Bioadhesion and enhanced bioavailability by wheat germ agglutinin-grafted lipid nanoparticles for oral delivery of poorly water-soluble drug bufalin

Lectin-modified drug delivery systems - Recent applications in the oncology field

Chemotherapy with cytotoxic drugs remains the core treatment for cancer but, due to the difficulty to find general and usable biochemical differences between cancer cells and normal cells, many of these drugs are associated with lack of specificity, resulting in side effects and collateral cytotoxicity that impair patients' adherence to therapy. Novel cancer treatments in which the cytotoxic effect is maximized while adverse effects are reduced can be implemented by developing targeted therapies that exploit the specific features of cancer cells, such as the typical expression of aberrant glycans. Modification of drug delivery systems with lectins is one of the strategies to implement targeted chemotherapies, as lectins are able to specifically recognize and bind to cancer-associated glycans expressed at the surface of cancer cells, guiding the drug treatment towards these cells and not affecting healthy ones. In this paper, recent advances on the development of lectin-modified drug delivery systems for targeted cancer treatments are thoroughly reviewed, with a focus on their properties and performance in diverse applications, as well as their main advantages and limitations. The synthesis and analytical characterization of the cited lectin-modified drug delivery systems is also briefly described. A comparison with free-drug treatments and with antibody-modified drug delivery systems is presented, emphasizing the advantages of lectin-modified drug delivery systems. Main constraints and potential challenges of lectin-modified drug delivery systems, including key difficulties for clinical translation of these systems, and the required developments in this area, are also signalled.

α-Tocopherol-loaded multi-layer nanoemulsion using chitosan, and dextran sulfate: Cellular uptake, antioxidant activity, and in vitro bioaccessibility

The potential of multi-layer nanoemulsions (NEs) for improving the cellular uptake, antioxidant activity, and in vitro bioaccessibility of α-tocopherol (ToC) was examined. ToC-loaded multi-layer NEs were prepared using lecithin (primary-NEs, P-NEs), chitosan (secondary-NEs, S-NEs), and dextran sulfate (tertiary-NEs, T-NEs) as wall materials. The bioadhesion, cellular permeability, and uptake of the multi-layer NEs were significantly higher than that of the free coumarin 6 (C6). As a result of cellular uptake, the mean fluorescence intensity of T-NEs was the highest among the three types of multi-layer NEs and was 9.8-fold higher than that of free C6. The cellular antioxidant abilities of P-NEs, S-NEs, and T-NEs were 40, 45, and 50 %, respectively. Multi-layer nanoencapsulation sustains free fatty acid release after digestion. Moreover, the bioavailability of T-NEs exhibited a two-fold increase compared with that of the free ToC. These findings indicate that by multi-layer NEs using a layer-by-layer method, the cellular uptake, in vitro bioaccessibility, and antioxidant activity of ToC can be improved. Furthermore, T-NEs using chitosan and dextran sulfate can potentially enhance the cellular uptake, in vitro bioaccessibility, and antioxidant activity of ToC. These findings would facilitate the application of multi-layer NEs for lipophilic bioactive compounds using biopolymers.

Arenobufagin-loaded PEG-PLA nanoparticles for reducing toxicity and enhancing cancer therapy

Arenobufagin (ArBu) is a natural anticancer drug with good anti-tumor effects, but its clinical applications and drug development potential are limited due to its toxicity. The purpose of this study is to reduce the toxic side effects of ArBu and improve the efficacy of tumor treatment by incorporating it into poly(ethylene glycol)-b-poly (lactide) co-polymer (PEG-PLA). ArBu@PEG-PLA micelles were prepared by a thin film hydration method. The optimized micelles were characterized by size, stability, drug loading, encapsulation rate, and drug release. The tumor-inhibition efficacy of the micelles was evaluated on A549 cells and tumor-bearing mice. The ArBu@PEG-PLA micelles have good drug-loading capacity, release performance, and stability. They can accumulate at the tumor site through the EPR effect. The micelles induce apoptosis through a mitochondrial apoptosis pathway. Compared with the free ArBu, the ArBu@PEG-PLA micelles had lower toxicity and higher safety in the acute toxicity evaluation experiment. The in vivo anti-tumor experiment with tumor-bearing mice showed that the tumor-inhibition rate of ArBu@PEG-PLA micelles was 72.9%, which was 1.28-fold higher than that of free ArBu (57.1%), thus showing a good tumor treatment effect. This study indicates that ArBu@PEG-PLA polymeric micelles can significantly improve the toxicity and therapeutic efficacy of ArBu. These can lead to a new therapeutic strategy to reduce the toxicity of ArBu and enhance tumor treatment.

