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Ischemia-reperfusion (I/R) injury causes oxidative stress, leading to severe cardiac dysfunction. Thus, biologically active compounds with antioxidant properties may be viewed as a promising therapeutic strategy against oxidative-related cardiac disorders. Usnic acid (UA), a natural antioxidant, was complexed with ß-cyclodextrin (ßCD) to improve its bioavailability. Wistar male rats were orally treated with the free form of UA (50 mg/kg) or the inclusion complex UA/ßCD (50 mg/kg) for seven consecutive days. Afterward, hearts were subjected to I/R injury, and the cardiac contractility, rhythmicity, infarct size, and antioxidant enzyme activities were evaluated. Here, we show that neither UA nor UA/ßCD treatments developed signs of toxicity. After I/R injury, animals treated with UA/ßCD showed improved post-ischemic cardiac functional recovery while the release of cell injury biomarkers decreased. Following reduced cardiac damage, a lower incidence of ventricular arrhythmias and smaller myocardial infarct size were associated with reduced lipid peroxidation, along with preserved activity of antioxidant enzymes compared to untreated rats. Surprisingly, uncomplexed UA did not protect hearts against IR injury. Altogether, our results indicate that the inclusion complex UA/ßCD is a critical determining factor responsible for the cardioprotection action of UA, suggesting the involvement of an antioxidant-dependent mechanisms. Moreover, our findings support that UA/ßCD is a structurally engineered compound with active cardioprotective properties.

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AIMS: B1- and B2-kinin receptors play a major role in several cardiovascular diseases. Therefore, we aimed to evaluate cardiac functional consequences of B1- and B2-kinin receptors ablation, focusing on the cardiac ROS and NO generation. MAIN METHODS: Cardiac contractility, ROS, and NO generation, and protein expression were evaluated in male wild-type (WT), B1- (B1-/-) and B2-kinin (B2-/-) knockout mice. KEY FINDINGS: Impaired contractility in B1-/- and B2-/- hearts was associated with oxidative stress through upregulation of NADPH oxidase p22phox subunit. B1-/- and B2-/- hearts presented higher NO and peroxynitrite levels than WT. Despite decreased sarcoplasmic reticulum Ca2+ ATPase pump (SERCA2) expression, nitration at tyrosine residues of SERCA2 was markedly higher in B1-/- and B2-/- hearts. SIGNIFICANCE: B1- and B2-kinin receptors govern ROS generation, while disruption of B1- and B2-kinin receptors leads to impaired cardiac dysfunction through excessive tyrosine nitration on the SERCA2 structure.

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Myrtenol is a monoterpene with multiple pharmacological activities. However, although monoterpenes have been proposed to play beneficial roles in a variety of cardiac disorders, pharmacological actions of myrtenol in the heart are not yet reported. Hence, the aim of this study was to evaluate whether myrtenol promotes cardioprotection against myocardial ischemia-reperfusion (IR) injury, and the mechanisms involved in these effects. Male Wistar rats were orally treated for seven consecutive days with myrtenol (50 mg/kg) or N-acetyl cysteine (1.200 mg/kg, NAC). Afterward, hearts were subjected to myocardial IR injury. Here, we show that the severe impairment of contractile performance induced by IR was significantly prevented by myrtenol or NAC. Moreover, myrtenol abolished aberrant electrocardiographic waveform (ST-segment elevation), as well as reduced life-threatening arrhythmias and infarct size induced by IR injury. Importantly, myrtenol fully prevented the massive increase of cardiac reactive oxygen species generation and oxidative stress damage. Accordingly, myrtenol restored the impairment of endogenous antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase and reductase) activities and balance of pro- and anti-apoptotic pathways (Bax and Bcl-2), associated with decreased apoptotic cells. Taken together, our data show that myrtenol promotes cardioprotection against IR injury through attenuation of oxidative stress and inhibition of pro-apoptotic pathway.

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Ulcerative colitis (UC) is a common intestinal inflammatory disease with an etiology that is not well understood. Although the anti-inflammatory and anti-oxidant effects of the hydroalcoholic extract of Brazilian red propolis (HERP) have been reported in various experimental models, its protective effect in models of UC have not been evaluated. The purpose of this study was to investigate the chemopreventive effect of hydroalcoholic extract of Brazilian red propolis (HERP) in acetic acid-induced colitis (AAIC) using a rodent model. The HERP was chemically characterised by HPLC/DAD analyses. Male rats were randomly assigned into four groups: sham, vehicle (with AAIC, treated with vehicle), P10 (with AAIC, treated with 10mg/kg HERP), and P100 (with AAIC, treated with 100mg/kg HERP). Treatments were performed for 7days, and colitis was induced on day seven. Animals were euthanized 24h after colitis induction and body weight, colon length, gross and histological scores, malondialdehyde (MDA) and myeloperoxidase (MPO) concentrations in colon tissue, and the immunohistochemical expression of inducible nitric oxide synthase (iNOS) were assessed. The major compounds found in HERP were liquiritigenin (68.8mg/g), formononetin (54.29mg/g), biochanin A (30.97mg/g), and daidzein (19.90mg/g). Rats treated with 10mg/kg HERP demonstrated significant decreases in MPO concentrations, gross and histological scores of tissue damage, and iNOS expression (p<0.05). Similarly, rats treated with 100mg/kg HERP demonstrated significant decreases in MPO levels (p<0.05) and histological scores of tissue damage (p<0.05). The results of this study indicate that oral administration of HERP attenuates AAIC in rats, which may be due to anti-inflammatory effects related to iNOS inhibition.

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