ABSTRACT
AIM To prepare the microemulsions loaded with total flavonoids from Potentilla discolor Bunge and to evaluate the therapeutic effect on diabetic mice.METHODS Total flavonoids,the extract from P.discolor by 70％ ethanol,were made into microemulsions after purification with.macroporous resin.With types and amount of oil phase,emulsifier and co-emulsifier,and addition amount of total flavonoids as influencing factors,together with drug loading,encapsulation efficiency,particle size and Zeta potential as evaluation indices,the formulation was optimized by drawing pseudo-ternary phase diagram.By establishing diabetic mouse models induced by streptozotocin (STZ) and high fat diet,the obtained microemulsions' effects on fasting blood glucose,oral glucose tolerance (OGT),insulin,glycosylated serum protein (GSP),triglyceride (TG),total cholesterol (TC),low density lipoprotein (LDL),high density lipoprotein (HDL),superoxide dismutase (SOD) and malondialdehyde (MDA) in mice were investigated.RESULTS The optimal formulation was determined to be 400 mg for isopropyl myristate (oil phase) amount,400 mg for Cremophor RH 40 (emulsifier) amount,200 mg for polyethylene glycol 400 (coemulsifier) amount,and 80 mg for addition amount of total flavonoids.The spherical-like and uniformly-sized microemulsions shared average drug loading of (7.28 ± 0.12)％,encapsulation efficiency of (91.79 ± 1.02)％,particle size of (36.79 ±0.17) nm and Zeta potential of (-15.77 ±2.89) mV.They could significantly reduce fasting blood glucose level,promote insulin secretion,regulate blood lipid,increase SOD activity,and decrease MDA level in diabetic mice.CONCLUSION Once prepared into microemulsions,the total flavonoids from P.discolor demonstrate an obviously enhanced activity in reducing blood glucose.