Fifty-two week chronic toxicity of enzymatically decomposed rutin in Wistar rats

Isoquercitrin attenuates the osteoclast-mediated bone loss in rheumatoid arthritis via the Nrf2/ROS/NF-κB pathway

An excess of osteoclastogenesis significantly contributes to the development of rheumatoid arthritis (RA). Activation of the nuclear factor erythroid-2 related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB) ligand (RANKL)-induced reactive oxygen species (ROS)-to-NF-κB signaling cascade are important mechanisms regulating osteoclastogenesis; however, whether Nrf2 is involved in RANKL-induced NF-κB activation is controversial. Isoquercitrin, a natural flavonoid compound, has been shown to have Nrf2-dependent antioxidant effects inprevious studies. We sought to verify whether isoquercitrin could modulate RANKL-induced NF-κB activation by activating Nrf2, thereby affecting osteoclastogenesis. Tartrate-resistant acid phosphatase staining, F-actin ring staining and resorption pit assay suggested that isoquercitrin significantly inhibited osteoclastogenesis and osteolytic function. Mitosox staining showed that RANKL-induced ROS generation was significantly inhibited by isoquercitrin from day 3 of the osteoclast differentiation cycle. Quantitative real-time PCR, Western blot, and immunofluorescence indicated that isoquercitrin activated the Nrf2 signaling pathway and inhibited NF-κB expression. And when we used the Nrf2-specific inhibitor ML385, the inhibition of NF-κB by isoquercitrin disappeared. Moreover, we found that Nrf2 is not uninvolved in RANKL-induced NF-κB activation and may be related to the timing of ROS regulation. When we limited isoquercitrin administration to 2 days, Nrf2 remained activated and the inhibition of NF-κB disappeared. In vivo experiments suggested that isoquercitrin attenuated RA modeling-induced bone loss. Overall, isoquercitrin-activated Nrf2 blocked the RANKL-induced ROS-to-NF-κB signaling cascade response, thereby inhibiting osteoclastogenesis and bone loss. These findings provide new ideas for the treatment of RA.

Rutin ameliorate PFOA induced renal damage by reducing oxidative stress and improving lipid metabolism

Perfluorooctanoic acid (PFOA) is a persistent environmental pollutant that can accumulate in the kidneys and eventually cause kidney damage. Rutin (RUTIN) is a natural flavonoid with multiple biological activities, and its use in against kidney damage has been widely studied in recent years. It is not yet known whether rutin protects against kidney damage caused by PFOA. In this study, 30 ICR mice were randomly divided into three groups: CTRL group, PFOA group and PFOA+RUTIN group. The mice were fed continuously by gavage for 28 days. Renal pathological changes were assessed by HE and PASM staining, and serum renal function and lipid indicators were measured. RNA-seq and enrichment analysis using GO, KEGG and PPI to detect differential expression of genes in treatment groups. Kidney tissue protein expression was determined by Western blot. Research has shown that rutin can improve glomerular and tubular structural damage, and increase serum CREA, HDL-C levels and decrease LDH, LDL-C levels. The expression of AQP1 and ACOT1 was up-regulated after rutin treatment. Transcriptomic analysis indicated that PFOA and rutin affect the transcriptional expression of genes related to lipid metabolism and oxidative stress, and may affected by PI3K-Akt, PPAR, NRF2/KEAP1 signaling pathways. In conclusion, rutin ameliorated renal damage caused by PFOA exposure, and this protective effect may be exerted by ameliorating oxidative stress and regulating lipid metabolism.

