γ-oryzanol (Orz), a steryl ferulate extracted from rice bran layer, exerts a wide spectrum of biological activities. In addition to its antioxidant activity, Orz is often associated with cholesterol-lowering, anti-inflammatory, anti-cancer and anti-diabetic effects. In recent years, the usefulness of Orz has been studied for the treatment of metabolic diseases, as it acts to ameliorate insulin activity, cholesterol metabolism, and associated chronic inflammation. Previous studies have shown the direct action of Orz when downregulating the expression of genes that encode proteins related to adiposity (CCAAT/enhancer binding proteins (C/EBPs)), inflammatory responses (nuclear factor kappa-B (NF-κB)), and metabolic syndrome (peroxisome proliferator-activated receptors (PPARs)). It is likely that this wide range of beneficial activities results from a complex network of interactions and signals triggered, and/or inhibited by its antioxidant properties. This review focuses on the significance of Orz in metabolic disorders, which feature remarkable oxidative imbalance, such as impaired glucose metabolism, obesity, and inflammation.

The role of oxidaTive sTress on The paThophysiology of meTabolic syndrome rev assoc Med Bras 2017; 63(1):85-91 85 REVIEW ARTICLEThe role of oxidative stress on the pathophysiology of metabolic syndrome Metabolic syndrome (MetS) has a high prevalence around the world. Considering the components used to classify MetS, it is clear that it is closely related to obesity. These two conditions begin with an increase in abdominal adipose tissue, which is metabolically more active, containing a greater amount of resident macrophages compared to other fat deposits. Abdominal adiposity promotes inflammation and oxidative stress, which are precursors of various complications involving MetS components, namely insulin resistance, hypertension and hyperlipidemia. One way to block the effects of oxidative stress would be through the antioxidant defense system, which offsets the excess free radicals. It is known that individuals with metabolic syndrome and obesity have high consumption of fats and sugars originated from processed foods containing high levels of sodium as well as low intake of fruits and vegetables, thus maintaining a state of oxidative stress, that can speed up the onset of MetS. Healthy eating habits could prevent or delay MetS by adding antioxidant-rich foods into the diet.

Background: The high consumption of fat and sugar contributes to the development of obesity and co-morbidities, such as diabetes, and cardiovascular and kidney diseases. Different strategies have been used to prevent these diseases associated with obesity, such as changes in eating habits and/or the addition of dietary components with anti-inflammatory and anti-oxidant properties, such as gamma-oryzanol (γOz) present mainly in bran layers and rice germ. Methods: Animals were randomly divided into four experimental groups and fed ad libitum for 20 weeks with control diet (C, n = 8), control diet + γOz (C + γOz, n = 8), high-sugar and high-fat diet (HSF, n = 8), and high-sugar and high-fat diet + γOz (HSF + γOz, n = 8). HSF groups also received water + sucrose (25%). The dose of γOz was added to diets to reach 0.5% of final concentration (w/w). Evaluation in animals included food and caloric intake, body weight, plasma glucose, insulin, triglycerides, uric acid, HOMA-IR, glomerular filtration rate, protein/creatinine ratio, systolic blood pressure, and Doppler echocardiographic. Results: Animals that consumed the HSF diet had weight gain compared to group C, increased insulin, HOMA, glucose and triglycerides, there were also atrial and ventricular structural alterations, deterioration of systolic and diastolic function, decreased glomerular filtration rate, and proteinuria. Gamma-oryzanol is significantly protective against effects on body weight, hypertriglyceridemia, renal damage, and against structural and functional alteration of the heart. Conclusion: Gamma-oryzanol shows potential as a therapeutic to prevent Cardiorenal Metabolic Syndrome.

The effects of hydroethanolic extract of Yacon leaves (HEYL) on antioxidant, glycemic, and inflammatory biomarkers were tested in diabetic rats. Outcome parameters included glucose, insulin, interleukin-6 (IL-6), and hydrophilic antioxidant capacity (HAC) in serum and IL-6, HAC, malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in soleus. The rats (10/group) were divided as follows: C, controls; C + Y, HEYL treated; DM, diabetic controls; and DM + Y, diabetic rats treated with HEYL. Diabetes mellitus was induced by administration of streptozotocin. C + Y and DM + Y groups received 100 mg/kg HEYL daily via gavage for 30 d. Hyperglycemia was improved in the DM + Y versus DM group. Insulin was reduced in DM versus C group. DM rats had higher IL-6 and MDA and lower HAC in the soleus muscle. HEYL treatment decreased IL-6 and MDA and increased HAC in DM rats. DM + Y rats had the highest CAT activity versus the other groups; GPx was higher in C + Y and DM + Y versus their respective controls. The apparent benefit of HEYL may be mediated via improving glucoregulation and ameliorating oxidative stress and inflammation, particularly in diabetic rats.

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