Metabolism, tissue distribution and excretion of taxifolin in rat

Exploring the metabolic fate of antioxidant and hypoglycemic compounds from Pistacia vera shells through in vitro simulated digestion and untargeted metabolomics

Pistacia vera L. shells (PS) are a sustainable source of health-promoting ingredients. The metabolic fate of a PS extract with antioxidant/antiradical and hypoglycemic properties prepared by microwave-assisted extraction (MAE) was investigated through in vitro gastrointestinal digestion to consider its potential value as nutraceutical ingredient. The results revealed significant changes in the phytochemical profile, bioactivity, and bioaccessibility of the extract during digestion. According to LC-ESI-LTQ-Orbitrap-MS analysis, compounds were mainly preserved in the oral (40.48 μg/mg DW) and gastric (73.67 μg/mg DW) phases, and less in the intestinal phase (13.24 μg/mg DW). α-Amylase inhibitory properties of PS extract remained consistent during digestion, whereas α-glucosidase inhibition and antioxidant/antiradical effects gradually decreased. Multivariate data analysis confirmed the interdependency between phytochemical composition and bioactivity of undigested extract and its digests. This study represents a step forward for developing PS-based functional foods, providing unique insights into the metabolism of PS bioactive constituents under simulated gastrointestinal conditions.

Analysis of untargeted metabolites of natural ingredient spine grape (Vitis davidii Foex) juices and provides new insights into biological activities

BACKGROUND

Consumer demand for natural products is driving innovation in clean label ingredients. Spine grape (Vitis davidii Foex), a wild East Asian species, and its fresh juice show great promise as versatile ingredients because of their rich composition. The present study assessed the physicochemical properties and metabolite profiles of fresh juices from four spine grape cultivars, exploring their application.

RESULTS

The physicochemical properties of spine grape juices highly depended on the cultivar. Total soluble solids ranged from 12.43% to 14.27%, whereas organic acid content varied between 5.35 and 6.85 g L-1. The phenolic content ranged from 520.17 to 611.68 mg L-1, and the anthocyanin content fluctuated from 72.70 to 155.54 mg L-1. Metabolite identification using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry revealed a total of 116 compounds, including flavonoids, phenolic acids, stilbenes, coumarins, amino acids, peptides, lipids and vitamins. Among these, 68 compounds including well-known phenolics and 11 bioactive peptides that are less extensively researched, contributed to the biofunctions of spine grape juices. The white juice 'Baci' exhibited the highest levels of bioactive compounds, including catechin, procyanidines, resveratrol and antioxidant peptides. This resulted in a significantly higher DPPH (i.e. 2,2-diphenyl-1-picrylhydrazyl) value (8481.78 μmol Trolox equivalents L-1) compared to other red spine grape juices.

CONCLUSION

This study provides comprehensive insights into spine grape juices, offering valuable guidance for commercial applications. The 'Tianci' and 'Ziqiu' red grape juices stand out as ideal sensory ingredients because of their favorable physicochemical properties, whereas the 'Baici' white spine grape juice, which contains higher levels of bioactive compounds, emerges as a promising functional ingredient. © 2025 Society of Chemical Industry.

Microbial Fermentation-Derived Dihydroquercetin Derivatives Exhibit Superior Efficacy in Ameliorating Insulin Resistance via JNK/PI3K/AKT Pathway Regulation Compared to Dihydroquercetin

