Comparative chemical examination of inclusion complexes formed with β-cyclodextrin derivatives and basic amino acids

Unveiling cyclodextrin conjugation as multidentate excipients: An exploratory journey across industries

The discovery of branched molecules like dextrin by Schardinger in 1903 marked the inception of cyclodextrin (CD) utilization, catalyzing its journey from laboratory experimentation to widespread commercialization within the pharmaceutical industry. CD, a cyclic oligosaccharide containing glucopyranose units, acts as a versatile guest molecule, forming inclusion complexes (ICs) with various host molecules. Computational studies have become instrumental in elucidating the intricate interactions between β-CD and guest molecules, enabling the prediction of binding energy, forces, affinity, and complex stability. The computational approach has established robust correlations with experimental outcomes, enhancing our understanding of CD-mediated complexation phenomena. This comprehensive review delves into the CD based Inclusion complex (CDIC) formation and a myriad of components, including drug molecules, amino acids, vitamins, and volatile oils. These complexes find applications across diverse industries, ranging from pharmaceuticals to nutraceuticals, food, fragrance, and beyond. In the pharmaceutical realm, β- CDICs offer innovative solutions for enhancing drug solubility, stability, and bioavailability, thus overcoming formulation challenges associated with poorly water-soluble drugs. Furthermore, the versatility of CDs extends beyond pharmaceuticals, with applications in the encapsulation of phytoactive compounds in nutraceuticals and the enhancing flavor, aroma in food and fragrance industries. This review underscores the pivotal role of CDs conjugation in modern drug delivery systems, emphasizing the importance of interdisciplinary approaches that integrate computational modeling with experimental validation. As the pharmaceutical landscape continues to evolve, CDs-based formulations stand poised to drive innovation and address the ever-growing demand for efficacious and patient-friendly drug delivery solutions.

Driving forces and large scale affinity calculations for piperine/γ-cyclodxetrin complexes: Mechanistic insights from umbrella sampling simulation and DFT calculations

Piperine (PiP), a bioactive molecule, exhibits numerous health benefits and is frequently employed as a co-delivery agent with various phytomedicines (e.g., curcumin) to enhance their bioavailability. This is attributed to PiP's inhibitory activity against drug-metabolizing proteins, notably CYP3A4. Nevertheless, PiP encounters solubility challenges addressed in this study using cyclodextrins (CDs). Specifically, γ-CD and its derivatives, Hydroxypropyl-γ-CD (HP-γ-CD), and Octakis (6-O-sulfo)-γ-CD (Octakis-S-γ-CD), were employed to form supramolecular complexes with PiP. The conformational space of the complexes was assessed through 1 μs molecular dynamics simulations and umbrella sampling. Additionally, quantum mechanical calculations using wB97X-D dispersion-corrected DFT functional and 6-311 + G(d,p) basis set were conducted on the complexes to examine the thermodynamics and kinetic stability. Results indicated that Octakis-S-γ-CD exhibits superior host capabilities for PiP, with the most favorable complexation energy (-457.05 kJ/mol), followed by HP-γ-CD (-249.16 kJ/mol). Furthermore, two conformations of the Octakis-S-γ-CD/PiP complex were explored to elucidate the optimal binding orientation of PiP within the binding pocket of Octakis-S-γ-CD. Supramolecular chemistry relies significantly on non-covalent interactions. Therefore, our investigation extensively explores the critical atoms involved in these interactions, elucidating the influence of substituted groups on the stability of inclusion complexes. This comprehensive analysis contributes to emphasizing the γ-CD derivatives with improved host capacity.

Establishment of nanoparticle screening technique: A pivotal role of sodium carboxymethylcellulose in enhancing oral bioavailability of poorly water-soluble aceclofenac

A novel nanoparticle screening technique was established to mostly enhance the aqueous solubility and oral bioavailability of aceclofenac using nanoparticle systems. Among the polymers investigated, sodium carboxymethylcellulose (Na-CMC) showed the greatest increase in drug solubility. Utilizing spray-drying technique, the solvent-evaporated solid dispersion (SESD), surface-attached solid dispersion (SASD), and solvent-wetted solid dispersion (SWSD) were prepared using aceclofenac and Na-CMC at a weight ratio of 1:1 in 50 % ethanol, distilled water, and ethanol, respectively. Using Na-CMC as a solid carrier, an aceclofenac-loaded liquid self-emulsifying drug delivery system was spray-dried and fluid-bed granulated together with microcrystalline cellulose, producing a solid self-nanoemulsifying drug delivery system (SNEDDS) and solid self-nanoemulsifying granule system (SNEGS), respectively. Their physicochemical properties and preclinical assessments in rats were performed. All nanoparticles exhibited very different properties, including morphology, crystallinity, and size. As a result, they significantly enhanced the solubility, dissolution, and oral bioavailability in the following order: SNEDDS ≥ SNEGS > SESD ≥ SASD ≥ SWSD. Based on our screening technique, the SNEDDS was selected as the optimal nanoparticle with the highest bioavailability of aceclofenac. Thus, our nanoparticle screening technique should be an excellent guideline for solubilization research to improve the solubility and bioavailability of many poorly water-soluble bioactive materials.