Tumor-Targeting Polymer–Drug Conjugate for Liver Cancer Treatment In Vitro

Bufalin (buf) has poor solubility in aqueous solution, poor tumor targeting, and many non-specific toxic and side effects. The advantages of high-molecular-weight polymer conjugates are that they can improve the water solubility of buf, prolong plasma half-life, and reduce non-specific toxicity. A novel water-soluble polymer–drug conjugate with buf and fluorescein pendants was prepared by the combination of reversible addition-fragmentation transfer (RAFT) polymerization and click chemistry. Its anticancer performance and cellular uptake behavior against liver cancer were investigated in vitro. The polymer–buf conjugates exhibit controlled release and tumor-targeting capabilities, showing promise for clinical applications.

Novel Strategies for Solubility and Bioavailability Enhancement of Bufadienolides

Toad venom contains a large number of bufadienolides, which have a variety of pharmacological activities, including antitumor, cardiovascular, anti-inflammatory, analgesic and immunomodulatory effects. The strong antitumor effect of bufadienolides has attracted considerable attention in recent years, but the clinical application of bufadienolides is limited due to their low solubility and poor bioavailability. In order to overcome these shortcomings, many strategies have been explored, such as structural modification, solid dispersion, cyclodextrin inclusion, microemulsion and nanodrug delivery systems, etc. In this review, we have tried to summarize the pharmacological activities and structure-activity relationship of bufadienolides. Furthermore, the strategies for solubility and bioavailability enhancement of bufadienolides also are discussed. This review can provide a basis for further study on bufadienolides.

Oral lipid nanomedicines: Current status and future perspectives in cancer treatment

Oral anticancer drugs have earned a seat at the table, as the need for homecare treatment in oncology has increased. Interest in this field is growing as a result of their proven efficacy, lower costs and positive patient uptake. However, the gastrointestinal barrier is still the main obstacle to surmount in chemotherapeutic oral delivery. Anticancer nanomedicines have been proposed to solve this quandary. Among these, lipid nanoparticles are described to be efficiently absorbed while protecting drugs from early degradation in hostile environments. Their intestinal lymphatic tropism or mucoadhesive/penetrative properties give them unique characteristics for oral administration. Considering that chronic cancer cases are increasing over time, it is important to be able to provide treatments with low toxicity and low prices. The challenges, opportunities and therapeutic perspectives of lipid nanoparticles in this area will be discussed in this review, taking into consideration the pre-clinical and clinical progress made in the last decade.

Pharmaceutical applications of starch nanoparticles: A scoping review

Starch nanoparticles (SNPs) have been applied to different areas of material sciences, especially in pharmaceuticals due to their characteristics such as small particle size, high surface ratio-volume, and biological compatibility. However, in pharmaceutical sciences, there are no records of a scoping review that had extensively mapped all available information about SNPs. A scoping review was performed here by searching electronic databases (Pubmed and Science Direct) to identify studies published previous to June 2020. From 699 total records, 37 matched the criteria for inclusion. The findings showed that SNPs have been used, not only for the development of different active pharmaceutical ingredient delivery systems, but also as an enzyme inhibitor, adsorption, and DNA precipitation agent. In conclusion, by combining different starch sources and methods SNPs show a remarkable diversity in pharmaceutical applications. Future studies should explore SNPs safety and provide information about variables that may affect important properties for this kind of application.

Molecular mechanisms of bufadienolides and their novel strategies for cancer treatment