Insulin resistance (IR) is a complex metabolic disorder characterized by diminished insulin sensitivity, leading to impaired glucose uptake and a potential progression to hyperglycemia and diabetes. While lifestyle modifications are essential, the limitations of current pharmacological interventions highlight the need for natural products with therapeutic benefits. This study introduces two novel dihydroquercetin (DHQ) derivatives, 8-hydroxy-dihydroquercetin (H-DHQ) and dihydroquercetin-7-O-β-d-(4″-O-methyl)-glucoside (DHQ-MG), developed through microbial fermentation using Beauveria bassiana. Results indicated that H-DHQ and DHQ-MG significantly enhanced the alleviation of IR in a HepG2 cell model compared with DHQ, with no significant differences noticed between DHQ-MG and H-DHQ. Mechanistic analyses revealed that these derivatives effectively reduced inflammation, oxidative stress, and endoplasmic reticulum (ER) stress, thereby activating the JNK/PI3K/AKT signaling pathway to promote glycogen synthesis, suppress gluconeogenesis, and stimulate glucose transport. This research highlights the potential of H-DHQ and DHQ-MG as effective natural alternatives for managing IR, while also providing indirect evidence for the application of microbial fermentation as a strategy to modify natural flavonoids for this purpose.

Integration of tissue distribution, PK-PD modeling and metabolomics reveals inflammatory-immune response alterations in Gaultheria leucocarpa var. yunnanensis alleviating rheumatoid arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Gaultheria leucocarpa var. yunnanensis, a distinguished member of the Gaultheria Kalm ex L. in the Ericaceae family, has been traditionally employed in the southwestern regions of China for the efficacious treatment of rheumatoid arthritis (RA). The anti-RA fraction (ARF) derived from Gaultheria leucocarpa var. yunnanensis has been previously demonstrated to effectively alleviate RA in vivo and in vitro.

AIM OF THE STUDY

This research endeavor is dedicated to surveying the pharmacokinetic (PK) processes of ARF within plasma and tissues, profiling its metabolites in vivo, discerning the material foundation of its therapeutic efficacy, and delineating its anti-RA mechanisms.

MATERIALS AND METHODS

The prototype components and metabolites of ARF in plasma and seven tissues of RA rats were analyzed by LC-MSn. Advanced LC-MS/MS and HPLC-DAD methodologies were developed to investigate the plasma PK profiles and tissue distribution characteristics of MSTG-A, MSTG-B, and Gaultherin in both RA model rats and healthy controls. A panel of four cytokines (TNF-α, IL-1, IL-6, and IL-2) was selected as pharmacodynamic (PD) biomarkers and quantified using ELISA. The PK, PD, and PK-PD modeling of ARF were skillfully constructed by combining WinNonlin with Matlab software, enabling a comprehensive analysis of the interrelationships between components and effect markers. A non-targeted plasma metabolomics approach employing LC-QE-MS was utilized to insight into the underlying mechanisms of ARF alleviating RA.

RESULTS

The quantity and diversity of identified prototypical components and metabolites of ARF in model rat plasma increased over time. The spleen exhibited the highest number of metabolites and prototypical compounds of ARF. The UPLC-QQQ-MS/MS and HPLC-DAD method were developed and validated for the quantification of three chemical markers in rat plasma and tissues, respectively. Three effective components (MSTG-B, MSTG-A, and Gautherin) demonstrated linear dynamics in plasma and tissues at an oral dosage of 3 g/kg ARF. The PK-PD models involving three components and four inflammatory cytokines aligned with the one company model, demonstrating a linear correlation through compartmental modeling and curve fitting analysis. Significant variations were identified in the concentrations of various amino acids and lipid metabolites among the CON, ARF, and MTX groups in comparison to the MOD group, which are intricately linked to the inflammation-immunity response.

CONCLUSIONS

The three components displayed favorable bioavailability and were rapidly eliminated in RA rats, collectively exerting an anti-RA effect. The mechanism by which ARF mitigates RA is associated with the modulation of inflammation-immunity related metabolic pathways. The spleen may serve as the target tissue for ARF attenuating RA. These findings provide a robust foundation for rationalizing intervention strategies, elucidating biological mechanisms, and advancing the clinical application of ARF in the amelioration of RA.

