Inhibitory Effect of Fisetin on α-Glucosidase Activity: Kinetic and Molecular Docking Studies.

The inhibition of α-glucosidase is a clinical strategy for the treatment of type 2 diabetes mellitus (T2DM), and many natural plant ingredients have been reported to be effective in alleviating hyperglycemia by inhibiting α-glucosidase. In this study, the α-glucosidase inhibitory activity of fisetin extracted from Cotinus coggygria Scop. was evaluated in vitro. The results showed that fisetin exhibited strong inhibitory activity with an IC50 value of 4.099 × 10-4 mM. Enzyme kinetic analysis revealed that fisetin is a non-competitive inhibitor of α-glucosidase, with an inhibition constant value of 0.01065 ± 0.003255 mM. Moreover, fluorescence spectrometric measurements indicated the presence of only one binding site between fisetin and α-glucosidase, with a binding constant (lgKa) of 5.896 L·mol-1. Further molecular docking studies were performed to evaluate the interaction of fisetin with several residues close to the inactive site of α-glucosidase. These studies showed that the structure of the complex was maintained by Pi-Sigma and Pi-Pi stacked interactions. These findings illustrate that fisetin extracted from Cotinus coggygria Scop. is a promising therapeutic agent for the treatment of T2DM.

Hydrogen sulfide extends the postharvest life and enhances antioxidant activity of kiwifruit during storage.

BACKGROUND: Exogenous hydrogen sulfide (H2S) treatment can prolong the postharvest life of cut flowers and strawberries. Little work has been done to explore the effects of H2S on respiratory climacteric fruits such as kiwifruits during storage. Therefore the aim of the present study was to evaluate the effects of H2S treatment at concentrations of 15­1000 µmol L⁻¹ on the postharvest life of kiwifruit during 25 °C storage and the role of H2S in regulating the antioxidant defensive system of kiwifruit. RESULTS: Treatments with 45 and 90 µmol L⁻¹ H2S significantly inhibited the increase in soluble sugar content and the decrease in vitamin C (Vit C), chlorophyll content and firmness, inhibited ethylene production and both superoxide production rate (O(·2)⁻) and hydrogen peroxide content. Kiwifruits with 45 and 90 µmol L⁻¹ H2S exhibited significantly higher activities of superoxide dismutase, catalase and peroxidase. Treatment with 180 µmol L⁻¹ H2S promoted the ripening of kiwifruits. CONCLUSION: Treatments with 45 and 90 µmol L⁻¹ H2S could delay the maturation and senescence of kiwifruits and maintain higher titratable acid (TA) and Vit C during eating-ripe storage by inhibiting ethylene production, improving protective enzyme activities and decreasing the accumulation of reactive oxygen species to protect the cell membrane during storage.

Lipopolysaccharide-induced persistent inflammation ameliorates fat accumulation by promoting adipose browning in vitro and in vivo.

This work aimed to explore whether the persistent inflammation induced by lipopolysaccharide (LPS) ameliorates fat accumulation by promoting adipose browning in vitro and in vivo. LPS over 1 ng/mL reduced lipid accumulation while increasing the expressions of specific genes involved in inflammation, mitochondrial biogenesis, and adipose browning in 3T3-L1 adipocytes. Moreover, LPS in intraperitoneal injection decreased white adipose tissue weight and elevated interscapular brown adipose tissue weight in mice. According to RT-PCR and western blot analysis results, the expressions of genes and proteins related to inflammation, mitochondrial biogenesis, lipolysis, and brown or beige markers in different tissues were elevated after LPS intervention. Cumulatively, LPS-induced persistent inflammation may potentially ameliorate fat accumulation by facilitating adipose browning in 3T3-L1 adipocytes and mice. These results offer new perspectives into the effect of persistent inflammation induced by LPS on regulating fat metabolism, thereby reducing fat accumulation by boosting adipose browning procedure.

Effect of planting and mowing cover crops as livestock feed on soil quality and pear production.

