The preparation of a complex of insulin-phospholipids and their interaction mechanism

The effect of naringenin-phospholipid complex on thermal oxidative stability of soybean oil under heating condition

Naringenin (NGE), a typical flavanone abundant in citrus fruits, exhibits remarkable antioxidant activities. However, its low solubility in oil restricts its widespread use in inhibiting lipid oxidation. In this study, we present a novel and effective approach to address this limitation by developing a naringenin-phospholipid complex (NGE-PC COM). Comprehensive analytical techniques including Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were employed to confirm the formation of the NGE-PC COM and elucidate the interaction mechanism between NGE and phospholipids molecules. Notably, the oil-solubility of NGE was significantly enhanced by approximately 2700-fold when formulated as a phospholipid complex in soybean oil. The improved oil-solubility of NGE-PC COM enabled effective inhibition of oil thermal oxidation under high temperature conditions. Generally, this investigation proposed a novel and promising strategy for employing flavanones with strong antioxidant activities to enhance the thermal oxidative stability of edible oil during heating processes.

Phospholipid Complexation for Bioavailability Improvement of Albendazole: Preparation, Characterization and In Vivo Evaluation

The current study aimed to improve the poor solubility of albendazole (ABZ) by means of phospholipid complexation, hence to improve its oral bioavailability. The solvent-evaporation method for ABZ-phospholipid complex (ABZ-PC) preparation was established for the first time. And a systematic optimization of preparation conditions of ABZ-PC was performed. Physicochemical studies of ABZ-PC were performed with FTIR, DSC, and XRD measurements to confirm the formation of the ABZ-PC and reveal the interaction mechanism between ABZ and phospholipid molecules. Solubility determination and morphological characterization were applied to verify the solubility improvement of prepared ABZ-PC. Moreover, the pharmacokinetic performance of ABZ-PC was further evaluated in vivo compared with raw materials of ABZ. Under optimal preparation conditions, the AE of ABZ-PC could be approximately 100%. Physicochemical studies indicated that the P = O group in the phospholipid molecule would interact with the N-H group in the ABZ molecule through hydrogen bonds and ABZ was dispersed in an amorphous state after being prepared into ABZ-PC. The aqueous solubility of ABZ-PC in deionized water (pH7.0) improved by 30-folds than free ABZ, and the AUC_0-t of ABZ-PC was significantly increased by 2.32 times in comparison with raw materials of ABZ through oral administration. The current study developed an effective method for the phospholipid complexation of ABZ. With significantly improved solubility in an aqueous environment, the prepared ABZ-PC exhibited improved oral bioavailability and pharmacokinetic characteristics indicating it could be potentially applied in the oral drug delivery of ABZ.

Engineering Nano- and Microparticles as Oral Delivery Vehicles to Promote Intestinal Lymphatic Drug Transport

Targeted oral delivery of a drug via the intestinal lymphatic system (ILS) has the advantages of protecting against hepatic first-pass metabolism of the drug and improving its pharmacokinetic performance. It is also a promising route for the oral delivery of vaccines and therapeutic agents to induce mucosal immune responses and treat lymphatic diseases, respectively. This article describes the anatomical structures and physiological characteristics of the ILS, with an emphasis on enterocytes and microfold (M) cells, which are the main gateways for the transport of particulate delivery vehicles across the intestinal epithelium into the lymphatics. A comprehensive overview of recent advances in the rational engineering of particulate vehicles, along with the challenges and opportunities that they present for improving ILS drug delivery, is provided, and the mechanisms by which such vehicles target and transport through enterocytes or M cells are discussed. The use of naturally sourced materials, such as yeast microcapsules and their derived polymeric β-glucans, as novel ILS-targeting delivery vehicles is also reviewed. Such use is the focus of an emerging field of research. Their potential use in the oral delivery of nucleic acids, such as mRNA vaccines, is proposed.

