Polyamidomine dendrimers: an excellent drug carrier for improving the solubility and bioavailability of puerarin

The potential of polyamidoamine (PAMAM) dendrimers as solubility enhancers and oral drug delivery system was well known. Herein, we investigated the possibility of PAMAM dendrimers for promoting the solubility and oral bioavailability of puerarin. In the present study, the effect of PAMAM dendrimers with different generations (G1.5, G2, G2.5, and G3) on the solubility of puerarin was evaluated at different concentrations and pH conditions. Further more, the puerarin–G2 dendrimer complex was conducted for the in vitro hemolytic toxicity studies and pharmacokinetics studies in rats. The solubility of puerarin was significantly higher in the presence of the full generation dendrimers (e.g. G2 and G3). No significant hemolysis was observed on erythrocytes (G2, 0–2.5?mg/mL) in the hemolytic toxicity studies. The pharmacokinetics parameters T_max, C_max, and AUC_{0–8 h} of puerarin suspension solution and puerarin–G2 dendrimer complex solution were 0.76?h, 1.50 µg/mL, 7.33 µg·h/mL and 0.33?h, 6.49 µg/mL, 14.02 µg·h/mL, respectively. These studies demonstrate that PAMAM dendrimers may be a promising strategy for peroral delivery of puerarin.     

Nose to brain microemulsion-based drug delivery system of rivastigmine: formulation and ex-vivo characterization

Abstract

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder leading to irreversible loss of neurons, cognition and formation of abnormal protein aggregates. Rivastigmine, a reversible cholinesterase inhibitor used for the treatment of AD, undergoes extensive first-pass metabolism, thus limiting its absolute bioavailability to only 36% after 3-mg dose. Due to extreme aqueous solubility, rivastigmine shows poor penetration and lesser concentration in the brain thus requiring frequent oral dosing. This investigation was aimed to formulate microemulsion (ME) and mucoadhesive microemulsions (MMEs) of rivastigmine for nose to brain delivery and to compare percentage drug diffused for both systems using in-vitro and ex-vivo study. Rivastigmine-loaded ME and MMEs were prepared by titration method and characterized for drug content, globule size distribution, zeta potential, pH, viscosity and nasal ciliotoxicity study. Rivastigmine-loaded ME system containing 8% w/w Capmul MCM EP, 44% w/w Labrasol:Transcutol-P (1:1) and 48% w/w distilled water was formulated, whereas 0.3% w/w chitosan (CH) and cetyl trimethyl ammonium bromide (as mucoadhesive agents) were used to formulate MMEs, respectively. ME and MMEs formulations were transparent with drug content, globule size and zeta potential in the range of 98.59% to 99.43%, 53.8?nm to 55.4?nm and ?2.73?mV to 6.52?mV, respectively. MME containing 0.3% w/w CH followed Higuchi model (r²?=?0.9773) and showed highest diffusion coefficient. It was free from nasal ciliotoxicity and stable for three months. However, the potential of developed CH-based MME for nose to brain delivery of rivastigmine can only be established after in-vivo and biodistribution study.     

Effects of glycyrrhizin on the pharmacokinetics of puerarin in rats

1. Puerarin has been reported to possess a wide range of pharmacological activities. This study investigated the effects of glycyrrhizin on the pharmacokinetics of puerarin in rats.

2. The pharmacokinetics of orally administered puerarin (50?mg/kg) with or without glycyrrhizin pretreatment (100?mg/kg/day for 7?days) were investigated. The plasma concentration of puerarin was determined using a sensitive and reliable LC-MS/MS method. The pharmacokinetics profiles were calculated and compared. Additionally, a Caco-2 cell transwell model was used to investigate the potential mechanism of glycyrrhizin’s effects on the pharmacokinetics of puerarin.

3. The results showed that when the rats were pretreated with glycyrrhizin, the maximum concentration (C_max) of puerarin decreased from 761.25?±?52.34 to 456.32?±?34.75?ng/mL, and the area under the concentration–time curve from zero to infinity (AUC_0–inf) also decreased from 4142.15?±?558.51 to 2503.74?±?447.57?μg·h/L. The oral clearance of puerarin increased significantly from 12.20?±?1.53 to 20.47?±?3.25?L/h/kg (p?4. In conclusion, these results indicated that glycyrrhizin could affect the pharmacokinetics of puerarin, possibly by decreasing the systemic exposure of puerarin by inducing the activity of P-gp.     