Introduction: The increasing demand for animal-products has led to an increasing demand for livestock feed. Using cover crop as green manure in orchards is an effective measure to improve fruit yield and quality. However, the effect of mowing cover forage crops as livestock feed on soil quality and crop production is unclear. Method: Therefore, a 4-year field experiment, which included two treatments, was conducted in pear orchards in Luniao County, China: natural grass (NG) and planting and mowing forage crop ryegrass as livestock feed (MF). Results: Under MF treatment, most soil nutrient content, especially alkalihydrolysable N (AN), total phosphate (TP), available phosphate (AP), and microbial biomass phosphate (MBP), had decreased significantly (P<0.05), while ß-D-glucosidase (BG, C-cycle enzyme) and soil C limitation at 10-20 cm depth and P limitation at subsoil (20-40 cm) was increased. In addition, the soil bacterial community component in topsoil (0-10 cm and 10-20 cm) and fungal community component in topsoil and subsoil were changed in the MF treatment. Network analysis showed that MF treatment had a lower edge number in topsoil but the community edge numbers increased from 12794 in NG to 13676 in MF in subsoil. The average weight degree of the three soil layers in MF treatment were reduced, but the modularity had increased than that in NG. For crop production, MF treatment was 1.39 times higher in pear yield and titratable acids (AC) reduced from 0.19% to 0.13% compared with NG. These changes were more associated with the indicators at the subsoil, especially for TP, AN, pH, and F-NMDS1 (non-metric multidimensional scaling (NMDS) axis 1 of fungi). Discussion: These results provide data support for the feasibility of planting and mowing forage crops as livestock feed on orchards as well as a new idea for the integration of crop and livestock.

Multi-Component Passivators Regulate Heavy Metal Accumulation in Paddy Soil and Rice: A Three-Site Field Experiment in South China.

To fulfill sustainability principles, a three-site field experiment was conducted to screen suitably mixed passivators from lime + biochar (L + C, 9000 kgha-1 with a rate of 1:1) and lime + biochar + sepiolite (L + C + S, 9000 kg ha-1 with a rate of 1:1:1), in Yuecheng (YC), Zhuji (ZJ), and Fuyang (FY), where there are typical contaminated soils, in South China. Treated with passivators in soil, DTPA-extractable Cd, Crand Pb in soil were decreased by 9.87-26.3%, 37.2-67.5%, and 19.0-54.2%, respectively; Cd, Cr, and Pb in rice were decreased by 85.9-91.5%, 40.0-76.5%, and 16.4-45.4%, respectively; and these were followed by slightly higher efficacy of L + C + S than L + C. The differences between L + C and L + C + S mainly lie in soil microbial communities, enzymes, and fertility. In YC, treatment with L + C + S increased microbial carbon and activities of urease (EC3.5.1.5) and phosphatase (EC3.1.3.1) by 21.0%, 85.5%, and 22.3%; while treatment with L + C decreased microbial carbon and activities of phosphatase and sucrose (EC3.2.1.26) by 1.31%, 34.9%, and 43.4%, respectively. Moreover, the treatment of FY soils with L + C + S increased microbial carbon and activities of urease, phosphatase, and sucrase by 35.4%, 41.6%, 27.9%, and 7.37%; and L + C treatment only increased the microbial carbon and the activity of phosphatase by 3.14% and 30.3%, respectively. Furthermore, the organic matter and available nitrogen were also increased by 8.8-19.0% and 7.4-14.6% with L + C + S treatments, respectively. These suggested that the combination of L + C + S stimulated the growth of soil microbial communities and increased the activity of soil enzymes. Therefore, the L + C + S strategy can be a practical and effective measure for safe rice production as it was more suitable for the remediation of heavy metals in our experimental sites.

α-Glucosidase inhibitory effect of anthocyanins from Cinnamomum camphora fruit: Inhibition kinetics and mechanistic insights through in vitro and in silico studies.

α-Glucosidase inhibitors are widely used to suppress postprandial glycemia in the treatment of type 2 diabetes mellitus. The present study evaluated the in vitro α-glucosidase inhibitory activity of three major pigment constituents of Cinnamomum camphora fruit, namely cyanidin, cyanidin 3-rutinoside, and cyanidin-3-O-glucoside. We found that cyanidin exerted strong inhibitory activity on α-glucosidase, with IC50 of 5.293 × 10-3 mM, whereas cyanidin 3-rutinoside and cyanidin-3-O-glucoside did not show inhibitory activity on α-glucosidase. The inhibitory activity of cyanidin was stronger than that of acarbose (IC50 1.644 mM), the current most commonly used drug for postprandial glycemia. Kinetic analysis indicated that cyanidin inhibited α-glucosidase through competition, with a Ki value of 0.0183 mM. Fluorescence spectrum titration showed only one binding site between cyanidin and α-glucosidase, and the binding constant was calculated. Further, molecular docking was conducted to simulate the binding interactions between cyanidin and α-glucosidase. Cyanidin was found to interact with several residues close to the catalytic site of α-glucosidase through π-π stack interaction and hydrogen bonds. The calculated binding energy of the cyanidin and enzyme complex was -105.031 kJ/mol. Molecular simulation and calculation showed that the van der Waals force played an essential role in the binding of α-glucosidase and cyanidin.

A modified receptor model for source apportionment of heavy metal pollution in soil.

