Asymmetric Synthesis of Rupestonic Acid and Pechueloic Acid.

In this report, the originally proposed rupestonic acid (5) and pechueloic acid (3) were efficiently synthesized. The chiral lactone 13, recycled from the degradation of saponin glycosides, was utilized to prepare the key chiral fragment 11. During the exploration of this convergent assembly strategy, the ring-closing metathesis (RCM), SmI2-prompted intermolecular addition, and [2,3]-Wittig rearrangement proved to be effective transformations for the synthesis of subunits.

Transport of aripiprazole across Caco-2 monolayer model.

This study aimed to investigate the transport characteristics of aripiprazole. A human intestinal epithelial cell model Caco-2 cell in vitro cultured had been applied to study the transport of aripiprazole. The effects of time, concentration of donor solutions, pH, temperature and P-glycoprotein inhibitor on the transport of aripiprazole were investigated. The determination of aripiprazole was performed by HPLC. It is concluded that aripiprazole is transported through the intestinal mucosa via a passive diffusion mechanism primarily, coexisting with a carrier-mediated transport. The transport of aripiprazole is positively correlated to transport time, pH, and temperature. Papp increased with donor concentrations up to 10 microg x mL(-1), and then decreased for higher concentrations. The P-glycoprotein inhibitor cyclosporine A significantly enhanced the transport amount of aripiprazole.

[Physicochemical stability and purification technology of caffeic acid tetramer from Arnebia euchroma].

OBJECTIVE: To purify caffeic acid tetramer (CAT) with macroporous resin on the basis of its fundamental physicochemical stability research. METHOD: The changes of CAT content were compared by HPLC method before and after the purification process, or while other conditions were altered. RESULT: LK001 was the best one among 7 kinds of macroporous resin in regard of purifying ability. The optimum absorbing technology was the solution concentration at 10 g x L(-1), pH at 4.5, and the flow rate at 3 BV x h(-1). The best eluting technology was 45% ethanol as eluting agent, pH at 5.0, eluting volume at 50 mL after applying super-purified water and 20% ethanol. The yield of product was 3. 6 percent, and the active compound CAT was 58 percent in the product. CONCLUSION: Macroporous resin LK001 is effective in enriching CAT from the crude extracts, thus this method of purification is advisable.

[Preparation, characterization of paclitaxel-loaded Pluronic P105 polymeric micelles and in vitro reversal of multidrug resistant tumor].

Drug delivery system (DDS) is a novel approach to overcome multidrug resistance (MDR) in tumors nowadays. This work was designed to investigate a new micellar delivery system for in vitro reversal of resistant ovarian tumor cells, based on a nonionic triblock copolymer Pluronic P105 and paclitaxel (PTX). The PTX-loaded polymeric micelles (P105/PTX) were prepared by thin film-hydration methods. Based on the results of single factor experiments, the P105/PTX micelle formulation was optimized by employing the central composite design-response surface methodology. The physico-chemical properties of the P105/PTX micelles were characterized, including micelle size, drug loading coefficient, in vitro release behavior, etc. The cytotoxicity of the P105/PTX micelles was assessed against human ovarian tumor cell line, SKOV-3/PTX, by a standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay. In order to understand the possible mechanism of Pluronic effects in resistant tumor cells, cellular uptake study of micellar PTX or Rhodamine-123 (R-123) was also carried out. The results showed that the micelle size was about 24 nm with drug loading coefficient of 1.1% and PTX concentration of 700 microg x mL(-1). The cumulative release amount of PTX from the P105/PTX micelles was only 45.4% in 6 h (P < 0.05) and 79.6% in 24 h, whereas Taxol injection in 6 h released 95.2% PTX. The IC50 values of the P105/PTX micelles and Taxol injection against SKOV-3/PTX were 1.14 and 5.11 microg x mL(-1), and resistance reversion index (RRI) was 9.65 and 2.15, respectively. The micellar PTX or R-123 exhibited a significant increase in cellular uptake in resistant SKOV-3/PTX cells compared with free PTX or R-123. These results indicated that PTX could effectively be solubilized by Pluronic P105 block copolymers via thin film-hydration process and formulation optimization, producing nano-scale polymeric micelles with sustained release property in vitro. The P105/PTX micelles were effectively able to reverse resistance to PTX in SKOV-3/PTX tumor cells compared with Taxol injection or free PTX solution, and the enhanced cytotoxicity in the resistant SKOV-3/PTX cell was related to the improved cellular uptake of PTX by Pluronic P105 copolymers.

Pharmacokinetics and bioequivalence studies of galantamine hydrobromide dispersible tablet in healthy male Chinese volunteers.

