Studies on the competitive binding of cleviprex and flavonoids to plasma protein by multi-spectroscopic methods: A prediction of food-drug interaction

The necessity of enhancing the human health risk assessment of 1,3,6,8-tetrabromocarbazole: Based on in vitro experiments, theoretical calculations, and model predictions

Industrial emissions have been identified as significant contributors to polyhalogenated carbazoles (PHCZs), a novel pollutant in the environment. Enhancing the health risk assessment of PHCZs is imperative, particularly for 1,3,6,8-tetrabromocarbazole (1368BCZ), the most commonly detected PHCZs in the environment. This study revealed that 1368BCZ could bind to the important transporters, human serum albumin (HSA), with high binding constant (KA: 1.02 × 105 L/mol). 1368BCZ primary bound to the HSA binding site 2, and the impact of 1368BCZ on HSA structure was minimal, indicating 1368BCZ may has strong accumulation in human. Theoretical analysis indicated that the uniformly distributed molecular surface electrostatic potential of the 1368BCZ molecule was crucial for its strong binding affinity to HSA. van der Waals forces serve as the primary interaction force stabilizing this binding. Further model predictions results showed that 1368BCZ may cause various toxic effects including hepatotoxicity, neurotoxicology, mutagenicity, etc. In summary, this study revealed the potential human health risks associated with 1368BCZ, providing an important basis for the formulation of relevant environmental control standards.

Explore the toxicological mechanism of 6PPD-Q on human health through a novel perspective: The interaction between lactate dehydrogenase and 6PPD-Q

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), an oxidative derivative of tire anti-degradant, has been linked to mortality in coho salmon (Oncorhynchus kisutch) and has exhibited potential human toxicity. Hence, exploring how 6PPD-Q interacts with biomacromolecules like enzymes is indispensable to assess its human toxicity and elucidate its mechanism of action. This investigation aims to explore the impact of 6PPD-Q on lactate dehydrogenase (LDH) through various methods. The findings indicate that 6PPD-Q can spontaneously embed in the coenzyme site of LDH and obviously change the biological activity of LDH by non-competitive inhibition. Simultaneously, this inhibitory effect is concentration-dependent. 6PPD-Q can affect both the level of LDH and the transcription of Ldha in AML-12 cells. Hydrogen bonding and van der Waals forces serve as the primary driving forces in LDH-6PPD-Q combination process. The apparent binding constant (Ka) value is (9.773 ± 0.699) × 103 L/mol (298 K). The presence of 6PPD-Q alters the conformation of LDH and decreases its structural stability. Moreover, the results of molecular docking indicate that the interaction of 6PPD-Q with Asp51 and Arg98 of LDH may be the reason that 6PPD-Q inhibits the biological activity of LDH. Meanwhile, the energy decomposition of residue analyses for LDH-6PPD-Q formation further highlight the energy contribution of Asp51 and Arg98 in this combination process.

Baicalin and lung diseases

Studies focusing on natural products have been conducted worldwide, and the results suggest that their natural ingredients effectively treat a wide range of illnesses. Baicalin (BIA) is a glycoside derived from the flavonoid baicalein present in Scutellaria baicalensis of the Lamiaceae family. Interestingly, BIA has been shown to protect the lungs in several animal models used in numerous studies. Therefore, we fully analyzed the data of the studies that focused on BIA's lung protective function against various injuries and included them in this review. Interestingly, BIA exhibits promising effects against acute lung injury, lung fibrosis, pulmonary embolism, and lung remodelling associated with COPD, LPS, and paraquat insecticide. BAI exhibits anticancer activity against lung cancer. Additionally, BIA potently attenuates lung damage associated with infections. BIA primarily exerts its therapeutic effects by suppressing inflammation, oxidative stress immune response, and apoptosis pathways. Nrf2/HO-1, PI3K/Akt, NF-κB, STAT3, MAPKs, TLR4, and NLRP3 are important targets in the pulmonary therapeutic effects of BIA on different lung disease models. Consequently, we recommend using it in future potential clinical applications, its contribution to treatment guidelines, and translating its promising effects to clinical practice in lung diseases.

