Computational and experimental analysis of Luteolin-β-cyclodextrin supramolecular complexes: Insights into conformational dynamics and phase solubility

Alkaline-heat induced the conformationally flexible regions of soy protein and their effect on subunit aggregation

Soy protein's processing traits such as gelation depend on molecular unfolding and aggregation; however, the relationship between structural changes and gelation remains unclear. The results show that the conformationally flexible regions of acidic subunits (A) are primarily composed of β-strands (E42 → P90) and an extended region featuring a helix (V186 → V262). The regions of the basic subunit (B) consist of a β-turn region (L34 → Q50) and a segment with three helical structures (K125 → S155). Under alkaline-heat treatment, the helical region of subunit A closes, resulting in a stable structure, leading to a 50 %-54 % decrease in the binding energy between subunits A and B, making them more prone to dissociation. The subunit B extends its structure, increasing the binding energy by 63 %-69 % and promoting the formation of highly stable aggregates through self-assembly. Provide theoretical support for SPI production in suitable-hardness gels.

Refining the Trapping of Therapeutic Agent Silybin A in Functionalized β- and γ-Cyclodextrin Cavitands for Improved Supramolecular Complexation

Silybin A (Slym), the principal bioactive constituent of silymarin, exhibits significant therapeutic potential but suffers from poor bioavailability due to its low aqueous solubility. This study addresses this by employing cyclodextrins (CDs) as cost-effective solubilizers to enhance Slym's solubility through the formation of stable supramolecular complexes. Our findings indicate that while β-CD and γ-CD have suitable cavity sizes for Slym, their derivatives 6-O-alpha-d-Glucosyl-β-CD (G-β-CD), Heptakis-O-(4-sulfobutyl)-β-CD (SBE-β-CD), and Hydroxypropyl-γ-CD (HP-γ-CD) exhibit superior binding affinity. The binding free energy results from the MM/PBSA analysis indicated that derivatives of β-CD and γ-CD exhibit superior encapsulation efficiency for Slym compared to the unsubstituted CD forms by performing 1 μs MD simulations. Detailed mechanistic insights of these were obtained through 5 μs MD simulations and triplicate analysis, confirming the stability of these complexes over extended durations, attributed to numerous nonbonded interactions. Furthermore, full DFT calculations with M06-2X/6-31g(d) model chemistry revealed that the SBE-β-CD/Slym complex showed the most favorable complexation energy -303.82 kJ/mol than G-β-CD/Slym (-224.82 kJ/mol) and HP-γ-CD/Slym (-246.75 kJ/mol). The QM-derived IR spectrum of the SBE-β-CD/Slym complex was compared with experimental data, and nonbonded interactions between CDs and Slym were analyzed using IGMH analysis. The conformational entry of Slym into CDs was also analyzed, highlighting the potential of SBE-β-CD as an effective carrier for enhancing the solubility and pharmaceutical efficacy of Slym.

Molecular insights into the controlled release process of cyclodextrin-resveratrol inclusion complexes in the stratum corneum

Cyclodextrins (CDs) are efficient drug carriers for improving drug solubility, stability, and bioavailability. However, the mechanism underlying the interaction between cyclodextrin-drug inclusion complexes and skin remains unclear. In this work, molecular simulations were employed to study the release process of cyclodextrin-resveratrol inclusion complexes on the surface of the lipid bilayer. The results showed that structural orientation significantly influences release kinetics. Resveratrol (RES) is able to form inclusion complexes with β-CD in two possible orientations: M-form (Mono-hydroxyl group toward the primary rim of β-CD) and D-form (Di-hydroxyl group toward the secondary rim of β-CD). M-form inclusion structures facilitated RES release more efficiently than D-form configurations. Cavity-specific lipid interactions are the dominant driver of the release process. Meanwhile, it was determined that the β-CD/RES inclusion complex exhibited greater stability than γ-CD/RES and demonstrated superior release efficiency at the lipid membrane surface in comparison to α-CD/RES. This suggests that the cavity size of β-CD is more suitable for delivering resveratrol. Furthermore, umbrella sampling simulations reveal that hydroxypropyl-substituted β-CD could lessen the irritation to the lipid bilayer. The present study provides a theoretical foundation for the rational design of CD-based drug delivery systems.

Innovative approaches for beetroot (Beta Vulgaris L.) aqueous extraction by cyclodextrins and its use to alleviate ethanol induced gastric ulcer in rats

One of the most common chronic conditions of peptic ulcer is gastric ulcer (GU), which is recognized as a high-risk illness in the present-day lifestyle. Originating from Asia and Europe, Beetroot (Beta vulgaris L.) is packed with high amounts of bioactive compounds like betanin and phenolics. These contribute to its nutritional value and overall health benefits. In this work, varying concentrations (0.5% to 7% w/v) of beta-cyclodextrin (β-CD) and hydroxypropyl-beta-cyclodextrin (HP-β-CD) were used to improve the efficiency of extracting beetroot components with water, using both stirring and ultrasound techniques. The presence of 5% (w/v) HP-β-CD during extraction appeared the maximum values of total phenolic compounds and betanin (3.1 mcg/mL and 3.01 mg/mL, respectively). The extraction recoveries of betanin at 5% (w/v) HP-β-CD emerging with magnetic stirring were 73%, 36% and 50% against water, ethanol and β-CD, respectively. The reproducibility of extraction procedure was found to be 0.86% relative standard deviation (RSD) indicating the highest precision of the beetroot modified HP-β-CD extraction procedure. Then, rats that had been treated with either HP-β-CD-modified aqueous extract of beetroot, omeprazole (20 mg/kg, orally administered) or both were studied to assess whether they helped reduce ethanol-induced GU. The combined treatment of HP-β-CD modified beetroot extract with omeprazole brought a significant decrease in the increased levels of serum oxidative stress malonaldehyde and nitric oxide, inflammatory markers myeloperoxidase, interleukin-10, interleukin-6 and tumor necrosis factor-α. It also restored the decreased levels of antioxidant glutathione and cyclo-protective prostaglandin E2 in comparison to the positive control. Furthermore, the proposed combination of beetroot-modified aqueous extract and omeprazole exhibited less severe histopathological damage in comparison to the positive control. Therefore, a novel synergistic pharmaceutical treatment using HP-β-CD modified aqueous extract of beetroot and omeprazole was presented to enhance GU healing.

Enhancement of gel characteristics of curdlan thermo-irreversible gels by β-cyclodextrin and its possible mechanisms

In this study, the influences of various concentrations of β-cyclodextrin (β-CD) on the gelation properties of curdlan thermo-irreversible gels were evaluated. The results revealed that water-holding capacity and freeze-thaw stability of the curdlan/β-CD complex gels initially increased but then decreased with increasing β-CD concentration, with the curdlan gel containing 1 % (w/v) β-CD demonstrating the best performance. Moreover, textural characteristics including hardness, gumminess, cohesiveness, and chewiness exhibited similar trends, but springiness showed minor effect. Compared with the pure curdlan gel, the curdlan/β-CD mixed gels exhibited better elastic behavior and greater thermal stability but lower crystallinity. Additionally, scanning electron microscopy (SEM) images of the curdlan/β-CD composite gels revealed fine network structures with relatively continuous pores. The intermolecular hydrogen bonds between curdlan and β-CD were responsible for the enhanced gel properties. Thus, these data suggest that the inclusion of β-CD ameliorates the texture and stability of the curdlan gel by forming hydrogen bonds.