Bufadienolides are cardioactive C24 steroids with an α-pyrone ring at position C17. In the last ten years, accumulating studies have revealed the anticancer activities of bufadienolides and their underlying mechanisms, such as induction of autophagy and apoptosis, cell cycle disruption, inhibition of angiogenesis, epithelial-mesenchymal transition (EMT) and stemness, and multidrug resistance reversal. As Na⁺/K⁺-ATPase inhibitors, bufadienolides have inevitable cardiotoxicity. Short half-lives, poor stability, low plasma concentration and oral bioavailability in vivo are obstacles for their applications as drugs. To improve the drug potency of bufadienolides and reduce their side effects, prodrug strategies and drug delivery systems such as liposomes and nanoparticles have been applied. Therefore, systematic and recapitulated information about the antitumor activity of bufadienolides, with special emphasis on the molecular or cellular mechanisms, prodrug strategies and drug delivery systems, is of high interest. Here, we systematically review the anticancer effects of bufadienolides and the molecular or cellular mechanisms of action. Research advancements regarding bufadienolide prodrugs and their tumor-targeting delivery strategies are critically summarized. This work highlights recent scientific advances regarding bufadienolides as effective anticancer agents from 2011 to 2019, which will help researchers to understand the molecular pathways involving bufadienolides, resulting in a selective and safe new lead compound or therapeutic strategy with improved therapeutic applications of bufadienolides for cancer therapy.

Solid lipid matrix mediated nanoarchitectonics for improved oral bioavailability of drugs

Introduction: Solid matrix mediated lipid nanoparticle formulations (LNFs) retain some of the best features of ideal drug carriers necessary for improving the oral absorption and bioavailability (BA) of both hydrophilic and hydrophobic drugs. LNFs with solid matrices may be typically categorized into three major types of formulations, viz., solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs) and lipid-drug conjugate nanoparticles (LDC-NPs). Solid matrix based LNFs are, potentially, the most appropriate delivery systems for poorly water soluble drugs in need of improved drug solubility, permeability, absorption, or increased oral BA. In addition, LNFs as matrices are able to encapsulate both hydrophobic and hydrophilic drugs in a single matrix based on their excellent ability to form cores and shells. Interestingly, LNFs also act as delivery devices to impart chemical stability to various orally administered drugs. Areas covered: Aim of the review is to forecast the presentation of pharmacokinetic characteristics of solid lipid matrix based nanocarriers which are typically biocompatible, biodegradable and non-toxic carrier systems for efficient oral delivery of various drugs. Efficient delivery is broadly mediated by the fact that lipophilic drugs are readily soluble in lipidic substrates that are capable of permeating across the gut epithelium following oral administration, subsequently delivering the moiety of interest more efficiently across the gut mucosal membrane. This enhances the overall BA of many drugs facing oral delivery challenges by improving their pharmacokinetic profile. This article specifically focuses on the biopharmaceutical and pharmacokinetic aspects of such solid lipid matrix based nanoformulations and possible mechanisms for better drug absorption and improved BA following oral administration. It also briefly reviews methods to access the efficacy of LNFs for improving oral BA of drugs, regulatory aspects and some interesting lipid-derived commercial formulations, with a concluding remark. Expert opinion: LNFs enhance the overall BA of many drugs facing oral delivery challenges by improving their pharmacokinetic profile.

New therapeutic aspects of steroidal cardiac glycosides: the anticancer properties of Huachansu and its main active constituent Bufalin

Aim of the review

In the past decade, increasing research attention investigated the novel therapeutic potential of steroidal cardiac glycosides in cancer treatment. Huachansu and its main active constituent Bufalin have been studied in vitro, in vivo and clinical studies. This review aims to summarize the multi-target and multi-pathway pharmacological effects of Bufalin and Huachansu in the last decade, with the aim of providing a more comprehensive view and highlighting the recently discovered molecular mechanisms.

Results

Huachansu and its major derivative, Bufalin, had been found to possess anti-cancer effects in a variety of cancer cell lines both in vitro and in vivo. The underlying anti-cancer molecular mechanisms mainly involved anti-proliferation, apoptosis induction, anti-metastasis, anti-angiogenesis, epithelial-mesenchymal transition inhibition, anti-inflammation, Na⁺/K⁺-ATPase activity targeting, the steroid receptor coactivator family inhibitions, etc. Moreover, the potential side-effects and toxicities of the toad extract, Huachansu, and Bufalin, including hematological, gastrointestinal, mucocutaneous and cardiovascular adverse reactions, were reported in animal studies and clinic trails.

Conclusions

Further research is needed to elucidate the potential drug-drug interactions and multi-target interaction of Bufalin and Huachansu. Large-scale clinical trials are warranted to translate the knowledge of the anticancer actions of Bufalin and Huachansu into clinical applications as effective and safe treatment options for cancer patients in the future.

