The degradation of flavonol glycosides extracted from Ginkgo biloba was performed under different conditions and the degraded products were determined by reversed-phase high performance liquid chromatography (RP-HPLC) method. Four stress conditions including acid(0.1 mol/L HCl), base(0.1 mol/L NaOH), temperature (70 °C) and oxidation(0.03% H 2 O 2 , volume fraction) were used for the forced degradation studies. The pH stabilities of the flavonol glycosides were determined in phosphate buffers of varying pH values from 4.5 to 7.4. The degradation rate constants and half-life of three Ginkgo flavonol aglycones(quercetin, kaempferol and isorhamnetin) which represent Ginkgo flavonol glycosides were calculated in forced degradation and pH-stability studies of them. The results indicate that the three substances were more stable when incubated under acid condition and showed pH-dependent stability. The degradation was observed to follow first-order kinetics in all degradation studies. The stability results could provide important bases on development, preparation and storage of products of Ginkgo biloba extract and should be significantly considered during the further formulation development.

Background The aim of this study was to develop an optimal niosomal system to deliver Ginkgo biloba extract (GbE) with improved oral bioavailability and to replace the conventional GbE tablets. Methods In this study, the film dispersion-homogenization method was used to prepare GbE niosomes. The resulting GbE niosome suspension was freeze-dried or spray-dried to improve the stability of the niosomes. GbE-loaded niosomes were formulated and characterized in terms of their morphology, particle size, zeta potential, entrapment efficiency, and angle of repose, and differential scanning calorimetry analysis was performed. In vitro release and in vivo distribution studies were also carried out. Results The particle size of the optimal delivery system prepared with Tween 80, Span 80, and cholesterol was about 141 nm. There was a significant difference (P < 0.05) in drug entrapment efficiency between the spray-drying method (about 77.5%) and the freeze-drying method (about 50.1%). The stability study revealed no significant change in drug entrapment efficiency for the GbE niosomes at 4°C and 25°C after 3 months. The in vitro release study suggested that GbE niosomes can prolong the release of flavonoid glycosides in phosphate-buffered solution (pH 6.8) for up to 48 hours. The in vivo distribution study showed that the flavonoid glycoside content in the heart, lung, kidney, brain, and blood of rats treated with the GbE niosome carrier system was greater than in the rats treated with the oral GbE tablet (P < 0.01). No flavonoid glycosides were detected in the brain tissue of rats given the oral GbE tablets, but they were detected in the brain tissue of rats given the GbE niosomes. Conclusion Niosomes are a promising oral system for delivery of GbE to the brain.

The aim of this study was to develop a simple and accurate isocratic RP-HPLC analytical method to qualify and quantify three flavonol glycosides(Quercetin,Kaempferol and Isorhamnetin) and four terpene lactones(Ginkgolide A,Ginkgolide B,Ginkgolide C and Bilobalide) of ginkgo leaf extract.The contents of flavonoid glycosides and terpene lactones from EGBN were measured by dialysis method.And the saturation solubility of flavonoid glycosides was also measured with this HPLC method.The condition of HPLC method for flavonol glycosides is: column: Agilent HC-C18(4.6 mm×250.0 mm,5 μm);mobile phase: ACN-0.4% phosphoric acid(28∶72,v/v).The drug elution was performed at 40 ℃ at a flow rate of 1.0 mL/min and detected at the wavelength of 360 nm.And the condition of HPLC method for terpene lactones is: column: Agilent HC-C18(250.0 mm×4.6 mm,5 μm);mobile phase: Methonal-THF-Water(46∶7∶47,v/v/v).The flow rate was kept at 0.8 mL/min.The temperature of NEB and EVA was performed at 60 ℃ and 105 ℃,respectively.The HPLC methods for flavonol glycosides and terpene lactones were shown to be linear,precise,sensitive,selective and accurate.And the contents of flavonoid glycosides and terpene lactones from EGBN can be measured by dialysis method.

