Distinct inhibitory mechanisms of isoquercitrin gallate and its aglycone on zymosan-induced peroxynitrite production in macrophages

Analysis of HETEs in human whole blood by chiral UHPLC-ECAPCI/HRMS

The biosynthesis of eicosanoids occurs enzymatically via lipoxygenases, cyclooxygenases, and cytochrome P450, or through nonenzymatic free radical reactions. The enzymatic routes are highly enantiospecific. Chiral separation and high-sensitivity detection methods are required to differentiate and quantify enantioselective HETEs in complex biological fluids. We report here a targeted chiral lipidomics analysis of human blood using ultra-HPLC-electron capture (EC) atmospheric pressure chemical ionization/high-resolution MS. Monitoring the high-resolution ions formed by the fragmentation of pentafluorobenzyl derivatives of oxidized lipids during the dissociative EC, followed by in-trap fragmentation, increased sensitivity by an order of magnitude when compared with the unit resolution MS. The 12(S)-HETE, 12(S)-hydroxy-(5Z,8E,10E)-heptadecatrienoic acid [12(S)-HHT], and 15(S)-HETE were the major hydroxylated nonesterified chiral lipids in serum. Stimulation of whole blood with zymosan and lipopolysaccharide (LPS) resulted in stimulus- and time-dependent effects. An acute exposure to zymosan induced ∼80% of the chiral plasma lipids, including 12(S)-HHT, 5(S)-HETE, 15(R)-HETE, and 15(S)-HETE, while a maximum response to LPS was achieved after a long-term stimulation. The reported method allows for a rapid quantification with high sensitivity and specificity of enantiospecific responses to in vitro stimulation or coagulation of human blood.

Synthesis and Antiradical Activity of Isoquercitrin Esters with Aromatic Acids and Their Homologues

Isoquercitrin, (IQ, quercetin-3-O-β-d-glucopyranoside) is known for strong chemoprotectant activities. Acylation of flavonoid glucosides with carboxylic acids containing an aromatic ring brings entirely new properties to these compounds. Here, we describe the chemical and enzymatic synthesis of a series of IQ derivatives at the C-6″. IQ benzoate, phenylacetate, phenylpropanoate and cinnamate were prepared from respective vinyl esters using Novozym 435 (Lipase B from Candida antarctica immobilized on acrylic resin). The enzymatic procedure gave no products with “hydroxyaromatic” acids, their vinyl esters nor with their benzyl-protected forms. A chemical protection/deprotection method using Steglich reaction yielded IQ 4-hydroxybenzoate, vanillate and gallate. In case of p-coumaric, caffeic, and ferulic acid, the deprotection lead to the saturation of the double bonds at the phenylpropanoic moiety and yielded 4-hydroxy-, 3,4-dihydroxy- and 3-methoxy-4-hydroxy-phenylpropanoates. Reducing capacity of the cinnamate, gallate and 4-hydroxyphenylpropanoate towards Folin-Ciocalteau reagent was significantly lower than that of IQ, while other derivatives displayed slightly better or comparable capacity. Compared to isoquercitrin, most derivatives were less active in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, but they showed significantly better 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid, ABTS) scavenging activity and were substantially more active in the inhibition of tert-butylhydroperoxide induced lipid peroxidation of rat liver microsomes. The most active compounds were the hydroxyphenylpropanoates.

Analgesic and anti-inflammatory activities of the methanol extract of Elaeagnus oldhamii Maxim. in mice

