Oxidative stress status occurs when ROS accumulate Superoxid

Oxidative stress status occurs when ROS accumulate. Superoxide dismutases (SOD), one of antioxidant enzymes, catalyzes the dismutation of superoxide anion () into O2 and hydrogen peroxide (H2O2). Subsequently, H2O2 is reduced to H2O by glutathione peroxidase (GSH-Px) in the cytosol, or by catalase (CAT) in the peroxisomes. SOD, CAT and GSH-Px are easily induced by oxidative stress. The activity levels of these enzymes have been used to quantify oxidative stress in cells [27,28]. Nitric oxide synthases (NOS) in a large number of different tissues synthesize nitric oxide (NO). NO is a very small, lipophilic, readily diffusible, chemically unstable molecule with a very short half-life (seconds). No plays a relevant role in signal transduction in physiopathology [29]. Pyruvate kinase (PK) is a key enzyme that regulates glycolytic flux in response to the intracellular energy level. Malonic dialdehyde (MDA) is a major reactive aldehyde resulting from the peroxidation of polyunsaturated fatty droperidol in biological membrane. MDA generally is used as an indicator of the tissue damage involving a series of chain reactions. Excessively activated radicals can react with the unsaturated fatty acid of cytomembrane, causing lipid peroxidation and forming MDA. The liver is an organ with the multi-functions in the body, such as storing glycogen, secreting protein. Aminotransferase (ALT) and aspartate aminotransferase (AST), mainly distributed in hepatocytes, are sensitive indicators of liver injury. In this work, activities of nitric oxide synthase (NOS), pyruvate kinase (PK), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined; malondialdehyde (MDA) and glucose levels in serum, were measured; activities of total superoxide dismutase (T-SOD), catalase enzyme (CAT), and glutathione peroxidase (GSH-Px) in the liver were also determined. Then, the improving oxidative stress status and hepatoprotective effect of Pu-erh tea extracts in normal rats fed with high-fat diet were carried out in order to provide some information on Pu-erh tea’s health benefits.
Materials and methods
Results and analysis
Discussion ROS induced by obesity involves in multi-mechanisms, including antioxidant defense system reduced in vivo and the activities of SOD, GSH-Px and catalase decreased, which leads to the oxidative stress status [38–41]. The reducing the body mass index (BMI) can markedly improve the oxidative stress state [42]. The experimental results showed that the body weight of rats in low-, middle-, and high- concentration groups were significantly lower than those in the high fat control group by gavaging with Pu-erh tea extracts for twelve weeks, confirming that Pu-erh tea extracts had the function of preventing obesity (Table 1). Meanwhile, by comparison with the normal control group, the T-SOD, GSH-Px and CAT activities were significantly reduced, and MDA level and NOS activity were significantly increased in the high fat control group, indicating ROS in the rats fed with high-fat diet was excessively produced, and the innate antioxidant defense system in vivo was damaged, thereby leading to the oxidative stress state and lipid peroxidation (Figs. 1–3). However, the SOD, GSH-PX, CAT, NOS activities and the MDA level in the high-dose treatment group were roughly equivalent to that of the normal control group, demonstrating that excessive ROS in the rats fed with high-fat diet was effectively removed and remained ROS at a lower level via the intervention of high-dose tea pigments. Therefore, neural tube study substantiated that Pu-erh tea extracts can efficiently reduce oxidative stress status and inhibit lipid peroxidation. This may be due to the mechanisms of preventing the weight of rats fed with high-fat diet from increasing, thus restoring the innate antioxidant defense system and effectively dampening the generation of free radicals, reducing oxidative stress status and inhibiting lipid peroxidation, and preventing the occurrence of diseases associated with oxidative stress. It has been reported that the tea water extracts can significantly decrease body weight in hyperlipidemia-rats, increasing the SOD and GSH-PX activities, decreasing MDA level [24], and this is consistent with the experimental results.