Deciphering the interactions of phytochemicals with ovalbumin, the major food allergen from egg white: spectroscopic and computational studies.

Ovalbumin (OVA), the major component of egg white, has been used as a model carrier protein to study the interaction of four bioactive phytochemicals 6-hydroxyflavone, chrysin, naringin, and naringenin. A static quenching mechanism was primarily associated with the complexation of the flavonoids with OVA. Hydrophobic forces play a major part in the stability of the complexes. The structural changes within the protein in response to flavonoid binding revealed a decrease in OVA's α-helical content. The hypothesized binding site for flavonoids in OVA overlaps with one or more immunoglobulin E-binding epitopes that may have some effect in the immunoglobulin E response pathway. The flavonoids remain in the same binding site throughout the simulation time and impart protein stability by forming different noncovalent interactions. This study presents comprehensive information about the interaction of the flavonoids with OVA and the associated structural variations after the binding, which might help researchers better comprehend similar medication pharmacodynamics and provide critical information for future therapeutic development.

Non-covalent binding interaction of bioactive coumarin esculetin with calf thymus DNA and yeast transfer RNA: A detailed investigation to decipher the binding affinities, binding location, interacting forces and structural alterations at a molecular level.

Esculetin is a well-known coumarin derivative found abundantly in nature possessing an extensive array of pharmacological and therapeutic properties. Consequently, to comprehend its molecular recognition mechanism, our objective is to conduct a complete investigation of its interactions with the nucleic acid, specifically ct-DNA, and t-RNA, using spectroscopic and computational techniques. The intrinsic fluorescence of esculetin is quenched when it interacts with ct-DNA and t-RNA, and this occurs through a static quenching mechanism. The thermodynamic parameters demonstrated that the interaction is influenced by hydrogen bonding and weak van der Waals forces. CD and FT-IR results revealed no conformational changes in ct-DNA and t-RNA structure on binding with esculetin. Furthermore, competitive displacement assay with ethidium bromide, melting temperature, viscosity measurement, and potassium iodide quenching experiments, reflected that esculetin probably binds to the minor groove of ct-DNA. The molecular docking results provided further confirmation for the spectroscopic findings, including the binding location of esculetin and binding energies of esculetin complexes with ct-DNA and t-RNA. Molecular dynamics simulation studies demonstrated the conformational stability and flexibility of nucleic acids.

Elucidation of inhibitory effects of bioactive anthraquinones towards formation of DNA advanced glycation end products (DNA-AGEs).

DNA is essential in biological processes as it directs transcription and translation assisting in RNA and protein synthesis. Extended periods of elevated blood glucose levels cause non-enzymatic DNA glycation, which results in the formation of DNA-AGEs and the production of free radicals, causing structural perturbation of DNA. In this work, we have investigated the glycation of calf thymus (ct-DNA) DNA and examined its inhibition by two anthraquinone derivatives, purpurin and aloin. Ribose sugar served as the glycating agent inducing non-enzymatic glycation of DNA and subsequent DNA-AGEs formation. UV-vis and fluorescence spectroscopic methods were utilized to characterize DNA-AGE formation in vitro. Circular dichroism (CD) spectroscopy was used to observe the structural disruption of DNA caused by glycation. The changes in AGEs fluorescence intensity and melting temperature (Tm) were measured to assess the inhibition of glycation process by aloin and purpurin. These derivatives demonstrated inhibitory effects via binding to glycating sites of ct-DNA or by scavenging free radicals generated during glycation. The current study elucidates the inhibitory actions of aloin and purpurin on DNA glycation, suggesting their possible applications in mitigating the adverse consequences linked to increased ribose concentrations.

Gold Nanorod-Collagen Nanocomposites as Photothermal Nanosolders for Laser Welding of Ruptured Porcine Intestines.

Surgical site infection and postoperative leakage are complications that may develop following colorectal surgery and result in fatal consequences. Rapid, fluid-tight wound closure through laser tissue welding (LTW) can reduce postoperative leakage and thus decrease infection. Laser tissue welding involves generation of localized heat by exposing an exogenous chromophore to near-infrared (NIR) irradiation in order to seal wounds. In this study, we generated gold nanorod (GNR)-collagen nanocomposites (NCs) for laser-facilitated welding of ruptured intestinal tissue. The fluid content, stiffness, elasticity, and laser-induced temperature response of these nanocomposites were modulated to optimize laser-induced tissue fusion and minimize tissue damage. In addition, the effect of laser operating parameters including power density, femtosecond pulsed wave (PW) or continuous wave (CW) laser, and exposure duration were all studied. Laser power density and treatment duration significantly affected the temperatures reached during welding, as well as tissue weld strength and burst pressure. CW laser was found to induce significantly higher temperatures of the nanocomposites during treatment than PW laser, but the differences in weld strength and burst pressure for the two laser types were insignificant. This suggests that PW lasers can result in robust welds while minimizing potential thermal damage compared to CW lasers. The ultimate tensile strength of welded ruptured tissue was returned to as high as 68% of the native tissue strength through laser treatment, and laser treatment with these nanocomposites restored up to 64% of native tissue leak pressure and 42% of burst pressure. To the best of our knowledge, the laser power densities used (≤2.50 W/cm2) are among the lowest reported for laser tissue welding, and the laser configuration and use require very little surgical skill. Our results indicate that GNR-collagen nanocomposites are promising photothermal biomaterials in laser tissue welding applications.