Abstract Background: (+)-catechin, as the most common catechin isomer, is recognized to be an antioxidant which benefits the skin in many ways. The purpose of the present study was to prepare and evaluate a suitable liposomal delivery systems for (+)-catechin topical application. Methods: In this study, catechin-loaded conventional liposomal delivery system, deformable conventional liposomal delivery system and deformable liposomes prepared by reverse-phase evaporation (REV) method were compared. The three systems were characterized for liposome particle size, zeta-potential, entrapment efficiency, drug release, permeability across porcine skin and catechin deposition in the skin. Results: It was revealed that the size of deformable conventional liposomes before freeze-drying and deformable REV liposomes after freeze-drying range from 335.6 ± 71.7 nm to 551.1 ± 53.4 nm, respectively, which were considered to be suitable for skin delivery. The deformable REV liposomes had a higher aqueous volume and thus were able to entrap greater amounts of hydrophilic (+)-catechin (50.0 ± 5.9%) compared to conventional (30.0 ± 3.8%) and deformable conventional liposomes (36.1 ± 4.6%). All liposomal formulations exhibited a prolonged catechin release. Compared to deformable liposomes, the REV deformable liposomes showed a significantly better deposition of (+)-catechin while catechin solution did not permeate into the porcine ear skin. Conclusion: Among all formulations studied, deformable REV liposomes were considered to be favorable for catechin topical delivery.

SUMMARY The purpose of this research was to test if the usage of niosomal system facilitates the drug cellular uptake and the drug-loaded niosomes are subject to active transport across biological membranes such as intestinal epithelia. INTRODUCTION Ginkgo biloba Extract (GbE) has many beneficial effects on cerebravascular diseases, however, the current oral dosage forms show low oral bioavailability, short half life and poor permeability across blood-brain barrier (BBB). Therefore, a number of researchers focus on using formulation delivery systems such as nanoparticles, liposomes and niosomes to enhance oral bioavailability of drug [4] . Niosome is a novel delivery system and evolved from liposome. Niosome has been reported to provide controlled release profiles for many active substances and enhances drug bioavailability. Whereas in contrast to liposome, noisome possesses greater stability and avoids the disadvantages of liposome, such as the high cost and variable purity of phospholipids in production. In this study, GbEloaded niosomes were prepared and the Caco-2 monolayer was used as the cell culture model of human intestinal epithelia. EXPERIMENTAL METHODS Preparation of GbE-loaded niosomes. In this study, to simplify the analytical process, fluorescein isothiocyanate (FITC) as labeling substance was conjugated with GbE and the FITC-conjugated GbE was encapsulated into niosomes. Briefly, the surfactant mixture (Tween 80 and Span 80) and cholesterol were dissolved in a mixture of methanol and dichloromethane (4:1, v/v) in a 50mL round bottom flask. The resulting solution was then rotary evaporated to form a thin film. The dried film was hydrated with 60 mL of ethyl ether, then a solution containing FITC-GbE was added and the hydration was continued using a swirl-evaporator (Bochi, Switzerland) at 100 rpm, 60 °C for 2 hours. The resultant niosomal suspension was set aside for at least 2 hours at room temperature to allow for the membrane to anneal before stored in a fridge. Cell culture. Caco-2 cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) medium supplemented with 10% Fetal bovine serum (FBS), 1% Non-essential amino acid (NEAA), penicillin-streptomycin (100 U/mL and 100 μg/mL, respectively). The cells were grown at 37°C in a humidified atmosphere (5% CO2 / 95% air) and exchange for fresh medium every 3-4 days. Cellular uptake study by Caco-2 cell line. Experiments were carried out after cells reached confluency in 100mm culture dishes. For timedependent studies, cells were incubated with GbEFITC niosomes and controlled GbE-FITC without niosomal carrier for various period of time (0.5 24 hours). For the concentration-dependent studies, cells were incubated with GbE-FITC niosomes at specified concentrations (50-2000 μg/mL) for 2hours. To determine the effect of temperature, incubation was carried out for 2hours at 4°C and 37°C. After incubation, cells were scraped off and lysed with 10% Triton in methanol. The cell lysates were used to determine the total cell protein by Pierce BCA protein assay kit and the amount of uptaken GbE-FITC was analyzed by fluorescein spectrophotometer (Perkin Elmer Precisely, USA, λex 495, λem 525 nm). Transport study by Caco-2 monolayer. For transport experiments, Caco-2 cells were grown as epithelial monolayer and seeded onto the Transwell inserts. Before each test, the integrity of the monolayer was determined by measuring the transepithelial electrical resistance (TEER) (Millipore, USA). To determine the energy dependency of GbE-FITC noisome transport from apical to basolateral, transport medium depleted in glucose was added on both sides of the cell monolayer. Sodium azide as the ATP inhibitor and niosomes were suspended in transport medium and added to apical side. The monolayers were incubated for 4hrs at 37°C. An aliquot 0.5 mL sample was collected from basolateral side and the fluorescence intensity was tested using the above method. RESULTS AND DISCUSSION Cellular uptake study by Caco-2 cell line. As shown in Fig. 1, the cellular uptake of GbE-FITC niosomes and GbE-FITC conjugate was time dependent. The uptake increased and reached a plateau after 6 and 2hours, respectively. Using the niosomal system could significantly increase the drug cellular uptake (p < 0.05). The results in Fig. 2 reveals that with the concentration increased from 50 to 100 μg/mL, the uptaken amount increased, whereas further increase of concentration from 100 μg/mL caused no increase in cellular uptake. Figure 1. Effect of exposure time on uptake of GbE-FITC, GbE-FITC noisome by Caco-2 cells. (n=3) Figure 2. Effect of particle concentration on uptake of GbE-FITC niosome by Caco-2 cells. * Indicates a value significantly (p < 0.05) higher than that of other groups. Experiments performed at 37°C showed 1.8 folds greater uptake than that at 4°C, as is shown in Fig. 3, which may be explained as the cellular uptake is an energy-dependent behavior. Figure 3. Effect of incubation temperature on uptake of GbE-FITC niosome by Caco-2 cells. ( =3)* Indicates a value significantly (p < 0.05) higher than that of 4°C

