The inhibition of Mpro, the primary protease of COVID-19, by Poria cocos and its active compounds: a network pharmacology and molecular docking study.

Poria cocos is a traditional Chinese medicine (TCM) that can clear dampness, promote diuresis, and strengthen the spleen and stomach. Poria cocos has been detected in many TCM compounds that are used for COVID-19 intervention. However, the active ingredients and mechanisms associated with the effect of Poria cocos on COVID-19 remain unclear. In this paper, the active ingredients of Poria cocos, along with their potential targets related to COVID-19, were screened using TCMSP, GeneCards, and other databases, by means of network pharmacology. We then investigated the active components, potential targets, and interactions, that are associated with COVID-19 intervention. The primary protease of COVID-19, Mpro, is currently a key target in the design of potential inhibitors. Molecular docking techniques and molecular dynamics simulations demonstrated that the active components of Poria cocos could bind stably to the active site of Mpro with high levels of binding activity. Pachymic acid is based on a triterpene structure and was identified as the main component of Poria cocos; its triterpene active component has low binding energy with Mpro. The pachymic acid of Mpro activity was further characterized and the IC50 was determined to be 18.607 µmol L-1. Our results indicate that pachymic acid exhibits a certain inhibitory effect on the Mpro protease.

Synthesis, characterization, and evaluation of paclitaxel loaded in six-arm star-shaped poly(lactic-co-glycolic acid).

BACKGROUND: Star-shaped polymers provide more terminal groups, and are promising for application in drug-delivery systems. METHODS: A new series of six-arm star-shaped poly(lactic-co-glycolic acid) (6-s-PLGA) was synthesized by ring-opening polymerization. The structure and properties of the 6-s-PLGA were characterized by carbon-13 nuclear magnetic resonance spectroscopy, infrared spectroscopy, gel permeation chromatography, and differential scanning calorimetry. Then, paclitaxel-loaded six-arm star-shaped poly(lactic-co-glycolic acid) nanoparticles (6-s-PLGA-PTX-NPs) were prepared under the conditions optimized by the orthogonal testing. High-performance liquid chromatography was used to analyze the nanoparticles' encapsulation efficiency and drug-loading capacity, dynamic light scattering was used to determine their size and size distribution, and transmission electron microscopy was used to evaluate their morphology. The release performance of the 6-s-PLGA-PTX-NPs in vitro and the cytostatic effect of 6-s-PLGA-PTX-NPs were investigated in comparison with paclitaxel-loaded linear poly(lactic-co-glycolic acid) nanoparticles (L-PLGA-PTX-NPs). RESULTS: The results of carbon-13 nuclear magnetic resonance spectroscopy and infrared spectroscopy suggest that the polymerization was successfully initiated by inositol and confirm the structure of 6-s-PLGA. The molecular weights of a series of 6-s-PLGAs had a ratio corresponding to the molar ratio of raw materials to initiator. Differential scanning calorimetry revealed that the 6-s-PLGA had a low glass transition temperature of 40°C-50°C. The 6-s-PLGA-PTX-NPs were monodispersed with an average diameter of 240.4±6.9 nm in water, which was further confirmed by transmission electron microscopy. The encapsulation efficiency of the 6-s-PLGA-PTX-NPs was higher than that of the L-PLGA-PTX-NPs. In terms of the in vitro release of nanoparticles, paclitaxel (PTX) was released more slowly and more steadily from 6-s-PLGA than from linear poly(lactic-co-glycolic acid). In the cytostatic study, the 6-s-PLGA-PTX-NPs and L-PLGA-PTX-NPs were found to have a similar antiproliferative effect, which indicates durable efficacy due to the slower release of the PTX when loaded in 6-s-PLGA. CONCLUSION: The results suggest that 6-s-PLGA may be promising for application in PTX delivery to enhance sustained antiproliferative therapy.

Amphiphilic glycopolymer nanoparticles as vehicles for nasal delivery of peptides and proteins.

