Elevated plasma dityrosine in patients with hyperlipidemia compared to healthy individuals.

BACKGROUND: Dityrosine, the modification of tyrosine residues, may contribute to metabolic disorders. This study was undertaken to investigate plasma dityrosine concentrations in patients with hyperlipidemia and to examine the correlation between dityrosine and lipid profiles. METHODS: Fluorescence spectrophotometry was used to measure dityrosine in the plasma of healthy subjects (n = 203) and dyslipidemic subjects, which included patients with mild hyperlipidemia (n = 246) and hyperlipidemia (n = 179). Advanced oxidation protein products (AOPP) and malondialdehyde (MDA) were also assayed in all subjects. RESULTS: Dityrosine levels were higher by 9.3 and 22.9% in mildly hyperlipidemic and hyperlipidemic patients, respectively, compared to controls after adjustment for age, gender, and BMI. AOPP and MDA levels showed similar trends. The levels of dityrosine related positively (p < 0.05) to total cholesterol (r = 0.362), triglycerides (r = 0.449), and low-density lipoprotein cholesterol (r = 0.359). Moreover, plasma dityrosine (r = 0.408), AOPP (r = 0.488), and MDA (r = 0.181) levels were elevated with an increase in the atherosclerosis index in the subjects. CONCLUSIONS: These findings suggest that dityrosine formation may be an early event in the pathological process of hyperlipidemia. Dityrosine as a biomarker detected by fluorescence spectrophotometry might be a useful tool to evaluate the plasma redox state in hyperlipidemia.

Antioxidant and antibacterial activities of extracts from Conyza bonariensis growing in Yemen.

This study aims to examine the antioxidant and antibacterial activities and phenolic contents of Conyza bonariensis growing in Yemen. The whole plants of C. bonariensis were ultrasonically extracted by ethanol. The antioxidant activity of the extract was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ß-carotene bleaching (BCB). The effectiveness of the extract on the growth inhibition of some indicators of foodborne illness bacteria were investigated by agar well diffusion assay. The total phenols (TP), total flavonoids (TF), total tannins (TT), and total anthocyanins (TA) were determined by Folin-Ciocalteu method, aluminium chloride method, Folin and Ciocalteu method, and pH-differential method, respectively. The extract of C. bonariensis possessed TP 144.1 mg/g, TF 143 mg/g, TT 0.99mg/g, and TA 0.97mg 100g, with 94.57% inhibition of DPPH and 92.47% inhibition of BCB, and strong inhibitory effects against tested bacteria, which was approximate to those of peel extract of Punica granatum.

Inhibition of Fe-induced colon oxidative stress by lactobacilli in mice.

Iron (Fe) can promote hydrogen peroxide (H(2)O(2)) and hydroxyl radical generation in the colonic surface and promote growth of Fe-dependent bacteria. Some Lactobacillus strains are resistant to oxygen free-radicals, allowing them to survive in a Fe-modulated mucosal environment and influence colon microbial ecology and redox state. Here, we investigated the capacity of lactobacilli with different antioxidant abilities to modify the bacterial profile and prevent oxidative stress in the colon of Fe-overloaded mice. Survival time of Lactobacillus rhamnosus LGG (LGG) in the presence of H(2)O(2) and hydroxyl radical was significantly longer compared with the mid- and non-antioxidative strains, Lactobacillus paracasei Fn032 and Lactobacillus plantarum Fn001, respectively. Different Lactobacillus strains are specific in free-radical scavenging activities of their cell-free extracts, which increased to varying extent depending on strains when bacteria were exposed to simulated gastric and pancreatic juice. Fe-overloaded mice showed increased colonic luminal ferrous Fe content, Enterococcus and Escherichia coli concentrations, mucosal malondialdehyde and free-radicals, and decreased mucosal total antioxidative capacity and oxidative enzymatic activity. Translocation of endotoxin to the liver was also significantly increased (P < 0.05). Lactobacilli inhibited ferrous Fe accumulation, especially in LGG and Fn032. LGG significantly inhibited the increase of colonic mucosal free-radicals and malondialdehyde content (P < 0.05). Fn032 only inhibited malondialdehyde (P < 0.05). LGG and Fn032 significantly inhibited increases in colonic Enterococcus (P < 0.05). Fn001 showed no significant antioxidative ability in vivo. The difference of these effects in vivo were well agreed with scavenging activities against reactive oxygen species (ROS) of simulated gastrointestinals fluid pretreated cells in vitro. In conclusion, ROS scavenging activities was essential for Lactobacillus to prevent oxidative stress in vivo and inhibition of ROS-producing bacterial growth and mucosal barrier injury.