Enhanced ocular bioavailability of fluconazole from niosomal gels and microemulsions: formulation,optimization, and in vitro–in vivo evaluation

Fungal keratitis may cause vision loss if it is not treated. Methods other than ocular delivery exhibited several limitations. No previous studies investigated and compared ocular bioavailability of fluconazole (FLZ) from niosomal gels and microemulsions. Niosomal gels of FLZ (0.3% w/w) based on Span^® 60 and cholesterol (CH) using 1% w/w carbopol^® 934 (CP) were evaluated. FLZ microemulsions (0.3% w/v) containing isopropyl myristate (IPM, as oil phase) and a 3:1 mixture of Tween^® 80 (as surfactant) and polyethylene glycol 400 (PEG 400, as cosurfactant) were characterized. Optimized formulations were compared for their ocular bioavailability in rabbit’s. Nanoscopic niosomes (63.67–117.13?nm) and microemulsions (57.05–59.93?nm) showed respective negative zeta potential ranges of ?45.37 to ?61.40 and ?20.50 to ?31.90?mV and sustained release up to 12?h. Entrapment efficiency (EE%) of niosomes ranged from 56.48% to 70.67%. Niosomal gels were more sustainable than niosomes and microemulsions. The most stable niosomal gel based on Span^® 60 and CH at a molar ratio of 5:5 and microemulsion containing 45% w/w IPM and 40% w/w of 3:1 Tween^® 80-PEG 400 mixture significantly (p?<?0.0001) enhanced FLZ ocular bioavailability compared with its solution. Niosomal gel showed higher bioavailability than microemulsion by ≈2-fold.     

Chitosan nanoconstructs for improved oral delivery of low molecular weight heparin: In vitro and in vivo evaluation

The aim of present study was to investigate the potential of mucoadhesive polymer chitosan (CS) and N-trimethyl chitosan (TMC) based nanoparticulate systems for oral bioavailability enhancement of low molecular weight heparin (LMWH). The TMC was synthesized by methylation of chitosan followed by characterization using infrared spectroscopy and (1)H-NMR spectroscopy. The IR and NMR spectra of TMC confirmed the presence of trimethyl groups and estimated the degree of quaternization for TMC about 46%. TMC nanoparticles were then prepared by ionic gelation method. The developed CS-NPs and TMC-NPs were characterized for various parameters including morphology, particle size, zeta potential, entrapment efficiency, in vitro release behavior and storage stability at different temperature and simulated gastrointestinal tract conditions. The fluorescent microscopy study confirmed the higher particle uptake of TMC-NPs by gastrointestinal epithelium in comparison to the CS-NPs. The concentration of LMWH in the systemic circulation followed by oral administration of formulations was estimated using FXa chromogenic assay. A significant increase (p<0.05) in the oral bioavailability of LMWH was observed with TMC-NPs than both CS-NPs as well as plain LMWH solution. These findings suggested that TMC nanoparicles hold promise for oral delivery of LMWH and clinical applicability for the treatment of vascular disorders like deep vein thrombosis and pulmonary embolism, etc.     

Enhancing both oral bioavailability and brain penetration of puerarin using borneol in combination with preparation technologies

Now there are few good oral preparations of puerarin used in cerebrovascular diseases because of its poor oral absorption caused by the low water solubility and the poor penetration into brain. In this study, three oral formulations of puerarin, nanocrystals suspension (NCS), inclusion compounds solution (ICS) and self-microemulsifying drug delivery system (SMEDDS) were prepared with borneol as an oral brain-targeting enhancer. A rat syngeneic in vitro model of the brain–blood barrier (BBB) was established to investigate effects of borneol on the permeability of puerarin across the BBB. The pharmacokinetics of puerarin in mice after oral administration was investigated by a high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) method. The in vitro BBB model study showed the permeability of puerarin was increased significantly (p?p?plasma) and in brain (AUC_brain) for SMEDDS were significantly higher than those for NCS (p?p?相似文献   

Pharmacokinetics of isoforskolin after administration via different routes in guinea pigs

1.?The objective of this study was to characterize the pharmacokinetics of isoforskolin after oral, intraperitoneal and intravenous administration, as well as to compare bioavailability.