Strategic use of nanotechnology in drug targeting and its consequences on human health: A focused review

Since the development of first lipid-based nanocarrier system, about 15% of the present pharmaceutical market uses nanomedicines to achieve medical benefits. Nanotechnology is an advanced area to meliorate the delivery of compounds for improved medical diagnosis and curing disease. Nanomedicines are gaining significant interest due to the ultra small size and large surface area to mass ratio. In this review, we discuss the potential of nanotechnology in delivering of active moieties for the disease therapy including their toxicity evidences. This communication will help the formulation scientists in understanding and exploring the new aspects of nanotechnology in the field of nanomedicine.

Development of a hybrid peptide dendrimer micellar carrier system and its application in the reformulation of a hydrophobic therapeutic agent derived from traditional Chinese medicine

The discovery that a cane toad poison-derived steroid, bufalin can significantly impact cancer cell proliferation supports its potential use in cancer therapy. However, its poor aqueous solubility and tissue deposition characteristics hamper its broader application as an anticancer therapeutic agent in its own right. To address this we developed an amphiphilic dendrimer-based delivery system, which self-assembles into discrete micelles in an aqueous environment. The bufalin-micelle inclusion complex was prepared by the co-precipitation method and their presence was confirmed by dynamic light scattering (DLS), zeta potential and differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) measurements. The self-assembled bufalin-containing micelles were found to form at/above the dendrimer concentration of 105.38 μmol L-1, and showed a more than threefold increase in the aqueous solubility (142.9 μg mL-1) of bufalin, when compared with a saturated bufalin aqueous solution (42.4 μg mL-1), and two non-assembling peptides of similar composition (79.3 and 62.5 μg mL-1 respectively).

Bufalin-loaded vitamin E succinate-grafted-chitosan oligosaccharide/RGD conjugated TPGS mixed micelles demonstrated improved antitumor activity against drug-resistant colon cancer

Background

Multidrug resistance (MDR) is the major reason for the failure of chemotherapy in colon cancer. Bufalin (BU) is one of the most effective antitumor active constituents in Chansu. Our previous study found that BU can effectively reverse P-glycoprotein (P-gp)-mediated MDR in colon cancer. However, the clinical application of BU is limited due to its low solubility in water and high toxicity. In the present study, a multifunctional delivery system based on vitamin-E- succinate grafted chitosan oligosaccharide (VES-CSO) and cyclic (arginine-glycine-aspartic acid peptide) (RGD)-modified d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) was prepared by emulsion solvent evaporation method for targeted delivery of BU to improve the efficacy of drug-resistant colon cancer therapy.

Methods

The cytotoxicity of BU-loaded micelles against drug-resistant colon cancer LoVo/ADR and HCT116/LOHP cells was measured by CCK-8 assay. The cellular uptake, Rho123 accumulation, and cell apoptosis were determined by flow cytometry. The expression of apoptosis-related protein and P-gp was measured by Western blot assay. The antitumor activity of BU-loaded micelles was evaluated in LoVo/ADR-bearing nude mice.

Results

BU-loaded VES-CSO/TPGS-RGD mixed micelles (BU@VeC/T-RGD MM) were 140.3 nm in diameter with zeta potential of 8.66 mV. The BU@VeC/T-RGD MM exhibited good stability, sustained-release pattern, higher intracellular uptake, and greater cytotoxicity in LoVo/ADR cells. Furthermore, the mechanisms of the BU@VeC/T-RGD MM to overcome MDR might be due to enhanced apoptosis rate and P-gp efflux inhibition. Subsequently, in vivo studies confirmed an enhanced therapeutic efficiency and reduced side effects associated with BU@VeC/T-RGD MM compared with free BU, owing to the enhanced permeation and retention effect, improved pharmacokinetic behavior, and tumor targeting, which lead to MDR-inhibiting effect in LoVo/ADR-bearing nude mice.

Conclusion

Our results demonstrated that VeC/T-RGD MM could be developed as a potential delivery system for BU to improve its antitumor activity against drug-resistant colon cancer.