A randomized, two-way, crossover study was conducted in 18 healthy male Chinese volunteers to compare pharmacokinetics profiles of galantamine hydrobromide dispersible tablet with that of conventional tablet. A single oral dose of 10 mg galantamine was administrated to each volunteer. Plasma concentrations of galantamine were determined by a validated high-performance liquid chromatography (HPLC) method with fluorescence detection, which allowed 1 ng/mL to be assayed as the lowest quantifiable concentration. From plasma concentrations, AUC(0-->t) (the area under the plasma concentration-time curve from time 0 to the last sampling time, 32 hr), AUC(0-->infinity) (the area under the plasma concentration-time curve from time 0 to infinity), t((1/2)) (elimination of half-life of the terminal log linear phase), C(max) (maximum plasma drug concentration) and T(max) (time to reach C(max)) were evaluated through noncompartmental pharmacokinetic analysis. AUC(0-->t) and AUC(0-->infinity) were calculated by the linear-log trapezoidal rule method. C(max) and T(max) were obtained directly from the plasma concentration-time curve. Analysis of variance was carried out using logarithmically transformed AUC(0-->t), AUC(0-->infinity) and C(max). As far as AUC(0-->t), AUC(0-->infinity) and C(max) were concerned, there was no statistically significant difference between the test and reference formulations. Ninety percent confidence intervals (90% CI) for the ratio of AUC(0-->t), AUC(0-->infinity) and C(max) values for the test and reference formulations were 100.4-107.8%, 99.0-107.2% and 87.5-111.3%, respectively. As the 90% CIs of AUC(0-->t), AUC(0-->infinity) and C(max) were entirely within 80-125%, two formulations were considered bioequivalent.

Determination of glucosamine sulfate in human plasma by precolumn derivatization using high performance liquid chromatography with fluorescence detection: its application to a bioequivalence study.

A simple, rapid, selective and specific high-performance liquid chromatography (HPLC) method with fluorescence detection was developed for determination of glucosamine sulfate in human plasma and application to a bioequivalence in healthy volunteers. Precipitation of plasma was accomplished with acetonitrile to separate interfering endogenous products from the compound of interest. After vortex mixing and centrifugation, the supernatant was transferred and derivatized with 9-fluorenylmethoxycarbonyl chloride-acetonitrile solution in borate buffer (pH=8.0) at 30 degrees C for 30 min. The chromatographic separation was performed on a Diamonsil C18 column (150.0 mmx4.6 mm, 5 microm) with a mobile phase gradient consisting of water and acetonitrile at a flow rate of 1 mL/min. The method was linear in the range of 0.1-10.0 microg/mL with a correlation coefficient (r) of 0.9996. The limit of detection was 15 ng/mL. Inter- and intra-day precisions were

[Effect of self-microemulsifying system on cell tight junctions].

AIM: To study the effect of negatively charged and positively charged self-microemulsifying systems (SMES) on the cellular tight junction complex was to be investigated at molecular cell level. METHODS: Human intestinal epithelial Caco-2 cell model was established. Effect of formulations on the transepithelial electrical resistance (TEER) and permeability of the paracellular transport marker mannitol were measured to evaluate the cell integrity. Changes in subcellular localization of the tight junction protein zona occludens 1 (ZO-1) and cytoskeleton protein actin by immunofluorescence were also assessed after treatment of two SMESs in different dilutions. RESULTS: The TEER of cell monolayers was not markedly affected by negatively charged SMES in different dilutions. The positively charged SMES could significantly decrease the TEER (P < 0.05) in three dilutions. The full recovery of TEER was found after the treatment of lower dilution for 2 h, then cultured for 48 h, while the recovery of TEER was 81.3% of control in 1 : 50 dilution. Two SMESs could enhance the apparent permeability coefficient of mannitol (2.9 - 64.6 folds), which depended on the dilution times. The immunofluorescent results indicated that the distribution of ZO-1 and actin were discrete in cell membrane after the treatment of formulation. Since the positively charged microemulsion could bind to the epithelial cell membrane by electrostatic interaction, the actin of the cells undergone some kind of stress stimulated by the higher concentration of microemulsion was more markedly affected than the negatively charged SMES. Effect of formulations on ZO-1 and actin relied on the dilution. CONCLUSION: SMES is able to enhance the paracellular transport marker mannitol. The mechanism of opening of tight junctions by SMES might be the change of distribution of ZO-1 and actin.

[The pharmacokinetics and pharmacodynamics of intranasal preparation of Panax notoginseng Saponins].

