Carbohydrate-Based Host-Guest Complexation of Hydrophobic Antibiotics for the Enhancement of Antibacterial Activity

Facile synthesis of 2-hydroxy-β-cyclodextrin/polyacrylamide/carbazole hydrogel and its application for the treatment of infected wounds in a murine model

This work aimed to synthesize hydrogels by combining carbazole (Carb) with 2-hydroxy, β-cyclodextrin (HPβCD)/polyacrylamide (PAA) hybrid complexes. The hydrogels were then evaluated for their potential use in treating infected wounds. The physicochemical structures of the preparations were evaluated using several characterization methods including FTIR, FESEM, EDX, XRD, pH sensitivity, and TGA. Moreover, In vitro release, toxicity, antibacterial activity and in vivo infected wound healing activity were evaluated. Physicochemical testing verified the effective synthesis of the preparations and the timely release of Carb. The P(AA-co-AM)/HPβCD material exhibited an open structure characterized by macroscopic voids, whereas the hydrogels displayed surfaces that were not uniform. The FTIR analysis revealed the creation of a novel polymeric hydrogel composed of HPβCD as the main polymer structure. The hydrogels exhibited good reversible swelling and recoverable deformation, with an optimal swelling ratio of 30.12 achieved at pH 7.4. The antibacterial and safety of the formulations were validated by in vitro studies. β.Dex/PAA/Carb hydrogels have been shown to effectively expedite the healing of infected wounds by promoting the production of CD31, FGF-2, and COL1A, while reducing the levels of ROS, CD68, COX-2, and NF-κB. Overall, the combination of Carb, β.Dex, and PAA molecules had a synergistic impact on the healing process of infected wounds.

Cyclodextrin: A prospective nanocarrier for the delivery of antibacterial agents against bacteria that are resistant to antibiotics

Supramolecular chemistry introduces us to the macrocyclic host cyclodextrin, which has a hydrophobic cavity. The hydrophobic cavity has a higher affinity for hydrophobic guest molecules and forms host-guest complexation with non-covalent interaction. Three significant cyclodextrin kinds are α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. The most often utilized is β-cyclodextrin (β-CD). An effective weapon against bacteria that are resistant to antibiotics is cyclodextrin. Several different kinds of cyclodextrin nanocarriers (β-CD, HP-β-CD, Meth-β-CD, cationic CD, sugar-grafted CD) are utilized to enhance the solubility, stability, dissolution, absorption, bioavailability, and permeability of the antibiotics. Cyclodextrin also improves the effectiveness of antibiotics, antimicrobial peptides, metallic nanoparticles, and photodynamic therapy (PDT). Again, cyclodextrin nanocarriers offer slow-release properties for sustained-release formulations where steady-state plasma antibiotic concentration is needed for an extended time. A novel strategy to combat bacterial resistance is a stimulus (pH, ROS)-responsive antibiotics released from cyclodextrin carrier. Once again, cyclodextrin traps autoinducer (AI), a crucial part of bacterial quorum sensing, and reduces virulence factors, including biofilm formation. Cyclodextrin helps to minimize MIC in particular bacterial strains, keep antibiotic concentrations above MIC in the infection site and minimize the possibility of antibiotic and biofilm resistance. Sessile bacteria trapped in biofilms are more resistant to antibiotic therapy than bacteria in a planktonic form. Cyclodextrin also involves delivering antibiotics to biofilm and resistant bacteria to combat bacterial resistance.

Combatting Antibiotic Resistance Using Supramolecular Assemblies

Antibiotic resistance has posed a great threat to human health. The emergence of antibiotic resistance has always outpaced the development of new antibiotics, and the investment in the development of new antibiotics is diminishing. Supramolecular self-assembly of the conventional antibacterial agents has been proved to be a promising and versatile strategy to tackle the serious problem of antibiotic resistance. In this review, the recent development of antibacterial agents based on supramolecular self-assembly strategies will be introduced.

Effect of glycyrrhizic acid on phospholipid membranes in media with different pH

Glycyrrhizic acid (GA) is the active ingredient in licorice root, which exhibits a wide range of biological activities, including anti-inflammatory and antiviral activities. In particular, the virus-inhibiting effect of GA on SARS-associated coronavirus was demonstrated. In addition, GA was found to be capable of increasing bioaccessibility of other drugs when used together. All these effects can be based on the ability of GA to incorporate into cell membranes and change their physical and functional properties. One of the possible mechanisms of the antiviral action of GA against COVID-19 is also considered to be the prevention of fusion of the virus envelope with the plasma membrane of the host cell. The interaction of GA with model lipid membranes was studied by the NMR method. Different factors influencing the incorporation of the GA molecule into the lipid bilayer (phospholipid structure, pH of the medium) were examined.