Preparation and Evaluation of a Self-Nanoemulsifying Drug Delivery System Loaded with Heparin Phospholipid Complex

A self-nanoemulsifying drug delivery system (SNEDDS) was developed to enhance the absorption of heparin after oral administration, in which heparin was compounded with phospholipids to achieve better fat solubility in the form of heparin-phospholipid (HEP-Pc) complex. HEP-Pc complex was prepared using the solvent evaporation method, which increased the solubility of heparin in n-octanol. The successful preparation of HEP-Pc complex was confirmed by differential scanning calorimetry (DSC), Fourier-transform infrared (FT-IR) spectroscopy, NMR, and SEM. A heparin lipid microemulsion (HEP-LM) was prepared by high-pressure homogenization and characterized. HEP-LM can enhance the absorption of heparin after oral administration, significantly prolong activated partial thromboplastin time (APTT) and thrombin time (TT) in mice, and reduce fibrinogen (FIB) content. All these outcomes indicate that HEP-LM has great potential as an oral heparin formulation.

Advances in Subcutaneous Delivery Systems of Biomacromolecular Agents for Diabetes Treatment

Diabetes mellitus is a major threat to human health. Both its incidence and prevalence have been rising steadily over the past few decades. Biomacromolecular agents such as insulin and glucagon-like peptide 1 receptor agonists are commonly used hypoglycemic drugs that play important roles in the treatment of diabetes. However, their traditional frequent administration may cause numerous side effects, such as pain, infection or local tissue necrosis. To address these issues, many novel subcutaneous delivery systems have been developed in recent years. In this review, we survey recent developments in subcutaneous delivery systems of biomacromolecular hypoglycemic drugs, including sustained-release delivery systems and stimuli-responsive delivery systems, and summarize the advantages and limitations of these systems. Future opportunities and challenges are discussed as well.

Phytophospholipid Complex of Caffeic Acid: Development, In vitro Characterization, and In Vivo Investigation of Antihyperlipidemic and Hepatoprotective Action in Rats

Caffeic acid (CA), a hydroxycinnamic acid possessing a variety of pharmacological activities, has caused a growing interest for the treatment of hyperlipidemia and associated conditions. This work endeavored to develop a novel formulation of CA-Phospholipon® 90H complex (CA-PC) using a solvent evaporation method. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectrophotometry (FTIR), and powder X-ray powder diffraction (PXRD) was carried to confirm the formation of CA-PC. The CA-PC was functionally evaluated in terms of solubility, in vitro and ex vivo drug release, and in vivo bioavailability and efficacy studies. SEM, DSC, FTIR, and XRD studies indicated the physical interaction of CA with Phospholipon® 90H to form a complex. Dynamic light scattering (DLS) studies described particle size of 168 ± 3.9 nm with a monodisperse distribution (PDI 0.17) and a negative zeta-potential of - 16.6 ± 2.1 mV. The phospholipid complex significantly improved (4.2-fold) the solubility of CA. In vitro and ex vivo dissolution studies of the formulated CA-PC revealed a significantly higher release compared with the pure CA. The pharmacokinetic study of CA-PC in rats demonstrated a significant increase (4.79-fold) in oral bioavailability when compared with pure CA as well. Additionally, a significant improvement in serum lipid profile, serum liver biomarker enzyme levels and, restoration of hepatic tissue architecture to normal, in high-fat diet (HFD) induced hyperlipidemic model was obtained upon CA-PC administration when compared with pure CA. These findings indicated that CA-PC would serve as an effective and promising formulation for CA delivery with improved antihyperlipidemic and hepatoprotective activity.Graphical abstract.

