Characterization, stabilization and activity of uricase loaded in lipid vesicles

Enhancing the Bioavailability of the Ellagitannin, Geraniin: Formulation, Characterization, and in vivo Evaluation

Geraniin (GE), an ellagitannin (ET) renowned for its promising health advantages, faces challenges in its practical applications due to its limited bioavailability. This innovative and novel formulation of GE and soy-phosphatidylcholine (GE-PL) complex has the potential to increase oral bioavailability, exhibiting high entrapment efficiency of 100.2 ± 0.8 %, and complexation efficiency of 94.6 ± 1.1 %. The small particle size (1.04 ± 0.11 μm), low polydispersity index (0.26 ± 0.02), and adequate zeta potential (-26.1 ± 0.12 mV), indicate its uniformity and stability. Moreover, the formulation also demonstrates improved lipophilicity, reduced aqueous and buffer solubilities, and better partition coefficient. It has been validated by various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) studies. Oral bioavailability and pharmacokinetics of free GE and GE-PL complex investigated in rabbits demonstrated enhanced plasma concentration of ellagic acid (EA) compared to free GE. Significantly, GE, whether in its free form or as part of the GE-PL complex, was not found in the circulatory system. However, EA levels were observed at 0.5 h after administration, displaying two distinct peaks at 2 ± 0.03 h (T1max) and 24 ± 0.06 h (T2max). These peaks corresponded to peak plasma concentrations (C1max and C2max) of 588.82 ng/mL and 711.13 ng/mL respectively, signifying substantial 11-fold and 5-fold enhancements when compared to free GE. Additionally, it showed an increased area under the curve (AUC), the elimination half-life (t1/2, el) and the elimination rate constant (Kel). The formulation of the GE-PL complex prolonged the presence of EA in the bloodstream and improved its absorption, ultimately leading to a higher oral bioavailability. In summary, the study highlights the significance of the GE-PL complex in overcoming the bioavailability limitations of GE, paving the way for enhanced therapeutic outcomes and potential applications in drug delivery and healthcare.

Rapidly separating dissolving microneedles with sustained-release colchicine and stabilized uricase for simplified long-term gout management

Despite growing prevalence and incidence, the management of gout remains suboptimal. The intermittent nature of the gout makes the long-term urate-lowering therapy (ULT) particularly important for gout management. However, patients are reluctant to take medication day after day to manage incurable occasional gout flares, and suffer from possible long-term toxicity. Therefore, a safe and easy-to-operate drug delivery system with simple preparation for the long-term management of gout is very necessary. Here, a chitosan-containing sustained-release microneedle system co-loaded with colchicine and uricase liposomes were fabricated to achieve this goal. This microneedle system was confirmed to successfully deliver the drug to the skin and maintain a one-week drug retention. Furthermore, its powerful therapeutic potency to manage gout was investigated in both acute gouty and chronic gouty models. Besides, the drug co-delivery system could help avoid long-term daily oral colchicine, a drug with a narrow therapeutic index. This system also avoids mass injection of uricase by improving its stability, enhancing the clinical application value of uricase. In general, this two-drug system reduces the dosage of uricase and colchicine and improves the patient's compliance, which has a strong clinical translation.

Characterization of a novel marine microbial uricase from Priestia flexa and evaluation of the effects of CMCS conjugation on its enzymatic properties

A novel uricase producing marine bacterium Priestia flexa alkaAU was isolated and identified. The 16S rDNA and the uricase coding gene were sequenced, analyzed and submitted to GenBank. The uricase from Priestia flexa alkaAU (PFU) was purified, determined to be 58.87 kDa, and conjugated with carboxymethyl chitosan (CMCS) by ionic gelation. CMCS conjugation had no effect on the optimum pH of PFU but decreased the optimum temperature by 10 °C. CMCS conjugation increased the specific activity of PFU by 53% at the human body temperature (37 °C) and small intestine's pH (pH 6.8). Uricase thermostabilizing ability of CMCS was significant in the range of 37-80 °C but not at lower temperatures. For improvement of the pH stability of PFU, CMCS was more effective at pHs 3-5 than pHs 6-11. CMCS increased the half-life of PFU against artificial intestinal fluid by 1.5 folds, which demonstrated the potential capability of CMCS-PFU for oral administration.