AIM: To investigate the pharmacokinetic course of intranasal powders of Panax notoginseng Saponins (PNS) in a rat model and its protective effects against cardio-cerebrovascular diseases administrated in the form of its suspension. METHODS: After administration, Rgl concentration in the serum was analyzed by HPLC and the absolute bioavailability was calculated. The protective effects against cardia-cerebrovascular diseases were studied on actue myocardial infarction model in rats built by occlusion of left coronary artery and cerebral ischemia-reperfusion model in gerbils built by occlusion of bilateral common carotid artery (CCA). RESULTS: The in vivo course of Rgl in rats conformed to two-compartment model after intranasal administration of PNS suspension and the absolute bioavailability was 103.56%. The suspension significantly reduced myocardial infarct size induced by occlusion of the left coronary artery, alleviated cerebral edema and the stroke symptoms induced by occlusion of bilateral common carotid artery (CCA). And the effects were dose-dependent, the higher dose, the better effects. CONCLUSION: The results of pharmacokinetics and pharmacodynamics demonstrated that PNS intranasal preparation has a pretty prospect to develop.

[9-nitrocamptothecin nanostructured lipid carrier system: in vitro releasing characteristics, uptake by cells, and tissue distribution in vivo].

AIM: To study the release and cell uptake characteristics of 9-nitrocamptothecin (9-NC) nanostructured lipid carrier system (NLC) in vitro and its tissue distribution characteristics in vivo. METHODS: Mouse peritoneal macrophages were used to investigate the uptake of nanoparticles by cells in vitro. The tissue distribution of 9-nitrocamptothecin solution and stealth nanostructured lipid carrier system (S-NLC) was determined after intravenous administration to mice at a single dose of 1.5 mg kg(-1). The release and crystalloid characteristics were also investigated. RESULTS: X-ray diffraction spectrum showed that 9-NC probably was amorphous in S-NLC. The liquid lipid did not change the characteristics of the solid matrix in nanoparticles. The in vitro release and cell uptake characteristics of stealth and non-stealth 9-NC-NLC were investigated, separately. The results showed that the stealth 9-NC-NLC had sustained-release characteristics and could resist the absorption effect of the additional plasmas to a certain extent. In addition, the cell uptake percentage of stealth 9-NC-NLC was much lower than that of the non-stealth ones. The tissues distribution results showed that 9-NC in the S-NLC was mainly found in the lung, liver, pancreas and ovary/uterus, while the quantity of 9-NC was much lower in heart and kidney. The AUQ(0-t), of S-NLC in blood, ovary/uterus, pancreas, liver and lung were higher than that of 9-nitrocamptothecin solution. The weight-average drug targeting efficiency (Te*) of S-NLC in liver and lung were significantly higher than that of 9-nitrocamptothecin solution. The mean residence times (MRT) of S-NLC was 44 h, while that of 9-nitrocamptothecin solution was 8 h. Therefore, S-NLC showed obvious targeting effects on liver and lung. CONCLUSION: S-NLC with PEG flexible chains has sustained-release characteristics and can prolong its circulation in blood and have good targeting efficiency on liver and lung.

[The in vitro kinetics of uptake, transport and efflux of 9-nitrocamptothecin in Caco-2 cell model].

AIM: To study the kinetics of uptake, transepithelial transport and efflux of 9-nitrocamptothecin (9-NC). METHODS: A human intestinal epithelial cell model Caco-2 cell in vitro cultured had been applied to study the kinetics of uptake, transport and efflux kinetics of 9-NC at small intestine. The effects of time, pH, temperature and P-glycoprotein inhibitors on the uptake of 9-NC were investigated. The determination of 9-NC was performed by HPLC. RESULTS: The uptake and absorption of 9-NC were passive diffusion as the dominating process. The uptake of 9-NC is positively correlated to uptake time, and negatively correlated to pH and temperature. The inhibitors, cyclosporine A and verapamil, significantly enhanced the uptake amount of 9-NC (P < 0.05). P(app) of Basolateral to Apical was much more than that of Apical to Basolateral (2.6-6.9 fold). The efflux of 9-NC was fitted to apparent two-order process. The m0 [(148.0 +/- 2.2) pmol x cm(-2)] and the efflux rate (41.1 pmol x cm2 min(-1)) on Apical side were higher than the m0 [(121 +/- 7) pmol x cm(-2)] (P < 0.05) and the efflux rate (29.2 pmol x cm2 x min(-1)) on Basolateral side (P < 0.01). CONCLUSION: The uptake and absorption of 9-NC were passive diffusion as the dominating process. P-glycoprotein had strong efflux effects on the uptake and transepithelial transport of 9-NC.