were determined based on single-factor experiments and optimized with Response Surface Methodology. The following parameters were considered, including solvent concentration, liquid/solid ratio, microwave power, ultrasonic power, and extraction time. The optimal parameters were determined to be:ethanol concentration 70%, liquid/solid ratio 1:40, microwave power 355 W, ultrasonic power 423 W, extraction time 15min, ultrasonic/time interval 1/0.(3) With STZ-induced diabetic mice as models, we studied the hypoglycemic effect of lotus plumule flavonoids on blood glucose. The results demonstrated that lotus plumule flavonoids could significantly reduce the level of glucose and lipid in blood, improve glucose tolerance, and increase insulin level.(4) We compared three kinds of polyamide resin in their effects on the absorption-desorption ability of total flavonoids from lotus plumule. The polyamide resin with 60-80 mesh was selected to purify total flavonoids from lotus plumule and technological parameters were optimized. The optimal parameters were determined as: sample concentration 2.085mg/mL, sample quantily lOmL, sample flow rate 1mL/min, water consumption 40mL, eluent was 50%(V/V) ethanol soloution, eluent quantily 50mL, eluent flow rate 1mL/min.(5) Flavonoids were extracted from lotus plumule with the solvents of petroleum ether, ethyl acetate and n-butyl alcohol. The inhibition of α-glycosidase enzyme activity was chosen as indicators for screening of the hypoglycemic part from lotus plumule flavonoids. The results suggested the ethyl acetate phase demonstrated the highest inhibition on α-glycosidase enzymes, meaning the presence of highest hypoglycemic activity at the site.(6) Chemical inspection and HPLC were employed to analyze and identify the structure of ethyl acetate phase in lotus plumule flavonoids. Results indicated the presence of dihydrogen flavonoids,5-hydroxy flavones,2-hydroxy ketone of chalcone and aurones in the ethyl acetate phase. Rutin was also identified in the phase with a conceration of 77.74μg/mg.