2.?Isoforskolin was administered to guinea pigs at a dose of 2?mg/kg. Plasma concentrations were determined by high-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (HPLC–ESI–MS/MS) method. The pharmacokinetic parameters were calculated by a noncompartmental method. A compartment model was also adopted to describe the pharmacokinetic profiles.

3.?The pharmacokinetic behavior of intravenously administered isoforskolin was characterized by rapid and extensive distribution (V_z?=?16.82?±?8.42?L/kg) followed by rapid elimination from the body (Cl?=?9.63?±?4.21?L/kg/h). After intraperitoneal administration, isoforskolin was absorbed rapidly (T_max?=?0.12?±?0.05?h). The pharmacokinetic profiles of isoforskolin were similar after intraperitoneal and intravenous administration, except for the concentrations at the initial sampling times. Isoforskolin was also absorbed rapidly following oral dosing; however, the concentration–time data were best fit to a one-compartment model, which was different from that observed after intravenous and intraperitoneal administration. Following intraperitoneal and oral administration, the absolute bioavailability of isoforskolin was 64.12% and 49.25%, respectively.

4.?Isoforskolin is a good candidate for oral administration because of its good oral bioavailability.     

Nasal absorption and local tissue reaction of insulin nanocomplexes of trimethyl chitosan derivatives in rats

Objectives The objective of this work was to explore the potential and safety of trimethyl chitosan (TMC) and PEGylated TMC for improved absorption of insulin after nasal administration. Methods The nasal absorption of insulin nanocomplexes of TMC or PEGylated TMC was evaluated in anaesthetized rats. Concomitantly, the histopathological effects of these nanocomplexes on rat nasal mucosa were studied using a perfusion fixation technique. Key findings All insulin nanocomplexes containing TMC or PEGylated TMC showed a 34–47% reduction in the blood glucose concentration, when the insulin absorption through the rat nasal mucosa was measured indirectly. In addition, the relative pharmacodynamic bioavailability (F_dyn) of the formulations was found to be dependent upon the charge ratio of insulin and polymer, regardless of polymer structure. The F_dyn apparently decreased with increasing charge ratio of insulin : polymer. Although acute alterations in nasal morphology by the formulations were affected by the charge ratio of insulin and polymer, the formulation of insulin/PEGylated TMC nanocomplexes was shown to be less toxic to the nasal epithelial membrane than insulin/TMC nanocomplexes. Conclusions PEGylated TMC nanocomplexes were a suitable absorption enhancer for nasal delivery of insulin.     

Polyamidoamine (PAMAM) dendrimers as potential release modulators and oral bioavailability enhancers of vardenafil hydrochloride

Vardenafil hydrochloride (VAR) is an erectile dysfunction treating drug. VAR has a short elimination half-life (4–5?h) and suffers low oral bioavailability (15%). This work aimed to explore the dual potential of VAR-dendrimer complexes as drug release modulators and oral bioavailability enhancers. VAR-dendrimer complexes were prepared by solvent evaporation technique using four dendrimer generations (G4.5, G5, G5.5 and G6) at three concentrations (190?nM, 380?nM and 950?nM). The systems were evaluated for intermolecular interactions, particle size, zeta potential, drug entrapment efficiency percentages (EE%) and drug released percentages after 2?h (Q_2h) and 24?h (Q_24h). The results were statistically analyzed, and the system showing the highest desirability was selected for further pharmacokinetic studies in rabbits, in comparison to Levitra^® tablets. The highest desirability (0.82) was achieved with D10 system comprising VAR (10?mg) and G6 (190?nM). It possessed small particle size (113.85?nm), low PDI (0.19), positive zeta potential (+21.53), high EE% (75.24%), promising Q_2?h (41.45%) and Q_24?h (74.05%). Compared to Levitra^® tablets, the significantly (p?<?0.01) delayed T_max, prolonged MRT_(0?∞) and higher relative bioavailability (3.7-fold) could clarify the dual potential of D10 as a sustained release system capable of enhancing VAR oral bioavailability.     