AIM:To optimize release in vitro of Ginkgo biloba extract niosome(GbEN) and pharmacodynamics in vivo.METHODS:The analysis was carried out on Dialysis-HPLC method,under the conditions of temperature of(37 ± 1) ℃ and rotation rate of 75 r/min.We studied the release condition of flavonol glycosides in three kinds of different media;including phosphate buffer solution(pH = 6.8),acetate buffer(pH = 4.0) and HCl solution(9→1 000).Sixty experimental hyperlipemia rats were used in the study and then fed with GbEN freeze-dried powder and Ginkgo respectively.Blood biochemical levels and hemorheology were compared between rats.RESULTS:GbEN had satisfactory release behavior in pH 6.8 phosphate buffer solution.,as cumulative release of drug reached up to 80% in 48 h.However cumulative release of drug in HCl solution(9→1000) and acetate buffer were(pH 4.0) only 20% in 48 h.GbEN and GbE tablets could enhance the level of high density lipoprotein cho-lesterol(HDL-C),decrease the levels of total cholestero(TG),triglycerid(TC),low density lipoprotein cholestero(LDL-C)、AI and the ratio of LDL-C/HDL-C.CONCLUSION:This method is simple,and reproducible.GbEN and GbE tablets both have the capability to improve the disorder of blood-fat metabolism of hyperlipoproteinemia rats.They also can decrease the viscosity of whole blood and plasma of hyperlipoproteinemia rats.

Objective To explore the effect of the prescription regarding Tong-jing-yi-sui on con- trolling function of allostimulatory factors from the rabbits with Experimental Autoimmune Neuritis.Meth- ods New Zealand rabbits were immuned with myelin P2 lipid bindin abstracted from sciatic nerve of cattle so that Animal Models suffered in EAN(Experimental Autoimmune Neuritis) were established.Lymphocyte were abstracted from the blood of experimental rabbits which were given different treatment and then the ex- pressive levels of allostimulatory factors-CD80,CD86 protein in lymphocyte were statistically analyzed.Re- sults The expressive levels of CD80 protein were obviously decreased (P0.05,P0.01) in both group tong-jing-yi-sui and group immunoglobulin after treatment simultaneously they were higher in the former than the latter within 7days after treatment(P0.05),they have not variances between the two group at 14th day(P0.05) and were lower than normal levels(P0.01).The expressive levels of CD86 protein were more higher(P0.01) in both group tong-jing-yi-sui and group immunoglobulin than in control group after treatment simultaneously they were lower in the former than the latter within 7days after treatment (P0.05),they have not variances between the two group at 14~(th) day (P0.05) and were higher than normal levels.Conclusions The prescription regarding Tong-jing-yi-sui has function in inhibitting CD80 secretion and promoting CD86 secretion,it can promote secretion of Th2 cell which has immunosuppressive action and it can play the role of immunity down regulation,accordingly it can accomplish treatment of EAN.