3,4-Dimethylpyrazole phosphate and 2-(N-3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture nitrification inhibitors: Quantification in plant tissues and toxicity assays.

Nitrification inhibitors are used to maintain ammonium available in the soil for longer periods while reducing nitrate leaching and N2O emission. In this work we evaluated the potential toxicity effects of 3,4-dimethylpyrazole phosphate (DMPP) and 2-(N-3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) nitrification inhibitors. In order to determine the potential plant capacity to take up and translocate these inhibitors, we grew clover plants in hydroponic conditions and we developed a novel methodology for extracting DMPP and DMPSA that we quantified by HPLC. In addition, we also did toxicity bioassays: seed germination and Vibrio fischeri test. When clover was exposed to high amounts of nitrification inhibitors, plants accumulated DMPP, predominantly in leaves, and also DMPSA that preferentially accumulated in roots. These inhibitors did not provoke phytotoxicity at the equivalent of the maximum amount estimated in agriculture (0.5mg/kg soil). DMPP only provoked detrimental effects in plants at very high dose (100mg/kg soil). Interestingly, DMPSA was innocuous.

Unsaturated compounds induce up-regulation of CD86 on dendritic cells in the in vitro sensitization assay LCSA.

Unsaturated compounds are known to cause false-positive reactions in the local lymph node assay (LLNA) but not in the guinea pig maximization test. We have tested a panel of substances (succinic acid, undecylenic acid, 1-octyn-3-ol, fumaric acid, maleic acid, linoleic acid, oleic acid, alpha-linolenic acid, squalene, and arachidonic acid) in the loose-fit coculture-based sensitization assay (LCSA) to evaluate whether unspecific activation of dendritic cells is a confounder for sensitization testing in vitro. Eight out of 10 tested substances caused significant up-regulation of CD86 on dendritic cells cocultured with keratinocytes and would have been classified as sensitizers; only succinic acid was tested negative, and squalene had to be excluded from data analysis due to poor solubility in cell culture medium. Based on human data, only undecylenic acid can be considered a true sensitizer. The true sensitizing potential of 1-octyn-3-ol is uncertain. Fumaric acid and its isomer maleic acid are not known as sensitizers, but their esters are contact allergens. A group of 18- to 20-carbon chain unsaturated fatty acids (linoleic acid, oleic acid, alpha-linolenic acid, and arachidonic acid) elicited the strongest reaction in vitro. This is possibly due to the formation of pro-inflammatory lipid mediators in the cell culture causing nonspecific activation of dendritic cells. In conclusion, both the LLNA and the LCSA seem to provide false-positive results for unsaturated fatty acids. The inclusion of T cells in dendritic cell-based in vitro sensitization assays may help to eliminate false-positive results due to nonspecific dendritic cell activation. This would lead to more accurate prediction of sensitizers, which is paramount for consumer health protection and occupational safety.

Triggering the succinate receptor GPR91 enhances pressure overload-induced right ventricular hypertrophy.

BACKGROUND: Pulmonary arterial hypertension (PAH) leads to pressure overload in the right ventricle (RV) and induces right ventricular hypertrophy (RVH). GPR91 is an orphan G-protein-coupled receptor (GPCR) that has been characterized as a receptor for succinate, which increases in RVH; however, its role remains unknown. METHODS AND RESULTS: We studied succinate-GPR91 signaling in a pulmonary arterial banding (PAB) model of RVH in the SD rats due to pressure overload. We report that GPR91 was located in cardiomyocytes. We found that the expressions of GPR91 and p-Akt in the RV significantly increased in the PAB model compared with the sham. In the PAB rats, the treatment of succinate further increased the p-Akt levels and aggravated RVH in vivo. In in vitro studies, succinate stimulated the up-regulation of the hypertrophic gene marker anp. All these effects were inhibited by the antagonist of PI3K, wortmannin, both in vivo and in vitro. Finally, we found that the GPR91-PI3K/Akt axis was also up-regulated compared with the sham in human RVH. CONCLUSIONS: Our results suggest that succinate-GPR91 is involved in RVH via PI3K/Akt signaling in vivo and in vitro. GPR91 may be a novel therapeutic target for RVH induced by pressure overload.

Anthrolysin O and fermentation products mediate the toxicity of Bacillus anthracis to lung epithelial cells under microaerobic conditions.