Nasal drug delivery system has been a very promising route for delivery of proteins and peptides for the reason that it can avoid degradation in gastrointestinal tract and metabolism by liver enzymes. However, the bioavailability of proteins and peptides is still low due to the rapid clearance of mucociliary. Here, to prolong the residence time of drugs and improve their absorption, we prepared amphiphilic glycopolymer poly(2-lactobionamidoethyl methacrylate-random-3-acrylamidophenylboronic acid) (p(LAMA-r-AAPBA), and the glycopolymer could assemble into the nanoparticles with narrow size distribution. Insulin, as a model drug, was efficiently encapsulated within the nanoparticles, and loading capacity was up to 12%. In vitro study revealed that the insulin release could be controlled by modifying the composition of glycopolymers. Cell viability showed that p(LAMA-r-AAPBA) nanoparticles had good cytocompatibility. Moreover, the mechanism of nanoparticle internalization into Calu-3 cells was a combination mechanism of clathrin-mediated endocytosis and lipid raft/caveolae-mediated endocytosis. Importantly, there was a significant decrease in the blood glucose levels after the nasal administration of p(LAMA-r-AAPBA) nanoparticles to diabetic rats. Therefore, p(LAMA-r-AAPBA) glycopolymers have a potential application as a nasal delivery systems for proteins and peptides.

Gene delivery of PEI incorporating with functional block copolymer via non-covalent assembly strategy.

A novel functional diblock polymer P(PEGMA-b-MAH) is prepared and incorporated to improve the gene delivery efficiency of poly(ethyleneimine) PEI via non-covalent assembly strategy. First, P(PEGMA-b-MAH) is prepared from l-methacrylamidohistidine methyl ester (MAH) by reversible addition fragmentation chain transfer polymerization, with poly[poly(ethylene glycol) methyl ether methacrylate] (P(PEGMA)) as the macroinitiator. Then P(PEGMA-b-MAH) is assembled with plasmid DNA (pDNA) and PEI (M(w)=10kDa) to form PEI/P(PEGMA-b-MAH)/pDNA ternary complexes. The agarose gel retardation assay shows that the presence of P(PEGMA-b-MAH) does not interfere with DNA condensation by the PEI. Dynamic light scattering tests show that PEI/P(PEGMA-b-MAH)/pDNA ternary complexes have excellent serum stability. In vitro transfection indicates that, compared to the P(PEGMA-b-MAH) free PEI-25k/pDNA binary complexes, PEI-10k/P(PEGMA-b-MAH)/pDNA ternary complexes have lower cytotoxicity and higher gene transfection efficiency, especially under serum conditions. The ternary complexes proposed here can inspire a new strategy for the development of gene and drug delivery vectors.

The effects of a multifunctional oligomer and its incorporation strategies on the gene delivery efficiency of poly(L-lysine).

A novel multifunctional oligomer is synthesized and incorporated to enhance the gene delivery efficiency of PLL via non-electrostatic assembly and covalent grafting strategies. The improvement of the gene delivery efficiency is dependent on the gene carrying complex properties, and the properties are dependent on the oligomer incorporation strategy.

Glycopolymer modification on physicochemical and biological properties of poly(L-lysine) for gene delivery.

Poly(L-lysine) (PLL) has excellent plasmid DNA (pDNA) condensation capacity. However, the relatively high cytotoxicity and low transfection efficiency limit its application as gene delivery vectors. Here, well-defined glycopolymers are synthesized by reversible addition fragmentation transfer polymerization and grafted onto PLL to improve the gene delivery performance. After glycopolymer modification, PLL shows reduced cytotoxicity. By regulating the glycopolymer length and amino group substitution degree, the glycopolymer modified PLL can condense pDNA with proper strength, protect the condensed pDNA from degradation and release them in time. Transfection with NIH3T3 and HepG2 cells shows that the glycopolymer modified PLL has improved transfection efficiencies. The low cytotoxicity, effective pDNA protection and enhanced transfection efficiencies indicate that glycopolymer modification would be an effective strategy to improve the polycation properties for gene delivery.

The target gene carrying validity to HePG2 cells with the brush-like glutathione modified chitosan compound.