[Molecular design, structural analysis and bactericidal activity of derivatives of antimicrobial peptide buforin II].

A novel peptide, named BF2-X, was designed based on the structure-activity analysis of an analogue of Buforin II, named BF2-A. The BF2-X was a hybrid peptide containing the N-terminal residues 5 to 13 of BF2-A and three repeats of the C-terminal regular alpha-helical motif RLLR, and the residues 8 valine were replaced by leucine. The results of bioinformatics analysis had showed that compared with BF2-A, the helicity, positive charge, hydrophobicity rate and C-terminal amphipathy of BF2-X had remarkably enhanced. Both peptides showed a random coil structure in an aqueous solution, while displaying a typical alpha-helical structure in 50% trifluoroethanol solution (a membrane mimic condition). BF2-X exhibited higher alpha-helical contents than BF2-A in hydrophobic environment. BF2-X displayed potent antimicrobial activities against a broad spectrum of microorganisms. And BF2-X showed stronger antimicrobial activities against bacteria tested than parent peptide BF2-A. These results suggest that the alpha-helical content was directly correlated with the enhanced antibacterial activity. Both peptides had no hemolytic action on mouse erythrocyte.

Microarray analysis of high-glucose diet-induced changes in mRNA expression in jejunums of C57BL/6J mice reveals impairment in digestion, absorption.

Long term intake of high-glucose diet (HGD) may induce many diseases such as dyslipidemia, fatty liver and diabetes disease. Most of the research for molecular mechanisms of the association between HGD and the above diseases focus on the metabolism of glucose and lipid. However, there are few studies on molecular mechanism of the effect of HGD on digestion and absorption. We used HGD (containing 20% glucose) to feed C57BL/6J mice for 4 weeks, detected the expressions of 13,098 genes in jejunums of C57BL/6J mice with DNA microarray. Microarray analysis showed the expression of genes related to digestive enzyme, gastrointestinal peptide and nutrient transporters were significantly changed, which indicated that HGD induced the suppression of digestive enzyme gene expression, attenuation of alimentary tract movement and nutrient transportation. In one word, the microarray analysis suggested that HGD impaired the function of digestion and absorption in jejunum of C57BL/6J mice. We validated our microarray findings by conducting real-time RT-PCR assays on selected genes and detecting the activities of disaccharidases such as lactase, maltase and sucrase in jejunum of C57BL/6J mice.

Oxidative stress induced by high-glucose diet in liver of C57BL/6J mice and its underlying mechanism.

High glycemic index diet can induce multiple diseases. Many research indicated that oxidative stress played important role in many pathological conditions. However, the impact of gene expression and dietary habit on oxidation process are still less clear. We used high-glucose diet to feed C57BL/6J mice for 4 weeks, measured the redox status, physiological and biochemical changes related to diabetes and consequence of metabolic syndrome (nonalcoholic fatty liver, cardiovascular disease), and detected the expressions of 14,446 genes in liver of C57BL/6J mice with DNA microarray. The results showed high-glucose diet induced elevated fatty acid accumulation in liver, insulin resistance index and higher weight in C57BL/6J mice, which indicated high-glucose diet caused to the initiation and development of diabetes and consequence of metabolic syndrome. The results also showed high-glucose diet induced oxidative stress in liver of C57BL/6J mice, which might the cause of initiation and development of diabetes and consequence of metabolic syndrome. Microarray analysis found expressions of genes related to thiol redox, fatty acid oxidation in peroxisome and cytochrome P450 were significantly changed, indicating system in which non-enzyme antioxidant capacity was impaired and sources from which reactive oxygen species (ROS) generated, which revealed the molecular mechanism of oxidative stress induced by high-glucose diet. We validated our microarray findings by conducting real-time RT-PCR assays on selected genes.

