Effects Of Different Metabolites Research Articles

Drying enhances the antioxidant activity of Allium mongolicum Regel through the phenylpropane and AA-MA pathway as shown by metabolomics

Fresh Allium mongolicum Regel (FA) and dried A. mongolicum Regel (DA) are significantly different in antioxidant activity. However, the relevant mechanisms have not yet been explored. We evaluated the antioxidant activities of two varieties of FA and DA and characterized their metabolites using targeted metabolomics. The effect of different metabolites on the antioxidant activity of A. mongolicum Regel was investigated by multivariate analysis. A total of 713 metabolites were detected in all samples. Pearson correlation analysis demonstrated that the key primary metabolites were directly and significantly correlated with the total phenolic content (TPC) and total flavonoid content (TFC), while the secondary metabolites were directly correlated with antioxidant activity. The higher antioxidant activity of DA may be mainly attributed to the higher TPC and TFC. This study revealed the potential mechanism by which drying enhances the antioxidant activity of A. mongolicum Regel.

Arginine and methionine increase the enzymatic activity of microbes involved in N and P cycles in arid soil from the Chihuahuan desert

Root exudates are mainly composed of sugars, organic acids, and amino acids. These are carbon sources that recruit beneficial bacterial communities in the rhizosphere. However, the composition of the root exudates is variable and mainly unknown for plants from arid lands, such as Agave lechuguilla Torr. This work studied the effect of different metabolites identified in the rhizosphere of A. lechuguilla Torr. (Maltose, lactose, oxalic and tartaric acids, arginine, and methionine), over the enzymatic activity and abundance of nitrogen-fixing bacteria and organic phosphorus mineralizing bacteria, as well as the changes in the nutrient availability in the soil. It was found that only the amino acids increased the nitrogenase and phosphatase activity, and these increments were reflected in the available nutrient concentration in the soil. Likewise, the presence of carbon and nitrogen from the amino acids may reduce the C:N ratio in the soil, enhancing the mineralization of organic matter and the concentration of ammonia, nitrite, and nitrates. This work shows the complexity of the nutrient recycling process in the soil and the essential role of bacteria in making nutrients available to plants. Understanding this process could aid in improving the establishment of plants in eroded ecosystems or under the harsh conditions of arid environments.

Effects of Vegetal Extracts and Metabolites against Oxidative Stress and Associated Diseases: Studies in Caenorhabditis elegans.

Oxidative stress is a natural physiological process where the levels of oxidants, such as reactive oxygen species (ROS) and nitrogen (RNS), exceed the strategy of antioxidant defenses, culminating in the interruption of redox signaling and control. Oxidative stress is associated with multiple pathologies, including premature aging, neurodegenerative diseases, obesity, diabetes, atherosclerosis, and arthritis. It is not yet clear whether oxidative stress is the cause or consequence of these diseases; however, it has been shown that using compounds with antioxidant properties, particularly compounds of natural origin, could prevent or slow down the progress of different pathologies. Within this context, the Caenorhabditis elegans (C. elegans) model has served to study the effect of different metabolites and natural compounds, which has helped to decipher molecular targets and the effect of these compounds on premature aging and some diseases such as neurodegenerative diseases and dyslipidemia. This article lists the studies carried out on C. elegans in which metabolites and natural extracts have been tested against oxidative stress and the pathologies associated with providing an overview of the discoveries in the redox area made with this nematode.

Selected Metabolites Found in Equine Oviductal Fluid do not Modify the Parameters Associated to Capacitation of the Frozen-thawed Equine Spermatozoa In Vitro