Biomimetic lipidic nanovectors for effective asparaginase supramolecule delivery

Effectiveness of enzyme therapy is limited by enzyme drawbacks such as short half-life, low bioavailability and high immunogenicity. We loaded asparaginase (Aase) into hydroxypropyl- or sulfonbutylether-beta cyclodextrin to form supramolecular amphiphilic molecules by self-assembly followed by entrapment inside the cores of two biomimetic lipidic nanovectors (AS-XLNs). Supramolecular structure was simulated by molecular docking. AS-XLNs maintained superior activity through isolating Aase from external environment due to docking with cyclodextrin and coating with biomimetic membrane. Fluorescent probes and computational simulations were used to reveal possible interactions between serum albumin/trypsin and Aase/nanovector membrane components which were partly responsible for enhanced bioavailability and bioactivity of AS-XLNs compared to Aase. AS-XLNs significantly increased cytotoxicity against pulmonary tumor cells due to synergistic effects of Aase and nanovector membrane components (killing tumor cells through apoptosis induced by asparagine depletion and autophagy inhibition or via targets such as vascular endothelial growth factor A, alpha-amylase, p-selectin or androgen receptor).

Biomimetic microbioreactor-supramolecular nanovesicles improve enzyme therapy of hepatic cancer

A novel biomimetic nanovesicle-loaded supramolecular enzyme-based therapeutics has been developed. Here, using a biomimetic lipid-D-α-tocopherol polyethylene glycol succinate (TPGS) hybrid semi-permeable membrane, cyclodextrin supramolecular docking, metal-ion-aided coordination complexing, we combined multiple functional motifs into a single biomimetic microbioreactor-supramolecular nanovesicle (MiSuNv) that allowed effective transport of arginine deiminase (ADI) to hepatic tumor cells to enhance arginine depletion. We compared two intercalated enzyme-carrying supermolecular motifs mainly comprising of 2-hydroxypropyl-β-cyclodextrin and sulfobutyl-ether-β-cyclodextrin, the only two cyclodextrin derivatives approved for injection by the United States Food and Drug Administration. The ADI-specific antitumor effects were enhanced by TPGS (one constituent of MiSuNv, having synergistic antitumor effects), as ADI was separated from adverse external environment by a semi-permeable membrane and sequestered in a favorable internal microenvironment with an optimal pH and metal-ion combination. ADI@MiSuNv contributed to cell cycle arrest, apoptosis and autophagy through the enhanced efficacy of enzyme treatment against Hep3B xenograft tumors in rats.

Ratite oils for local transdermal therapy of 4-OH tamoxifen: development, characterization, and ex vivo evaluation

The anti-inflammatory property of ratite oils as well as its ability to act as a penetration enhancer makes it an ideal agent to be used in transdermal formulations. The present study aims to develop an effective transfersomal delivery of 4-hydroxytamoxifen (4-OHT), an anti-cancer drug, using ratite oil as a carrier agent for the treatment of breast cancer (BC). The 4-OHT transfersomes were prepared with and without ratite oils using soy phosphatidylcholine and three different edge activators (EAs) in five different molar ratios using the rotary evaporation-ultrasonication method. Optimal transfersome formulations were selected using physical-chemical characterization and ex vivo studies. Results from physical-chemical characterization of the developed formulations found sodium taurocholate to be the most suitable EA, which recorded highest entrapment efficiency of 95.1 ± 2.70% with 85:15, (w/w) and lowest vesicle size of 82.3 ± 0.02 nm with 75:25, (w/w) molar ratios. TEM and DSC studies showed that the vesicles were readily identified and present in a nearly perfect spherical shape. In addition, formulations with emu oil had better stability than formulations with ostrich oil. Physical stability studies at 4 °C showed that ratite oil transfersomes were stable up to 4 weeks, while transfersomes without ratite oils were stable for 8 weeks. Ex vivo permeability studies using porcine skin concluded that 4-OHT transfersomal formulations with (85:15, w/w) without emu oil have the potential to be used in transdermal delivery approach to enhance permeation of 4-OHT, which may be beneficial in the treatment of BC.

