Design, synthesis and applications of hyaluronic acid-paclitaxel bioconjugates

Curvilinear regression analysis of benzenoid hydrocarbons and computation of some reduced reverse degree based topological indices for hyaluronic acid-paclitaxel conjugates

Graph theoretical molecular descriptors alias topological indices are a convenient means for expressing in numerical form the chemical structure encoded in a molecular graph. The structure descriptors derived from molecular graphs are widely used in quantitative structure-property relationship (QSPR) and quantitative structure-activity relationship (QSAR) studies. The reason for introducing new indices is to obtain predictions of target properties of considered molecules that are better than the predictions obtained using already known indices. In this paper, we apply the reduced reverse degree based indices introduced in 2021 by Vignesh et al. In the QSPR analysis, we first compute the reduced reverse degree based indices for a family of benzenoid hydrocarbon molecules and then we obtain the correlation with the Physico-chemical properties of the considered molecules. We show that all the properties taken into consideration for the benzenoid hydrocarbons can be very effectively predicted by the reduced reverse degree based indices. Also, we have compared the predictive capability of reduced reverse degree based topological descriptors against 16 existing degree based indices. Further, we compute the defined reduced reverse degree based topological indices for Hyaluronic Acid-Paclitaxel Conjugates [Formula: see text], [Formula: see text].

Hyaluronic acid-entecavir conjugates-core/lipid-shell nanohybrids for efficient macrophage uptake and hepatotropic prospects

Drug covalently bound to polymers had formed, lately, platforms with great promise in drug delivery. These drug polymer conjugates (DPC) boosted drug loading and controlled medicine release with targeting ability. Herein, the ability of entecavir (E) conjugated to hyaluronic acid (HA) forming the core of vitamin E coated lipid nanohybrids (EE-HA LPH), to target Kupffer cells and hepatocyte had been proved. The drug was associated to HA with efficiency of 93.48 ± 3.14 % and nanohybrids loading of 22.02 ± 2.3 %. DiI labelled lipidic nanohybrids improved the macrophage uptake in J774 cells with a 21 day hepatocytes retention post intramuscular injection. Finally, in vivo biocompatibility and safety with respect to body weight, organs indices and histopathological alterations were demonstrated. Coating with vitamin E and conjugation of E to HA (a CD44 ligand), could give grounds for prospective application for vectored nano-platform in hepatitis B.

Bacteria-based nanodrug for anticancer therapy

Bacteria-based immunotherapy has become a promising strategy to induce innate and adaptive responses for fighting cancer. The advantages of bacteriolytic tumor therapy mainly lie in stimulation of innate immunity and colonization of some bacteria targeting the tumor microenvironment (TME). These bacteria have cytotoxic proteins and immune modulating factors that can effectively restrain tumor growth. However, cancer is a multifactorial disease and single therapy is typically unable to eradicate tumors. Rapid progress has been made in combining bacteria with nanotechnology. Using the nanomolecular properties of bacterial products for tumor treatment preserves many features from the original bacteria while providing some unique advantages. Nano-bacterial therapy can enhance permeability and retention of drugs, increase the tolerability of the targeted drugs, promote the release of immune cell mediators, and induce immunogenic cell death pathways. In addition, combining nano-bacterial mediated antitumor therapeutic systems with modern therapy is an effective strategy for overcoming existing barriers in antitumor treatment and can achieve satisfactory therapeutic efficacy. Overall, exploring the immune antitumor characteristics of adjuvant clinical treatment with bacteria can provide potential efficacious treatment strategies for combatting cancer.

Heptamethine Cyanine Dye MHI-148-Mediated Drug Delivery System to Enhance the Anticancer Efficiency of Paclitaxel

Introduction

Paclitaxel (PTX) is a conventional chemotherapeutic drug that effectively treats various cancers. The cellular uptake and therapeutic potential of PTX are limited by its slow penetration and low solubility in water. The development of cancer chemotherapy methods is currently facing considerable challenges with respect to the delivery of the drugs, particularly in targeting the tumor site without exerting detrimental effects on the healthy surrounding cells. One possibility for improving the therapeutic potential is through the development of tumor-targeted delivery methods.