In the horse, a repeatable protocol for in vitro fertilization has not been developed, possibly due to incomplete sperm capacitation. We have previously identified the metabolites present in equine oviductal fluid (OF). We aimed to test the effects of different metabolites found in equine oviductal fluid on quality parameters of frozen-thawed spermatozoa. Different concentrations of myoinositol (5–25 mM), lactate (6–60 mM), glycine (0.1–5 mM), β-alanine (1–6 mM), and histamine (0.05–0.4 mM) were added independently to modified Whitten's medium (pH = 7.25). Thawed equine spermatozoa (three stallions, one ejaculate per stallion, n = 3) were incubated for 2 hours at 37˚C in presence of the selected metabolites. After sperm incubation, total motility (TM), and progressive motility (PM) were evaluated by computer-assisted sperm analysis. Viability (SYBR-14+/PI−), mitochondrial membrane potential (ΔΨm) (JC-1), acrosome reaction (PNA+/PI−) and reactive oxygen species (ROS) production (CellRox+/PI−), were evaluated by flow cytometry. Protein tyrosine phosphorylation (PY) was evaluated by indirect immunofluorescence. Our results show that the addition of the metabolites at the dosages tested does not exert any effect on the sperm parameters analyzed. More research is needed to ascertain if metabolite addition at the dosages found in the equine OF exerts any remarkable effect on in vitro equine sperm capacitation.

Moringin and Its Structural Analogues as Slow H2S Donors: Their Mechanisms and Bioactivity.

Moringin (rhamnobenzyl isothiocyanate) is a major bioactive compound in moringa seeds, which have been used as a healthy food. However, its bioactivity mechanisms are not well understood. We investigated moringin and its structurally similar analogues, including benzyl isothiocyanate and 4-hydroxylbenzyl isothiocyanate, for their hydrogen sulfide (H2S)-releasing activity triggered by cysteine. These isothiocyanates rapidly formed cysteine adducts, which underwent intramolecular cyclization followed by slowly releasing (a) organic amine and raphanusamic acid and (b) H2S and 2-carbylamino-4,5-dihydrothiazole-4-carboxylic acids. The product distributions are highly dependent on para-substituents on the phenyl group. Moringin has higher cytotoxicity to cancer cells and is a more potent anti-inflammatory agent than benzyl and hydroxybenzyl analogues, while benzyl isothiocyanate is a better antibacterial agent. Taken together, their bioactivity may not be directly related to their H2S donation activity. However, other metabolites alone do not have cytotoxicity and anti-inflammatory activity. These findings indicated that their activity may be the combination effects of different metabolites via competitive pathways as well the para-substituent groups of benzyl ITCs.

A new perspective on evaluation of medicinal plant biological activities: The correlation between phytomics and matrix metalloproteinases activities of some medicinal plants

Phytomics or metabolomics is analysis of large-scale primary and secondary metabolites of plant extracts and provides very meaningful data to monitor or evaluate cellular function or systems biology. The activity of plant extracts depends on the synergistic/antagonistic effect of different metabolites rather than single active metabolites. Matrix metalloproteinases (MMPs) have an active role in the formation of many diseases. To our knowledge, there is no study on the correlation between the phytomics and MMP inhibitory activity of Achillea millefolium, Achillea filipendulina (Asteraceae), Mentha piperita, and Salvia officinalis (Lamiaceae), (AAMS). Therefore, this study aimed to correlate the metabolomics profiling of AAMS extracts to identify the metabolites responsible for the MMP inhibitory activity based on phytomics data. The AAMS extracts showed a significant MMP inhibitory effect (57.73–92.73%) at different concentrations (25–500 μg/mL). In order to identify the metabolites responsible for such activities in the extract, the metabolomic profiling of the plants was investigated using gas chromatography-mass spectrometry (GC-MS). After deconvolution and aligning of the chromatograms, 284 metabolites were detected, of which 149 were annotated using retention index libraries. Multivariate analyses results indicated that A. millefolium and A. filipendulina showed similar metabolomic profiles, while M. piperita and S. officinalis differed both from each other and from Achillea species. The correlation analysis was applied to evaluate the correlation between metabolomic levels and MMP inhibitory activities, and 96 metabolites had a negative correlation (r ≤ −0.70) and 55 had a highly positive correlation (r ≥ 0.70) with MMP inhibitory activity. This is the first study which revealed that phytomics, plant metabolomics, can be used for activity evaluation and a single metabolite may not be responsible for a specific activity. In conclusion, phytomics can be a more useful tool for the evaluation of the activities than investigating a single metabolite. This new perspective can also provide a better understanding of plant metabolomics and can be easily employed for future research on plant activity.

Biochemical and Kinetic Characterization of the Eukaryotic Phosphotransacetylase Class IIa Enzyme from Phytophthora ramorum.