Molecular-level enhanced clusterization-triggered emission of nonconventional luminophores in dilute aqueous solution

Nonconjugated and nonaromatic luminophores based on clustering-triggered emission derived from through-space conjugation have drawn emerging attention in recent years. The reported nonconventional luminophores are emissive in concentrated solution and/or in the solid state, but they tend to be nonluminescent in dilute solution, which greatly limits their sensing and imaging applications. Herein, we design unique clusteroluminogens through modification of cyclodextrin (CD) with amino acids to enable the intermolecular and intramolecular clusterization of chromophores in CD-based confined space. The resulted through-space interactions along with conformation rigidification originated from hydrogen bond interaction and complexation interaction generate blue to cyan fluorescence even in the dilute solution (0.035 wt.%, quantum yield of 40.70%). Moreover, the prepared histidine-modified CD (CDHis) is demonstrated for fluorescent detection of chlortetracycline with high sensitivity and selectivity. This work provides a new and universal strategy to synthesize nonconventional luminophores with bright fluorescence in dilute aqueous solution through molecular-level enhanced clusterization-triggered emission.

Mechanistic understanding and the rational design of a SiO2@CD catalyst for selective protection of L-lysine

The mechanism of the selective protection of L-lysine mediated by β-cyclodextrin (β-CD) was investigated by preliminary experiments, including the reaction efficiency influenced by different reaction conditions, and the existence of (1a·CD)' and 1a·CD·2a was evidenced by ESI-MS and 2D Rotating Frame Overhauser Effect Spectroscopy (ROESY) analysis. The results indicated that the formation of (1a·CD)' is critical for the product selectivity and the further formation of the ternary complex 1·CD·2 is responsible for the reaction efficiency. Thus, the yields and selectivity were significantly influenced by the structure, size and reactivity of the reactants. During the mechanistic investigations, we realized that the formation of the product and the β-CD complex at the final stage of the reaction would cause difficulty in product purification by a previously reported homogeneous method. In light of this understanding, an efficient and practical protocol for selective protection of L-lys based on a heterogeneous catalyst SiO₂@CD was developed. The use of the SiO₂ immobilized β-CD catalyst prevented the formation of the "capped" products by controlling the spatial rearrangement of β-CDs on solid supports, which represents a considerable synthetic improvement over the tedious and wasteful organic solvent extraction for product purification.

New potential application of hydroxypropyl-β-cyclodextrin in solid self-nanoemulsifying drug delivery system and solid dispersion

The purpose of this study was to use hydroxypropyl-β-cyclodextrin (HP-β-CD) as a novel carrier in solid SNEDDS and solid dispersions to enhance the solubility and oral bioavailability of poorly water-soluble dexibuprofen. The novel dexibuprofen-loaded solid SNEDDS was composed of dexibuprofen, corn oil, polysorbate 80, Cremophor® EL, and HP-β-CD at a weight ratio of 45/35/50/15/100. This solid SNEDDS spontaneously formed a nano-emulsion with a size of approximately 120 nm. Unlike the conventional solid SNEDDS prepared with colloidal silica as a carrier, this dexibuprofen-loaded solid SNEDDS exhibited a spherical structure. Similar to the dexibuprofen-loaded solid dispersion prepared with HP-β-CD, the transformation of the crystalline drug to an amorphous state with no molecular interactions were observed in the solid SNEDDS. Compared to the solid dispersion and dexibuprofen powder, solid SNEDDS significantly enhanced drug solubility and AUC. Therefore, HP-β-CD is a novel potential carrier in SNEDDS for improving the oral bioavailability of dexibuprofen.

Scaffold Searching of FDA and EMA-Approved Drugs Identifies Lead Candidates for Drug Repurposing in Alzheimer's Disease

Clinical trials of novel therapeutics for Alzheimer's Disease (AD) have consumed a significant amount of time and resources with largely negative results. Repurposing drugs already approved by the Food and Drug Administration (FDA), European Medicines Agency (EMA), or Worldwide for another indication is a more rapid and less expensive option. Therefore, we apply the scaffold searching approach based on known amyloid-beta (Aβ) inhibitor tramiprosate to screen the DrugCentral database (n = 4,642) of clinically tested drugs. As a result, menadione bisulfite and camphotamide substances with protrombogenic and neurostimulation/cardioprotection effects were identified as promising Aβ inhibitors with an improved binding affinity (ΔGbind) and blood-brain barrier permeation (logBB). Finally, the data was also confirmed by molecular dynamics simulations using implicit solvation, in particular as Molecular Mechanics Generalized Born Surface Area (MM-GBSA) model. Overall, the proposed in silico pipeline can be implemented through the early stage rational drug design to nominate some lead candidates for AD, which will be further validated in vitro and in vivo, and, finally, in a clinical trial.