Bacillus anthracis generates virulence factors such as lethal and edema toxins, capsule, and hemolytic proteins under conditions of reduced oxygenation. Here, we report on the acute cytotoxicity of culture supernatants (Sups) of six nonencapsulated B. anthracis strains grown till the stationary phase under static microaerobic conditions. Human small airway epithelial, umbilical vein endothelial, Caco-2, and Hep-G2 cells were found to be susceptible. Sups displayed a reduction of pH to 5.3-5.5, indicating the onset of acid anaerobic fermentation; however, low pH itself was not a major factor of toxicity. The pore-forming hemolysin, anthrolysin O (ALO), contributed to the toxicity in a concentration-dependent manner. Its effect was found to be synergistic with a metabolic product of B. anthracis, succinic acid. Cells exposed to Sups demonstrated cytoplasmic membrane blebbing, increased permeability, loss of ATP, mitochondrial membrane potential collapse, and arrest of cell respiration. The toxicity was reduced by inhibition of ALO by cholesterol, decomposition of reactive oxygen species, and inhibition of mitochondrial succinate dehydrogenase. Cell death appears to be caused by an acute primary membrane permeabilization by ALO, followed by a burst of reactive radicals from the mitochondria fuelled by the succinate, which is generated by bacteria in the hypoxic environment. This mechanism of metabolic toxicity is relevant to the late-stage conditions of hypoxia and acidosis found in anthrax patients and might operate at anatomical locations of the host deprived from oxygen supply.

The effect of protectants and pH changes on the cellular growth and succinic acid yield of Mannheimia succiniciproducens LPK7.

The harmful effects of succinic acid and oxidative stress on cell growth were determined during batch fermentation with Mannheimia succiniciproducens LPK7, a powerful succinic acid-producing strain, and conditions were optimized to minimize these effects. In terms of toxicity, the cell concentration decreased as the concentration of succinic acid increased. By changing the pH from 6.5 to 7 during fermentation, the cell concentration increased by about 10%, and the level of succinic acid production was 6% higher than that of the control. In addition, by introducing protectants, the cell concentration increased by about 10%, and the level of succinic acid produced was increased by 3%.

Chemically assisted microbial production of succinic acid by the yeast Yarrowia lipolytica grown on ethanol.

A new two-step process of production of succinic acid (SA) has been developed, which includes the microbial synthesis of alpha-ketoglutaric acid by the yeast Yarrowia lipolytica (step 1) and subsequent oxidation of the acid by hydrogen peroxide to SA (step 2). The maximum concentration of SA and its yield were found to be 63.4 g l(-1) and 58% of the ethanol consumed, respectively. The purity of the SA isolated from the culture liquid filtrate reached 100%. The yield of SA was as high as 82% of its amount in the culture liquid filtrate. The quality of the SA produced by the invented method meets the biochemical grade definitions, as is evident from the respiratory and other relevant parameters of rat liver mitochondria upon the oxidation of this SA.

Effects of succinic acid derivatives on ex vivo acetylcholinesterase activity.

In the present study the acetylcholinesterase (AChE) inhibition and acute toxicity of two succinic acid derivatives were compared with tacrine. Administration of a single dose of each of two succinic acid derivatives produced a time and dose-dependent inhibition of brain AChE activity. Although the magnitude of the cholinergic effects observed with the two succinic acid derivatives was similar to that seen with tacrine and other AChE inhibitors, the toxicity study showed that the new inhibitors have less adverse side effects.

[Effect of ammonium succinate on pharmacological effects of acetylsalicylic acid]. / Vliianie ammoniia suktsinata na farmacologicheskie éffekty kisloty atsetilsalitsilovoi.

Ammonia succinate potentiates the main pharmacological properties and reduces the toxic effects (ulcerogenic action and general toxicity) of acetylsalicylic acid. The new preparation astam, representing a combination of acetylsalicylic acid with ammonia succinate in a 2:1 ratio, is proposed. Astam exhibits antiexudative, capillary-reinforcing, antiproliferative, pain-relieving, antipyretic, antiaggregant, and antioxidant properties. In addition, the drug inhibits the development of structural-metabolic disorders in the case of chronic immune inflammation of joints and various internal organs.