Comparative study of the interaction mechanism of astilbin, isoastilbin, and neoastilbin with CYP3A4

The interactions of human CYP3A4 with three selected isomer flavonoids, such as astilbin, isoastilbin and neoastilbin, were clarified using spectral analysis, molecular docking, and molecular dynamics simulation. During binding with the three flavonoids, the intrinsic fluorescence of CYP3A4 was statically quenched in static mode with nonradiative energy conversion. The fluorescence and ultraviolet/visible (UV/vis) data revealed that the three flavonoids had a moderate and stronger binding affinity with CYP3A4 due to the order of the Ka1 and Ka2 values ranging from 104 to 105  L·mol-1 . In addition, astilbin had the highest affinity with CYP3A4, then isoastilbin and neoastilbin, at the three experimental temperatures. Multispectral analysis confirmed that binding of the three flavonoids resulted in clear changes in the secondary structure of CYP3A4. It was found from fluorescence, UV/vis and molecular docking analyses that these three flavonoids strongly bound to CYP3A4 by means of hydrogen bonds and van der Waals forces. The key amino acids around the binding site were also elucidated. Furthermore, the stabilities of the three CYP3A4 complexes were evaluated using molecular dynamics simulation.

The Pharmacological Efficacy of Baicalin in Inflammatory Diseases

Baicalin is one of the most abundant flavonoids found in the dried roots of Scutellaria baicalensis Georgi (SBG) belonging to the genus Scutellaria. While baicalin is demonstrated to have anti-inflammatory, antiviral, antitumor, antibacterial, anticonvulsant, antioxidant, hepatoprotective, and neuroprotective effects, its low hydrophilicity and lipophilicity limit the bioavailability and pharmacological functions. Therefore, an in-depth study of baicalin's bioavailability and pharmacokinetics contributes to laying the theoretical foundation for applied research in disease treatment. In this view, the physicochemical properties and anti-inflammatory activity of baicalin are summarized in terms of bioavailability, drug interaction, and inflammatory conditions.

Study on the interaction of two quinazoline derivatives as novel PI3K/mTOR dual inhibitors and anticancer agents to human serum albumin utilizing spectroscopy and docking

Interactions of human serum albumin (HSA) with two structurally similar quinazoline derivatives, S₁ and S₂ , which are potential anticancer drugs acting on PI3K/mTOR targets, were investigated in vitro utilizing multiple spectroscopy as well as molecular docking. The fluorescence quenching study demonstrated that HSA fluorescence could be statically quenched by S₁ and S₂ through the formation of an HSA-drug complex. Furthermore, the details of the binding site number, binding constant, as well as the thermodynamic parameters, were estimated at 298, 303, and 310 K. The results revealed that hydrogen bond interactions, as well as van der Waals forces, were the predominant factors responsible for binding HSA to S₁ or S₂ . Synchronous fluorescence and ultraviolet (UV) absorption spectra suggested that S₁ and S₂ had little effect on the polarity of the microenvironment and conformation of HSA. Energy transfer from HSA to S₁ or S₂ most probably occurred. The docking study revealed that S₁ and S₂ were able to bind to the hydrophobic cavity that was located in the HSA subdomain IIA and formed varying numbers of hydrogen bonds with amino acid residues nearby. Due to the subtle difference in the chemical structure, the binding of S₁ and S₂ to HSA was slightly different.

The influence of several nutritional supplements on the rational use of cabozantinib

To promote the rational use of cabozantinib (CBZ), this paper studied the influence of several nutritional supplements on the interaction between CBZ and bovine serum albumin (BSA), an appropriate alternative model for human serum albumin (HSA) that is one of the important transporter proteins in plasma, by fluorescence spectroscopy and UV-vis spectroscopy. The results showed that CBZ could quench the fluorescence of BSA via a dynamic-static quenching process, and the six nutritional supplements did not change the quenching mode of BSA by CBZ. However, all of them could reduce the binding constant of the CBZ-BSA system at 293 K and increase the polarity around tryptophan residues. Among them, nicotinamide and vitamin B₁₂ (VB₁₂ ) had a greater effect on the binding constants of the CBZ-BSA system. In the meantime, the thermodynamic parameters of the CBZ-BSA system were examined, indicating that the interaction of CBZ with BSA was spontaneous and dominated by hydrophobic forces. Further research discovered that the combining of CBZ with BSA was primarily located within Site I of BSA, and the binding distance r was 2.48 nm. Consequently, while taking CBZ, patients should use VB₁₂ and nicotinamide carefully, which may interfere with the transport of drugs.