Dietary Isoquercetin Ameliorates Bone Loss via Restoration of the Gut Microbiota and Lipopolysaccharide-Triggered Inflammatory Status in Ovariectomy Mice

Osteoporosis is one of the skeletal degenerative diseases accompanied by bone loss and microstructure disruption. Given that the gut-bone signaling axis highly contributes to bone health, here, dietary isoquercetin (IQ) was shown to effectively improve postmenopausal osteoporosis (PMO) in an ovariectomy (OVX) mouse model through the modulation of the gut-bone cross-talk. An in vivo study showed that OVX induced striking disruption of the microbial community, subsequently causing gut leakage and gut barrier dysfunction. As a result, lipopolysaccharide (LPS)-triggered inflammatory cytokines released from the intestine to bone marrow were determined to be associated with bone loss in OVX mice. Long-term dietary IQ effectively improved microbial community and gut barrier function in the OVX mice and thus markedly improved bone loss and host inflammatory status by repressing the NF-κB signaling pathway. An in vitro study further revealed that IQ treatments dose-dependently inhibited LPS-induced inflammation and partly promoted the proliferation and differentiation of osteoblasts. These results provide new evidence that dietary IQ has the potential for osteoporosis treatment.

Acute, subchronic toxicity and genotoxicity studies of JointAlive, a traditional Chinese medicine formulation for knee osteoarthritis

AIM

In vivo and in vitro toxicity tests of JointAlive® were studied in animal models to support the safe use of JointAlive® as a drug for knee osteoarthritis treatment.

METHODS

The acute toxicity study in Sprague Dawley (SD) rats was conducted at a 20 g/kg bw/day dose of JointAlive®. For 13-week subchronic toxicity tests, SD rats were orally dosed daily with 0.5, 1.5 and 5 g/kg bw/day of JointAlive®. To assess the potential genotoxicity, Ames test, cellular chromosome aberration and mouse micronucleus test in vivo were carried out.

RESULTS

Based on a lack of notable findings other than histopathology finding of co-incidental prostate inflammation at the high dose, the "No Observed Adverse Effect Level (NOAEL)" of JointAlive® was concluded as 5 g/kg bw/day in males and females. Results also indicated that JointAlive® has no risk of genotoxicity.

CONCLUSIONS

General toxicity and genotoxicity studies empirically demonstrated that JointAlive® poses a low risk of potential health risks, providing safety supports for the application of JointAlive® as a potential drug candidate to treat knee osteoarthritis.

Toxicological profile of the Hymenaea courbaril stem bark hydroalcoholic extract using in vitro bioassays and an alternative in vivo Caenorhabditis elegans model

Hymenaea genus has been used in folk medicine in Brazil, but few studies investigated its toxicity profile. Thus, the aim of this study was to determine toxicological parameters of Hymenaea courbaril stem bark hydroalcoholic extract by utilizing three cell lines including murine macrophages (RAW 264.7), mouse fibroblast cells (L929) and human lung fibroblast (MRC-5), as well as Salmonella/microsome assay, and in vivo Caenorhabditis elegans model. The predominant detected phytoconstituents in the extract were coumarins, flavonoids, phenolics, tannins and saponins and by HPLC analysis, astilbin (AST) was found to be the main component. The DPPH assay demonstrated that H. courbaril hydroalcoholic extract exhibited potent antioxidant activity, with an IC50 of 3.12 μg/ml. The extract at concentrations of 400 and 800 μg/ml decreased cell viability 48 hr after treatment in L929 and MRC-5 cell lines. In the Raw 264.7 strain, just the highest concentration (800 μg/ml) lowered cell viability within 48 hr following exposure. The concentration of 100 μg/ml did not markedly affect cell viability in the trypan blue assay. In the alkaline comet assay the extract was found to be non-genotoxic. In the Ames test, the extract exhibited low mutagenic potential without metabolic activation, since only the highest concentrations produced an effect. H. courbaril extract only affected the survival of C. elegans at concentrations of 800 and 1600 μl/ml. These findings demonstrate that H. courbaril extract appears to exert low toxicity as evidenced in vitro and mutagenicity assays; however, the biological relevance of the response of C. elegans survival to safety assessments needs further studies.