Antioxidative peptides derived from enzyme hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection.

This study focused on the preparation method of antioxidant peptides by enzymatic hydrolysis of bone collagen after microwave assisted acid pre-treatment and nitrogen protection. Phosphoric acid showed the highest ability of hydrolysis among the four other acids tested (hydrochloric acid, sulfuric acid and/or citric acid). The highest degree of hydrolysis (DH) was 9.5% using 4 mol/L phosphoric acid with a ratio of 1:6 under a microwave intensity of 510 W for 240 s. Neutral proteinase gave higher DH among the four protease tested (Acid protease, neutral protease, Alcalase and papain), with an optimum condition of: (1) ratio of enzyme and substrate, 4760 U/g; (2) concentration of substrate, 4%; (3) reaction temperature, 55 °C and (4) pH 7.0. At 4 h, DH increased significantly (P < 0.01) under nitrogen protection compared with normal microwave assisted acid pre-treatment hydrolysis conditions. The antioxidant ability of the hydrolysate increased and reached its maximum value at 3 h; however DH decreased dramatically after 3 h. Microwave assisted acid pre-treatment and nitrogen protection could be a quick preparatory method for hydrolyzing bone collagen.

Dityrosine suppresses the cytoprotective action of thyroid hormone T3 via inhibiting thyroid hormone receptor-mediated transcriptional activation.

Dityrosine (Dityr) is the most common oxidized form of tyrosine. In the previous studies of mice treated with dityrosine, cell death in the pancreas, kidneys, and liver was detected in the presence of enhanced plasma triiodothyronine (T3) content. Due to its structural similarity with the thyroid hormone T3, we hypothesized that dityrosine might disrupt T3-dependent endocrine signaling. The cytotoxic effect of dityrosine was studied in C57BL/6 mice by gavage with a dityrosine dose of 320 µg per kg per day for 10 weeks. Cell death in the liver was detected in the presence of enhanced plasma thyroid hormone content in mice treated with dityrosine. The antagonistic effect of dityrosine on T3 biofunction was studied using HepG2 cells. Dityrosine incubation reduced T3 transport ability and attenuated the T3-mediated cell survival via regulation of the PI3k/Akt/MAPK pathway. Furthermore, dityrosine inhibited T3 binding to thyroid hormone receptors (TRs) and suppressed the TR-mediated transcription. Dityrosine also downregulated the expressions of T3 action-related factors. Taken together, this study demonstrates that dityrosine inhibits T3-dependent cytoprotection by competitive inhibition, resulting in downstream gene suppression. Our findings offer insights into how dityrosine acts as an antagonist of T3. These findings shed new light on cellular processes underlying the energy metabolism disorder caused by dietary oxidized protein, thus contributing to a better understanding of the diet-health axis at a cellular level.

[Correlation of serum carnitine levels with age and sex among Chinese adults in Nanjing].