Retrograded starch as colonic delivery carrier of taxifolin for treatment of DSS-induced ulcerative colitis in mice

Taxifolin, a natural dihydroflavonol compound, possesses notable anti-inflammatory properties and regulatory effects on intestinal microbiota. In this study, gelatinized-retrograded corn starch (GCS) was utilized as a carrier for colonic delivery of taxifolin, and its therapeutic efficacy against dextran sulfate sodium (DSS)-induced colitis in mice were systematically investigated. Taxifolin can integrate into the helical structure of starch, and the formation of GCS-Taxifolin complexes (GCS-Tax) significantly delayed the release of taxifolin in vitro. After oral administration of GCS-Tax, fecal excretion of taxifolin increased from 0.42 % to 10.89 % within 24 h compared to free taxifolin. Moreover, GCS-Tax facilitated the production of short-chain fatty acid in mice and effectively alleviated DSS-induced colitis symptoms, including weight loss, bloody stools, and colonic tissue damage. Additionally, GCS-Tax significantly suppressed proinflammatory factors such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and lipopolysaccharide (LPS), while elevating anti-inflammatory interleukin-10 (IL-10) level in mice serum. Furthermore, it restored intestinal mucosal barrier function by upregulating the expression of Mucin 2, Occludin, and zonula occludens-1 (ZO-1), reducing Beclin 1 expression, and exhibited hepatoprotective effects by enhancing total antioxidant capacity (T-AOC), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities. High-throughput sequencing analysis revealed that GCS-Tax improved intestinal flora diversity, reducing inflammation-related Bacterium 1 and Staphylococcus, while promoting the abundance of beneficial bacteria like Lachnospiraceae.

Excretion characteristics of main compounds of Yigong San in urine, feces, and bile of rats

Yigong San (YGS) is a traditional Chinese medicine formula used for pediatric anorexia, chronic atrophic gastritis, and irritable bowel syndrome. In this study, the excretion of eight main compounds, including liquiritin; isoliquiritin; hesperidin; ginsenosides Rb1, Re, and Rg1; and atractylenolides I and II, in rat urine, feces, and bile, was investigated by ultra-high performance liquid chromatography-tandem mass spectrometry. The results showed that the cumulative excretion rates of the compounds in rat urine, feces, and bile were 0.018-1.15%, 0.024-19.89%, and 0.0025-0.72%, respectively. Among the eight compounds detected, liquiritin was the richest in urine, and ginsenosides Re and Rg1 and atractylenolide I were mainly found in feces and bile. In summary, the main components of YGS are excreted via multiple approaches. Liquiritin is mainly through urine, whereas isoliquiritin; hesperidin; ginsenosides Rb1, Re, and Rg1; and atractylenolides I and II are mainly through feces. The excretion of these compounds in bile is usually positively correlated with that in feces. This study lays a foundation for further pharmacological research and application of YGS.

In Vivo Tissue Distribution and Pharmacokinetics of FITC-Labelled Hizikia fusiforme Polyphenol-Polysaccharide Complex in Mice

In this study, a quantitative method based on fluorescein isothiocyanate (FITC)-labelled Hizikia fusiforme polyphenol-polysaccharide complex (HPC) and its purified fractions (PC1, PC4) was used, and its pharmacokinetics and tissue distribution were investigated in mice. The results showed that the FITC-labelled method had good linearity (R2 > 0.99), intra-day and inter-day precision (RSD, %) consistently lower than 15%, recovery (93.19-106.54%), and stability (RSD < 15%), which met the basic criteria for pharmacokinetic studies. The pharmacokinetic and tissue distribution results in mice after administration showed that all three sample groups could enter the blood circulation. and HPC-FITC had a longer half-life (T1/2: 26.92 ± 0.76 h) and mean retention time (MRT0-∞: 36.48 h) due to its larger molecular weight. The three groups of samples could be absorbed by the organism in a short time (0.5 h) mainly in the stomach and intestine; the samples could be detected in the urine after 2 h of administration indicating strong renal uptake, and faecal excretion reached its maximum at 12 h. The samples were also detected in the urine after 2 h of administration. This study provides some theoretical basis for the tissue distribution pattern of polyphenol-polysaccharide complex.

