New targeting system for antimycotic drugs: β-Glucosidase sensitive Amphotericin B–star poly(ethylene glycol) conjugate

Combatting Fungal Infections: Advances in Antifungal Polymeric Nanomaterials

Fungal pathogens cause over 6.5 million life-threatening systemic infections annually, with mortality rates ranging from 20 to 95%, even with medical intervention. The World Health Organization has recently emphasized the urgent need for new antifungal drugs. However, the range of effective antifungal agents remains limited and resistance is increasing. This Review explores the current landscape of fungal infections and antifungal drugs, focusing on synthetic polymeric nanomaterials like nanoparticles that enhance the physicochemical properties of existing drugs. Additionally, we examine intrinsically antifungal polymers that mimic naturally occurring peptides. Advances in polymer characterization and synthesis now allow precise design and screening for antifungal activity, biocompatibility, and drug interactions. These antifungal polymers represent a promising new class of drugs for combating fungal infections.

Chemical and physical approaches for improved biopharmaceutical activity of amphotericin B: Current and future prospective

Over the last 50 years, the number of patients with mycotic infections has been increasing gradually. Amphotericin-B is a gold standard drug used in serious systemic fungal infections. However, limited solubility and permeability are challenging issues associated with Amphotericin-B. Chemical modification is one of the ways to get its broader applicability along with improved physicochemical properties. The review article provides a comprehensive overview of the chemical modification approach for investigation of the mechanism of action, biological activity, bioavailability, toxicity of Amphotericin B. Further, several drug delivery approaches have also been utilized to provide better therapeutic outcomes. This gives an overview of chemical approaches for the exploration of various factors associated with Amphotericin B and information on its drug delivery approaches for improved biopharmaceutical outcomes.

Caspofungin Functionalized Polymethacrylates with Antifungal Properties

We describe the synthesis of hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PmPEGMA) and hydrophobic poly(methyl methacrylate) (PMMA) caspofungin conjugates by a post-polymerization modification of copolymers containing 10 mol % pentafluorophenyl methacrylate (PFPMA), which were obtained via reversible addition-fragmentation chain transfer copolymerization. The coupling of the clinically used antifungal caspofungin was confirmed and quantified in detail by a combination of ¹H-, ¹⁹F- and diffusion-ordered NMR spectroscopy, UV-vis spectroscopy, and size exclusion chromatography. The trifunctional amine-containing antifungal was attached via several amide bonds to the hydrophobic PMMA, but sterical hindrance induced by the mPEGMA side chains prohibited intramolecular double functionalization. Both polymer-drug conjugates revealed activity against important human-pathogenic fungi, that is, two strains of Aspergillus fumigatus and one strain of Candida albicans (2.5 mg L^-1 < MEC < 8 mg L^-1, MIC₅₀ = 4 mg L^-1), whereas RAW 264.7 macrophages as well as HeLa cells remained unaffected at these concentrations.

Polymer–Drug Conjugates for Treating Local and Systemic Fungal Infections

In immunocompromised patients, fungal infections are the major cause of morbidity and mortality. Currently, three major classes of drugs—polyenes, azoles, and echinocandins—with different mechanisms of action are used as antifungals for systemic infections. However, these conventional drugs were reported to induce toxic effects due to their low specificity, narrow spectrum of activity and drug–drug interactions. Some of these limitations could be overcome by altering the properties of existing drugs through physical and chemical modifications. For example, modification of amphotericin B (AmB), a polyene antibiotic includes the micellar suspension of AmB in deoxycholic acid (Fungizone®), non-covalent AmB lipid complexes (ABLC™), liposomal AmB (AmBisome®), and AmB colloidal dispersion (Amphocil™). All these formulations ensure the smoother release of AmB accompanied by its restricted distribution in the kidney, thereby lowering its nephrotoxicity. Although various methods such as polymeric micelles, nanoparticles and dendrimers were explored for enhancing the efficacy of the antifungal drugs, polymer–drug conjugates of antifungal drugs have received more attention in recent years. Polymer–drug conjugates improve the aqueous solubility of water-insoluble drugs, are stable in storage and reduce the toxicity of highly toxic drugs and are capable of releasing the drug at the site of action. This chapter discusses the polymer conjugates of antifungal drugs, their merits, and demerits. Studies reported so far show that the polymer–drug conjugates have significant advantages compared to conventional dosage forms for antifungal therapy.

Drug carriers with star polymer structures

In this review we summarize several synthetic approaches to the advanced synthesis of star-like polymer-based drug carriers. Moreover, their application as nanomedicines for therapy or the diagnosis of neoplastic diseases and their biodistribution are reviewed in detail. From a broad spectrum of star-like systems, we focus only on fully water-soluble systems, mainly based on poly(ethylene glycol) or N-(2-hydroxypropyl)methacrylamide polymer and copolymer arms and polyamidoamine dendrimers serving as the core of the star-like systems.

Smart branched polymer drug conjugates as nano-sized drug delivery systems

Branched polymers own special properties derived from their intrinsic characteristics. These properties make them ideal candidates to be used as carriers for an improved generation of polymer-drug conjugates.

Toxicity mechanisms of amphotericin B and its neutralization by conjugation with arabinogalactan

Amphotericin B (AMB) is an effective antifungal agent. However, its therapeutic use is hampered by its toxicity, mainly due to channel formation across kidney cell membranes and the disruption of postendocytic trafficking. We previously described a safe injectable AMB-arabinogalactan (AG) conjugate with neutralized toxicity. Here we studied the mechanism of the toxicity of free AMB and its neutralization by conjugation with AG. AMB treatment of a kidney cell line modulated the trafficking of three receptors (C-X-C chemokine receptor type 4 [CXCR4], M1 receptor, and human transferrin receptor [hTfnR]) due to an increase in endosomal pH. Similar data were also obtained in yeast but with an increase in vacuolar pH and the perturbation of Hxt2-green fluorescent protein (GFP) trafficking. The conjugation of AMB with AG neutralized all elements of the toxic activity of AMB in mammalian but not in fungal cells. Based on these results, we provide an explanation of how the conjugation of AMB with AG neutralizes its toxicity in mammalian cells and add to the knowledge of the mechanism of action of free AMB in both fungal and mammalian cells.

Polymer–drug conjugates for novel molecular targets

Polymer therapeutics can be already considered as a promising field in the human healthcare context. The discovery of the enhanced permeability and retention effect by Maeda, together with the modular model for the polymer–drug conjugate proposed by Ringsdorf, directed the early steps of polymer therapeutics towards cancer therapy. Orthodox anticancer drugs were preferentially chosen in the development of the first conjugates. The fast evolution of polymer chemistry and bioconjugation techniques, and a deeper understanding of cell biology has opened up exciting new challenges and opportunities. Four main directions have to be considered to develop this ‘platform technology’ further: the control of the synthetic process, the exhaustive characterization of the conjugate architectures, the conquest of combination therapy and the disclosure of new therapeutic targets. We illustrate in this article the exciting approaches offered by polymer–drug conjugates beyond classical cancer therapy, focusing on new, more effective and selective targets in cancer and in their use as treatments for other major human diseases.