Effects of astragaloside IV on the pharmacokinetics of puerarin in rats

Abstract

1. Radix astragali and puerarin are always used together for cardiovascular disease in China clinics.

2. This study investigates the effects of astragaloside IV (AS-IV, the main components of radix astragali) on the pharmacokinetics of puerarin in rats.

3. The pharmacokinetics of orally administered puerarin (50?mg/kg) with or without AS-IV pretreatment (100?mg/kg/day for seven days) were investigated. The plasma concentration of puerarin was determined using LC–MS/MS method, and the pharmacokinetics profiles were calculated and compared. Caco-2 cell transwell model was also used to investigate the effects of AS-IV on the transport pf puerarin.

4. The results showed that when the rats were pretreated with AS-IV, the maximum concentration (C_max) of puerarin decreased from 760 to 467?ng/mL (p?<?.05, n?=?6, 90% CI, 293?±?61.28), and the area under the concentration-time curve from zero to infinity (AUC_0–inf) also decreased from 4097 to 2330?μg·h/L (p?<?.05, n?=?6). The oral clearance of puerarin increased significantly from 11.9 to 22.4?L/h/kg (p?<?.05, n?=?6). The Caco-2 cell transwell experiments indicated that AS-IV could increase the efflux ratio of puerarin from 1.81 to 2.79 through inducing the activity of P-gp.

5. In conclusion, these results indicated that AS-IV could affect the pharmacokinetics of puerarin, possibly by decreasing the systemic exposure of puerarin by inducing the activity of P-gp.

     

Effects of verapamil on the pharmacokinetics of puerarin in rats

Abstract

1. The oral bioavailability of puerarin is poor which hindered its clinical performance.

2. This study investigates the effects of verapamil on the pharmacokinetics of puerarin in rats.

3. The pharmacokinetics of orally administered puerarin (50?mg/kg) with or without verapamil pretreatment (10?mg/kg/day for 7?days) were investigated. The plasma concentration of puerarin was determined using LC-MS/MS method, and the pharmacokinetics profiles were calculated and compared. Caco-2 cell transwell model was also used to investigate the effects of verapamil on the transport pf puerarin.

4. The results showed that when the rats were pretreated with verapamil, the maximum concentration (C_max) of puerarin increased from 683.7?±?51.2 to 933.5?±?75.8?ng/mL (p?<?0.05), and the area under the concentration-time curve from zero to infinity (AUC_0-inf) also increased from 3687.3?±?444.6 to 5006.1?±?658.6?μg·h/L (p?<?0.05). The Caco-2 cell transwell experiments indicated that verapamil could decrease the efflux ratio of puerarin from 1.90 to 1.19 through inhibiting the activity of P-gp.

5. In conclusion, these results indicated that verapamil could affect the pharmacokinetics of puerarin, possibly by increasing the systemic exposure of puerarin by inhibiting the activity of P-gp.

     

N-trimethyl chitosan-modified liposomes as carriers for oral delivery of salmon calcitonin

Therapeutic peptide and protein drugs have high specificity and activity in their functions but present challenges in their administration route, requiring development of new delivery systems to improve their bioavailability. The aim of this work was to investigate the role of N-trimethyl chitosan- (TMC-) coated liposomes in the oral administration of calcitonin. TMC with a degree of quaternization around 78% was synthesized and its mucoadhesive properties were examined in vitro using the mucin-particle method, which confirmed that TMC showed mucoadhesion comparable to that of chitosan. TMC-coated liposomes containing calcitonin were prepared and characterized as having a particle size of 262?nm, zeta potential of 35.8 mV and high entrapment efficiency (89.1%). The in vivo evaluation of mucoadhesion was carried out using confocal laser microscopy to observe the residence time and permeation extent after intragastric administration. The results showed that TMC-coated liposomes prolonged the residence time and increased the penetration effect of the liposomal system compared to non-coated liposomes. The study of pharmacological effects confirmed that TMC-coated liposomes increased the area above the blood calcium concentration-time curves (AAC) from 3.13?±?20.50 to 448.84?±?103.56 compared to the calcitonin solution. These results support the feasibility of TMC-coated liposomes as a new oral delivery system for peptide and protein drugs.     