Effectiveness of a new rutin Cu(II) complex in the prevention of lipid peroxidation and hepatotoxicity in hypercholesterolemic rats

A new rutin copper(II) complex (R-Cu2) was prepared and characterized by spectroscopic methods and elemental analysis. The effects of rutin and R-Cu2 were evaluated on the prevention of hypercholesterolemia in animals feed with high-cholesterol diet (HCD) for 8 weeks. The animals (n = 5) were neither fed with HCD nor treated (control group), or were treated with vehicle, 10 mg/kg simvastatin, rutin (16 and 160 μmol/kg), and R-Cu2 (16 and 160 μmol/kg) administered orally. Total cholesterol (TC) levels were significantly increased (p < .01) in all HCD groups. In rutin and R-Cu2 groups, it was observed a discrete, but not significant, TC and LDL-induced increase inhibition compared with vehicle-treated group. R-Cu2 treatment significantly decreased (p < .05) plasma triglycerides compared with the vehicle-treated group. All groups receiving treatments maintained the malondialdehyde at normal levels. Serum NO levels were reduced in animals treated with rutin and R-Cu2 compared with the vehicle-treated group. In addition, the results also showed that the groups treated with rutin and R-Cu2 reduced significantly (p < .01), the number of neutrophils and prevented histological changes in all evaluated liver zones. R-Cu2 group maintained the ALT, AST, and ALP enzymes at normal levels. Thus, the effects of R-Cu2 in modulating inflammation and protecting liver damage were confirmed. PRACTICAL APPLICATIONS: Rutin, a plant-derived flavonoid, is one of phenolic compounds well known as a nutraceutical due to its antioxidant and anti-inflammatory properties. Findings of this study demonstrate the effects of both rutin and R-Cu2 in modulating inflammation and protecting liver damage in hypercholesterolemic rats. However, some effects analyzed became more evident in R-Cu2. Thereby, it was shown that the synthesis of a new flavonoid compound (R-Cu2) could be applied as a nutraceutical benefit option to prevent hypercholesterolemia condition.

Effects of quercetin on heart nitric oxide metabolism in l-NAME treated rats

This study investigated the effects of a quercetin-supplemented diet on the biochemical changes installed in the heart of NO-deficient rats in terms of oxidants production and NO bioavailability determinants. Sprague-Dawley rats were subjected to N^ω-nitro-l-arginine methyl ester (l-NAME) treatment (360 mg/L l-NAME in the drinking water, 4 d) with or without supplementation with quercetin (4 g/kg diet). l-NAME administration led to increased blood pressure (BP) (30%), decreased nitric oxide synthase (NOS) activity (50%), and increases in NADPH oxidase (NOX)-dependent superoxide anion production (60%) and p47^phox protein level (65%). The co-administration of quercetin prevented the increase in BP and the activation of NOX but did not modify the decrease in NOS activity caused by l-NAME. In addition, quercetin affected oxidative stress parameters as glutathione oxidation, and the activities of oxidant detoxifying enzymes superoxide dismutase, glutathione peroxidase, and catalase. Thus, quercetin administration counteracts l-NAME effects on NO bioavailability determinants in vivo, essentially through controlling NOX-mediated superoxide anion production.

3-O-Glucosylation of quercetin enhances inhibitory effects on the adipocyte differentiation and lipogenesis