Methods

We successfully synthesized paclitaxel-MHI-148 conjugates (PTX-MHI) by coupling PTX with the tumor-targeting heptamethine cyanine dye MHI-148. Synthesis and purification were characterized using the absorbance spectrum and the results of time-of-flight mass spectrometry. Cellular uptake and cytotoxicity studies were conducted in vitro and in vivo.

Results

PTX-MHI accumulates in tumor cells but not in normal cells, as observed by in vitro near-infrared fluorescent (NIRF) imaging along with in vivo NIRF imaging and organ biodistribution studies. We observed that MHI-148-conjugated PTX shows greater efficiency in cancer cells than PTX alone, even in the absence of light treatment. PTX-MHI could also be used for specific drug delivery to intracellular compartments, such as the mitochondria and lysosomes of cancer cells, to improve the outcomes of tumor-targeting therapy.

Conclusion

The results indicated that PTX-MHI-mediated cancer therapy exerts an excellent inhibitory effect on colon carcinoma (HT-29) cell growth with low toxicity in normal fibroblasts (NIH3T3).

Hyaluronic acid prodrug micelles for tumour therapy

Hyaluronic acid (HA), an important component of the extracellular matrix, has high water solubility and biocompatibility, and good application prospects in biomedicine. Especially in tumour treatment, prodrug polymer micelles prepared from HA and chemotherapeutics can increase water solubility, prolong drug release time, improve organ distribution and therapeutic effects, and show good tumour targeting and biocompatibility. Therefore, this study introduces strategies for using HA to prepare prodrug polymer micelles and discusses recent research on HA prodrug micelles for antitumor applications.

Mitotic Poisons in Research and Medicine

Cancer is one of the greatest challenges of the modern medicine. Although much effort has been made in the development of novel cancer therapeutics, it still remains one of the most common causes of human death in the world, mainly in low and middle-income countries. According to the World Health Organization (WHO), cancer treatment services are not available in more then 70% of low-income countries (90% of high-income countries have them available), and also approximately 70% of cancer deaths are reported in low-income countries. Various approaches on how to combat cancer diseases have since been described, targeting cell division being among them. The so-called mitotic poisons are one of the cornerstones in cancer therapies. The idea that cancer cells usually divide almost uncontrolled and far more rapidly than normal cells have led us to think about such compounds that would take advantage of this difference and target the division of such cells. Many groups of such compounds with different modes of action have been reported so far. In this review article, the main approaches on how to target cancer cell mitosis are described, involving microtubule inhibition, targeting aurora and polo-like kinases and kinesins inhibition. The main representatives of all groups of compounds are discussed and attention has also been paid to the presence and future of the clinical use of these compounds as well as their novel derivatives, reviewing the finished and ongoing clinical trials.

Synthesis of HA-SS-MP: A Prodrug With High Specificity for Cancer Cells

Thiolated hyaluronic acid was synthesized, and a quantification method was established to determine the content of the thiol group. Three thiol compounds, 2-nitro-5-mercapto-benzoic acid (TNB), 2- mercaptonicotinic acid (2-MNA), and mercaptopyridine (MPD), were tested for their efficiency in forming adducts with hyaluronic acid (HA) through disulfide bonds. Our results showed that MPD exhibited the highest disulfide exchange efficiency when the reaction was conducted at the optimal pH value. The synthesized hyaluronic acid-SS-mercaptopurine (HA-SS-MP) was characterized by1H-nuclear magnetic resonance spectroscopy. The HA-SS-MP micelle showed a particle size of 264.4 nm in aqueous solution. An in vitro release experiment demonstrated that the releasing rate of 6-MP from HA-SS-MP in the release medium containing glutathione (GSH) was much higher than that in the release medium without GSH. Cell uptake experiments demonstrated the CD44 targeting of hyaluronic acid. Cytotoxicity tests in mouse melanoma cells (B16F10) showed that HA-SS-MP can kill melanoma cells effectively and with lower cytotoxicity, compared with the active ingredient, 6-MP.