Biomimetic polysaccharide-cloaked lipidic nanovesicles/microassemblies for improving the enzymatic activity and prolonging the action time for hyperuricemia treatment

The improvement and maintenance of enzymatic activities represent major challenges. However, to address these we developed novel biomimetic polysaccharide hyaluronan (Hn)-cloaked lipidic nanovesicles (BHLN) and microassemblies (BHLNM) as enzyme carriers that function by entrapping enzymes in the core or by tethering them to the inner/outer surfaces via covalent interactions. The effectiveness of these enzyme carriers was demonstrated through an evaluation of the enzymatic activity and anti-hyperuricemia bioactivity of urate oxidase (also called uricase, Uase). We showed that Uase was effectively loaded within the BHLN/BHLNM (UHLN/UHLNM) and maintained good enzymatic bioactivity through a range of effects, including isolation from the external environment due to the vesicle-carrying (shielding effect), avoidance of recognition by the reticuloendothelial system due to Hn-cloaking (long-term effect), production of beneficial conformational changes (allosteric effect) due to a favorable internal microenvironment of construction and vesicle loading, and stabilization due to the reversible conjugation of Uase or vesicle and serum albumin (deposit effect). UHLN/UHLNM had significantly increased bioavailability (∼533% and ∼331% compared to Uase) and demonstrated greatly improved efficacy, whereby the time required for UHLN/UHLNM to lower the plasma uric acid concentration to a normal level was much shorter than that for free Uase. The interactions of the therapeutic enzyme (Uase), biomimetic membrane components (Hn and phospholipid), and serum albumin were investigated with a fluorescent probe and computational simulations to help understand the superior properties of UHLN/UHLNM.

Biomimetic Membrane-Structured Nanovesicles Carrying a Supramolecular Enzyme to Cure Lung Cancer

Platforms for enzyme delivery must simultaneously have plasma stability, high catalytic activity, and low/no immunogenicity of the enzyme. Here, we designed a novel biomimetic membrane-structured nanovesicle (BNV) to efficiently carry supramolecular enzymes to meet the above requirements. We complexed l-asparaginase (Aase) with hydroxypropyl-β-cyclodextrin (HPCD) to form a supramolecular amphiphile (AS) by self-assembly via noncovalent reversible interactions. We then used the first synthesized polyethylene glycol (PEG 2 kDa)-decorated hyaluronan (12 kDa) and HPCD to self-assemble a semipermeable biomimetic membrane-structured nanovesicle (BNV) together with AS loading. As compared to native Aase, AS@BNV exhibited superior catalytic activity preservation, improved catalytic activity, better pharmacokinetics in rats, enhanced cytotoxic effects, increased antitumor efficacy, and decreased side effects. The underlying mechanisms, such as the autophagy inhibition action against tumor cells, protein-protein docking of the interaction between Aase-serum albumin, and decreased hepatic enzymatic activity, were investigated. This approach paves the way for new types of powerful biomimetic-, supramolecular-, and nanocarrier-based enzymatic therapies.

Cytomembrane-mimicking nanocarriers with a scaffold consisting of a CD44-targeted endogenous component for effective asparaginase supramolecule delivery

Highly effective and safe delivery of therapeutic enzymes is pivotal to the success of antitumor therapy. Herein, we report on a targeted enzyme delivery system based on cytomembrane-mimicking nanocarriers (CmN) and a supramolecular technique (SmT). Specifically, each CmN had a scaffold that mainly consisted of a CD44-targeted endogenous component conjugated with polyethylene glycol 2000 (HA-g-PEG) that self-assembled with α-cyclodextrin (ACD). The CmN acted as a microbioreactor with an inner hollow space with the capacity to confine the large molecule asparaginase (Asp) in an Asp/ACD-supramolecular complex conjugated to the inner region. The supramolecular Asp loaded into the CmN (A-S-CmN) exhibited superior stability, kinetic properties, catalytic activity and antitumor effects compared to free Asp due to the dual protection of the supramolecular complex and the nanovesicle, the CD44 targeting-homing ability, the prolonged effects of HA-g-PEG, and the favorable inner microenvironment of the constructed supramolecular CmN. The A-S-CmN also showed a decrease in in vivo toxicity and immunogenicity. CmN combined with SmT therapeutics are easy to implement and extend for use in the delivery of various enzymes and for many types of cancer treatment.