Antibiotic resistance in agriculture: Perspectives on upcoming strategies to overcome upsurge in resistance

Antibiotic resistance is a massive problem rising constantly and spreading rapidly since the past decade. The major underlying mechanism responsible for this problem is an overuse or severe misuse of antibiotics. Regardless of this emerging global threat, antibiotics are still being widely used, not only for treatment of human infections, but also to a great extent in agriculture, livestock and animal husbandry. If the current scenario persists, we might enter into a post-antibiotic era where drugs might not be able to treat even the simplest of infections. This review discusses the current status of antibiotic utilization and molecular basis of antibiotic resistance mechanisms acquired by bacteria, along with the modes of transmittance of the resultant resistant genes into human pathogens through their cycling among different ecosystems. The main focus of the article is to provide an insight into the different molecular and other strategies currently being studied worldwide for their use as an alternate to antibiotics with an overall aim to overcome or minimize the global problem of antibiotic resistance.

Antimicrobial Nanogels with Nanoinjection Capabilities for Delivery of the Hydrophobic Antibacterial Agent Triclosan

With the ever-growing problem of antibiotic resistance, developing antimicrobial strategies is urgently needed. Herein, a hydrophobic drug delivery nanocarrier is developed for combating planktonic bacteria that enhances the efficiency of the hydrophobic antimicrobial agent, Triclosan, up to a 1000 times. The poly(N-isopropylacrylamide-co-N-[3-(dimethylamino)propyl]methacrylamide), p(NIPAM-co-DMAPMA), based nanogel is prepared via a one-pot precipitation polymerization, followed by quaternization with 1-bromododecane to form hydrophobic domains inside the nanogel network through intraparticle self-assembly of the aliphatic chains (C12). Triclosan, as the model hydrophobic antimicrobial drug, is loaded within the hydrophobic domains inside the nanogel. The nanogel can adhere to the bacterial cell wall via electrostatic interactions and induce membrane destruction via the insertion of the aliphatic chains into the cell membrane. The hydrophobic antimicrobial Triclosan can be actively injected into the cell through the destroyed membrane. This approach dramatically increases the effective concentration of Triclosan at the bacterial site. Both the minimal inhibitory concentration and minimal bactericidal concentration against the Gram-positive bacteria S. aureus and S. epidermidis decreased 3 orders of magnitude, compared to free Triclosan. The synergy of physical destruction and active nanoinjection significantly enhances the antimicrobial efficacy, and the designed nanoinjection delivery system holds great promise for combating antimicrobial resistance as well as the applications of hydrophobic drugs delivery for many other possible applications.

Glycyrrhizin-induced changes in phospholipid dynamics studied by 1H NMR and MD simulation

Phospholipid bilayer constitutes the basis of the cell membrane. Any changes in its structure and dynamics could significantly affect the properties and functions of the cell membrane and associated proteins. It could, in its turn, affect the mechanism and strength of drug-membrane interaction. Phase transitions in lipid bilayer play an important role in cell life and in transmembrane transport of ions and drug molecules. In the present study we have tried to clarify the mechanism of glycyrrhizin bioactivity by the study of its influence on the lipid dynamics and phase transition of the lipid bilayer. For this purpose, a combination of nuclear magnetic resonance (NMR) and molecular dynamic (MD) simulations was used. Glycyrrhizin is the saponin extracted from licorice root. It displays a wide spectrum of biological activity and is frequently used in traditional medicine since ancient times. Now glycyrrhizin attracts additional attention as a novel multifunctional drug delivery system. We have established that glycyrrhizin interaction with dipalmitoylphosphatidylcholine lipid bilayers leads to changes in lipid mobility and phase transition temperature. NMR and MD results demonstrated that a glycyrrhizin molecule is able to integrate into a lipid bilayer and form stable aggregates inside. We hypothesize that surface curvatures caused by local changes in the lipid composition and the presence of phase boundaries might affect the permeability of the cell membrane.

Contrasting interactions of DNA-intercalating dye acridine orange with hydroxypropyl derivatives of β-cyclodextrin and γ-cyclodextrin hosts

The present study demonstrates contrasting binding interactions of acridine orange dye with HPβCD and HPγCD hosts, always illustrating fluoresence “turn on” in the case of HPβCD and showing an interesting fluorescence “off/on switching” in the case of the HPγCD host.

The uncommon strong inhibition of α-glucosidase by multivalent glycoclusters based on cyclodextrin scaffolds

New inhibitors of α-glucosidase based on perglycosylated cyclodextrins were synthesized via click-chemistry and compared to acarbose.

Polymeric bile acid sequestrants: Review of design, in vitro binding activities, and hypocholesterolemic effects

Polymeric bile acid sequestrants (BAS) have recently attracted much attention as lipid-lowering agents. These non-absorbable materials specifically bind bile acids (BAs) in the intestine, preventing bile acid (BA) reabsorption into the blood through enterohepatic circulation. Therefore, it is important to understand the structure-property relationships between the polymer sequestrant and its ability to bind specific BAs molecules. In this review, we describe pleiotropic effects of bile acids, and we focus on BAS with various molecular architectures that result in different mechanisms of BA sequestration. Here, we present 1) amphiphilic polymers based on poly(meth)acrylates, poly(meth)acrylamides, polyalkylamines and polyallylamines containing quaternary ammonium groups, 2) cyclodextrins, and 3) BAS prepared via molecular imprinting methods. The synthetic approaches leading to individual BAS preparation, as well as results of their in vitro BA binding activities and in vivo lipid-lowering activities, are discussed.