Qualitative and Quantitative Analysis of Phytochemicals in Sayeok-Tang via UPLC-Q-Orbitrap-MS and UPLC-TQ-MS/MS

Sayeok-tang (SYT) is a traditional herbal formula comprising three medicinal herbs: Glycyrrhiza uralensis, Zingiber officinale, and Aconitum carmichaeli. Several studies have employed liquid chromatography-mass spectrometry (LC-MS) to qualitatively analyze the components and metabolites of SYT in vitro and in vivo; however, studies on quantitative analysis of SYT, which is important for quality control, are absent or limited to only a few components. In this study, ultrahigh-performance liquid chromatography coupled with quadrupole (UPLC-Q)-Orbitrap-MS was used to screen the phytochemicals of SYT, revealing a total of 42 compounds. Among them, 24 compounds were simultaneously quantified within 20 min via UPLC-TQ-MS/MS in the multiple reaction monitoring mode. The developed analytical method was validated for its linearity (r2 ≥ 0.9992), precision (0.36-2.96%), accuracy (-6.52-4.64%), and recovery (94.39-119.07%) for all analytes, exhibiting acceptable results. The validated method was applied in the analysis of SYT extracts, and the 24 compounds were quantified in the range of 0.004-6.882 mg/g (CV ≤ 3.746%). Among them, liquiritin apioside (6.870-6.933 mg/g), glycyrrhizic acid (5.418-5.540 mg/g), and liquiritin (1.303-1.331 mg/g) from G. uralensis were identified as the relatively abundant compounds. The presented validated analytical method is highly promising for the comprehensive quality control of SYT, offering fast, highly sensitive, and reliable analysis.

A comparative study on the preparation and evaluation of solubilizing systems for silymarin

Silymarin (SM) exhibits clinical efficacy in treating liver injuries, cirrhosis, and chronic hepatitis. However, its limited water solubility and low bioavailability hinder its therapeutic potential. The primary objective of this study was to compare the in vitro and in vivo characteristics of the four distinct SM solubilization systems, namely SM solid dispersion (SM-SD), SM phospholipid complex (SM-PC), SM sulfobutyl ether-β-cyclodextrin inclusion complex (SM-SBE-β-CDIC) and SM self-microemulsifying drug delivery system (SM-SMEDDS) to provide further insights into their potential for enhancing the solubility and bioavailability of SM. The formation of SM-SD, SM-PC, and SM-SBE-β-CDIC was thoroughly characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffractometry (PXRD) techniques to analyze the changes in their microscopic structure, molecular structure, and crystalline state. The particle size and polydispersity index (PDI) of SM-SMEDDS were 71.6 ± 1.57 nm, and 0.13 ± 0.03, respectively. The self-emulsifying time of SM-SMEDDS was 3.0 ± 0.3 min. SM-SMEDDS exhibited an improved in vitro dissolution rate and demonstrated the highest relative bioavailability compared to pure SM, SM-SD, SM-PC, SM-SBE-β-CDIC, and Legalon®. Consequently, SMEDDS shows promise as a drug delivery system for orally administered SM, offering enhanced solubility and bioavailability.

Pharmacological investigation of taxifolin for its therapeutic potential in depression