OBJECTIVE: Carnitine, the only carrier for fatty acid to enter mitochondria for oxidation, has significant effects on serum lipids metabolism and male fertility. This study aimed to investigate the correlation of serum carnitine levels with sex and age among healthy Chinese adults in Nanjing. METHODS: We obtained fasting blood samples from 347 healthy Chinese adults in Nanjing (182 males, 165 females, aged from 20 to 89), determined the levels of serum free, acylcarnitine and total carnitine by high performance liquid chromatography with pre-column ultraviolet derivatization, and analyzed the correlation of serum carnitine levels with the age and sex of the subjects. RESULTS: Total and free carnitine levels were significantly higher in the males than in the females (P < 0.05) while no statistically significant differences were found in the acylcarnitine level (P > 0.05). Among those aged between 20 to 50 years, levels of serum free and total carnitine were significantly higher in men than in women (P < 0.05) and they increased with age in females, but with no significant differences between males and females older than 50 years. The acylcarnitine level showed no obvious differences in any age and sex groups. CONCLUSION: Serum free and total carnitine levels are correlated with sex and age in healthy adults.

Lipoic acid prevents high-fat diet-induced dyslipidemia and oxidative stress: a microarray analysis.

OBJECTIVE: We previously found that lipoic acid (LA) improved high-fat diet (HFD)-induced dyslipidemia in rats. To elucidate the molecular mechanisms of that effect, we carried out experiments aimed at analyzing biochemical parameters and gene expression profiles. METHODS: C57BL/6 mice were randomly assigned to one of three groups (n = 8). The control group consumed an ordinary diet (4.89% fat, w/w). The other two experimental groups were fed with an HFD (21.45% fat, w/w) or an HFD plus 0.1% LA. After 6 wk, plasma lipid level and antioxidant status were examined. To investigate the molecular mechanisms underlying the effects of LA on lipid metabolism and oxidative stress, we examined gene expression profiles in liver using the GeneChip microarray system. The differential expression of genes of interest identified by microarray technique was validated by real-time reverse transcription-polymerase chain reaction. RESULTS: HFD resulted in significant alterations in lipid profiles and a depressed antioxidant defense system. LA supplementation induced decreases in lipid peroxidation, plasma cholesterol, triacylglycerols, and low-density lipoprotein cholesterol and an increase in high-density lipoprotein in HFD-fed mice. DNA microarray analysis of the liver showed that LA ingestion upregulated the expression of genes related to beta-oxidation and free radical scavenger enzymes, whereas those involved in cholesterol synthesis were downregulated. CONCLUSION: LA can prevent HFD-induced dyslipidemia by modulating lipid metabolism, especially by increasing beta-oxidation and decreasing cholesterol synthesis, and oxidative stress by increasing those of free radical scavenger enzyme gene expression.

Insertion mode of a novel anionic antimicrobial peptide MDpep5 (Val-Glu-Ser-Trp-Val) from Chinese traditional edible larvae of housefly and its effect on surface potential of bacterial membrane.

Antimicrobial molecules from insects may serve as a potentially significant group of antibiotics. To identify the effect of antimicrobial peptides (AMPs) on bacterial membrane and obtain further insight in the mechanism of membrane transport of AMPs, the interaction of surface potential and permeation of a novel antimicrobial peptide MDpep5 (Val-Glu-Ser-Trp-Val) from Chinese traditional edible larvae of housefly was examined using liposomes from bacterial lipids extract. Compared with the cationic AMPs, MDpep5 cannot completely disrupt membrane. The uptake of MDpep5 by bacterial liposomes was dependent on the membrane surface potential. The mutual inhibition of the transport of MDpep5 through the cell membrane was caused by the change in surface potential due to the binding of MDpep5 to the membrane. Furthermore, formation of MDpep5-enriched lipid aggregates could lead to the disorder of the bilayer structure. Based on our experimental data, we propose that MDpep5 initiated its antimicrobial activity by profoundly disordering the structure and affecting physical properties of bacterial membrane when binding to the phospholipid which accounts for its bactericidal activity.

Increasing Oxidative Stress with Progressive Hyperlipidemia in Human: Relation between Malondialdehyde and Atherogenic Index.