Optimizing liposomes for delivery of Bowman-Birk protease inhibitors - Platforms for multiple biomedical applications

One of the major challenges in the administration of therapeutic proteins involves delivery limitations. Liposomes are well-known drug delivery systems (DDS) that have been used to overcome this drawback; nevertheless, low protein entrapment efficiency (EE) still limits their wide biomedical application on a commercial scale. In the present work, different methods for protein entrapment into liposomes were tested in order to obtain tailored DDS platforms for multiple biomedical applications. The protein used as model was the Black-eyed pea Trypsin and Chymotrypsin Inhibitor (BTCI), a member of the Bowman-Birk protease inhibitor family (BBIs), which has been largely explored for its potential application in many biomedical therapies. We optimized reverse-phase evaporation (REV) and freeze/thaw (F/T) entrapment methods, using a cationic lipid matrix to entrap expressive amounts of BTCI (∼100 μM) in stable liposomes without affecting its protease inhibition activity. The influence of various parameters (e.g. entrapment method, liposome composition, buffer type) on particle size, charge, polydispersity, and EE of liposomes was investigated to provide an insight on how to control such parameters in view of obtaining a high entrapment yield. In addition, BTCI liposome platforms obtained herein showed to be versatile vesicles, allowing surface modification with moieties/polymers of interest (e.g. PEG, transferrin). The aforementioned results are relevant to focusing on the entrapment of other promising BBIs or protein agents sharing similar structural features. These findings encourage future studies to investigate the advantages of using the liposome platforms presented herein to broaden the use of this type of DDS for BBI biomedical applications.

Therapeutic Enzymes Used for the Treatment of Non-Deficiency Diseases

Therapeutic enzymes have a broad variety of specific uses and clinical applications, particularly as antineoplasic agents, wound debridement therapeutics, and anti-inflammatory drugs, etc. These enzymes can elicit immune response, contributing allergic reactions. Newer drugs with improved stability and less antigenicity have been developed. Covalent modification of enzymes is used to circumvent this immunogenicity. Advancements in drug delivery have revolutionized enzyme therapy. Microencapsulation and artificial liposomal entrapment are some of the techniques used to increment the stability and half-life of enzyme drugs. Several enzymes are now used as prodrug that metabolizes inactive substances into active metabolites through bioactivation process. This approach comprises a suit of techniques that allow activation of drugs locally and at the site of action. This chapter gives an outline of clinical uses of therapeutic enzymes used in non-deficiency diseases. Developments of these enzymes are reviewed with a particular focus on bioengineering applied to the native proteins.

Uricase alkaline enzymosomes with enhanced stabilities and anti-hyperuricemia effects induced by favorable microenvironmental changes

Enzyme therapy is an effective strategy to treat diseases. Three strategies were pursued to provide the favorable microenvironments for uricase (UCU) to eventually improve its features: using the right type of buffer to constitute the liquid media where catalyze reactions take place; entrapping UCU inside the selectively permeable lipid vesicle membranes; and entrapping catalase together with UCU inside the membranes. The nanosized alkaline enzymosomes containing UCU/(UCU and catalase) (ESU/ESUC) in bicine buffer had better thermal, hypothermal, acid-base and proteolytic stabilities, in vitro and in vivo kinetic characteristics, and uric acid lowering effects. The favorable microenvironments were conducive to the establishment of the enzymosomes with superior properties. It was the first time that two therapeutic enzymes were simultaneously entrapped into one enzymosome having the right type of buffer to achieve added treatment efficacy. The development of ESU/ESUC in bicine buffer provides valuable tactics in hypouricemic therapy and enzymosomal application.

