Influence of enzyme source and catechins on theaflavins formation during in vitro liquid-state fermentation

LWT ◽  
2021 ◽  
Vol 139 ◽  
pp. 110291
Author(s):  
Jinjie Hua ◽  
Huajie Wang ◽  
Yongwen Jiang ◽  
Jia Li ◽  
Jinjin Wang ◽  
...  
Keyword(s):  
Liquid State ◽  
Enzyme Source

scholarly journals Valorization of onion extracts as anti-browning agents

2020 ◽  
Vol 3 (1) ◽  
pp. 16
Author(s):  
Anna Lante ◽  
Federica Tinello ◽  
Dasha Mihaylova
Keyword(s):  
Fruits And Vegetables ◽  
Colour Change ◽  
Electrophoretic Analysis ◽  
In Vitro Assays ◽  
Enzymatic Browning ◽  
Inhibitor Type ◽  
Enzyme Source ◽  
New Strategies

The enzymatic browning, whose main responsible is polyphenol oxidase (PPO, EC 1.14.18.1), is involved in the phenolic oxidation and colour alteration of minimally-processed fruits and vegetables. Currently, the research of new strategies to inactivate PPO is moving towards replacing synthetic additives such as organic acids and sulphites with natural inhibitors. The present study is focused on investigating the anti-browning performance of juices and distillates obtained from three onion varieties (white, yellow, and red) and Borettana onion wastes (inner layers). Their inhibitory activity on a commercial mushroom tyrosinase and some plant PPOs has been evaluated by spectrophotometric and electrophoretic analysis. The in vivo trials has been also carried out by monitoring over time at room temperature the colour change on potato slices under accelerated browning conditions. The effectiveness of onion samples in limiting enzymatic browning was affected by not only the enzyme source but also inhibitor type. Although distillates had higher anti-PPO capacity as confirmed by in vitro assays, juices showed better in vivo effectiveness. Hence, onions and their wastes can be valorised as a natural source of anti-browning agents to control PPO activity thus preserving sensory, antioxidant and nutritional properties of agro-food products.

The Effects of Pretreatment of Mice with Norethindrone on the Metabolism of 14C-imipramine by the Liver Microsomal Drug-Metabolizing Enzymes

1974 ◽  
Vol 52 (1) ◽  
pp. 28-38 ◽  
Author(s):  
G. D. Bellward ◽  
R. G. Morgan ◽  
V. H. Szombathy
Keyword(s):  
Female Mouse ◽  
Mouse Liver ◽  
Competitive Inhibition ◽  
Drug Metabolizing Enzymes ◽  
Concurrent Administration ◽  
Metabolizing Enzymes ◽  
Assay Procedure ◽  
Cytochrome P 450 ◽  
Enzyme Source

An assay procedure for the metabolism of 14C-imipramine in vitro is described. Using female mouse liver as the enzyme source, the conditions of the assay have been determined for the formation of 2-hydroxyimipramine, desmethylimipramine, and imipramine-N-oxide. Demethylation was linear up to a substrate concentration of 120 μg/3.5 ml, N-oxidation was linear up to a concentration of imipramine of 70 μg/3.5 ml, and hydroxylation up to 20 μg/3.5 ml of reaction mixture. Desmethylimipramine competitively inhibited both hydroxylation and demethylation, whereas imipramine-N-oxide had no effect. Pretreatment of mice with norethindrone decreased hydroxylation, and increased demethylation. Cytochrome P-450 was also increased by this progestin; N-oxidation was not changed. The effects of concurrent administration of norethindrone with known inducers or inhibitors of drug metabolism have been determined. From these experiments, it was concluded that the induction of cytochrome P-450 by norethindrone is not responsible for the increased demethylation of imipramine. Rather, it appeared that competitive inhibition of hydroxylation of imipramine by the norethindrone allowed more of the drug to be demethylated.