The current study aimed to investigate the influence of taxifolin on depression symptoms alleviation in Male Sprague-Dawley rats by targeting underlying pathways of depression. Molecular docking analyses were conducted to validate taxifolin's binding affinities against various targets. In silico analysis of taxifolin revealed various aspects of post docking interactions with different protein targets. Depression was induced in rats via intraperitoneal injection of Lipopolysaccharide (LPS; 500 μ g/Kg) for 14 alternative days. Rats (n = 6/group) were randomly assigned to four groups: (i) Saline/Control, (ii) Disease (LPS 500 μg/kg), (iii) Standard (fluoxetine 20 mg/kg), and (iv) Treatment (taxifolin 20 mg/kg). At the end of the in vivo study, brain samples were used for biochemical and morphological analysis. Taxifolin exhibited neuroprotective effects, as evidenced by behavioral studies, antioxidant analysis, histopathological examination, immunohistochemistry, ELISA and RT PCR, indicating an increase number of surviving neurons, normalization of cell size and shape, and reduction in vacuolization. Taxifolin also decreased inflammatory markers such as TNF-α, NF-κb, IL-6 and COX-2, while significantly upregulating and activating the protective PPAR-γ pathway, through which it reduces the oxidative stress, neuroinflammation, neurodegeneration, thereby ameliorating depression symptoms in experimental rat model of depression. Our finding suggests that taxifolin act as neuroprotective agent partially mediated through PPAR-γ pathway.

A Natural Small Molecule Mitigates Kidney Fibrosis by Targeting Cdc42-mediated GSK-3β/β-catenin Signaling

Kidney fibrosis is a common fate of chronic kidney diseases (CKDs), eventually leading to renal dysfunction. Yet, no effective treatment for this pathological process has been achieved. During the bioassay-guided chemical investigation of the medicinal plant Wikstroemia chamaedaphne, a daphne diterpenoid, daphnepedunin A (DA), is characterized as a promising anti-renal fibrotic lead. DA shows significant anti-kidney fibrosis effects in cultured renal fibroblasts and unilateral ureteral obstructed mice, being more potent than the clinical trial drug pirfenidone. Leveraging the thermal proteome profiling strategy, cell division cycle 42 (Cdc42) is identified as the direct target of DA. Mechanistically, DA targets to reduce Cdc42 activity and down-regulates its downstream phospho-protein kinase Cζ(p-PKCζ)/phospho-glycogen synthase kinase-3β (p-GSK-3β), thereby promoting β-catenin Ser33/37/Thr41 phosphorylation and ubiquitin-dependent proteolysis to block classical pro-fibrotic β-catenin signaling. These findings suggest that Cdc42 is a promising therapeutic target for kidney fibrosis, and highlight DA as a potent Cdc42 inhibitor for combating CKDs.

Fabrication of Luteolin Loaded Zein-Caseinate Nanoparticles and its Bioavailability Enhancement in Rats

Luteolin loaded zein nanoparticles (Lut-ZNP) were prepared by using sodium caseinate as an electrostatic stabilizer. The formulation of the nanoparticles was optimized. Lut-ZNP were spray-dried, and the physicochemical properties were characterized by SEM, XRD, FT-IR and DSC. Then, the bioavailability of luteolin in rats was determined. Under the formulation of luteolin, zein and sodium caseinate with mass ratio of 1:5:15, the particle size, ζ-potential, encapsulation efficiency and loading efficiency of Lut-ZNP were 171.8 nm, -49.05 mV, 85.85% and 3.15%, respectively. Luteolin existed in the nanoparticles with amorphous form. Lut-ZNP exhibited good redispersibility in water after drying. Compared with free luteolin, the solubility, stability and release of luteolin in Lut-ZNP were greatly improved. Besides, the fecal excretion of luteolin in rats was significantly reduced after oral administration of Lut-ZNP. In addition to native luteolin, its metabolites including sulfate, glucuronidate and methylated glucuronidate were found in rat plasma. Lut-ZNP significantly increased the plasma concentrations of luteolin and its metabolites, and the bioavailability of luteolin was enhanced by 2.92 times.