Topological Indices of Hyaluronic Acid-Paclitaxel Conjugates’ Molecular Structure in Cancer Treatment

A large number of medical experiments have confirmed that the features of drugs have a close correlation with their molecular structure. Drug properties can be obtained by studying the molecular structure of corresponding drugs. The calculation of the topological index of a drug structure enables scientists to have a better understanding of the physical chemistry and biological characteristics of drugs. In this paper, we focus on Hyaluronic Acid-Paclitaxel conjugates which are widely used in the manufacture of anticancer drugs. Several topological indices are determined by virtue of the edge-partition method, and our results remedy the lack of medicine experiments, thus providing a theoretical basis for pharmaceutical engineering.

Bacterial components as naturally inspired nano-carriers for drug/gene delivery and immunization: Set the bugs to work?

Drug delivery is a rapidly growing area of research motivated by the nanotechnology revolution, the ideal of personalized medicine, and the desire to reduce the side effects of toxic anti-cancer drugs. Amongst a bewildering array of different nanostructures and nanocarriers, those examples that are fundamentally bio-inspired and derived from natural sources are particularly preferred. Delivery of vaccines is also an active area of research in this field. Bacterial cells and their components that have been used for drug delivery, include the crystalline cell-surface layer known as "S-layer", bacterial ghosts, bacterial outer membrane vesicles, and bacterial products or derivatives (e.g. spores, polymers, and magnetic nanoparticles). Considering the origin of these components from potentially pathogenic microorganisms, it is not surprising that they have been applied for vaccines and immunization. The present review critically summarizes their applications focusing on their advantages for delivery of drugs, genes, and vaccines.

Crystalline paclitaxel coated DES with bioactive protective layer development

Drug eluting stents (DES) based on polymeric-carriers currently lead the market, however, reports on clinical complications encourage the development of safer and more effective DES. We recently reported on carrier-free DES based on rapamycin crystalline coating as a potential therapeutic solution. Here, we report for the first time surface crystallization of paclitaxel (PT) onto metallic stents. The physicochemical principles of crystallization and key process parameters were extensively studied for fabrication of controllable and homogeneous crystalline coatings on stent scaffolds. Stents loaded with nearly 100μg PT were chosen as a potential therapeutic device with a multilayer coating of 4-7μm thickness. In vitro PT release from these coated stents shows constant release for at least 28days with 10% cumulatively released. The effect of fast dissolving top coating on the physical stability of the coated stent was determined. The top coating enhances the mechanical stability of the crystalline coating during deployment and expansion simulations. Also, incorporating PT in the protective top coating for developing bioactive top coating for multilayer controlled release purpose was intensively studied. This process has wide applications that can be further implemented for other drugs for effective local drug delivery from implantable medical devices.

Novel targets for paclitaxel nano formulations: Hopes and hypes in triple negative breast cancer

