Adding polyphenols to improve the absorption of functional proteins has become a hot topic. Chlorogenic acid is a natural plant polyphenol with anti-inflammatory, antioxidant, and anticancer properties. Bovine lactoferrin is known for its immunomodulatory, anticancer, antibacterial, and iron-chelating properties. Therefore, the non-covalent binding of chlorogenic acid (CA) and bovine lactoferrin (BLF) with different concentrations under neutral conditions was studied. CA was grafted onto lactoferrin molecules by laccase catalysis, free radical grafting, and alkali treatment. The formation mechanism of non-covalent and covalent complexes of CA-BLF was analyzed by experimental test and theoretical prediction. Compared with the control BLF, the secondary structure of BLF in the non-covalent complex was rearranged and unfolded to provide more active sites, the tertiary structure of the covalent conjugate was changed, and the amino group of the protein participated in the covalent reaction. After adding CA, the covalent conjugates have better functional activity. These lactoferrin-polyphenol couplings can carry various bioactive compounds to create milk-based delivery systems for encapsulation.

Potentially significant drug candidates often face elimination from consideration due to the lack of an effective method for systemic delivery. The poor solubility of these candidates has posed a major obstacle for their development as oral pills or injectables. Niclosamide, a host-directed antiviral, is a good example. In this study, a nanoformulation technology that allows for the non-covalent formulation of niclosamide with cholic acids was developed. This formulation enables efficient systemic delivery through endocytosis and enterohepatic circulation of bile-acid-coated nanoparticles. The oral bioavailability of niclosamide-delivery nanoparticles (NDNs) was significantly enhanced to 38.3%, representing an eight-fold increase compared with pure niclosamide. Consequently, the plasma concentration of niclosamide for the NDN formulation reached 1179.6 ng/mL, which is 11 times higher than the therapeutic plasma level. This substantial increase in plasma level contributed to the complete resolution of clinical symptoms in animals infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This nanoformulation not only provides an orally deliverable antiviral drug for SARS-CoV-2 with improved pharmaceutical bioavailability, but also offers a solution to the systemic delivery challenges faced by potentially significant drug candidates.

Polyphenols have widely accepted health benefits which are limited by their low uptake, low bioavailability, and rapid degradation in the gut. While milk proteins are excellent carriers for polyphenols, the specific interactions of the polyphenols with the milk proteins, need to be understood to facilitate the utilization of these delivery systems in food and pharmaceutical applications. We have evaluated the relevance of different factors affecting milk protein-polyphenol interactions and the subsequent impact on the bioavailability and health promoting aspects of polyphenols. Hydrophobic forces are the primary binding forces of polyphenols to milk proteins. The significant factors affecting the interactions and binding affinity are the molecular weight and the hydrophobicity of the polyphenols. The interaction of polyphenols with milk proteins improved the antioxidant activity in comparison to milk proteins, while conflicting results exists for comparisons with polyphenols. In-vitro and cell line studies demonstrated enhanced bioavailability of polyphenols in the presence of milk proteins as well as higher anti-cancer and anti-allergy benefits. Overall, this work will pave the way for better understanding of polyphenol interactions with milk proteins and enable the tailoring of complexes through sustainable green processes, enabling higher bioavailability and health promoting effects of the polyphenols in food and pharmaceutical applications.

The objective of this paper was to investigate the interactions between (-)-Epigallocatechin-3-gallate (EGCG) and whey protein isolate (WPI) by covalent and non-covalent combinations and the effects of the interactions on the conformational and functional changes of whey protein. Conformational changes in the secondary structure of whey protein with various concentrations of EGCG were studied using FTIR spectra. EGCG was more likely to form covalent bonds than non-covalent bonds when it interacted with whey proteins. The addition of EGCG altered the conformation of whey protein. The content of β-sheet decreased, while that of β-turn increased, however, the random coil remained unchanged. An reduction in surface hydrophobicity was observed in all the WPI-EGCG complexes, suggesting that modification in secondary structure of WPI were induced by EGCG. Additionally, the emulsifying and foaming attributes of WPI were enhanced after interaction with EGCG. This study confirms that EGCG can enhance the functional properties of WPI. It is also a pointer to the possible application of WPI-EGCG complexes in the dairy industry.