Bispyridinium Oximes As Antidotal Treatment of Cyclosarin Poisoning—In Vitro and In Vivo Testing

2005 ◽  
Vol 24 (6) ◽  
pp. 399-402 ◽  
Author(s):  
Lucie Bartosova ◽  
Kamil Kuca ◽  
Daniel Jun ◽  
Gabriela Kunesova
Keyword(s):  
Rat Brain ◽  
Organophosphorus Compounds ◽  
Brain Homogenate ◽  
Chemical Structures ◽  
Hi 6 ◽  
In Vivo Testing ◽  
Acetylcholinesterase Enzyme ◽  
Enzyme Source

The mechanism of intoxication with organophosphorus compounds, including highly toxic nerve agents and less toxic pesticides, is based on the formation of irreversibly inhibited acetylcholinesterase, which causes cumulation of neuromediator acetylcholine in synaptic clefts and subsequent overstimulation of cholinergic receptors, that is followed by a generalized cholinergic crisis. Nerve agent poisoning is conventionally treated using a combination of a cholinolytic (atropine mostly) to counteract the accumulation of acetylcholine and acetylcholinesterase reactivators (pralidoxime or obidoxime) to reactivate inhibited acetylcholinesterase. In this study of cyclosarin poisoning treatment, oximes of different chemical structures (obidoxime, HI-6, BI-6, and HS-6) were tested in vitro on rat brain acetylcholinesterase (enzyme source: rat brain homogenate), and afterwards, they were tested in vivo in equimolar doses, in mice and rats. The HI-6 oxime appeared to be the most effective oxime in vitro and in vivo.

scholarly journals In Vitro Expanded Bioaccessibility of Quercetin-3-Rutinoside and Quercetin Aglycone from Buckwheat Biscuits Formulated from Flours Fermented by Lactic Acid Bacteria

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 571
Author(s):  
Henryk Zieliński ◽  
Wiesław Wiczkowski ◽  
Joanna Honke ◽  
Mariusz Konrad Piskuła
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Liquid State ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
Lower Content ◽  
Gastrointestinal Digestion ◽  
High Q ◽  
Quercetin Aglycone

The expanded bioaccessibility of rutin (Ru) and quercetin (Q) from buckwheat biscuits (BBs) formulated from liquid-state fermented flours by selected lactic acid bacteria (LAB) were determined after gastrointestinal digestion. Fermentation of buckwheat flours caused a LAB-dependent variation in Ru and Q content. BBs baked at 220 °C for 30 min showed lower content of Ru and Q, and no correlation was found between the content of these compounds in fermented flours and BBs. The expanded bioaccessibility of Ru from BBs was low when its content in the soluble and insoluble fractions remaining after digestion in vitro was taken into account. Contrary results were found for Q bioaccessibility which had an index greater than 1, indicating the high Q bioaccessibility from BBs. Since very low Q content was noted in the insoluble fraction remaining after BBs digestion, the high Q bioaccessibility was determined to be due to its concentration in the soluble fraction.

scholarly journals Different digestion of caprine whey proteins by human and porcine gastrointestinal enzymes

2010 ◽  
Vol 104 (3) ◽  
pp. 374-381 ◽  
Author(s):  
Ellen K. Eriksen ◽  
Halvor Holm ◽  
Einar Jensen ◽  
Ragnhild Aaboe ◽  
Tove G. Devold ◽  
...  
Keyword(s):  
Whey Proteins ◽  
Heavy Chains ◽  
Commercial Enzymes ◽  
Gastrointestinal Enzymes ◽  
Stomach Ph ◽  
Peptide Profiles ◽  
Β Lactoglobulin ◽  
Enzyme Source

The objective of the present study was twofold: first to compare the degradation patterns of caprine whey proteins digested with either human digestive juices (gastric or duodenal) or commercial porcine enzymes (pepsin or pancreatic enzymes) and second to observe the effect of gastric pH on digestion. An in vitro two-step assay was performed at 37°C to simulate digestion in the stomach (pH 2, 4 or 6) and the duodenum (pH 8). The whey proteins were degraded more efficiently by porcine pepsin than by human gastric juice at all pH values. Irrespective of the enzyme source, gastric digestion at pH 2 followed by duodenal digestion resulted in the most efficient degradation. Lactoferrin, serum albumin and the Ig heavy chains were highly degraded with less than 6 % remaining after digestion. About 15, 56 and 50 % Ig light chains, β-lactoglobulin (β-LG) and α-lactalbumin remained intact, respectively, when digested with porcine enzymes compared with 25, 74 and 81 % with human digestive juices. For comparison, purified bovine β-LG was digested and the peptide profiles obtained were compared with those of the caprine β-LG in the digested whey. The bovine β-LG seemed to be more extensively cleaved than the caprine β-LG in the whey. Commercial enzymes appear to digest whey proteins more efficiently compared with human digestive juices when used at similar enzyme activities. This could lead to conflicting results when comparing human in vivo protein digestion with digestion using purified enzymes of non-human species. Consequently the use of human digestive juices might be preferred.