Novel aspects of taxifolin pharmacokinetics: Dose proportionality, cumulative effect, metabolism, microemulsion dosage forms

Taxifolin (TFL) is a small drug molecule with a broad therapeutic potential limited by its poor aqueous solubility and excessive metabolism. Despite comprehensive research, some aspects of the TFL pharmacokinetics, e.g., dose proportionality and possible cumulative effect, remain unexplored. In the current study, we have tried to fill this gap. Our results revealed that the TFL pharmacokinetics in rats had nonlinear character in the dose range of 10-50 mg/kg after its single oral administration (AUC). For Cmax, the data are ambiguous: linearity was confirmed via the equivalence criterion and was disproved using the power model approach. Also, the cumulative drug effect was observed on the 4th day after its multiple-dose oral administration (25 mg/kg; compared to the 1st day). Interestingly, biologically active TFL metabolites such as aromadendrin and luteolin were putatively found in plasma samples, although they were previously detected only in feces. In addition, oil-in-water and water-in-oil microemulsions were fabricated to design novel drug delivery systems. These carrier dosage forms did not improve the TFL bioavailability but significantly affected its metabolism. To support pharmacokinetic studies, the bioanalytical liquid chromatography-tandem mass spectrometry method was developed and validated in the concentration range of 1-1000 ng/mL using candesartan as an internal standard. Liquid-liquid extraction with methyl tert-butyl ether was used to isolate the analytes from plasma followed by evaporation and reconstitution of the residues in acetonitrile. Thus, the present findings broaden our understanding of the TFL behavior in vivo and provide novel ideas and reference directions for its continued use in medical practice.

Unraveling the Antioxidant Activity of 2R,3R-dihydroquercetin

It has been reported that in an oxidative environment, the flavonoid 2R,3R-dihydroquercetin (2R,3R-DHQ) oxidizes into a product that rearranges to form quercetin. As quercetin is a very potent antioxidant, much better than 2R,3R-DHQ, this would be an intriguing form of targeting the antioxidant quercetin. The aim of the present study is to further elaborate on this targeting. We can confirm the previous observation that 2R,3R-DHQ is oxidized by horseradish peroxidase (HRP), with H2O2 as the oxidant. However, HPLC analysis revealed that no quercetin was formed, but instead an unstable oxidation product. The inclusion of glutathione (GSH) during the oxidation process resulted in the formation of a 2R,3R-DHQ-GSH adduct, as was identified using HPLC with IT-TOF/MS detection. GSH adducts appeared on the B-ring of the 2R,3R-DHQ quinone, indicating that during oxidation, the B-ring is oxidized from a catechol to form a quinone group. Ascorbate could reduce the quinone back to 2R,3R-DHQ. No 2S,3R-DHQ was detected after the reduction by ascorbate, indicating that a possible epimerization of 2R,3R-DHQ quinone to 2S,3R-DHQ quinone does not occur. The fact that no epimerization of the oxidized product of 2R,3R-DHQ is observed, and that GSH adducts the oxidized product of 2R,3R-DHQ on the B-ring, led us to conclude that the redox-modulating activity of 2R,3R-DHQ quinone resides in its B-ring. This could be confirmed by chemical calculation. Apparently, the administration of 2R,3R-DHQ in an oxidative environment does not result in 'biotargeting' quercetin.

Ingestion of taxifolin-rich foods affects brain activity, mental fatigue, and the whole blood transcriptome in healthy young adults: a randomized, double-blind, placebo-controlled, crossover study

The antioxidant properties of polyphenols, which are found in most plants, have been shown to be useful for maintaining health, including enhancing brain function and alleviating stress. We aimed to investigate the effect of a single intake of taxifolin-containing foods on cognitive task performance and whole blood gene expression in healthy young adults. This study was a randomized, placebo-controlled, double-blind, crossover trial in which healthy young adults were administered a single dose of either a placebo or food containing taxifolin. Cognitive tests (serial 3s, serial 7s, and rapid visual information processing) to examine brain activity and visual analog scale questionnaires to analyze mental fatigue were applied. The set of tests was repeated four times. The findings showed that taxifolin intake improved calculation abilities and reduced mental fatigue. An analysis of whole blood gene expression before and after the test revealed that the expression of foreign substance removal-related genes increased following the ingestion of taxifolin and that most differentially expressed genes were enriched in granulocytes. Taxifolin intake was shown to affect the brain activity of healthy young adults and demonstrated an antifatigue effect, thereby reducing subjective fatigue. A single intake of taxifolin may enhance the removal of foreign substances by strengthening the innate immune system and suppressing the occurrence of injury.