Nanosomal Microassemblies for Highly Efficient and Safe Delivery of Therapeutic Enzymes

Enzyme therapy has unique advantages over traditional chemotherapies for the treatment of hyperuricemia, but overcoming the delivery obstacles of therapeutic enzymes is still a significant challenge. Here, we report a novel and superior system to effectively and safely deliver therapeutic enzymes. Nanosomal microassemblies loaded with uricase (NSU-MAs) are assembled with many individual nanosomes. Each nanosome contains uricase within the alkaline environment, which is beneficial for its catalytic reactions and keeps the uricase separate from the bloodstream to retain its high activity. Compared to free uricase, NSU-MAs exhibited much higher catalytic activity under physiological conditions and when subjected to different temperatures, pH values and trypsin. NSU-MAs displayed increased circulation time, improved bioavailability, and enhanced uric acid-lowering efficacy, while decreasing the immunogenicity. We also described the possible favorable conformational changes occurring in NSU-MAs that result in favorable outcomes. Thus, nanosomal microassemblies could serve as a valuable tool in constructing delivery systems for therapeutic enzymes that treat various diseases.

Enzyme therapeutics for systemic detoxification

Life relies on numerous biochemical processes working synergistically and correctly. Certain substances disrupt these processes, inducing living organism into an abnormal state termed intoxication. Managing intoxication usually requires interventions, which is referred as detoxification. Decades of development on detoxification reveals the potential of enzymes as ideal therapeutics and antidotes, because their high substrate specificity and catalytic efficiency are essential for clearing intoxicating substances without adverse effects. However, intrinsic shortcomings of enzymes including low stability and high immunogenicity are major hurdles, which could be overcome by delivering enzymes with specially designed nanocarriers. Extensive investigations on protein delivery indicate three types of enzyme-nanocarrier architectures that show more promise than others for systemic detoxification, including liposome-wrapped enzymes, polymer-enzyme conjugates, and polymer-encapsulated enzymes. This review highlights recent advances in these nano-architectures and discusses their applications in systemic detoxifications. Therapeutic potential of various enzymes as well as associated challenges in achieving effective delivery of therapeutic enzymes will also be discussed.

Structure and enzymatic properties of molecular dendronized polymer-enzyme conjugates and their entrapment inside giant vesicles

Macromolecular hybrid structures were prepared in which two types of enzymes, horseradish peroxidase (HRP) and bovine erythrocytes Cu,Zn-superoxide dismutase (SOD), were linked to a fluorescently labeled, polycationic, dendronized polymer (denpol). Two homologous denpols of first and second generation were used and compared, and the activities of HRP and SOD of the conjugates were measured in aqueous solution separately and in combination. In the latter case the efficiency of the two enzymes in catalyzing a two-step cascade reaction was evaluated. Both enzymes in the two types of conjugates were highly active and comparable to free enzymes, although the efficiency of the enzymes bound to the second-generation denpol was significantly lower (up to a factor of 2) than the efficiency of HRP and SOD linked to the first-generation denpol. Both conjugates were analyzed by atomic force microscopy (AFM), confirming the expected increase in object size compared to free denpols and demonstrating the presence of enzyme molecules localized along the denpol chains. Finally, giant phospholipid vesicles with diameters of up to about 20 μm containing in their aqueous interior pool a first-generation denpol-HRP conjugate were prepared. The HRP of the entrapped conjugate was shown to remain active toward externally added, membrane-permeable substrates, an important prerequisite for the development of vesicular multienzyme reaction systems.

Nanosized sustained-release pyridostigmine bromide microcapsules: process optimization and evaluation of characteristics

Background

Pyridostigmine bromide (3-[[(dimethylamino)-carbonyl]oxy]-1-methylpyridinium bromide), a reversible inhibitor of cholinesterase, is given orally in tablet form, and a treatment schedule of multiple daily doses is recommended for adult patients. Nanotechnology was used in this study to develop an alternative sustained-release delivery system for pyridostigmine, a synthetic drug with high solubility and poor oral bioavailability, hence a Class III drug according to the Biopharmaceutics Classification System. Novel nanosized pyridostigmine-poly(lactic acid) microcapsules (PPNMCs) were expected to have a longer duration of action than free pyridostigmine and previously reported sustained-release formulations of pyridostigmine.