We investigated possible mechanisms of analgesic and anti-inflammatory activities of the methanol extract from the leaf of Elaeagnus oldhamii Maxim. (EO(MeOH)). EO(MeOH) was evaluated for its analgesic activity in acetic acid-induced writhing response and formalin test, and anti-inflammatory effect was examined by λ-carrageenan-induced paw edema assay. We detected the activities of GPx, GRd and SOD in the liver, and the levels of inflammatory mediators including IL-1β, IL-6, TNF-α, COX-2, MDA and NO in the edema paw to investigate the mechanism of action against inflammation. Total polyphenol, flavonoid and flavanol contents of EO(MeOH) were detected to explore its antioxidant activities. Results showed that, in the analgesic test, EO(MeOH) decreased acetic acid-induced writhing response and the licking time in the late phase of formalin test. In the anti-inflammatory test, EO(MeOH) decreased paw edema at the 2nd, 3rd, 4th and 5th h after λ-carrageenan had been injected. EO(MeOH) increased the activities of SOD and GPx in liver tissue and decreased MDA, NO, IL-1β, IL-6, TNF-α and COX-2 levels in paw edema tissue at the 3rd h after λ-carrageenan-induced inflammatory reaction. EO(MeOH) exhibited abundant polyphenol, flavonoid and flavanol contents. In HPLC fingerprint test of EO(MeOH), two index ingredients, ursolic acid and pomolic acid, were isolated from EO(MeOH) and were exhibited in HPLC chromatographic analysis. The results demonstrated analgesic and anti-inflammatory effects of EO(MeOH). It was indicated that the anti-inflammatory mechanism of EO(MeOH) may be due to declined levels of NO and MDA in the edema paw through increasing the activities of SOD, GPx and GRd in the liver. Additionally, EO(MeOH) decreased IL-1β, IL-6, TNF-α and COX-2 levels in the edema paw. The results suggested its value in future development of herbal medicine for the treatment of inflammatory diseases.

Effects of flavonoids and other polyphenols on inflammation

Flavonoids are a family of polyphenolic compounds which are widespread in nature (vegetables) and are consumed as part of the human diet in significant amounts. There are other types of polyphenols, including, for example, tannins and resveratrol. Flavonoids and related polyphenolic compounds have significant antiinflammatory activity, among others. This short review summarizes the current knowledge on the effects of flavonoids and related polyphenolic compounds on inflammation, with a focus on structural requirements, the mechanisms involved, and pharmacokinetic considerations. Different molecular (cyclooxygenase, lipoxygenase) and cellular targets (macrophages, lymphocytes, epithelial cells, endothelium) have been identified. In addition, many flavonoids display significant antioxidant/radical scavenging properties. There is substantial structural variation in these compounds, which is bound to have an impact on their biological profile, and specifically on their effects on inflammatory conditions. However, in general terms there is substantial consistency in the effects of these compounds despite considerable structural variations. The mechanisms have been studied mainly in myeloid cells, where the predominant effect is an inhibition of NF-κB signaling and the downregulation of the expression of proinflammatory markers. At present there is a gap in knowledge of in vitro and in vivo effects, although the pharmacokinetics of flavonoids has advanced considerably in the last decade. Many flavonoids have been studied for their intestinal antiinflammatory activity which is only logical, since the gastrointestinal tract is naturally exposed to them. However, their potential therapeutic application in inflammation is not restricted to this organ and extends to other sites and conditions, including arthritis, asthma, encephalomyelitis, and atherosclerosis, among others.

Antihypertensive effects of isoquercitrin and extracts from Tropaeolum majus L.: evidence for the inhibition of angiotensin converting enzyme

AIM OF THE STUDY

Previous studies have shown that the extracts obtained from Tropaeolum majus L. exhibit pronounced diuretic properties. In the present study, we assessed whether the hypotensive and/or antihypertensive mechanism of hydroethanolic extract (HETM), semi-purified fraction (TMLR) obtained from T. majus and the flavonoids isoquercitrin (ISQ) and kaempferol (KPF) can be mediated by their interaction with angiotensin converting enzyme (ACE).

METHODS AND METHODS

Firstly, to evaluate changes in mean arterial pressure (MAP), different groups of normotensive and spontaneously hypertensive rats (SHR) were orally and intraduodenally treated with HETM (10-300 mg/kg) and TMLR (12.5-100mg/kg) and intravenously treated with ISQ and KPF being later anesthetized with ketamine (100mg/kg) and xylazine (20mg/kg). The left femoral vein and the right carotid artery were isolated, and polyethylene catheters were inserted for ISQ and KPF (0.5-4 mg/kg) administration and blood pressure recording, respectively. The plasmatic ACE activity was evaluated to indirect fluorimetry, in serum samples after orally treatment with HETM, TMLR, ISQ and KPF.