Preparation and Characterization of Protein-loaded PFC Nanoemulsions for the Treatment of Heart Diseases by Pulmonary Administration

In the treatment of heart disease, strategies for the targeted delivery of protein therapeutics to the heart by inhalation are still immature. Perfluorocarbons (PFCs) are inert chemicals with good biocompatibility, and unique physico-chemical properties that have recently led to their applications in numerous fields. In this study, we combined the advantages of protein-phospholipid complexes and PFC emulsions and then synthesized protein-loaded PFC nanoemulsions (PNEs) to test whether, after inhalation, these nanoemulsions could deliver therapeutic proteins to the heart. After preparing protein-phospholipid complexes by lyophilization, we obtained PNEs by extrusion. The particle size and surface charge of PNEs were about 140 nm and -50 mV, respectively. In vitro results showed that the PNEs had a fine particle fraction of 35% and exhibited sustained protein release. Translocation studies were done using three types of pulmonary epithelial cells, and ~7% translocation was observed in the Calu-3 cell line. Further, they were easily absorbed by cells and had therapeutic effects in culture. In vivo results showed that the PNEs successfully delivered proteins to the myocardial tissue of rats and reduced ischemic myocardial injury caused by acute myocardial infarction (AMI). This study suggests that inhalation of PNEs is a new potential strategy to deliver proteins to cardiac tissues for treating heart diseases.

Phospholipid complex based nanoemulsion system for oral insulin delivery: preparation, in vitro, and in vivo evaluations

Purpose: The aim of this research was to develop a phospholipid complex based nanoemulsion system for oral insulin delivery.

Methods: Insulin-phospholipid complex (IPC) was firstly prepared by an anhydrous co-solvent lyophilization method, and then encapsulated into the oil phase of nanoemulsion to obtain the IPC-based nanoemulsion (IPC-NE). Both water-in-oil (W/O) IPC-NE and oil-in-water (O/W) IPC-NE were formulated and evaluated for comparison.

Results: The obtained W/O IPC-NE and O/W IPC-NE were both spherical in shape with a mean particle size of 18.6±0.79 nm and 27.3±1.25 nm, respectively. While both IPC-NEs exhibited enhanced Caco-2 cell monolayers permeability than IPC and insulin solution, W/O IPC-NE showed relatively greater protective effects against enzymatic degradation than O/W IPC-NE. Moreover, oral administration of W/O IPC-NE exhibited significant hypoglycemic effects, with 12.4-fold and 1.5-fold higher oral bioavailability compared with insulin solution and O/W IPC-NE, respectively.

Conclusion: IPC-NEs, especially the W/O IPC-NE showed promising efficiency in vitro and in vivo, thus could be a potential strategy for oral insulin delivery.

The preparation and investigation of spinosin–phospholipid complex self-microemulsifying drug delivery system based on the absorption characteristics of spinosin

Objectives

The aim of this research was to investigate the intestinal absorption characteristics and mechanisms of spinosin (SPI), and a new dosage form was prepared to increase the intestinal absorption of SPI.

Methods

In this study, the intestinal absorption characteristics and mechanisms of SPI were first investigated using in situ absorption model and Caco-2 monolayer model. Subsequently, the phospholipid complex (PLC) loaded with SPI was prepared followed by a self-microemulsifying drug delivery system (SMEDDS) technique for developing a more efficient formulation.

Key findings

The results showed that the absorption rate constant (0.02 h−1) and absorption percentage (10%) of SPI were small. Paracellular and active transport pathways mainly mediated the intestinal absorption of SPI. Moreover, SPI-PLC-SMEDDS showed a nanoscale particle size and excellent dispersibility in vitro. The cellular uptake and transportation properties of SPI-PLC-SMEDDS in the Caco-2 cell model were improved significantly. Besides, a statistically dramatically higher oral bioavailability (almost fivefold) was observed following the oral administration of SPI-PLC-SMEDDS than free SPI on the basis of pharmacokinetic experiment results. Furthermore, the SPI-PLC-SMEDDS exhibited certain immunization.

Conclusions

SPI-PLC-SMEDDS could be a promising oral drug delivery system to improve the absorption of SPI.