Lymphatic transport of puerarin occurs after oral administration of different lipid-based formulations to unconscious lymph duct-cannulated rats

Abstract

This study investigated the potential of targeted intestinal lymphatic transport of puerarin via a lipid formulation approach. Three formulations of PEG nanoemulsion, nanosuspension and an oil suspension containing puerarin were examined with the lymph-cannulated anaesthetized rat model. Plasma and lymph samples were analyzed by HPLC. Lymph triglyceride was measured using an enzymatic colorimetric technique. After 8?h, the total administered dose accumulated in the thoracic lymph duct was analyze. Nanoemulsion, nanosuspension and oil suspension was 0.065?±?0.006%, 0.137?±?0.018%, 0.021?±?0.002% of the administered dose, respectively. In nanoemulsion, nanosuspension and oil suspension group, the systemic bioavailability of oral puerarin was 11%, 16% and 11% for lymph-cannulated rats, 41%, 67% and 18% for control rats. Absorption into the intestinal lymph should thus contribute to ～30%, 51% and 7% of the systemic bioavailable puerarin. This data indicated that lipid-based nano drug formulation produced higher lymph concentrations of puerarin than oil suspension. The nanosuspension formulation may be considerable in terms of increased local concentrations in lymphoid tissue.     

Synthesis of tritium‐labeled puerarin—a potential antidipsotropic agent

Puerarin 1 (8‐β‐D ‐Glucopyranosyl‐4′‐7‐dihydroxyisoflavone, NPI‐031G) is the major isoflavone C‐glycoside isolated from Pueraria lobata, a traditional Chinese medicine widely used for the treatment of alcohol intoxication. In order to understand the mode of action of puerarin in the reward pathway of the central nervous system and to study its bioavailability and pharmacokinetics, we developed a synthetic route for the preparation of tritium‐labeled puerarin. The key intermediate 4 was obtained by trimethylsilyl protection of all hydroxyl groups followed by selective deprotection. The corresponding aldehyde 5 was obtained through the subsequent oxidation of the primary alcohol. Standard NaB[³H]₄ reduction and hydrolysis produced the tritium‐labeled puerarin 6 . Copyright © 2007 John Wiley & Sons, Ltd.     

Absorptive interactions of concurrent oral administration of (+)-catechin and puerarin in rats and the underlying mechanisms

Aim:

(+)-Catechin and puerarin are polyphenol and flavonoid, respectively, in green tea and foodstuffs. They exhibit potent antioxidant activity and are widely used for treating cardiocerebrovascular diseases. The aim of this work was to investigate the potential interactions between (+)-catechin and puerarin following concurrent oral administration in rats, and their absorption mechanisms in Caco-2 cell monolayers.

Methods:

Pharmacokinetic studies were conducted in male rats received (+)-catechin (140 mg/kg, po) and/or puerarin (200 mg/kg, po). The cell uptake and transport behavior in Caco-2 cell monolayers and the interactions of the two compounds were analyzed.

Results:

When (+)-catechin and puerarin were administered concurrently, the AUC_{0-12 h} and C_max values of puerarin were 2.48-fold and 3.91-fold, respectively, as large as those of puerarin alone; the AUC_{0-12 h} and C_max values of (+)-catechin were decreased to 57.62% and 77.55%, respectively, compared with those of (+)-catechin alone. In Caco-2 cell monolayers, (+)-catechin (300 and 600 μmol/L) significantly increased the cell uptake and transport of puerarin, whereas puerarin (300 and 600 μmol/L) significantly decreased the cellular uptake and transport of (+)-catechin. Furthermore, both cyclosporine A (P-glycoprotein inhibitor) and MK-571 (MRP-2 inhibitor) significantly increased the cellular uptake and transport of (+)-catechin and puerarin.