Glycosylation of natural flavonoids with various sugar moieties can affect their physicochemical and pharmacological properties. In this study, the plant flavonoids quercetin aglycon (Quer) and quercetin 3-O-glucoside (Q3G) were evaluated and compared for their potential anti-obesity effects. The Q3G dose-dependently reduced the TG contents and lipid accumulation in 3T3-L1 adipocyte cells, by 52% and 60% at 20μM, respectively, compared to differentiated control (100%), which were 1.6-fold and 2.4-fold higher reduction than Quer. The Q3G (20μM) also more significantly reduced the expression of adipogenic markers such as C/EBP-β, C/EBP-α, PPAR-γ, and aP2 than Quer, indicating that the Q3G suppresses both adipocyte differentiation and lipogenesis more effectively than Quer in vitro. Comparing to those in the high-fat diet (HFD) fed mice control group for 10 weeks, both the body and liver weights and the size of adipocytes in epididymal adipose tissues were significantly reduced in HFD mice fed with Q3G for another 6 weeks (30mg/kg body weight by oral administration), accompanied by the reductions of TG, total cholesterol, and HDL-cholesterol in serum. The Q3G also reduced the levels of the lipid metabolism-associated proteins, PPAR-γ, SREBP-1c, and FAS in the liver tissues. These results clearly demonstrated that Q3G exhibits a stronger anti-obesity effect than Quer and its anti-obesity effect is mediated via inhibition of adipocyte differentiation and lipogenesis, decreasing serum lipid levels by altering hepatic lipid metabolism, and reducing body weight gain. The results of this study suggest that the Q3G, but not Quer, can be a potent functional ingredient of beneficial health foods or a therapeutic agent to prevent or treat obesity.

Antigenotoxic effects of (-)-epigallocatechin-3-gallate (EGCG), quercetin, and rutin on chromium trioxide-induced micronuclei in the polychromatic erythrocytes of mouse peripheral blood

This study was conducted to investigate the modulating effects of (-)-epigallocatechin-3-gallate (EGCG), quercetin, and rutin on the genotoxic damage induced by Cr(VI) in polychromatic erythrocytes of CD-1 mice. The animals were divided into the following groups: (i) vehicle only; (ii) flavonoids (10 mg/kg EGCG, 100 mg/kg quercetin, 625 mg/kg rutin, or 100-625 mg/kg quercetin-rutin); (iii) Cr(VI) (20 mg/kg of CrO3); and (iv) flavonoids concomitantly with Cr(VI). All of the treatments were administered intraperitoneally (i.p.). The genotoxic damage was evaluated based on the number of micronucleated polychromatic erythrocytes (MN-PCE) obtained from the caudal vein 0, 24, 48, and 72 h after treatment. Groups treated with EGCG and quercetin exhibited no significant statistical changes in induction of MN-PCE. However, CrO3 treatment significantly increased MN-PCE induction 24 and 48 h after injection. Treatment with flavonoids prior to CrO3 exposure decreased MN-PCE induction compared with CrO3 only. The magnitudes of the potency of flavonoids were in the following order: rutin (82%) > quercetin (64%) > quercetin-rutin (59%) and EGCG (44%). The group treated with rutin significantly reduced genotoxic damage in mice treated with Cr(VI) (antioxidant effect). However rutin exerted a marginal genotoxic effect when administered alone (pro-oxidant effect). Our findings suggest protective effects of EGCG, quercetin, and rutin against genotoxic damage induced by Cr(VI).

Rutin (quercetin rutinoside) induced protein-energy malnutrition in chronic kidney disease, but quercetin acted beneficially