The Current Role of Clevidipine in the Management of Hypertension

Acute hypertension, which may damage blood vessels, causes irreversible organ damage to the vasculature, central nervous system, kidney, and heart. Clevidipine, the first third-generation calcium channel antagonist approved by the Food and Drug Administration (FDA) in the past 20 years, is an ultra-short-acting calcium channel blocker that inhibits L-type calcium channels with high clearance and low distribution, can be rapidly metabolized into the corresponding inactive acid, and is rapidly hydrolyzed into inactive metabolites by esterase in arterial blood. Clevidipine is the same as nicardipine in that the main physiological effect is vasodilation and the main target is the arterial system, which has a limited effect on capacitor vessels. Unlike nitroglycerin, clevidipine has a limited effect on preload. In contrast to other direct-acting vasodilators, clevidipine has an ultra-short half-life due to metabolism by nonspecific blood and tissue esterases. Clevidipine trials conducted in adult populations have proven that it can rapidly control blood pressure in cardiac surgery situations and that adverse reactions to clevidipine are similar to those with other antihypertensive agents. In recent years, clinical trials have shown that clevidipine has excellent blood pressure-lowering capability in patients with acute neurological injury (hemorrhage, stroke, and subarachnoid and acute intracerebral hemorrhage), those  undergoing coronary artery bypass graft or spinal surgery, and in those with cerebral aneurysm/pheochromocytoma, acute heart failure, acute aortic syndromes, or renal insufficiency with severe hypertension, and it is equivalent to commonly used blood pressure-lowering medicines such as nicardipine or nitroglycerin. However, there is a lack of large-scale clinical trial data on the efficacy and safety of clevidipine in children during the perioperative period.

Insights on the interaction mechanism of exemestane to three digestive enzymes by multi-spectroscopy and molecular docking

Exemestane is an irreversible steroidal aromatase inhibitor, typically used to treat breast cancer. As an anti-tumor drug, exemestane has more obvious side effects on the gastrointestinal tract. The purpose of this work is to investigate the combination of exemestane with three important digestive enzymes including pepsin (Pep), trypsin (Try) and α-Chymotrypsin (α-ChT) so as to analyze the mechanism of the gastrointestinal adverse effects causing by exemestane binding. Enzyme activity experiment showed that the enzyme activity of Pep was decreased in the presence of exemestane. Fluorescence spectra revealed that exemestane formed stable complexes with digestive enzymes, and the quenching mechanism of drug-digestive enzymes interaction were all static quenching. The binding constants of Pep, Try and α-ChT at 298 K were 2.34 × 10⁵, 1.45 × 10⁵, and 2.05 × 10⁵ M^-1, respectively. Synchronous fluorescence and 3D fluorescence spectroscopy showed that the conformation of exemestane was slightly changed after combining with digestive enzymes, and non-radiative energy transfer occurred. Circular dichroism results indicated that exemestane could change the secondary structure of digestive enzymes via increase the α-helix content and decrease in the β-sheet content. Thermodynamic parameters (ΔH⁰, ΔS⁰, and ΔG⁰) revealed that exemestane interacted with α-ChT through electrostatic force, and the binding force with Pep and Try was van der Waals interactions and hydrogen, which was basically consistent with the molecular docking results.

Insights into the Binding of Dietary Phenolic Compounds to Human Serum Albumin and Food-Drug Interactions

The distribution of drugs and dietary phenolic compounds in the systemic circulation de-pends on, among other factors, unspecific/specific reversible binding to plasma proteins such as human serum albumin (HSA). Phenolic substances, present in plant-derived feeds, foods, beverages, herbal medicines, and dietary supplements, are of great interest due to their biological activity. Recently, considerable research has been directed at the formation of phenol-HSA complexes, focusing above all on structure-affinity relationships. The nucleophilicity and planarity of molecules can be altered by the number and position of hydroxyl groups on the aromatic ring and by hydrogenation. Binding affinities towards HSA may also differ between phenolic compounds in their native form and conjugates derived from phase II reactions. On the other hand, food-drug interactions may increase the concentration of free drugs in the blood, affecting their transport and/or disposition and in some cases provoking adverse or toxic effects. This is caused mainly by a decrease in drug binding affinities for HSA in the presence of flavonoids. Accordingly, to avoid the side effects arising from changes in plasma protein binding, the intake of flavonoid-rich food and beverages should be taken into consideration when treating certain pathologies.