Methods

The PPNMCs were prepared using a double emulsion-solvent evaporation method to achieve sustained-release characteristics for pyridostigmine. The preparation process for the PPNMCs was optimized by single-factor experiments. The size distribution, zeta potential, and sustained-release behavior were evaluated in different types of release medium.

Results

The optimal volume ratio of inner phase to external phase, poly(lactic acid) concentration, polyvinyl alcohol concentration, and amount of pyridostigmine were 1:10, 6%, 3% and 40 mg, respectively. The negatively charged PPNMCs had an average particle size of 937.9 nm. Compared with free pyridostigmine, PPNMCs showed an initial burst release and a subsequent very slow release in vitro. The release profiles for the PPNMCs in four different types of dissolution medium were fitted to the Ritger-Peppas and Weibull models. The similarity between pairs of dissolution profiles for the PPNMCs in different types of medium was statistically significant, and the difference between the release curves for PPNMCs and free pyridostigmine was also statistically significant.

Conclusion

PPNMCs prepared by the optimized protocol described here were in the nanometer range and had good uniformity, with significantly slower pyridostigmine release than from free pyridostigmine. This novel sustained-release delivery nanosystem for pyridostigmine might alleviate the need to identify new acetylcholinesterase inhibitors.

Thermal inactivation of uricase (urate oxidase): mechanism and effects of additives

Uricase (Urc) is an oxidoreductase enzyme of both general and commercial interest, the former because of its lack of a cofactor and the latter because of its use in the treatment of hyperuricemic disorders. Results of fluorometry and circular dichroism (CD) spectroscopy indicate that the main phase of thermal Urc inactivation follows an irreversible two-state mechanism, with loss of ~20% of the helical structure, loss of the majority of the tertiary structure, and partial exposure of tryptophan residues to solution being approximately concurrent with activity loss. Results of size exclusion chromatography and 8-anilinonaphthalene-1-sulfonate binding studies confirm that this process results in the formation of aggregated molten globules. In addition to this process, CD studies indicate the presence of a rapid reversible denaturation phase that is not completely coupled to the main phase. Urc inactivation is inhibited by the presence of glycerol and trimethylamine oxide, stabilizers of hydrophobic interactions and backbone structure respectively, confirming that loss of hydrophobic bonding and loss of helical structure are key events in the loss of Urc activity. NaCl, however, destabilizes the enzyme at elevated temperature, emphasizing the importance of ionic interactions to Urc stability. A model is developed in which interfacial disruption, involving local loss of hydrophobic interactions, ionic bonds, and helical structure, leads to Urc inactivation and aggregation. Additional studies of Urc inactivation at a more ambient temperature indicate that the inactivation process followed under such conditions is different from that followed at higher temperatures, highlighting the limitations of high-temperature enzyme stability studies.

PEGylation enhancement of pH stability of uricase via inhibitive tetramer dissociation

Objectives

Previously, PEGylated uricase was demonstrated to maintain catalytic activity at pH 5.8, the isoelectric point of uricase, where native uricase ceases to function. To find out whether PEGylation could enhance pH stability of uricase, the enzyme activity to pH curve was completely characterized.

Methods

Complete characterization of the enzyme activity to pH curve, indicating an inverted bell-shaped relationship not previously documented, is presented. PEGylation enhancement of uricase stability at a pH lower than that commonly found in the liver, can be explored by dynamic dissociation of uricase using ultrafiltration and size-exclusion chromatography.

Key findings

The results suggest the role of PEGylation in enhanced pH stability is via inhibition of subunit disintegration. The mechanism of this effect is characterized by the wrapping of PEG chains around uricase, providing a flexible shell preventing subunit disintegration. The presence of notable PEGylation-induced changes in uricase supports this mechanism and include improved enzyme-substrate affinity and elevated thermal stability.

Conclusions

Characterization of PEGylated uricase provides a basis for the rational design of therapeutic PEGylated proteins.

