Horizontal comparison of "red or blue shift" and binding energy of six fluoroquinolones: Fluorescence quenching mechanism, theoretical calculation and molecular modeling method

In this article, the interaction between six fluoroquinolones (FQs) and bovine serum albumin (BSA) was initially studied at 298 K, 303 K and 310 K respectively under simulated physiological conditions by fluorescence spectroscopy. At the same time, the sub-structural domains on BSA that may bind to FQs were investigated by molecular docking simulation technique. A combination of quantitative and qualitative approaches was used in the analysis of the binding constants, binding sites and corresponding thermodynamic parameters in the interaction system, it was found that FQs forms a complex with BSA and undergoes static quenching, which is the main cause of fluorescence quenching. The results indicated that hydrogen bonds, Van der Waals force and electrostatic interaction were the main binding forces between the complexes, it also showed that these six fluoroquinolones mainly bound to the IIA and IIIA structural domains of BSA, while DANO and SARA may be more toxic than other antibiotics. Based on Foster's non-radiative energy transfer theory, the binding distance between FQs and BSA was calculated to be less than 7 nm, indicating the existence of energy transfer between small molecule drugs and proteins. Synchronous fluorescence and UV-Vis absorption spectroscopy further confirmed that FQs can alter the secondary conformational change of BSA. Lomefloxacin has a different effect from the other five fluoroquinolone antibiotics because it causes a decrease in polarity and an increase in hydrophobicity around tryptophan residues, while the other five FQs have the opposite effect. Together, the study of FQs-BSA is of great significance to elucidate the pharmacokinetics and pharmacodynamics of FQs.

Insights into the Pharmacological Effects of Flavonoids: The Systematic Review of Computer Modeling

Computer modeling is a method that is widely used in scientific investigations to predict the biological activity, toxicity, pharmacokinetics, and synthesis strategy of compounds based on the structure of the molecule. This work is a systematic review of articles performed in accordance with the recommendations of PRISMA and contains information on computer modeling of the interaction of classical flavonoids with different biological targets. The review of used computational approaches is presented. Furthermore, the affinities of flavonoids to different targets that are associated with the infection, cardiovascular, and oncological diseases are discussed. Additionally, the methodology of bias risks in molecular docking research based on principles of evidentiary medicine was suggested and discussed. Based on this data, the most active groups of flavonoids and lead compounds for different targets were determined. It was concluded that flavonoids are a promising object for drug development and further research of pharmacology by in vitro, ex vivo, and in vivo models is required.

Primary aminomethyl derivatives of kaempferol: hydrogen bond-assisted synthesis, anticancer activity and spectral properties

Primary aminomethyl derivatives of kaempferol with anticancer activity were synthesized by a combination strategy involving a hydrogen bond-assisted process.

Characterizing the binding interaction of fungicide boscalid with bovine serum albumin (BSA): A spectroscopic study in combination with molecular docking approach

Boscalid, a carboxamide fungicide, is used in the treatment of grey mould and powdery mildew, widely applied to a variety of crops and fruits such as rice, wheat, grapes and pears. It will become a potential risk for health due to its widely application and residue in crops and fruits. In this study, the binding interaction between boscalid and bovine serum albumin (BSA) was characterized using steady-state fluorescence spectroscopy, ultraviolet spectroscopy (UV), synchronous fluorescence spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and molecular docking to ascertain the store, transport and distribution of boscalid in vivo. The experimental results indicated that the fluorescence of BSA was quenched due to the forming the static boscalid-BSA complex with the binding constant of 4.57×10³M^-1 at 298 K and boscalid bound on the subdomain III A (site II) of BSA through van der Waals force and hydrogen bonding interaction. The binding process of boscalid with BSA was spontaneous and enthalpy-driven process based on ΔG⁰<0 and |ΔH⁰|>T|ΔS⁰| over the studied temperature range. Meanwhile, the obvious change in the conformation of boscalid was observed while the slight change in the conformation of BSA when binding boscalid to the BSA, implying that the flexibility of boscalid contributes to increasing the stability of the boscalid-BSA complex.