The Interaction between Zein and Lecithin in Ethanol-Water Solution and Characterization of Zein-Lecithin Composite Colloidal Nanoparticles

Lecithin, a naturally small molecular surfactant, which is widely used in the food industry, can delay aging, enhance memory, prevent and treat diabetes. The interaction between zein and soy lecithin with different mass ratios (20:1, 10:1, 5:1, 3:1, 2:1, 1:1 and 1:2) in ethanol-water solution and characterisation of zein and lecithin composite colloidal nanoparticles prepared by antisolvent co-precipitation method were investigated. The mean size of zein-lecithin composite colloidal nanoparticles was firstly increased with the rise of lecithin concentration and then siginificantly decreased. The nanoparticles at the zein to lecithin mass ratio of 5:1 had the largest particle size (263 nm), indicating that zein and lecithin formed composite colloidal nanoparticles, which might aggregate due to the enhanced interaction at a higher proportion of lecithin. Continuing to increase lecithin concentration, the zein-lecithin nanoparticles possibly formed a reverse micelle-like or a vesicle-like structure with zein in the core, which prevented the formation of nanoparticle aggregates and decreased the size of composite nanoparticles. The presence of lecithin significantly reduced the ζ-potential of zein-lecithin composite colloidal nanoparticles. The interaction between zein and lecithin enhanced the intensity of the fluorescence emission of zein in ethanol-water solution. The secondary structure of zein was also changed by the addition of lecithin. Differential scanning calorimetry thermograms revealed that the thermal stability of zein-lecithin nanoparticles was enhanced with the rise of lecithin level. The composite nanoparticles were relatively stable to elevated ionic strengths. Possible interaction mechanism between zein and lecithin was proposed. These findings would help further understand the theory of the interaction between the alcohol soluble protein and the natural small molecular surfactant. The composite colloidal nanoparticles formed in this study can broaden the application of zein and be suitable for incorporating water-insoluble bioactive components in functional food and beverage products.

Liposomal delivery systems for intestinal lymphatic drug transport

Intestinal lymphatic drug delivery has been widely studied because drugs can bypass the first-pass metabolism in the liver via the lymphatic route, which increases oral bioavailability. Various lipid-based nanoparticles have been used to deliver hydrophobic drugs to the lymphatic pathway. This review focuses on the liposomal delivery systems used for intestinal lymphatic drug transport. Liposomal formulations have attracted particular attention because they can stimulate the production of chylomicrons and the incorporated drugs readily associate with enterocyte-derived chylomicrons, enhancing lymphatic drug transport. We believe that a full understanding of their contribution to intestinal drug translocation will lead to effective oral delivery with liposomal formulations.

Self-assembled lecithin/chitosan nanoparticles for oral insulin delivery: preparation and functional evaluation

Purpose

Here, we investigated the formation and functional properties of self-assembled lecithin/chitosan nanoparticles (L/C NPs) loaded with insulin following insulin–phospholipid complex preparation, with the aim of developing a method for oral insulin delivery.

Methods

Using a modified solvent-injection method, insulin-loaded L/C NPs were obtained by combining insulin–phospholipid complexes with L/C NPs. The nanoparticle size distribution was determined by dynamic light scattering, and morphologies were analyzed by cryogenic transmission electron microscopy. Fourier transform infrared spectroscopy analysis was used to disclose the molecular mechanism of prepared insulin-loaded L/C NPs. Fast ultrafiltration and a reversed-phase high-performance liquid chromatography assay were used to separate free insulin from insulin entrapped in the L/C NPs, as well as to measure the insulin-entrapment and drug-loading efficiencies. The in vitro release profile was obtained, and in vivo hypoglycemic effects were evaluated in streptozotocin-induced diabetic rats.

Results

Our results indicated that insulin-containing L/C NPs had a mean size of 180 nm, an insulin-entrapment efficiency of 94%, and an insulin-loading efficiency of 4.5%. Cryogenic transmission electron microscopy observations of insulin-loaded L/C NPs revealed multilamellar structures with a hollow core, encircled by several bilayers. In vitro analysis revealed that insulin release from L/C NPs depended on the L/C ratio. Insulin-loaded L/C NPs orally administered to streptozotocin-induced diabetic rats exerted a significant hypoglycemic effect. The relative pharmacological bioavailability following oral administration of L/C NPs was 6.01%.

