ESI-TOF MS analysis of complexes formed between quercetin and five metal ions in hot water and a study into their DNA cleavage activity

Quercetin inhibits calcium oxalate crystallization and growth but promotes crystal aggregation and invasion

Recent evidence has shown an association between kidney stone pathogenesis and oxidative stress. Many anti-oxidants have been studied with an aim for stone prevention. Quercetin, a natural flavonol, is one among those eminent anti-oxidants with satisfactory anti-inflammatory property to cope with renal tissue injury in kidney stone disease. Nevertheless, its direct effect (if any) on calcium oxalate (CaOx) crystals and the stone formation mechanism had not been previously explored. This study has addressed the ability of quercetin at various concentrations (2.5, 5, 10, 20, 40, 80 and 160 μM) to directly modulate CaOx crystallization, growth, aggregation, adhesion on kidney cells, and invasion through the matrix. The data have shown that quercetin significantly inhibits CaOx crystallization and crystal growth but promotes crystal aggregation in concentration-dependent manner. However, quercetin at all these concentrations do not affect CaOx adhesion on kidney cells. For the invasion, quercetin at all concentrations constantly promotes CaOx invasion through the matrix without concentration-dependent pattern. These discoveries have demonstrated for the first time that quercetin has direct but dual modulatory effects on CaOx crystals. While quercetin inhibits CaOx crystallization and growth, on the other hand, it promotes CaOx crystal aggregation and invasion through the matrix. These data highlight the role for quercetin in direct modulation of the CaOx crystals that may intervene the stone pathogenesis.

Simultaneous Elimination of Reactive Oxygen Species and Activation of Nrf2 by Ultrasmall Nanoparticles to Relieve Acute Kidney Injury

Excess reactive oxygen species (ROS) can induce serious acute kidney injury (AKI) to result in numerous deaths annually in clinical practice. Elimination of excess ROS by advanced nanotechnology is a very promising AKI therapy. In this Article, we report that PVP-stabilized and quercetin-functionalized ultrasmall Cu_2-xSe nanoparticles (abbreviated as CSPQ NPs) can efficiently scavenge ROS and increase the expression of intracellular antioxidative enzymes by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) protein, which drastically alleviates the cellular oxidative stress. Our ultrasmall nanoparticles exhibit excellent biocompatibility. They can be rapidly accumulated into the injured kidney to simultaneously eliminate ROS and activate Nrf2 to improve the renal function. This work demonstrates the great potential of simultaneous elimination of ROS and activation of intracellular Nrf2 in treatment of AKI. It also highlights the potential of CSPQ NPs in protection and prevention of AKI.

Supermolecules as a quality markers of herbal medicinal products

Herbal medicines have greatly contributed to human health worldwide for thousands of years. In particular, traditional Chinese medicine plays an essential role in the prevention and treatment of COVID-19. With the exponentially increasing use and global attention to herbal medicinal products (HMPs), efficacy and safety have become major public concerns in many countries. In general, the quantification and qualification of quality markers (Q-markers) is the most common way to solve this issue. In the last few decades, small molecules, including flavonoids, terpenes, phenylpropanoids, alkaloids, phenols, and glycosides have been extensively investigated as Q-markers for HMP quality control. With the development of biotechnology in the last decade, scientists have begun to explore HMPs macromolecules, including polysaccharides and DNA, for their establishment as Q-markers. In recent years, supermolecules with stronger biological activities have been found in HMPs. In this review, we summarize and discuss the current Q-markers for HMP quality control; in particular, the possibility of using supermolecules as Q-markers based on structure and activity was discussed.

Search for new antimicrobials: spectroscopic, spectrometric, and in vitro antimicrobial activity investigation of Ga(III) and Fe(III) complexes with aroylhydrazones

The in vitro antimicrobial activity of Fe(III) and Ga(III) complexes with N'-(2,3-dihydroxy-phenylmethylidene)-3-pyridinecarbohydrazide (H₂L¹), N'-(2,4-dihydroxy-phenyl-methylidene)-3-pyridinecarbohydrazide (H₂L²), N'-(2,5-dihydroxy-phenylmethylidene)-3-pyridinecarbohydrazide (H₂L³), N'-(2-hydroxy-3-methoxyphenyl-methylidene)-3-pyridine-carbohydrazide (H₂L⁴), N'-(2-hydroxy-4-methoxyphenylmethyl-idene)-3-pyridine-carbohydrazide (H₂L⁵), and N'-(2-hydroxy-5-methoxyphenylmethylidene)-3-pyridinecarbo-hydrazide (H₂L⁶) toward several Gram-positive strains of Staphylococcus aureus, a Gram-negative strain of Escherichia coli, and a yeast Candida albicans were investigated. Fe(III)-complexes do not possess antimicrobial activity against all tested strains at concentrations up to 10 mg mL^-1. Ga(III) complexes with dihydroxy derivatives showed selective activity, while the broadest range of antibacterial and antifungal activities was observed for complex with 2-hydroxy-3-methoxy-derivative, ligand H₂L⁵. In addition, the coordination properties of ligands H₂L¹-H₂L³ in solution were investigated by UV-Vis spectroscopy. The stability constants (logK) for Ga(III)-H₂L 1:1 complexes in MeOH/H₂O 1/1 at pH 2.52 were determined, and amounted to 5.8, 5.68, and 4.7, respectively. Detailed characterization of complexes was performed by high-resolution mass spectrometry. The fragmentation pathways for dimer [Fe₂(L¹)₂]²⁺, [Fe(HL)₂]⁺, [Ga(HL²)₂]⁺ and adduct ions are given. The comparison with analogue Ga(III) and Fe(III) complexes with compounds H₂L⁴-H₂L⁶ was made as well.