The aim of this study was to examine whether malondialdehyde (MDA) formation, a marker of oxidant stress, is altered in different stages of development of hyperlipidemia and whether it correlates with atherogenic index (AI), an important risk factor of atherosclerosis. Commercial kits were used to measure the levels of lipid profile and antioxidant status in the serum of 15 hyperlipidemic patients and 30 age and sex-matched normolipidemic subjects. The normolipidemic subjects were divided into lower and higher lipid groups according to their blood lipid level. The activities of superoxide dismutase and glutathione peroxidase decreased in higher lipid group compared with lower lipid group, and were even lower in hyperlipidemic subjects. An increase in the levels of MDA, triglycerides, total cholesterol and LDL-C concentration were observed in higher lipid group, and even significantly increased in hyperlipidemic patients. A significant progressive decline in HDL-C concentration was found during hyperlipidemia evolution. There was a positive correlation between MDA and AI (r = 0.61, p<0.05). These data indicate that oxidative stress is an early event in the evolution of hyperlipidemia, and appropriate support for enhancing antioxidant supply in higher lipid subjects may help prevent the course of the disease.

In vitro free radical scavenging activities and effect of synthetic oligosaccharides on antioxidant enzymes and lipid peroxidation in aged mice.

In this study we synthesized oligosaccharides using glucose as reactant via a route assisted by microwave irradiation and evaluated their antioxidant activity in vivo and in vitro. The results show that the oligosaccharides exhibited antioxidant activity in vitro as compared to standard antioxidants such as butylated hydroxytoluene (BHT), and alpha-tocopherol. This antioxidant activity depended on concentration and increased with increasing dose of sample. In addition, increased endogenous lipid peroxidation and decreased total antioxidant capacity (TAOC) were observed in aged mice. Thirty-day intraperitoneal administration of the oligosaccharides significantly decreased the lipid peroxidation in a dose-dependent manner. Oligosaccharides treatment increased TAOC and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in all organs tested in aged mice. The present study suggests that the synthetic oligosaccharides possess promising future for their strong free radical scavenging activity. Therefore they can be employed in compensating the decline in TAOC and the activities of antioxidant enzymes and in reducing the risks of lipid peroxidation.

Role of miR-383 and miR-146b in different propensities to obesity in male mice.

The study was designed to investigate the possible mechanisms of hepatic microRNAs (miRs) in regulating local thyroid hormone (TH) action and ultimately different propensities to high-fat diet (HFD)-induced obesity. When obesity-prone (OP) and obesity-resistant (OR) mice were fed HFD for 7 weeks, OP mice showed apparent hepatic steatosis, with significantly higher body weight and lower hepatic TH receptor b (TRb) expression and type 1 deiodinase (DIO1) activity than OR mice. Next-generation sequencing technology revealed that 13 miRs in liver were dysregulated between the two phenotypes, of which 8 miRs were predicted to target on Dio1 or TRb When mice were fed for 17 weeks, OR mice had mild hepatic steatosis and increased Dio1 and TRb expression than OP mice, with downregulation of T3 target genes (including Srebp1c, Acc1, Scd1 and Fasn) and upregulation of Cpt1α, Atp5c1, Cox7c and Cyp7a1 A stem-loop qRT-PCR analysis confirmed that the levels of miR-383, miR-34a and miR-146b were inversely correlated with those of DIO1 or TRb. Down-regulated expression of miR-383 or miR-146b by miR-383 inhibitor (anti-miR-383) or miR-146b inhibitor (anti-miR-146b) in free fatty acid-treated primary mouse hepatocytes led to increased DIO1 and TRb expressions, respectively, and subsequently decreased cellular lipid accumulation, while miR-34a inhibitor (anti-miR-34a) transfection had on effects on TRb expression. Luciferase reporter assay illustrated that miR-146b could directly target TRb 3'untranslated region (3'UTR). These findings suggested that miR-383 and miR-146b might play critical roles in different propensities to diet-induced obesity via targeting on Dio1 and TRb, respectively.