Transition metal dichalcogenides (TMDCs) are widely used in biosensing applications due to their excellent physical and chemical properties. Due to the properties of biomaterial targets, the biggest challenge that biosensors face now is how to improve the sensitivity and stability. A lot of materials had been used to enhance the target signal. Among them, TMDCs show excellent performance in enhancing biosensing signals because of their metallic and semi-conducting electrical capabilities, tunable band gap, large specific surface area and so on. Here, we review different functionalization methods and research progress of TMDCs-based biosensors. The modification methods of TMDCs for biosensor fabrication mainly include two strategies: non-covalent and covalent interaction. The article summarizes the advantages and disadvantages of different modification strategies and their effects on biosensing performance. The authors present the challenges and issues that TMDCs need to be addressed in biosensor applications. Finally, the review expresses the positive application prospects of TMDCs-based biosensors in the future.

Because of the emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different regions of the world, the battle with infectious coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has been seesawing. Therefore, the identification of antiviral drugs is of particular importance. In order to rapidly identify inhibitors for SARS-CoV-2 3-chymotrypsin-like protease (3CLpro), an enzyme essential for viral replication, we combined the fluorescence polarization (FP) technique with biotin-avidin system (BAS) and developed a novel sandwich-like FP screening assay. Through high-throughput screening, two hits of 3CLpro inhibitors, ginkgolic acid (GA) and anacardic acid (AA) were identified, which showed IC50 values of 11.29 ± 0.48 and 12.19 ± 0.50 μM, respectively. Their binding modes were evaluated by HPLC-Q-TOF-MS. There was no mass increase detected for SARS-CoV-2 3CLpro incubated with either GA or AA, indicating the absence of covalent adducts. The kinetic analysis clearly demonstrated that both GA and AA inhibit SARS-CoV-2 3CLpro via reversible and mixed-inhibition manner. Our results argue against conclusion that GA and AA act as irreversible and covalent inhibitors against SARS-CoV-2 3CLpro, which is based on the studies by Chen et al.

A series of novel non-covalent peptidomimetic proteasome inhibitors possessing bulky group at the C-terminus and N-alkylation at the N-terminus were designed with the aim to increase metabolic stabilities in vivo. All the target compounds were screened for their inhibitory activities against human 20S proteasome, and most analogs exhibited notable potency compared with the positive control bortezomib with IC50 values lower than 10 nM, which also displayed potent cytotoxic activities against multiple myeloma (MM) cell lines and human acute myeloid leukemia (AML) cells. Furthermore, whole blood stability and in vivo proteasome inhibitory activity experiments of selected compounds were conducted for further evaluation, and the representative compound 43 (IC50 = 8.39 ± 2.32 nM, RPMI-8226: IC50 = 15.290 ± 2.281 nM, MM-1S: IC50 = 9.067 ± 3.103 nM, MV-4-11: IC50 = 2.464 ± 0.713 nM) revealed a half-life extension of greater than 9-fold (329.21 min VS 36.79 min) and potent proteasome inhibitory activity in vivo. The positive results confirmed the reliability of the metabolism guided optimization strategy, and the analogs discovered are potential leads for exploring new anti-MM drugs.

Based on the interaction modes of the natural 20S proteasome inhibitors TMC-95A, we have previously discovered a dipeptide 1. To explore the SAR around compound 1, we designed and synthesized a series of dipeptides (8-38) with a fragment-based strategy. Among them, nine compounds showed significant inhibitory activities against the chymotrypsin-like activity of human 20S proteasome with IC50 values at the submicromolar level, which were comparable or even superior to the parent compound 1. Meanwhile, they displayed no significant inhibition against trypsin-like and caspase-like activities of 20S proteasome. The results suggested the feasibility to design dipeptides as novel and potent 20S proteasome inhibitors.[Formula: see text].

Ibrutinib is a BTK-targeted irreversible inhibitor. In this study, we demonstrate that ibrutinib potently inhibits SRC activity in a non-covalent manner via mass spectrometry and crystallography. The S345C mutation renders SRC to bind covalently with ibrutinib, and restores the potency of ibrutinib against the gatekeeper mutant. The co-crystal structure of ibrutinib/SRC shows Ser345 of SRC did not form covalent bond with ibrutinib, leading to a decrease of potency and loss of the ability to overcome the gatekeeper mutation of SRC. The X-ray crystallographic studies also provide structural insight into why ibrutinib behaves differently against gatekeeper mutants of different kinases.

Thirty novel triaryl compounds were designed and synthesized based on the known proteasome inhibitor PI-1840. Most of them showed significant inhibition against the β5c subunit of human 20S proteasome, and five of them exhibited IC50 values at the sub-micromolar level, which were comparable to or even more potent than PI-1840. The most active two (1c and 1d) showed IC50 values of 0.12 and 0.18 μM against the β5c subunit, respectively, while they displayed no obvious inhibition against the β2c, β1c and β5i subunits. Molecular docking provided informative clues for the subunit selectivity. The potent and subunit selective proteasome inhibitors identified herein represent new chemical templates for further molecular optimization.