Nutraceutically, much of the literature has indicated that an aglycon and its related glycoside would act similarly. However, controversial reports are accumulating. We hypothesize that rutin (RT) and quercetin (QT) pharmacodynamically could act differently. To confirm this, doxorubicin (DR) (8.5 mg/kg) was used to induce rat chronic kidney disease (CKD) and then treated with QT and RT (each 70 mg/kg body weight per day) for 13 weeks. QT exhibited better body weight gaining effect (420 ± 45) vs RT, 350 ± 57 g/rat (p < 0.001). DR raised the ratio kidney-to-body weight (%) to 0.82 (p < 0.001) vs RT, 0.62 (p < 0.01), and QT, 0.35 (p < 0.01). DR reduced the glomerular filtration rate to 25.2 vs RT, 48 ± 11.3; QT, 124.7 ± 12.8 (p < 0.001) and the control, 191.5 ± 15.7 mL/h (p < 0.001). DRCKD reduced hematocrit to 29 ± 5; RT, to 28 ± 5 (p < 0.05); QT, to 36 ± 6 vs the control 37.5 ± 4%, (p < 0.01). DRCKD reduced the serum albumin (s-Ab) to 2.1 ± 0.2 (p < 0.001); QT, to 2.7 ± 0.2 (p < 0.05) vs the normal 4.3 ± 0.5 g/dL, yet RT was totally ineffective. DRCKD raised serum cholesterol level to 340 ± 30; vs RT, 260 ± 12; QT, 220 ± 25; and the normal value, 70 ± 25 mg/dL. DRCKD increased serum triglyceride to 260 ± 15 (p < 0.001), RT and QT restored it to 170 ± 25 and 200 ± 15 (p < 0.05) vs the normal 26-145 mg/dL. DRCKD elevated blood urea nitrogen to 38 ± 3 vs RT, to 98 ± 6 mg/dL (p < 0.001), implicating "protein-energy malnutrition". RT stimulated serum creatinine (sCr) production to reach 6.0 ± 0.9 mg/dL (p < 0.001). QT did not alter the sCr level. RT but not QT induced uremia and hypercreatininemia. DR significantly downregulated Bcl-2, but highly upregulated Bax, Bad, and cleaved caspase-3, implicating the intrinsic mitochondrial pathway. DR damaged DNA, but QT completely rescued such an effect and recovered renal amyloidosis and collagen deposition. Conclusively, RT and QT act differently, and RT is inferior to QT with respect to treating CKD.

Blood pressure-lowering effect of dietary (-)-epicatechin administration in L-NAME-treated rats is associated with restored nitric oxide levels

Epidemiological and intervention studies have shown that the intake of certain chocolates or cocoa products decreases blood pressure (BP) in humans. (-)-Epicatechin is the most abundant flavanol present in cocoa seeds and its derived foods. This work investigates the effects of dietary (-)-epicatechin on BP in rats that received N(ω)-nitro-l-arginine methyl ester (L-NAME) for 4 days. (-)-Epicatechin administration prevented the 42mm Hg increase in BP associated with the inhibition of NO production in a dose-dependent manner (0.2-4.0g/kg diet). This BP effect was associated with a reduction in L-NAME-mediated increase in the indexes of oxidative stress (plasma TBARS and GSSG/GSH(2) ratio) and with a restoration of the NO concentration. At the vascular level, none of the treatments modified NOS expression, but (-)-epicatechin administration avoided the L-NAME-mediated decrease in eNOS activity and increase in both superoxide anion production and NOX subunit p47(phox) expression. In summary, (-)-epicatechin was able to prevent the increase in BP and in oxidative stress and restored NO bioavailability. The fact that (-)-epicatechin is present in several plants usually consumed by humans gives the possibility of developing diets rich in those plants or pharmacological strategies using that flavonoid to diminish BP in hypertensive subjects.

Evaluation of subchronic toxicity of the hydroethanolic extract of Tropaeolum majus in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

The use of medicinal plants for the treatment of diseases usually comes from the belief that they present low toxicity due their natural origin. However, it is necessary a toxicological and pharmacological evaluation for these plants. Tropaeolum majus is a medicinal plant used in popular medicine to treat several diseases, including cardiovascular disorders, urinary tract infections and asthma. Even though several studies proved its therapeutic effects, there are few toxicological studies with this species.

AIM OF THE STUDY

The present study was carried out to evaluate the subchronic toxicity of the hydroethanolic extract obtained from leaves of T. majus (HETM) in Wistar rats.

MATERIAL AND METHODS

Male and female Wistar rats received three doses of HETM (75, 375 and 750 mg/kg) for 28 days. After the treatments biochemical, hematological and histopathological parameters were analyzed.

RESULTS

No significant alterations in the animal's body weight gain, relative organs weight, serum biochemical analysis, hematological or histopathological analyses of liver, kidneys and spleen were observed.

CONCLUSIONS

These results demonstrate the absence of subchronic toxicity due to oral treatment with HETM for 28 days in Wistar rats. However, other toxicological studies are necessary to evaluate the total safety of this plant.