Improved biological properties and hypouricemic effects of uricase from Candida utilis loaded in novel alkaline enzymosomes

Objective:

Previous studies on various enzymosomes (functional lipid vesicles encapsulating an enzyme) have been mostly carried out in vitro and have focused on preserving catalytic activity and improving the stability of the enzyme. Until now, few studies have focused on their in vivo fate. Similarly, although we have previously reported the increased in vitro uricolytic activity (about 2.2 times higher than that of free uricase, or three times higher than that of PEGylated uricase, Puricase^®, under physiological pH and temperature) and improved stability of the novel alkaline enzymosomes (functional lipid vesicles encapsulating uricase from Candida utilis: uricase-containing lipid vesicles, UOXLVs), it is still necessary to study the biological properties and hypouricemic effects of UOXLVs in vivo.

Methods:

The enzyme kinetics, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary safety of UOXLVs were evaluated.

Results:

The Michaelis constant (K_m) value of the UOXLVs was slightly lower than that of the free enzyme. The enzyme release from the UOXLVs lasted over 12 hours and their circulation half-life was about sevenfold longer than that of the free uricase. Meanwhile, the UOXLVs had a 22-fold increase in the area under the curve compared with the free uricase. Furthermore, it took less than 3 hours for the UOXLVs to lower the plasma uric acid concentration from a high to a normal level, compared with 6 hours for the free uricase. In addition, the UOXLVs had much less immunogenicity than free uricase and were well tolerated by all animals throughout the observation period.

Conclusion:

The UOXLVs markedly improved the biological properties and enhanced the hypouricemic effects of uricase in vivo.

Design and evaluation of a novel evodiamine-phospholipid complex for improved oral bioavailability

A novel evodiamine (EVO)-phospholipid complex (EPLC) was designed to improve the bioavailability of EVO. A central composite design approach was employed for process optimization. EPLC were characterized by differential scanning calorimetry, ultraviolet spectroscopy, Fourier transformed infrared spectroscopy, (1)H-NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectroscopy, apparent solubility, and dissolution rate. After oral administration of EPLC, the concentrations of EVO at different time points were determined by high-performance liquid chromatography. The optimal formulation for EPLC was obtained where the values of X (1), X (2), and X (3) were 2, 0.5, and 2.5 mg/mL, respectively. The average particle size and zeta potential of EPLC with the optimized formulation were 246.1 nm and -26.94 mV, respectively. The EVO and phospholipids in the EPLC were associated with non-covalent interactions. The solubility of EPLC in water and the dissolution rate of EPLC in phosphate-buffered solution (pH 6.8) were substantially enhanced. The plasma EVO concentration-time curves of EPLC and free EVO were both in accordance with the two-compartment model. The peak concentration and AUC(0-∞) of EPLC were increased, and the relative bioavailability was significantly increased to 218.82 % compared with that of EVO.

Design and evaluation of a novel evodiamine-phospholipid complex for improved oral bioavailability

A novel evodiamine (EVO)-phospholipid complex (EPLC) was designed to improve the bioavailability of EVO. A central composite design approach was employed for process optimization. EPLC were characterized by differential scanning calorimetry, ultraviolet spectroscopy, Fourier transformed infrared spectroscopy, (1)H-NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectroscopy, apparent solubility, and dissolution rate. After oral administration of EPLC, the concentrations of EVO at different time points were determined by high-performance liquid chromatography. The optimal formulation for EPLC was obtained where the values of X (1), X (2), and X (3) were 2, 0.5, and 2.5 mg/mL, respectively. The average particle size and zeta potential of EPLC with the optimized formulation were 246.1 nm and -26.94 mV, respectively. The EVO and phospholipids in the EPLC were associated with non-covalent interactions. The solubility of EPLC in water and the dissolution rate of EPLC in phosphate-buffered solution (pH 6.8) were substantially enhanced. The plasma EVO concentration-time curves of EPLC and free EVO were both in accordance with the two-compartment model. The peak concentration and AUC(0-∞) of EPLC were increased, and the relative bioavailability was significantly increased to 218.82 % compared with that of EVO.