Source apportionment is a crucial step toward reduction of heavy metal pollution in soil. Existing methods are generally based on receptor models. However, overestimation or underestimation occurs when they are applied to heavy metal source apportionment in soil. Therefore, a modified model (PCA-MLRD) was developed, which is based on principal component analysis (PCA) and multiple linear regression with distance (MLRD). This model was applied to a case study conducted in a peri-urban area in southeast China where soils were contaminated by arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb). Compared with existing models, PCA-MLRD is able to identify specific sources and quantify the extent of influence for each emission. The zinc (Zn)-Pb mine was identified as the most important anthropogenic emission, which affected approximately half area for Pb and As accumulation, and approximately one third for Cd. Overall, the influence extent of the anthropogenic emissions decreased in the order of mine (3 km) > dyeing mill (2 km) ≈ industrial hub (2 km) > fluorescent factory (1.5 km) > road (0.5 km). Although algorithm still needs to improved, the PCA-MLRD model has the potential to become a useful tool for heavy metal source apportionment in soil.

Effects of a new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils.

In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate (NO3(-)-N) and potassium (K) leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate (ASN) ((NH4)2SO4 and NH4NO3) or urea could reduce NO3(-)-N leaching significantly, whereas ammonium (NH4(+)-N) leaching increased slightly. In case of total N (NO3(-)-N+NH4(+)-N), losses by leaching during the experimental period (40 d) were 37.93 mg (urea), 31.61 mg (urea+DMPP), 108.10 mg (ASN), 60.70 mg (ASN+DMPP) in the sandy loam soil, and 30.54 mg (urea), 21.05 mg (urea+DMPP), 37.86 mg (ASN), 31.09 mg (ASN+DMPP) in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4(+)-N and low levels of NO3(-)-N in soil, and nitrification was slower. DMPP supplementation also resulted in less potassium leached, but the difference was not significant except the treatment of ASN and ASN+DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.

The Akt inhibitor MK-2206 enhances the cytotoxicity of paclitaxel (Taxol) and cisplatin in ovarian cancer cells.

Abnormalities in the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway are commonly observed in human cancers and contribute to chemotherapy resistance. Combination therapy, involving the use of molecular targeted agents and traditional cytotoxic drugs, may represent a promising strategy to lower resistance and enhance cytotoxicity. Here, we demonstrate the efficacy of an Akt inhibitor, MK-2206, in increasing the cytotoxic effect of either paclitaxel (Taxol) or cisplatin against the ovarian cancer cell lines SKOV3 (with constitutively active Akt) and ES2 (with inactive Akt). Sequential treatment of Taxol or cisplatin, followed by MK-2206, induced a synergistic inhibition of cell proliferation and effectively promoted cell death, either by inhibiting the phosphorylation of Akt and its downstream effectors 4E-BP1 and p70S6K in SKOV3 cells or by restoring p53 levels, which were downregulated after Taxol or cisplatin treatment, in ES2 cells. Combination treatment also downregulated the pro-survival protein Bcl-2 in both SKOV3 and ES2 cells, which may have contributed to cell death. In addition, we discovered that Taxol/MK-2206 or cisplatin/MK-2206 combination treatment resulted in significant enhancement of intracellular reactive oxygen species (ROS) induced by MK-2206, in both SKOV3 and ES2 cells; however, MK-2206-induced growth inhibition was reversed by a ROS scavenger only in ES2 cells. MK-2206 also suppressed DNA repair, particularly in SKOV3 cells. Taken together, our results demonstrate that the Akt inhibitor MK-2206 enhances the efficacy of cytotoxic agents in both Akt-active and Akt-inactive ovarian cancer cells but through different mechanisms.

[Effects of DMPP-compound fertilizer on greenhouse celery growth and nutritional quality].

A field study with greenhouse celery (Apium graveolens L. ) showed that compared with basal application of ordinary compound fertilizer, one-time basal application of DMPP-compound fertilizer ( ENTEC , 12-12-17) at the rates of 67. 5 kg N x hm(-2) and 54. 0 kg N x hm(-2) increased the yield by 5. 78% and 10. 14% , respectively. The application of ENTEC also improved the nutritional quality of edible parts, e. g. , the Vc, amino acid, soluble sugar, N and P contents increased, while nitrate content decreased. Compared with basal plus side dressing applications, appropriately reducing the application rate and times of ENTEChad more beneficial effects on celery yield and quality, and reduced the production costs. ENTEC could suppress the transformation of soil NH4+ -N to NO3 - -N effectively, and thus, its application could retain soil residual N more in NH4+ -N than in NO3- -N form after celery harvested, resulting in a reduction of nitrate leaching.