Conclusion:

Concurrent oral administration of (+)-catechin and puerarin significantly increased the absolute oral bioavailability of puerarin, but decreasing that of (+)-catechin. The competitive efflux of (+)-catechin and puerarin by P-glycoprotein and MRP-2 might lead to this interaction during their absorption process in the small intestine.     

Improvement of oral bioavailability of glycyrrhizin by sodium deoxycholate/phospholipid-mixed nanomicelles

Glycyrrhizin (GL), extracted from the Glycyrrhiza glabra L., is active triterpenoid saponin components. However, due to its impermeability across the gastrointestinal mucosa, oral bioavailability of the drug was relatively low. To improve its oral bioavailability, formulation of GL as sodium deoxycholate/phospholipid-mixed nanomicelles (SDC/PL-MMs) has been performed in this study. GL-SDC/PL-MMs were produced by a film dispersion method and then investigated using photon correlation spectroscopy (PCS), zeta potential measurement, as well as its physical stability after storage for 10, 20, 30, 60, 90 and 120 days. To verify the theoretical hypothesis, pharmacokinetics and pharmacodynamic studies based on carbon tetrachloride (CCl₄)-induced acute liver injury was investigated. Results showed that a narrow size distributed nanomicelles with a mean particle size of 82.99?±?7.5?nm and a zeta potential of ?32.23?±?1.05 mV was obtained. In the pharmacokinetics, GL-SDC/PL-MMs show a significant superiority in AUC_0–t, C_max and other pharmacokinetic parameters compared with the control group. In the pharmacodynamic studies, compared with the bifendate control group, GL-SDC/PL-MMs showed an equivalent effect in reducing alanine aminotransferase (ALT), aspartate aminotransferase (AST) and improving the pathological changes of liver tissue. These results revealed that SDC/PL-MMs could enhance GL absorption in gastrointestinal tract and pharmacodynamic effect in the treatment of acute liver injury caused by CCl₄, and SDC/PL-MMs might be a good choice for oral delivery of poor bioavailability drug like GL.     

Essential oil of Psidium cattleianum leaves: Antioxidant and antifungal activity

Abstract

Context: Psidium cattleianum Sabine (Myrtacea) is rich in vitamin C and phenolic compounds, including epicatechin and gallic acid as the main components.

Objective: To evaluate the antifungal and antioxidant capacity in vitro of the essential oil of araçá (EOA). The acute toxicity of the EOA also was evaluated in mice.

Materials and methods: The leaves of the P. cattleianum were extracted by steam distillation. The antioxidant capacity was evaluated by in vitro tests [1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), ferric ion reducing antioxidant power (FRAP), linoleic acid oxidation, thiobarbituric acid reactive species (TBARS)], and ex vivo analysis [TBARS, δ-aminulevunilate dehydratase (δ-Ala-D) and catalase activity, non-protein thiols (NPSH), and ascorbic acid levels]. The toxicity was studied in mice by a single oral administration of EOA; and the antifungal activity was performed with five strains of fungi.

Results: The EOA exhibited antioxidant activity in the FRAP assay and reduced lipid peroxidation in the cortex (I_max?=?32.90?±?2.62%), hippocampus (IC₅₀?=?48.00?±?3.00?µg/ml and I_max?=?32.90?±?2.62%), and cerebellum (I_max?=?45.40?±?14.04%) of mice. Acute administration of the EOA by the oral route did not cause toxicological effects in mice (LD₅₀?>?500?µg/ml). The EOA also showed antifungal activity through of the determination minimum inhibitory concentration (MIC) values ranging from 41.67?±?18.04 to 166.70?±?72.17?µg/ml for tested strains.

Conclusion: The results of present study indicate that EOA possess antioxidant properties, antifungal and not cause toxicity at tested doses.     