Chemical profiling and identification of Radix Cudramiae and their metabolites in rats using an ultra-high-performance liquid chromatography method coupled with time-of-flight tandem mass spectrometry

Radix Cudramiae, known as "Chuan-Po-Shi" in China, is a herbal medicine widely used in the southwest of the country, especially applied by the Miao and Zhuang nationalities for the treatment of liver diseases, such as acute liver injury and liver fibrosis. As a kind of ethnomedicine, the report on its chemical analysis was still blank, which restricted its clinical application. Therefore, this paper aimed to illustrate the chemical characteristics of Radix Cudramiae. A rapid analytical strategy based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was developed to profile the natural small-molecular compounds in Radix Cudramiae, as well as the related prototypes and their metabolites in rats after drug administration. As a result, a total of 74 compounds were detected in the aqueous exact of Radix Cudramiae. In vivo, 45 chemicals including 16 prototypes and 29 metabolites in rat serum, along with 35 chemicals including 17 prototypes and 18 metabolites in rat liver, were screened out and identified. For the first time, the chemical constituents of Radix Cudramiae and their metabolic characteristics were discovered. It was hoped that this work would be beneficial for the safe and effective application of Radix Cudramiae in a clinic.

[Dihydroquercetin as a systemic neuroprotector for the prevention and treatment of β-amyloid-associated brain diseases]

Dihydroquercetin (DHQ) is a plant-derived polyphenol belonging to the group of flavonoids. In models associated with abnormal accumulation of β-amyloid in the brain (Alzheimer's disease and cerebral amyloid angiopathy), DHQ demonstrates the ability to disaggregate toxic forms of β-amyloid and prevent their formation. It is believed that this phenomenon underlies the protective effect of DHQ on brain neurons. However, pharmacokinetic data doubt the central mechanism of action of DHQ because this compound does not penetrate well into the brain. A hypothesis is put forward about the systemic nature of the neuroprotective action of DHQ, since this compound has multiple biological activities at the level of the whole organism. To characterize DHQ (and similar compounds), it is proposed to introduce the term «systemic neuroprotector».

Effects of Taxifolin in Spontaneously Hypertensive Rats with a Focus on Erythrocyte Quality

Oxidative stress and multiple erythrocyte abnormalities have been observed in hypertension. We focused on the effects of angiotensin-converting enzyme 2 (ACE2) inhibition by MLN-4760 inhibitor on angiotensin peptides, oxidative stress parameters, and selected erythrocyte quality markers in spontaneously hypertensive rats (SHR). We also investigated the potential effects of polyphenolic antioxidant taxifolin when applied in vivo and in vitro following its incubation with erythrocytes. SHRs were divided into four groups: control, taxifolin-treated, MLN-4760-treated, and MLN-4760 with taxifolin. MLN-4760 administration increased the blood pressure rise independent of taxifolin treatment, whereas taxifolin decreased it in control SHRs. Body weight gain was also higher in ACE2-inhibited animals and normalized after taxifolin treatment. However, taxifolin did not induce any change in angiotensin peptide concentrations nor a clear antioxidant effect. We documented an increase in Na,K-ATPase enzyme activity in erythrocyte membranes of ACE2-inhibited SHRs after taxifolin treatment. In conclusion, ACE2 inhibition deteriorated some selected RBC properties in SHRs. Although taxifolin treatment did not improve oxidative stress markers, our data confirmed the blood pressure-lowering potential, anti-obesogenic effect, and some "erythroprotective" effects of this compound in both control and ACE2-inhibited SHRs. In vitro investigations documenting different effects of taxifolin on erythrocyte properties from control and ACE2-inhibited SHRs accentuated the irreplaceability of in vivo studies.