Increasing the anticancer performance of bufalin (BUF) by introducing an endosome-escaping polymer and tumor-targeting peptide in the design of a polymeric prodrug

A well-defined multifunctional brush-type polymeric prodrug covalently linked with an anticancer drug (bufalin, BUF), a tumor-targeting peptide (RGD), and an endosome-escaping polymer, poly(N,N-diethylaminoethyl methacrylate-co-butyl methacrylate (P(DEA-co-BMA)), was developed. Its anticancer performance against colon cancer was investigated in vitro and in vivo. Reversible addition-fragmentation transfer (RAFT) polymerization of oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), 2-((3-(tert-butoxy)-3-oxopropyl)thio)ethyl methacrylate (BSTMA), and 2-(2-bromoisobutyryloxy)ethylmethacrylate (BIEM) afforded the multifunctional random copolymer, P(OEGMA-co-BSTMA-co-BIEM), in which hydrophilic POEGMA can stabilize nanoparticles in water, PBSTMA can be converted into carboxyl groups, and PBIEM can be employed as a macromolecular atom radical transfer polymerization (ATRP) initiator. The ATRP of DEA and BMA using P(OEGMA-co-BSTMA-co-BIEM) as a macromolecular ATRP initiator led to the formation of the pH-responsive brush-type copolymer, P(OEGMA-co-BSTMA)-g-P(DEA-co- BMA). After hydrolysis by trifluoroacetic acid and post-functionalization the final polymeric prodrug, P(OEGMA-co-BUF-co-RGD)-g-P(DEA-co-BMA), was obtained with a drug content of ∼7.8 wt%. P(OEGMA-co-BUF-co-RGD)-g-P(DEA-co-BMA) can be assembled into nanoparticles (BUF- NP-RGD) in aqueous solution with a diameter of 148.4 ± 0.7 nm and a zeta potential of -7.6 ± 0.4 mV. BUF-NP-RGD exhibited controlled drug release in the presence of esterase. Additionally, P(OEGMA-co- BSMA)-g-P(DEA-co-BMA) showed a significant hemolysis effect at a pH comparable to that of endosomes/lysosomes. Cell viability and a tumor-bearing nude mouse model were employed to evaluate the anticancer efficacy of BUF-NP-RGD. It was revealed that BUF-NP-RGD showed improved anticancer performance compared with that of free BUF both in vitro and in vivo. Histological and immunochemical analysis further demonstrated that BUF-NP-RGD exhibited improved cell apoptosis, angiogenesis inhibition, and an anti-proliferation effect.

Plant protein-based hydrophobic fine and ultrafine carrier particles in drug delivery systems

For thousands of years, plants and their products have been used as the mainstay of medicinal therapy. In recent years, besides attempts to isolate the active ingredients of medicinal plants, other new applications of plant products, such as their use to prepare drug delivery vehicles, have been discovered. Nanobiotechnology is a branch of pharmacology that can provide new approaches for drug delivery by the preparation of biocompatible carrier nanoparticles (NPs). In this article, we review recent studies with four important plant proteins that have been used as carriers for targeted delivery of drugs and genes. Zein is a water-insoluble protein from maize; Gliadin is a 70% alcohol-soluble protein from wheat and corn; legumin is a casein-like protein from leguminous seeds such as peas; lectins are glycoproteins naturally occurring in many plants that recognize specific carbohydrate residues. NPs formed from these proteins show good biocompatibility, possess the ability to enhance solubility, and provide sustained release of drugs and reduce their toxicity and side effects. The effects of preparation methods on the size and loading capacity of these NPs are also described in this review.

Enhanced Intestinal Permeability of Bufalin by a Novel Bufalin-Peptide-Dendrimer Inclusion through Caco-2 Cell Monolayer

Bufalin (BFL) has excellent physiological activities such as defending tumors, improving cardiac function, and so on. However, due to its poor water-solubility and bioavailability, the clinical application of BFL remains limited. In order to improve bioavailability of BFL, in our previous research, a novel peptide-dendrimer (PD) was synthesized and applied to encapsulate BFL. In the present study, we investigate the absorption property and mechanism of BFL in free form and BFL-peptide-dendrimer inclusion (BPDI) delivery system by using the Caco-2 cell monolayer model in vitro. The apparent permeability coefficient (P_app) values of BFL in free or BPDI form were over 1.0 × 10⁻⁶ cm/s. Meanwhile, their almost equal bi-directional transport and linear transport percentage with time and concentration course indicated that BFL in both forms was absorbed mainly through passive diffusion. The most important result is that the P_app values of BFL increased about three-fold more BPDI than those of its free form, which indicated the intestinal permeability of BFL could be improved while BFL was encapsulated in BPDI form. Therefore, PD encapsulation may be a potential delivery system to increase the bioavailability of BFL.