Isolation and analyses of genes preferentially expressed during early cotton fiber development by subtractive PCR and cDNA array.

Cotton fibers are differentiated epidermal cells originating from the outer integuments of the ovule. To identify genes involved in cotton fiber elongation, we performed subtractive PCR using cDNA prepared from 10 days post anthesis (d.p.a.) wild-type cotton fiber as tester and cDNA from a fuzzless-lintless (fl) mutant as driver. We recovered 280 independent cDNA fragments including most of the previously published cotton fiber-related genes. cDNA macroarrays showed that 172 genes were significantly up-regulated in elongating cotton fibers as confirmed by in situ hybridization in representative cases. Twenty-nine cDNAs, including a putative vacuolar (H+)-ATPase catalytic subunit, a kinesin-like calmodulin binding protein, several arabinogalactan proteins and key enzymes involved in long chain fatty acid biosynthesis, accumulated to greater than 50-fold in 10 d.p.a. fiber cells when compared to that in 0 d.p.a. ovules. Various upstream pathways, such as auxin signal transduction, the MAPK pathway and profilin- and expansin-induced cell wall loosening, were also activated during the fast fiber elongation period. This report constitutes the first systematic analysis of genes involved in cotton fiber development. Our results suggest that a concerted mechanism involving multiple cellular pathways is responsible for cotton fiber elongation.

In silico study on ß-aminoketone derivatives as thyroid hormone receptor inhibitors: a combined 3D-QSAR and molecular docking study.

In order to explore the structure-activity correlation of a series of ß-aminoketone analogs as inhibitors of thyroid hormone receptor (TR), a set of three-dimensional quantitative structure-activity relationship (3D-QSAR) models based on comparative molecular field analysis (CoMFA) and comparative molecular similarity analysis (CoMSIA), for the first time, were developed in the present work. The best CoMFA model with steric and electrostatic fields exhibited [Formula: see text], [Formula: see text] for TRß, and [Formula: see text], [Formula: see text] for TRα. 3D contour maps produced from the optimal models were further analyzed individually, which provide the areas in space where interactive fields would affect the inhibitory activity. In addition, the binding modes of inhibitors at the active site of TRs were examined using molecular docking, the results indicated that this series of inhibitors fit into the active site of TRs by forming hydrogen bonding and electrostatic interactions. The docking studies also revealed that Leu305, Val458 for TRß, and Asp407 for TRα are showing hydrogen bonds with the most active inhibitors. In any case, the 3D-QSAR models combined with the binding information will serve as a useful approach to explore the chemical space for improving the activity of TRß and TRα inhibitors.

Structure-based approach for the study of thyroid hormone receptor binding affinity and subtype selectivity.

Thyroid hormone (TH) possesses the ability to lower cholesterol and improve cardiac performance, which have prompted the efforts to design analogs that can utilize the cholesterol-lowering property without adversely affecting heart function. In order to gain insights into the interaction mechanism for agonists at the active site of thyroid hormone receptor ß (TRß), quantitative structure-activity relationship (QSAR) models have been developed on TRß agonists, significant statistical coefficients were obtained (CoMFA, R(2)cv, .732), (CoMSIA, R(2)cv, .853), indicating the internal consistency of the models, the obtained models were further validated using the test set, the acquired R(2)pred values .7054 and .7129 were in good agreement with the experimental results. The key amino acids affecting ligand binding were identified by molecular docking, and the detailed binding modes of the compounds with different activities were also determined. Furthermore, molecular dynamics (MD) simulations were conducted to assess the reliability of the derived models and the docking results. Moreover, TH exerts significant physiological effects through modulation of the two human thyroid hormone receptor subtypes. Because TRß and TRα locate in different target cells, selective TR ligands would target specific tissues regulated by one receptor without affecting the other. Thus, the 3D information was analyzed to reveal the most relevant structural features involved in selectivity. The findings serve as the basis for further investigation into selective TRß/TRα agonists.