The grafting modified chitosan with L-glutathione (GSH) end capped PEG brush-like poly [poly(ethylene glycol) methacrylate] (PMPEG), CS-PMPEG-GSH, as the pDNA condensed vector material could result in a much higher transfection efficiency and lower cytotoxity for NIH3T3 cells. In this work, we have further examined the morphology stabilities of CS-PMPEG-GSH/pDNA vectors at different medium pH values and in the presence of serum protein in detail. And then the targeted characters for HepG2 cells have been probed by tracing the cell uptake behavior and transfection efficiency.

A novel glutathione modified chitosan conjugate for efficient gene delivery.

A novel non-viral gene vector based on poly[poly(ethylene glycol) methacrylate] (PMPEG) and l-glutathione (GSH) grafted chitosan (CS) has been fabricated. First, well-defined brush-like PMPEG living polymers with dithioester residues were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization and grafted onto the allylchitosan via radical coupling method. Then, the tripeptide GSH was introduced onto the end of PMPEG chain to give a CS-PMPEG-GSH conjugate. In comparison with pristine chitosan, CS-PMPEG-GSH conjugate could not only condense plasmid DNA (pDNA) and prevent the condensed CS-PMPEG-GSH/pDNA nanoparticle self-aggregation, but also increase the binding ability to cell membrane efficiently and improve decondensed ability of pDNA from the nanoparticles in cytoplasm which thus has resulted in the higher transfection efficiency in mouse embryonic fibroblast cells (NIH3T3). In addition, cytotoxicity assays showed that the conjugate is less cytotoxic than CS, and still retain the cationic polyelectrolyte characteristic as chitosan. These results indicate that the non-viral vector is a promising candidate for gene therapy in clinical application.

Flow injection on-line solid phase extraction coupled with inductively coupled plasma mass spectrometry for determination of (ultra)trace rare earth elements in environmental materials using maleic acid grafted polytetrafluoroethylene fibers as sorbent.

A new sorbent, maleic acid grafted polytetrafluoroethylene fiber (MA-PTFE), was prepared and evaluated for on-line solid-phase extraction coupled with inductively coupled plasma mass spectrometry (ICP-MS) for fast, selective, and sensitive determination of (ultra)trace rare earth elements (REEs) in environmental samples. The REEs in aqueous samples at pH = 3.0 were selectively extracted onto a microcolumn packed with the MA-PTFE fiber, and the adsorbed REEs were subsequently eluted on-line with 0.9 mol l(-1) HNO3 for ICP-MS determination. The new sorbent extraction system allows effective preconcentration and separation of the REEs from the major matrix constituents of alkali and alkali earth elements, particularly their separation from barium that produces considerable isobaric interferences of 134Ba16O1H+, 135Ba16O+, 136Ba16O1H+, and 137Ba16O+ on 151Eu+ and 153Eu+. With the use of a sample loading flow rate of 7.4 ml min(-1) for 120 s preconcentration, enhancement factors of 69-97 and detection limits (3s) of 1-20 pg l(-1) were achieved at a sample throughput of 22 samples h(-1). The precision (RSD) for 16 replicate determinations of 50 ng l(-1) of REEs was 0.5-1.1%. The developed method was successfully applied to the determination of (ultra)trace REEs in sediment, soil, and seawater samples.

[Expression and significance of the matrix metalloproteinase inhibitor RECK gene in prostate cell strains].

OBJECTIVE: To investigate the expression and significance of RECK gene and MMP-9 in prostate cell strains such as BPH-1, DU45, LNCaP and PC-3. METHODS: The expression of mRNA of RECK and MMP-9 was measured by RT-PCR and RECK protein was evaluated by Western blot. RESULTS: The mRNA level of the RECK gene in the prostate carcinoma cell strains, such as DU45, LNCaP and PC-3, was lower than that in the benign prostate hyperplasia cell line BPH-1, while MMP-9 had a higher expression. The protein level of RECK in DU-45, LNCaP and PC-3 was lower than that in the BPH-1. CONCLUSION: The RECK gene is supposed to be a kind of tumor suppressor gene, which may act by inhibiting the activity of MMP-9.