Phosphotransacetylase (Pta), a key enzyme in bacterial metabolism, catalyzes the reversible transfer of an acetyl group from acetyl phosphate to coenzyme A (CoA) to produce acetyl-CoA and Pi. Two classes of Pta have been identified based on the absence (Pta(I)) or presence (Pta(II)) of an N-terminal regulatory domain. Pta(I) has been fairly well studied in bacteria and one genus of archaea; however, only the Escherichia coli and Salmonella enterica Pta(II) enzymes have been biochemically characterized, and they are allosterically regulated. Here, we describe the first biochemical and kinetic characterization of a eukaryotic Pta from the oomycete Phytophthora ramorum. The two Ptas from P. ramorum, designated PrPta(II)1 and PrPta(II)2, both belong to class II. PrPta(II)1 displayed positive cooperativity for both acetyl phosphate and CoA and is allosterically regulated. We compared the effects of different metabolites on PrPta(II)1 and the S. enterica Pta(II) and found that, although the N-terminal regulatory domains share only 19% identity, both enzymes are inhibited by ATP, NADP, NADH, phosphoenolpyruvate (PEP), and pyruvate in the acetyl-CoA/Pi-forming direction but are differentially regulated by AMP. Phylogenetic analysis of bacterial, archaeal, and eukaryotic sequences identified four subtypes of Pta(II) based on the presence or absence of the P-loop and DRTGG subdomains within the N-terminal regulatory domain. Although the E. coli, S. enterica, and P. ramorum enzymes all belong to the IIa subclass, our kinetic analysis has indicated that enzymes within a subclass can still display differences in their allosteric regulation.

Feedback Inhibition of Deoxy-d-xylulose-5-phosphate Synthase Regulates the Methylerythritol 4-Phosphate Pathway

The 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway leads to the biosynthesis of isopentenyl diphosphate (IDP) and dimethylallyl diphosphate (DMADP), the precursors for isoprene and higher isoprenoids. Isoprene has significant effects on atmospheric chemistry, whereas other isoprenoids have diverse roles ranging from various biological processes to applications in commercial uses. Understanding the metabolic regulation of the MEP pathway is important considering the numerous applications of this pathway. The 1-deoxy-D-xylulose-5-phosphate synthase (DXS) enzyme was cloned from Populus trichocarpa, and the recombinant protein (PtDXS) was purified from Escherichia coli. The steady-state kinetic parameters were measured by a coupled enzyme assay. An LC-MS/MS-based assay involving the direct quantification of the end product of the enzymatic reaction, 1-deoxy-D-xylulose 5-phosphate (DXP), was developed. The effect of different metabolites of the MEP pathway on PtDXS activity was tested. PtDXS was inhibited by IDP and DMADP. Both of these metabolites compete with thiamine pyrophosphate for binding with the enzyme. An atomic structural model of PtDXS in complex with thiamine pyrophosphate and Mg(2+) was built by homology modeling and refined by molecular dynamics simulations. The refined structure was used to model the binding of IDP and DMADP and indicated that IDP and DMADP might bind with the enzyme in a manner very similar to the binding of thiamine pyrophosphate. The feedback inhibition of PtDXS by IDP and DMADP constitutes an important mechanism of metabolic regulation of the MEP pathway and indicates that thiamine pyrophosphate-dependent enzymes may often be affected by IDP and DMADP.

TRIENNIAL GROWTH SYMPOSIUM: Effects of polymeric carbohydrates on growth and development in pigs1