Cloning and functional characterization of two cDNAs encoding NADPH-dependent 3-ketoacyl-CoA reductased from developing cotton fibers.

Genes encoding enzymes involved in biosynthesis of very long chain fatty acids were significantly up-regulated during early cotton fiber development. Two cDNAs, GhKCR1 and GhKCR2 encoding putative cotton 3-ketoacyl-CoA reductases that catalyze the second step in fatty acid elongation, were isolated from developing cotton fibers. GhKCR1 and 2 contain open reading frames of 963 bp and 924 bp encoding proteins of 320 and 307 amino acid residues, respectively. Quantatitive RT-PCR analysis showed that both these genes were highly preferentially expressed during the cotton fiber elongation period with much lower levels recovered from roots, stems and leaves. GhKCR1 and 2 showed 30%-32% identity to Saccharomyces cerevisiae Ybr159p at the deduced amino acid level. These cotton cDNAs were cloned and expressed in yeast haploid ybr159wD mutant that was deficient in 3-ketoacyl-CoA reductase activity. Wild-type growth rate was restored in ybr159wD cells that expressed either GhKCR1 or 2. Further analysis showed that GhKCR1 and 2 were co-sedimented within the membranous pellet fraction after high-speed centrifugation, similar to the yeast endoplasmic reticulum marker ScKar2p. Both GhKCR(s) showed NADPH-dependent 3-ketoacyl-CoA reductase activity in an in vitro assay system using palmitoyl-CoA and malonyl-CoA as substrates. Our results suggest that GhKCR1 and 2 are functional orthologues of ScYbr159p.

Distinct immune response induced by peptidoglycan derived from Lactobacillus sp.

AIM: To analyze the distinct immune responses induced by Lactobacillus peptidoglycan (PG). METHODS: BALB/c mice were intraperitoneally injected with PG once a day for three consecutive days. Peritoneal macrophage and splenocyte mRNA was extracted and the gene expression profile was studied using high-density oligonucleotide microarrays. Inhibitory effects of Lactobacillus PG on colon tumor tissue were studied in vitro and in vivo. RESULTS: The gene expression profiles revealed that the TLR-NF-kappaB; and Jak-STAT signaling pathways were highly activated. An inflammatory phenotype was induced when peritoneal macrophages were initially exposed to Lactobacillus PG and switched to a more complex phenotype when BALB/c mice were treated with three doses of Lactobacillus PG. A protective physiological inflammatory response was induced after three consecutive days of PG treatment. It was tending toward Th1 dominant immune response. Lactobacillus PG also appeared to induce a significant in vivo anti-colon tumor effect. CONCLUSION: Lactobacillus PG is responsible for certain immune responses induced by Lactobacilli. Anti-tumor effects of Lactobacilli are likely to attribute to the activation of macrophages by PG expressed on the bacterial cell surface.

Direct spectrophotometric measurement of angiotensin I-converting enzyme inhibitory activity for screening bioactive peptides.

A direct, extraction-free spectrophotometric assay was developed for determination of angiotensin I-converting enzyme activity (ACE) in the presence of ACE inhibitors using hippuryl-l-histidyl-l-leucine (HHL) as the ACE-specific substrate. This method relies on previously published spectrophotometric determination of hippuric acid (HA) content in the urine, the method of which was based on the specific colorimetric reaction of HA with benzene sulfonyl chloride (BSC) in the presence of quinoline. The proposed ACE inhibition assay was applied to the measurement of the ACE inhibitory activity of Captopril. IC(50) value of Captopril corresponded well with literature data. Furthermore, Alcalase hydrolysates of mung bean and rice protein isolates were assessed for ACE inhibitory activity by this method. These two hydrolysates showed high ACE inhibitory activity. This method proposed here was shown to be direct, sensitive, accurate, reproducible, and less expensive without separation of HA from ACE reaction mixture, and can be used for the screening of ACE inhibitory peptides derived from food proteins.