scholarly journals Cloning and Characterization of Archaeal Type I Signal Peptidase from Methanococcus voltae

2003 ◽  
Vol 185 (20) ◽  
pp. 5936-5942 ◽  
Author(s):  
Sandy Y. M. Ng ◽  
Ken F. Jarrell
Keyword(s):  
Gene Product ◽  
Signal Peptidase ◽  
Type I ◽  
Peptidase Activity ◽  
E Coli ◽  
Methanococcus Voltae ◽  
Signal Peptidase I ◽  
Archaeal Gene ◽  
Enzyme Source

ABSTRACT Archaeal protein trafficking is a poorly characterized process. While putative type I signal peptidase genes have been identified in sequenced genomes for many archaea, no biochemical data have been presented to confirm that the gene product possesses signal peptidase activity. In this study, the putative type I signal peptidase gene in Methanococcus voltae was cloned and overexpressed in Escherichia coli, the membranes of which were used as the enzyme source in an in vitro peptidase assay. A truncated, His-tagged form of the M. voltae S-layer protein was generated for use as the substrate to monitor the signal peptidase activity. With M. voltae membranes as the enzyme source, signal peptidase activity in vitro was optimal between 30 and 40°C; it was dependent on a low concentration of KCl or NaCl but was effective over a broad concentration range up to 1 M. Processing of the M. voltae S-layer protein at the predicted cleavage site (confirmed by N-terminal sequencing) was demonstrated with the overexpressed archaeal gene product. Although E. coli signal peptidase was able to correctly process the signal peptide during overexpression of the M. voltae S-layer protein in vivo, the contribution of the E. coli signal peptidase to cleavage of the substrate in the in vitro assay was minimal since E. coli membranes alone did not show significant activity towards the S-layer substrate in in vitro assays. In addition, when the peptidase assays were performed in 1 M NaCl (a previously reported inhibitory condition for E. coli signal peptidase I), efficient processing of the substrate was observed only when the E. coli membranes contained overexpressed M. voltae signal peptidase. This is the first proof of expressed type I signal peptidase activity from a specific archaeal gene product.

THE ROLE OF REDUCED GLUTATHIONE IN THYROGLOBULIN PROTEOLYSIS IN VITRO

1975 ◽  
Vol 79 (1) ◽  
pp. 76-85 ◽  
Author(s):  
M. A. Pisarev ◽  
J. E. Dumont
Keyword(s):  
Tissue Concentration ◽  
Reduced Glutathione ◽  
Hormone Secretion ◽  
Low Ph ◽  
Acid Protease ◽  
Ph Optimum ◽  
Distribution Studies ◽  
Enzyme Source

ABSTRACT During the process of secretion of the thyroid hormones, stored thyroglobulin (Tg) is digested within the lysosomes. An acid protease has been found, but this enzyme hydrolyses Tg at a relatively slow rate and has a low pH optimum (3.6). Since previous work has shown a stimulatory effect of reduced glutathione (GSH) on Tg digestion the following studies have been performed. Homogenates were obtained from dog thyroid and total homogenate or different subcellular fractions were used as enzyme source. Labelled thyroglobulin (125I) was purified from prelabelled dog thyroid and its hydrolysis, judged from the increase in butanol soluble radioactivity, was studied. The greatest stimulatory effect of GSH on Tg hydrolysis was found around pH 5.6. When butanol soluble radioactivity was considered as a function of incubation time and tissue concentration a linear relationship was found. GSH effect was evident at 2 mm. Subcellular distribution studies showed that the GSH-stimulated proteolytic activity was mainly found in the 15 000 × g pellet. Labelled Tg hydrolysis was progressively decreased with increasing amounts of non-labelled purified Tg. GSH also stimulated labelled insulin hydrolysis, but failed to alter haemoglobin or casein degradation. GSH could also be replaced by other reducing agents, like cysteine or dithiothreitol. The significance of these findings is discussed in relation to the process of thyroid hormone secretion.

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