Recent advances in oral delivery of drugs and bioactive natural products using solid lipid nanoparticles as the carriers

Chemical and enzymatic barriers in the gastrointestinal (GI) tract hamper the oral delivery of many labile drugs. The GI epithelium also contributes to poor permeability for numerous drugs. Drugs with poor aqueous solubility have difficulty dissolving in the GI tract, resulting in low bioavailability. Nanomedicine provides an opportunity to improve the delivery efficiency of orally administered drugs. Solid lipid nanoparticles (SLNs) are categorized as a new generation of lipid nanoparticles consisting of a complete solid lipid matrix. SLNs used for oral administration offer several benefits over conventional formulations, including increased solubility, enhanced stability, improved epithelium permeability and bioavailability, prolonged half-life, tissue targeting, and minimal side effects. The nontoxic excipients and sophisticated material engineering of SLNs tailor the controllable physicochemical properties of the nanoparticles for GI penetration via mucosal or lymphatic transport. In this review, we highlight the recent progress in the development of SLNs for disease treatment. Recent application of oral SLNs includes therapies for cancers, central nervous system-related disorders, cardiovascular-related diseases, infection, diabetes, and osteoporosis. In addition to drugs that may be active cargos in SLNs, some natural compounds with pharmacological activity are also suitable for SLN encapsulation to enhance oral bioavailability. In this article, we systematically introduce the concepts and amelioration mechanisms of the nanomedical techniques for drug- and natural compound-loaded SLNs.

How to design the surface of peptide-loaded nanoparticles for efficient oral bioavailability?

The oral administration of proteins is a current challenge to be faced in the field of therapeutics. There is currently much interest in nanocarriers since they can enhance oral bioavailability. For lack of a clear definition, the key characteristics of nanoparticles have been highlighted. Specific surface area is one of these characteristics and represents a huge source of energy that can be used to control the biological fate of the carrier. The review discusses nanocarrier stability, mucus interaction and absorption through the intestinal epithelium. The protein corona, which has raised interest over the last decade, is also discussed. The universal ideal surface is a myth and over-coated carriers are not a solution either. Besides, common excipients can be useful on several targets. The suitable design should rather take into account the composition, structure and behavior of unmodified nanomaterials.

Wheat germ agglutinin modification of lipid–polymer hybrid nanoparticles: enhanced cellular uptake and bioadhesion

WGA-modified lipid–polymer hybrid nanoparticles (WGA-LPNs) showed increased intestinal bioadhesion and cellular uptake and have the potential to improve the oral delivery of poorly water-soluble drugs.

Designing polymers with sugar-based advantages for bioactive delivery applications

Sugar-based polymers have been extensively explored as a means to increase drug delivery systems' biocompatibility and biodegradation. Here,we review he use of sugar-based polymers for drug delivery applications, with a particular focus on the utility of the sugar component(s) to provide benefits for drug targeting and stimuli responsive systems. Specifically, numerous synthetic methods have been developed to reliably modify naturally-occurring polysaccharides, conjugate sugar moieties to synthetic polymer scaffolds to generate glycopolymers, and utilize sugars as a multifunctional building block to develop sugar-linked polymers. The design of sugar-based polymer systems has tremendous implications on both the physiological and biological properties imparted by the saccharide units and are unique from synthetic polymers. These features include the ability of glycopolymers to preferentially target various cell types and tissues through receptor interactions, exhibit bioadhesion for prolonged residence time, and be rapidly recognized and internalized by cancer cells. Also discussed are the distinct stimuli-sensitive properties of saccharide-modified polymers to mediate drug release under desired conditions. Saccharide-based systems with inherent pH- and temperature-sensitive properties, as well as enzyme-cleavable polysaccharides for targeted bioactive delivery, are covered. Overall, this work emphasizes inherent benefits of sugar-containing polymer systems for bioactive delivery.

Discovery and Current Status of Evaluation System of Bioavailability and Related Pharmaceutical Technologies for Traditional Chinese Medicines--Flos Lonicerae Japonicae--Fructus Forsythiae Herb Couples as an Example

Traditional Chinese medicines (TCMs) have attracted extensive interest throughout the world due to their long history of health protection and disease control, and the internalization of TCM preparations or patented drugs has been considered a wind vane in the process of TCM modernization. However, multi-target effects, caused by multiple components in TCMs, hinder not only the construction of the quality evaluation system (bioavailability), but also the application of pharmaceutical technologies, which results in the poor efficacy in clinical practice. This review describes the methods in the literature as well as in our thoughts about how to identify the marker components, establish the evaluation system of bioavailability, and improve the bioavailability in TCM preparations. We expect that the current study will be positive and informative.