Polymeric carbohydrates, starch and nonstarch polysaccharides (NSP), quantitatively represent the largest portion of the diets for pigs and are, therefore, the largest energy contributor. The 2 types of polysaccharides, however, have different fates and functions in the gastrointestinal tract and lead to different metabolites upon digestion. Pancreatic and mucosal enzymes in the small intestine break down the majority of starch, whereas NSP primarily are degraded by the microflora in the large intestine. Starch degradation leads to the release of glucose, which is absorbed by an active absorption process that triggers the release of insulin from the pancreas, whereas the fermentation of NSP to short-chain fatty acids (SCFA; i.e., acetate, propionate, and butyrate) occurs at a slower and more constant rate and with SCFA being absorbed by passive diffusion. Type and amounts of polymeric carbohydrates influence growth and development through different mechanisms. First, the proportion of starch to NSP plays an important role for the content of available energy (i.e., DE, ME, and NE); available energy relative to protein is crucial for performance and carcass quality. Second, the proportion of starch to NSP will influence rate and type of metabolites (i.e., glucose vs. SCFA) deriving from carbohydrate assimilation. Third and finally, the type of starch (i.e., types A, B, and C) and soluble NSP will influence the release of insulin, the hormone that facilitates nutrient uptake by tissues, organs, and cells, and thus plays a critically essential role in protein synthesis and muscle growth, as well as lipid synthesis and adipose tissue growth. In conclusion, polymeric carbohydrates influence growth and development through events in the gut and direct and indirect effects of different metabolites deriving from carbohydrate assimilation.

Cytosolic 5′-nucleotidase/nucleoside phosphotransferase: a single assay for a bifunctional enzyme

Cytosolic 5'-nucleotidase/nucleoside phosphotransferase has been purified from calf thymus. Since the same protein is able to catalyze both the hydrolysis and the interconversion of several nucleoside monophosphates, it is necessary to study the effect of different metabolites and assay conditions on both activities in order to elucidate their physiological roles. We describe herein a method which allowed us to follow both activities contemporaneously in the same assay mixture. The method takes advantage of the observation that deoxyGMP is both a good substrate for hydrolysis and a good phosphate donor for the phosphotransferase reaction, but its dephosphorylated product, deoxyguanosine, is not a phosphate acceptor. As a consequence, it is possible to follow both the deoxyguanosine production and the transfer of phosphate from deoxyGMP to the best phosphate acceptor, inosine, during the reaction, applying a method for the chromatographic separation on HPLC of both substrates (inosine and deoxyGMP) and both products (IMP and deoxyguanosine). The method was applied to the determination of the KM for inosine.

Regulation of food intake by hepatic oxidative metabolism

It has been proposed that the turnover of metabolic fuels affects feeding. In the present study the effects of different metabolites (glycerol, L-malate, D-3-hydroxybutyrate, L-lactate) or their oxidation products (dihydroxyacetone, oxaloacetate, acetoacetate, pyruvate) on food intake were investigated under various feeding conditions. The results of these experiments increase our knowledge about the nature and origin of metabolic signals in the energostatic control of food intake. In the experiments, glycerol, malate, 3-hydroxybutyrate, lactate or pyruvate (4.5–7.7 mmoles/kg metabolic body weight injected subcutaneously reduced food intake in rats, whereas dihydroxyacetone, acetoacetate or oxaloacetate did not. The effect of glycerol disappeared with high levels of dietary protein, whereas the effects of lactate and pyruvate disappeared with high levels of dietary fat. The hypophagic effects of glycerol, malate, 3-hydroxybutyrate, lactate and pyruvate were abolished by selective hepatic vagotomy. The results suggest that vagally mediated signals originating from hepatic oxidation of metabolic fuels contribute to the regulation of food intake.

Selective hepatic vagotomy eliminates the hypophagic effect of different metabolites

To test the hypothesis that vagally mediated metabolic signals from the liver affect feeding, we investigated the influence of selective hepatic vagotomy on the anorectic effect of different metabolites in rats. Subcutaneous injection of glycerol (GLY), d-3 hydroxybutyrate (DHB), l-malate (MAL), l-lactate (LAC), or pyruvate (PYR) (5.7 mmol/kg metabolic body weight = b.wt. 0.75, each) reduced food intake in sham-vagotomized rats. Selective hepatic vagotomy eliminated the hypophagic effect of all metabolites. In an additional experiment, LAC retained its potency to inhibit feeding in sham-vagotomized rats after an intraperitoneal injection of atropine methylnitrate (5 mg/kg b.wt. 0.75). The results demonstrate that the hypophagic effect of GLY, DHB, MAL, LAC and PYR originates in the liver and is mediated by hepatic vagal afferents. This implicates the existence of adequate hepatic receptors which might contribute to the control of food intake.