Preparation of novel butyryl galactose ester-modified coix component microemulsions and evaluation on hepatoma-targeting in vitro and in vivo

The butyryl galactose ester-modified coix component microemulsions (But-Gal-CMEs) was developed for enhanced liver tumor-specific targeting. The study was aimed to evaluate the hepatoma-targeting potential of But-Gal-CMEs in vitro and in vivo. But-Gal-CMEs with a uniform spherical shape exhibited a small particle size (56.68?±?0.07?nm), a narrow polydispersity (PDI, 0.144?±?0.005) and slightly negative surface charge (?0.102?±?0.008?mV). In the cell uptake studies, But-Gal-CMEs showed a significant enhancement on the intracellular fluorescent intensity on HepG2 cells model, which was 1.93-fold higher relative to coix component microemulsions (CMEs). The IC₅₀ of But-Gal-CMEs against HepG2 cells was 64.250?μg/mL, which was notably stronger than that of CMEs. In the cell apoptosis studies, compared with CMEs, But-Gal-CMEs (50?μg/mL) treatment resulted in a 1.34-fold rise in total apoptosis cells of HepG2. In the biodistribution studies in vivo, the intratumorous fluorescence of Cy5-loaded But-Gal-CMEs was 1.43-fold higher relative to that of Cy5-loaded CMEs, suggesting an obviously enhanced accumulation in the tumor sites. Taken as together, But-Gal could be incorporated into the coix component microemulsions as a novel ligand for realizing hepatoma-targeting drugs delivery.     

Water-in-Oil Microemulsions Containing Medium-chain Fatty Acids/Salts: Formulation and Intestinal Absorption Enhancement Evaluation

Purpose. Water-in-oil (w/o) microemulsions have been developed which, in addition to non-ionic medium-chain glycerides, incorporate ionic lipids, primarily medium-chain fatty acids, such as caprylic (C₈) capric (C₁₀) and lauric (C₁₂) acids and their corresponding sodium salts. The absorption enhancing activity of w/o microemulsions incorporating these lipids was evaluated in the rat using Calcein (MW = 623) a water-soluble and poorly absorbed marker molecule. Methods. Phase diagrams were constructed where C₈/C₁₀ or C₁₂ fatty acids were treated as lipophilic surfactants and their sodium salts as hydrophilic ones. The anesthetised rat model was employed to evaluate Calcein absorption upon a single intraduodenal administration from a solution and the various w/o microemulsions. Results. A wide range of clear and transparent w/o microemulsions were obtained at ambient temperature either in liquid or solid form when a fixed blend of medium chain fatty acid/salt was titrated by a fixed ratio of the oil containing the oil-soluble mono- and diglycerides and deionized water or physiological saline. Upon intraduodenal administration in the anesthetised rat, the absorption of Calcein was improved from about 2% in aqueous solution up to about 37% in w/o microemulsions. Solid and liquid formulations were equally effective in improving bioavailability. The absorption enhancement activity of the fatty acids/salts followed the order C₈ C₁₀ > C₁₂. Absorption enhancement of Calcein was significantly reduced in the absence or presence of low levels of C₈/C₁₀ mono-/diglycerides. Conclusions. These results further support the use of medium-chain glycerides and fatty acids/salts in microemulsion formulations to improve intestinal absorption of water-soluble compounds.     

In vitro evaluation of the antioxidant activity of liposomal flavonols by the HRP–H2O2–luminol system

Considering that antioxidant flavonols have been reported to be beneficial to human health, but that their low water solubility and bioavailability limit their administration through systemic route, the development of suitable flavonol-carriers is of great importance for clinical therapeutics. The aim of this study was to prepare liposomes containing flavonols or not and evaluate their antioxidant activity. Vesicles were obtained by ethanol injection method and characterized in terms of entrapment efficiency, size and zeta potential. Inhibitory activity of liposomal flavonols on reactive oxygen species generation was assessed in vitro using luminol–H₂O₂–horseradish peroxidase technique. Antioxidant activity of liposomal flavonols is dependent on concentration and chemical structure of active compound. Quercetin and myricetin are the most active flavonols (IC₅₀?=?0.6–0.9?µmol/L), followed by kaempferol (IC₅₀?=?3.0–4.5?µmol/L) and galangin (IC₅₀?=?4.0–7.0?µmol/L). Our results suggest that antioxidant-loaded liposomes may be promising tools for therapy of diseases where oxidative stress is involved.