Enhancement of skin permeation of bufalin by limonene via reservoir type transdermal patch: formulation design and biopharmaceutical evaluation

A reservoir-type transdermal delivery system (TDS) of bufalin was designed and evaluated for various formulation variables like different penetration enhancers, formulation matrix, rate controlling membranes as well as biopharmaceutical characteristics. Hairless mouse skin was used in permeation experiments with Franz diffusion cells. In vitro skin permeation study showed that terpenes, especially d-limonene was the most effective enhancer when ethanol and PG were used as the vehicle with a synergistic effect. Among different rate controlling membranes, ethylene vinyl acetate (EVA) membrane containing 19% vinyl acetate demonstrated a more suitable release rate for bufalin than the other membranes. In vivo pharmacokinetic study of the bufalin patch in rat showed steady-state of bufalin from 3h to 12 h. In vivo release rate and cumulative amount analyzed by deconvolution method demonstrated the sustained release of bufalin as long as the patch remained on the animal for at least 12 h. The MRT increased from 1h of IV administration to 9h of transdermal administration. In vitro permeation across mouse skin was found to have biphasic correlation with plasma AUC in the in vivo pharmacokinetic study. Current in vitro-in vivo correlation (IVIVC) enabled the prediction of pharmacokinetic profile of bufalin from in vitro permeation results. In conclusion, current reservoir transdermal patch containing 10% D-limonene as a permeation enhancer, 40% ethanol, 30% PG and 15% carbopol-water gel complex provided an improved sustained release of bufalin through transdermal administration. The bufalin patch was successfully applied to biopharmaceutical study in rats and demonstrated the feasibility of this transdermal formulation for future development and clinical trials.

Medicinal Applications of Plant Lectins

Plant lectins are a unique group of proteins and glycoproteins with potent biological activity and have received widespread attention for many years. They can be found in wheat, corn, tomatoes, peanuts, kidney beans, bananas, peas, lentils, soybeans, mushrooms, tubers, seeds, mistletoe and potatoes among many others. Due to their ability to bind reversibly with specific carbohydrate structures and their abundant availability, plant lectins have commonly been used as a molecular tool in various disciplines of biology and medicine. Whilst once thought of being a dietary toxin, the focus on plant lectins has since shifted to understanding the useful properties of these lectins and utilizing them in medicinal applications to advance human health. This chapter reviews the current and potential applications of plant lectins in various areas of medically related research.

Mollusk glue inspired mucoadhesives for biomedical applications

Chitosan (CH), partially N-deacetylated chitin, is a biodegradable and biocompatible polymer that has shown great potential in drug delivery and tissue engineering applications. Although bioadhesive, CH has limited mucoadhesion in wet conditions due to weak interactions with biological surfaces. DOPA (3,4-dihydroxy-L-phenylalanine), a catechol-containing molecule naturally present in marine mussel foot proteins, has been shown to increase the mucoadhesion of several polymers. We report here a simple and bioinspired approach to enhance CH mucoadhesion in wet conditions by preparing mixed hydrogels including CH and different catechol-containing compounds, namely DOPA, hydrocaffeic acid (HCA), and dopamine (DA). We characterized the hydrogels for their swelling, release kinetics of the catechol compounds, and mucoadhesive strength to rabbit small intestine. The swelling of the hydrogels was pH dependent with maximum swelling at pH 1. The hydrogel swelling was higher in the presence of the DOPA and DA but lower in the presence of HCA. HCA/CH hydrogel also showed the slowest catechol release, most likely due to electrostatic interactions between CH and HCA. Lower hydrogel swelling and slower HCA release resulted in increased mucoadhesion: HCA/CH showed more than 2-fold enhancement of mucoadhesion to rabbit small intestine compared to CH alone. Since it is known that catechol compounds can be oxidized, we analyzed the oxidation of DOPA, HCA, and DA at different pH values and its effect on mucoadhesion. We found that oxidation occurring before contact with the intestinal mucosa did not improve mucoadhesion, while oxidation occurring during the contact further increased the mucoadhesion of HCA/CH hydrogels. These results show that mucoadhesion of CH hydrogels can be increased with a simple bioinspired approach, which has the potential to be applied to other polymers since it does not require any chemical modification.