RESULTS

The oral administration of the HETM and its TMLR significantly reduced, in a dose-dependent manner, the MAP in both normotensive and SHR. In addition, these preparations significantly decreased the MAP for up to 3h after the administration of the extract. Additionally, the intravenous administration of ISQ, but not KPF, decreased MAP in rats. Otherwise, neither the extracts nor ISQ affected the heart rate. The oral administration of the HETM, TMLR or ISQ reduced ACE activity in serum samples at 90 min after administration. Finally, the intravenous administration of ISQ caused a significant reduction in the hypertensive response to angiotensin I, but not angiotensin II in normotensive rats.

CONCLUSION

Our results show that the hypotensive effects caused by the HETM, as well as by its TMLR, may be associated with the high levels of the flavonoid ISQ found in this plant. In addition, ISQ-induced hypotension in rats is an event dependent on the inhibition of angiotensin II generation by ACE.

Effects of a flavonoid extract from Cynomorium songaricum on the swimming endurance of rats

The present study investigated the effects of a flavonoid extract from Cynomorium songaricum on the swimming endurance of rats by measuring changes of free radical scavenging enzymes, such as CuZn-SOD (copper, zinc-superoxide dismutase) and GSH-px (glutathione peroxidase), and body weights. Significant and dose-dependent antioxidant and anti-fatigue effects of flavonoids (rutin, catechin and isoquercitrin) on swimming rats were observed during 10 days of swimming exercise. After treatment with the flavonoid extract at doses of 0.5, 1.0, and 2.0 g/kg body weight, the CuZn-SOD and GSH-px activities in swimming rats were increased by 1.4%, 3.3%, 4.1% and 112.2%, 208.7%, 261.7%, respectively, while the levels of MDA (malondialdehyde) were decreased by 64.7%, 79.4%, and 86.4% respectively. Furthermore, the average body weight and the total swimming time were increased by 3.1%, 8.8%, 10.6%, and 7.7%, 34.5%, 61.5%, respectively. Our experimental results suggest that flavonoid supplementation could not only reduce free radical formation and scavenge free radicals, but also enhance endurance exercise performance by reducing muscle fatigue.

Evaluation of Resveratrol and Piceatannol Cytotoxicity in Macrophages, T Cells, and Skin Cells

The cytotoxicity of resveratrol and of piceatannol, a structural analog of resveratrol, was examined in cultured cells. Using a MTT-based assay, which measures the conversion of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) to a colored formazan product in living cells, resveratrol was found to inhibit the viability of transformed mouse macrophages, tumor-derived human T cells and human epidermoid carcinoma cells in a concentration-dependent manner, with the effect decreasing in the order: T cells (LC50 ~27 μmol L-1, 24 h; ~9 μmol L-1; 48h) > macrophages (LC50~29 μmol L-1, 24 h; 39 μmol L-1, 48 h) > skin cells (LC50 ~91 μmol L-1, 24 h; ~66 μmol L-1, 48 h). Paradoxically, a high concentration of resveratrol (50 μmol L-1) inhibited the proliferation of all three cell types, and a low concentration (5 μmol L-1) stimulated the proliferation of macrophages. The viability of macrophages was also decreased by piceatannol in a concentration-dependent manner. The stimulation of macrophages with zymosan lowered the cytotoxicity of both resveratrol and piceatannol. Scanning electron microscopy of cells treated with resveratrol revealed changes in cellular morphology that were consistent with toxicity. In macrophages and skin cells, resveratrol (50 μmol L-1) induced a time-dependent increase in reduced glutathione levels but did not alter the background levels of thiobarbituric acid-reactive substances. Taken together, the present data indicate that resveratrol is toxic to cultured macrophages, T cells and skin cells at concentrations ≥25 μmol L-1, and that the cytotoxicity occurs via a mechanism that does not involve oxidative stress. Furthermore, the degree of toxicity of both resveratrol and piceatannol towards macrophages depends on the activation status of these cells, with zymosan-activated cells appearing more resistant than nonstimulated cells.