Effective dose/duration of natural flavonoid quercetin for treatment of diabetic nephropathy: A systematic review and meta-analysis of rodent data

BACKGROUND

Given the challenges on diabetic nephropathy (DN) treatment, research has been carried out progressively focusing on dietary nutrition and natural products as a novel option with the objective of enhancing curative effect and avoiding adverse reactions. As a representative, Quercetin (Qu) has proved to be of great value in current data.

PURPOSE

We aimed to synthetize the evidence regarding the therapeutic effect and specific mechanism of quercetin on DN via systematically reviewing and performing meta-analysis.

METHODS

Preclinical literature published prior to August 2021, was systematical retrieval and manually filtrated across four major databases including PubMed, Web of Science, EMBASE and Cochrane library. Pooled overall effect sizes of results were generated by STATA 16.0, and underlying mechanisms were summarized. Three-dimensional dose/time-effect analyses and radar maps were conducted to examine the dosage/time-response relations between Qu and DN.

RESULTS

This paper pools all current available evidence in a comprehensive way, and shows the therapeutic benefits as well as potential action mechanisms of Qu in protecting the kidney against damage. A total of 304 potentially relevant citations were identified, of which 18 studies were enrolled into analysis. Methodological quality was calculated, resulting in an average score of 7.06/10. This paper provided the preliminary evidence that consumption of Qu could induce a statistical reduction in mesangial index, Scr, BUN, 24-h urinary protein, serum urea, BG, kidney index, TC, TG, LDL-C, AST, MDA, AGE, TNF-α, TGF-β1, TGF-β1 mRNA, CTGF and IL-1β, whereas HDL-C, SOD, GSH, GSH-Px, CAT and smad-7 were significantly increased. Furthermore, Qu could remarkably improve the renal pathology. In terms of the mechanisms underlying therapy of DN, Qu exerts anti-diabetic nephropathy properties possibly through PI3K/PKB, AMPK-P38 MAPK, SCAP/SREBP2/LDLr, mtROS-TRX/TXNIP/NLRP3/IL-1β, TGF-β1/Smad, Nrf2/HO-1, Hippo, mTORC1/p70S6K and SHH pathways. Dose/time-response images predicted a modest association between Qu dosage consumption/administration length and therapeutic efficacy, with the optimal dosage at 90-150 mg/kg/d and administration length ranging from 8 weeks to 12 weeks.

CONCLUSIONS

Quercetin exhibit highly pleiotropic actions, which simultaneously contributes to prevent fundamental progression of DN, such as hyperglycemia, dyslipidemia, inflammation, fibrotic lesions and oxidative stress. The therapeutic effect becomes stronger when Qu administration at higher dosages lasts for longer durations. Taken together, quercetin could be used in patients with DN as a promising agent, which has well-established safety profiles and nontoxicity according to existing literature.

Preparation of crystalline nanocellulose/hydroxypropyl β cyclodextrin/carboxymethyl cellulose polyelectrolyte complexes and their controlled release of neohesperidin-copper (II) in vitro

A natural hydrogel film was prepared using carboxymethyl cellulose (CMC), cellulose nanocrystals (CNC), and hydroxypropyl β cyclodextrin (HP-β-CD) as reactants and citric acid as the cross-linking agent and used for the controlled release of neohesperidin-copper(II)(NH-Cu (II)). The hydrogel film was characterized by ATR-FTIR, XRD, TGA and DSC. The film showed controlled swelling behavior; the release behavior of NH-Cu(II) from the hydrogel film was also investigated in different solutions including distilled water, various salt solutions including 0.9% NaCl, and solutions having different pH values. Thiazolyl blue tetrazolium bromide assay and relative growth rates were adopted to evaluate the biocompatibility and cytotoxicity of the prepared hydrogel films. The results indicated that the expansion kinetics followed Fickian diffusion and Schott's second-order kinetics model. The hydrogel film exhibited enhanced mechanical properties and improved thermal stability at high temperatures due to the addition of CNC, with the amount of added CNC affecting the swelling ratio, salt sensitivity, and pH sensitivity of the hydrogel film in different solutions. Additionally, the CNC largely improved the loading and encapsulation efficiency of the hydrogel films, with the optimal CNC addition amount being 4% which yielded a loading amount of 753.75 mg/g and an accumulated release rate of 85.08%. The hydrogel film with proven cell compatibility and non-cytotoxicity can potentially be used as a drug delivery and controlled release material.