Triple negative breast cancer is defined as one of the utmost prevailing breast cancers worldwide, possessing an inadequate prognosis and treatment option limited to chemotherapy and radiotherapy, creating a challenge for researchers as far as developing a specific targeted therapy is concerned. The past research era has shown several promising outcomes for TNBC such as nano-formulations of the chemotherapeutic agents already used for the management of the malignant tumor. Taking a glance at paclitaxel nano formulations, it has been proven beneficial in several researches in the past decade; nevertheless its solubility is often a challenge to scientists in achieving success. We have henceforth discussed the basic heterogeneity of triple negative breast cancer along with the current management options as well as a brief outlook on pros and cons of paclitaxel, known as the most widely used chemotherapeutic agent for the treatment of the disease. We further analyzed the need of nanotechnology pertaining to the problems encountered with the current paclitaxel formulations available discussing the strategic progress in various nano-formulations till date taking into account the basic research strategies required in terms of solubility, permeability, physicochemical properties, active and passive targeting. A thorough review in recent advances in active targeting for TNBC was carried out whereby the various ligands which are at present finding its way into TNBC research such as hyaluronic acid, folic acid, transferrin, etc. were discussed. These ligands have specific receptor affinity to TNBC tumor cells hence can be beneficial for novel drug targeting approaches. Conversely, there are currently several novel strategies in the research pipeline whose targeting ligands have not yet been studied. Therefore, we reviewed upon the numerous novel receptor targets along with the respective nano-formulation aspects which have not yet been fully researched upon and could be exemplified as outstanding target strategies for TNBC which is currently an urgent requirement.

Co-delivery of paclitaxel and gemcitabine via CD44-targeting nanocarriers as a prodrug with synergistic antitumor activity against human biliary cancer

Multi-drug delivery focuses on different signaling pathways in cancer cells that have synergistic anti-proliferative effects. In this study, we developed multi-prodrug nanocarriers (MPDNCs) consisting of poly (l-lysine)-carboxylate PTX (PLL-PTX) and hyaluronic acid-conjugated GEM (HA-GEM) for CD44-targeted synergistic biliary cancer therapy. An in vitro study of cell viability and mRNA expression levels and an in vivo study showed that MPDNCs more effectively inhibit proliferation in CD44-overexpressing cancer cells (HuCCT1) than in cells with lower CD44 expression (SCK) by synergistically inducing apoptosis. Consequently, these results demonstrate that MPDNCs are prodrugs with synergistic cancer therapeutic efficacy and effective cellular uptake at target cells compared to free drugs, indicating their strong potential as efficient multi-drug-carrying nano-platforms for cancer treatment.

Pharmaceuticals that contain polycyclic hydrocarbon scaffolds

This review comprehensively explores approved pharmaceutical compounds that contain polycyclic scaffolds and the properties that these skeletons convey.

Current research on hyaluronic acid-drug bioconjugates

Hyaluronic acid (HA) is a mucopolysaccharide acid composed of repeating disaccharide units of D-glucuronic acid and N-acetyl-D-glucosamine. Based on numerous characteristics such as viscoelastic properties, water-binding ability, biocompatibility and non-immunogenicity, HA has been approved by FDA for biological and medical applications. In addition, multifarious receptors of HA like CD44, RHAMM and TSG6 are over-expressed on the surface of malignant cells, which play important roles in targeting ability. Bioconjugates linking drugs to HA could improve solubility, prolong half-life, provide active targeting capability and then increase the bioavailability of these coupled drugs by pro-drug strategy. Therefore, a large number of HA-drug bioconjugates have been studied. The purpose of this review was to summarize these HA-drug bioconjugates and further discuss synthetic methods and the relevant application in pharmaceuticals.

Paclitaxel-hyaluronic nanoconjugates prolong overall survival in a preclinical brain metastases of breast cancer model

Brain (central nervous system; CNS) metastases pose a life-threatening problem for women with advanced metastatic breast cancer. It has recently been shown that the vasculature within preclinical brain metastasis model markedly restricts paclitaxel delivery in approximately 90% of CNS lesions. Therefore to improve efficacy, we have developed an ultra-small hyaluronic acid (HA) paclitaxel nanoconjugate (∼5 kDa) that can passively diffuse across the leaky blood-tumor barrier and then be taken up into cancer cells (MDA-MB-231Br) via CD44 receptor-mediated endocytocis. Using CD44 receptor-mediated endocytosis as an uptake mechanism, HA-paclitaxel was able to bypass p-glycoprotein-mediated efflux on the surface of the cancer cells. In vitro cytoxicity of the conjugate and free paclitaxel were similar in that they (i) both caused cell-cycle arrest in the G2-M phase, (ii) showed similar degrees of apoptosis induction (cleaved caspase), and (iii) had similar IC50 values when compared with paclitaxel in MTT assay. A preclinical model of brain metastases of breast cancer using intracardiac injections of Luc-2 transfected MDA-MB-231Br cells was used to evaluate in vivo efficacy of the nanoconjugate. The animals administered with HA-paclitaxel nanoconjugate had significantly longer overall survival compared with the control and the paclitaxel-treated group (P < 0.05). This study suggests that the small molecular weight HA-paclitaxel nanoconjugates can improve standard chemotherapeutic drug efficacy in a preclinical model of brain metastases of breast cancer.

