Green Tea Polyphenols Alleviate Autophagy Inhibition Induced by High Glucose in Endothelial Cells.

Bovine aortic endothelial cells (BAECs) were cultured with high glucose (33 mmol/L), 4 mg/L green tea polyphenols (GTPs) or 4 mg/L GTPs co-treatment with high glucose for 24 h in the presence or absence of Bafilomycin-A1 (BAF). We observed that high glucose increased the accumulation of LC3-II. Treatment with BAF did not further increase the accumulation of LC3-II. Results also showed an increased level of p62 and decreased Beclin-1. However, GTPs showed inversed trends of those proteins. Furthermore, GTPs co-treatment with high glucose decreased the level of LC3-II and a much higher accumulation of LC3-II was observed in the presence of BAF in comparison with high glucose alone. Results also showed a decreased p62 and increased Beclin-1. The results demonstrated that GTPs alleviated autophagy inhibition induced by high glucose, which may be involved in the endothelial protective effects of green tea against hyperglycemia.

Green Tea Polyphenols Attenuate High-Fat Diet-Induced Renal Oxidative Stress through SIRT3-Dependent Deacetylation.

Fifty male Wistar rats were fed a standard chow diet or a high-fat (HF) diet, and different concentrations of green tea polyphenols (GTPs) (0.8, 1.6, and 3.2 g/L) were administered in the drinking water. We found that the malondialdehyde (MDA) level in the HF diet group was significantly higher than that in the control (CON) group (P<0.05). Decreased peroxisome proliferator-activated receptor (PPAR)-α and sirtuin 3 (SIRT3) expression, and increased manganese superoxide dismutase (MnSOD) acetylation levels were also detected in the HF diet group (P<0.05). GTP treatment upregulated SIRT3 and PPARα expression, increased the pparα mRNA level, reduced the MnSOD acetylation level, and decreased MDA production in rats fed a HF diet (P<0.05). No significant differences in total renal MnSOD and PPAR-γ coactivator-1α (PGC1-α) expression were detected. The reduced oxidative stress detected in kidney tissues after GTP treatment was partly due to the higher SIRT3 expression, which was likely mediated by PPARα.

[Effects of carbon source and flooding time on microbial Fe(III) reduction in paddy soils].

Paddy soil samples were collected from six provinces of China, and an anaerobic incubation test was conducted to examine the microbial Fe(III) reduction potential under the conditions of different flooding time and with glucose, pyruvate, lactate, or acetate as the sole carbon source. The results showed that flooding time had significant effects on the eigenvalue of Fe(III) reduction, Vmax, with the order of 20 d > 30 d > 12 d > 1 d > 5 d, which suggested that the difference in the microbial community structure in different flooding periods was the main reason inducing the different potential of Fe(III) reduction. In all test flooding periods, glucose and pyruvate were the superior carbon sources, with the Fe(III) reduction rate being 88.1%-99.9% and 58.0%-97.9%, respectively. When lactate was amended, the Fe(III) reduction rate varied greatly among different paddy soils. For the paddy soils from Hunan and Zhejiang, the Fe(III) reduction rate during flooding period could reach 87.1%-100%; while for other soils, it was 5.0%-49.4% in the first 5 days of flooding and 52.2%-99.9% in 12 days after flooding. When acetate was used as a carbon source, the Fe(III) reduction rate increased with flooding time. Especially in the paddy soil from Zhejiang, the Fe(III) reduction rate changed greatly from 5.3% to 75.8%.