Conclusion

With the aid of phospholipid-complexation techniques, some hydrophilic peptides, such as insulin, can be successfully entrapped into L/C NPs, which could improve oral bioavailability, time-dependent release, and therapeutic activity.

Intraoral film containing insulin-phospholipid microemulsion: formulation and in vivo hypoglycemic activity study

Non-invasive administration of insulin is expected for better diabetes mellitus therapy. In this report, we developed intraoral preparation for insulin. Insulin was encapsulated into nanocarrier using self-assembly emulsification process. To increase lipophilicity of insulin, it was dispersed in phospholipid resulted in insulin-phospholipid solid dispersion. The microemulsion formula was established from our previous work which contained glyceryl monooleate (GMO), Tween 20, and polyethylene glycol (PEG 400) in a ratio of 1:8:1. To confirm the formation of insulin-phospholipid solid dispersion, PXRD, FTIR spectroscopy, and Raman spectroscopy were performed. Then, the microemulsion was evaluated for droplet size and distribution, zeta potential, entrapment efficiency, physical stability, and Raman spectroscopy. In addition, microemulsion with expected characteristic was evaluated for in vitro release, in vitro permeation, and in vivo activity. The droplets size of ∼100 nm with narrow distribution and positive charge of +0.56 mV were formed. The insulin encapsulated in the oil droplet was accounted of >90%. Water-soluble chitosan seems to be a promising film matrix polymer which also functioned as insulin release controller. Oral administration of insulin microemulsion to healthy Swiss-Webster mice showed hypoglycemic effect indicating the success of this protein against a harsh environment of the gastrointestinal tract. This effectiveness significantly increased by fourfold as compared to free insulin. Taken together, microemulsion seems to be a promising carrier for oral delivery of insulin.

Mitomycin C-soybean phosphatidylcholine complex-loaded self-assembled PEG-lipid-PLA hybrid nanoparticles for targeted drug delivery and dual-controlled drug release

Most present drug-phospholipid delivery systems were based on a water-insoluble drug-phospholipid complex but rarely water-soluble drug-phospholipid complex. Mitomycin C (MMC) is a water-soluble anticancer drug extensively used in first-line chemotherapy but is limited by its poor aqueous stability in vitro, rapid elimination from the body, and lack of target specificity. In this article, we report the MMC-soybean phosphatidylcholine complex-loaded PEG-lipid-PLA hybrid nanoparticles (NPs) with Folate (FA) functionalization (FA-PEG-PE-PLA NPs@MMC-SPC) for targeted drug delivery and dual-controlled drug release. FA-PEG-PE-PLA NPs@MMC-SPC comprise a hydrophobic core (PLA) loaded with MMC-SPC, an amphiphilic lipid interface layer (PE), a hydrophilic shell (PEG), and a targeting ligand (FA) on the surface, with a spherical shape, a nanoscaled particle size, and high drug encapsulation efficiency of almost 95%. The advantage of the new drug delivery systems is the early phase controlled drug release by the drug-phospholipid complex and the late-phase controlled drug release by the pH-sensitive polymer-lipid hybrid NPs. In vitro cytotoxicity and hemolysis assays demonstrated that the drug carriers were cytocompatible and hemocompatible. The pharmacokinetics study in rats showed that FA-PEG-PE-PLA NPs@MMC-SPC significantly prolonged the blood circulation time compared to that of the free MMC. More importantly, FA-PEG-PE-PLA NPs@MMC-SPC presented the enhanced cell uptake/cytotoxicity in vitro and superior tumor accumulation/therapeutic efficacy in vivo while reducing the systemic toxicity. A significant accumulation of MMC in the nuclei as the site of MMC action achieved in FA-PEG-PE-PLA NPs@MMC-SPC made them ideal for MMC drug delivery. This study may provide an effective strategy for the design and development of the water-soluble drug-phospholipid complex-based targeted drug delivery and sustained/controlled drug release.