CD44: a validated target for improved delivery of cancer therapeutics

INTRODUCTION

Advances in cancer therapeutics, namely more effective and less toxic treatments, will occur with targeting strategies that enhance the tumor biodistribution and thwart normal tissue exposure of the drug. This review focuses on cancer drug targeting approaches that exploit the expression of the cell-surface proteoglycan family, CD44, on the tumor cell surface followed by some form of ligand binding and induced CD44 internalization and intracellular drug release: in effect using this as a 'Trojan Horse' to more selectively access tumor cells.

AREAS COVERED

This review defines the origins of evidence for a linkage between CD44 expression and malignancy, and invokes contemporary views of the importance of putative CD44(+) cancer stem cells in disease resistance. Although the primary emphasis is on the most advanced and developed paths, those that have either made it to the clinic or are well-poised to get there, a wide scope of additional approaches at various preclinical stages is also briefly reviewed.

EXPERT OPINION

The future should see development of drug targeting approaches that exploit CD44 expression on CSCs/TICs, including applications to cytotoxic agents currently in the clinic.

Paclitaxel as an anticancer agent: isolation, activity, synthesis and stability

Paclitaxel is isolated from the Pacific yew. It can be obtained from the European yew, but only after chemical modification of the isolated compound by a semi-synthesis procedure. The procedure for total synthesis of paclitaxel is very complicated, involving multiple steps, and the yields of paclitaxel are meagre. This substance is also a metabolite of certain kinds of fungus. The microbiological pathway for producing paclitaxel compared with isolation from plant material involves shorter procuction times but a small yield. Cyclodextrins are usually used for improving the solubility of paclitaxel in aqueous media, with polymeric and other substances added. Paclitaxel has anticancer activity and use for preparing the formulations intravenously administrated to patients with tumors. The paclitaxel concentration in these formulations is determined using validated HPLC methods.

A Biodegradable Polymeric Carrier Based on PEG for Drug Delivery

A biodegradable copolymer (PEG- fum), based on poly(ethylene glycol) (PEG) and fumarate ( fum) units, was synthesized and studied as a drug carrier. PEG and fum were linked together by ester bonds to confer biodegradability to the polymeric backbone in vivo. Hence, this copolymer can be used with molecular weights above the kidney clearance threshold for PEG without body accumulation. The PEG- fum was designed to be a high drug loading carrier due to the fumarate units, thus, overcoming the limitations of linear PEGs. Suitable reactive groups for drug coupling were added by reacting fumarate with tioglycolic acid (TGA). The pendant TGA carboxylic groups were conjugated to the camptothecin derivative, SN38, taxol, and epirubicin. The SN38 and taxol linked to the PEG- fum-(TGA) increased their solubility 15- and 100-fold, respectively. The rate of SN38 release in plasma was adequate for prolonged circulation n vivoi, while taxol was rapidly hydrolyzed. This relatively fast degradation could hamper the conjugate from accumulating in the tumor tissue by enhanced permeability and retention effect (EPR). Instead, EPR effect could be exploited with the epirubicin conjugate coupled by means of a hydrazone bond. This linkage provides good blood stability, while readily cleaved in acidic environment like those in endosomes and lysosomes. Therefore, the drug is released intercellularly in its active form only after, thus reducing toxic effects.