Unraveling the Molecular Mechanism of Traditional Chinese Medicine: Formulas Against Acute Airway Viral Infections as Examples

Herbal medicine, including traditional Chinese medicine (TCM), is widely used worldwide. Herbs and TCM formulas contain numerous active molecules. Basically, they are a kind of cocktail therapy. Herb-drug, herb-food, herb-herb, herb-microbiome, and herb-disease interactions are complex. There is potential for both benefit and harm, so only after understanding more of their mechanisms and clinical effects can herbal medicine and TCM be helpful to users. Many pharmacologic studies have been performed to unravel the molecular mechanisms; however, basic and clinical studies of good validity are still not enough to translate experimental results into clinical understanding and to provide tough evidence for better use of herbal medicines. There are still issues regarding the conflicting pharmacologic effects, pharmacokinetics, drug interactions, adverse and clinical effects of herbal medicine and TCM. Understanding study validation, pharmacologic effects, drug interactions, indications and clinical effects, adverse effects and limitations, can all help clinicians in providing adequate suggestions to patients. At present, it would be better to use herbs and TCM formulas according to their traditional indications matching the disease pathophysiology and their molecular mechanisms. To unravel the molecular mechanisms and understand the benefits and harms of herbal medicine and TCM, there is still much work to be done.

Evaluating the effect of aminoglycosides on the interaction between bovine serum albumins by atomic force microscopy

Characterization and determination of protein-protein interactions (PPIs) plays an important role in molecular biological science. In this study, the effect of aminoglycosides (AGs: streptomycin, gentamycin, lincomycin and clindamycin) on interactions between bovine serum albumin (BSA) was evaluated employing imaging and probing adhesion event by AFM. Multi-spectroscopy and molecular docking were supplementary to investigate the acting forces of the effect. AFM measurements revealed the aggregation of BSA grains and changes of adhesion forces at single molecule level. With adhesion forces between BSA pairs decomposed by Poisson method, specific forces in streptomycin, gentamycin, lincomycin and climdamycin were obviously decreased with the rate of 33.1%, 26.4%, 32.3% and 31.3% while non-specific forces slightly decreased with 5.5%, 3.3%, 4.0% and 7.7%. Combined with results of multi-spectroscopy as well as molecular docking, the whole determination showed AGs affected PPIs by multiple forces, where the hydrogen bonding and hydration effect were the main reasons. The binding of drugs and proteins acted by hydrogen bonding affected the interaction forces between BSA. Consequently, AFM was proposed to be an effective and precise tool in application including evaluating the effects of exogenous compounds on biomacromolecular interactions and rapid screening of drug candidates to avoid potential damages in disease treatment.

Pharmacokinetics and Bioavailability Enhancement of Baicalin: A Review

Baicalin is one of the major bioactive components of Scutellaria radix, a Chinese herb that has been used since ancient times. Baicalin has various pharmacological activities, including antitumor, antimicrobial, and antioxidant, and has wide clinical applications. Baicalin displays a distinct pharmacokinetic profile including gastrointestinal hydrolysis, enterohepatic recycling, carrier-mediated transport, and complicated metabolism. The in vivo disposition of baicalin is affected by combinations of other herbs and baicalin can interact with other co-administered drugs due to competition between metabolic enzymes and protein binding. Furthermore, baicalin exhibits altered pharmacokinetic properties under different pathological conditions. Due to its low bioavailability, emerging novel baicalin preparations including nano/micro-scale baicalin delivery systems show better absorption and higher bioavailability in preclinical studies, and show promise for future clinical applications. Thus, this current review offers a comprehensive report on the pharmacokinetic behavior of baicalin and strategies to improve its bioavailability.

Studies on the Interaction between Three Small Flavonoid Molecules and Bovine Lactoferrin

The interaction between three flavonoids, i.e., Luteolin (LTL), Quercetin (QCT), and Naringenin (NGN) and bovine lactoferrin (BLF) at pH 7.4 was investigated by fluorescence quenching spectra, synchronous fluorescence spectra, and UV-visible absorption spectra. The results indicate the fluorescence of BLF quenched by Luteolin (LTL), Quercetin (QCT), and Naringenin (NGN) via static quenching. The main force between QCT and LTL with BLF was van der Waals interactions and hydrogen bonds. Electrostatic interactions played a major role in the binding process of interaction between NGN and BLF. Synchronous fluorescence was used to study the conformational changes of BLF. The values of binding constant (Ka) and number of binding sites (n) at different temperatures (300K, 305K, 310K) were also calculated, respectively. The results of corresponding thermodynamic parameters as well as binding distance between BLF and LTL, QCT, or GNG were obtained. These results implied that Luteolin (LTL), Quercetin (QCT), and Naringenin (NGN) could provide important guides for compound quantity (e.g., medicine dosage) and the design of new compounds (or drugs).