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Oxidative damage has been implicated in the pathogenesis of numerous disorders by affecting the normal functions of several tissues. Further, oxidative stress acts within cells to influence cell morphology and the behavior of cell migration. The movement and migration of cells are crucial during the development of organisms as they transition from embryo to adult, and for the homeostasis of adult tissues. Epicatechin (EC) is a natural flavonoid derived mostly from tea, chocolate, and red wine. We investigated the protective impact of EC on D-galactose(D-gal)/rotenone-injured NIH3T3 cells and found alterations in cell dynamics throughout the procedure. The results reveal that D-gal/rotenone stimulation can cause the cell area to expand and the number of cellular protrusions to increase. EC intervention can considerably minimize the oxidative damage of rotenone on NIH3T3 cells (p < 0.05) but showed little influence on cell damage induced by D-gal. Furthermore, the corrective ability of EC as an antioxidant is reflected in a dose-dependent effect on cell movement, including variations in movement speed and distance. Overall, from the perspective of cell morphology and cell motility, EC has a good protective impact on cells harmed by rotenone induced oxidative damage, as well as corrective properties as an antioxidant to balance intracellular oxidative stress, which allowing for a more comprehensive evaluation of antioxidant performance of EC., (© 2023 American Institute of Chemical Engineers.)

The antioxidative activity of natural products has commonly been studied by free radical scavenging methods. However, the mechanisms by which antioxidation is explored by free radical scavenging methods remain largely unknown. This study analyzed the composition of walnut-derived pentapeptides PW5 with potential biological activity and its oxidation reaction products in 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) test by nuclear magnetic resonance (NMR) spectroscopy. The amino acid sequence of PW5 peptide successfully characterized as Proline-Proline-Lysine-Asparagine-Tryptophan exhibited significant antioxidant activity with lower IC 50 value (0.2210 ± 0.0032 mM) compared to glutathione (GSH, 0.2567 ± 0.0023 mM, p < 0.001). Furthermore, we found that the tryptophan residue was the only residue in PW5 with obvious alteration after treatment with ABTS free radicals, which was linked to its potential antioxidant properties. These findings revealed how NMR-characterized structures and oxidation reaction products may be used to explore the antioxidative mechanisms of food-derived peptides as well as other natural products., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Schizochytrium limacinum residue was hydrolyzed with various proteases (papain, trypsin, Flavourzyme, Protamex, and Alcalase 2.4L) to obtain antioxidative peptides. The results showed that the S. limacinum hydrolysates (SLHs) prepared with compound proteases (Protamex and Alcalase 2.4L) had the highest antioxidant activity, which was measured using methods such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability (IC 50 = 1.28 mg/mL), hydroxyl radical scavenging ability (IC 50 = 1.66 mg/mL), and reducing power (1.42 at 5.0 mg/mL). The hydrolysates were isolated and purified by ultrafiltration, gel filtration chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). Through analysis of electrospray ionization-mass spectrometer (ESI-MS/MS), the purified antioxidant peptide was identified as Pro-Tyr-Lys (406 Da). Finally, the identified peptide was synthesized for evaluating its antioxidant activity. The •OH scavenging ability and reducing power of Pro-Tyr-Lys were comparable to those of reduced L-glutathione (GSH). These results demonstrated that the antioxidant peptides from SLHs could potentially be used as effective antioxidants.

Two novel peptides WW4 and WW7 were evaluated for their antioxidant activity, membrane penetrance and inhibiting activity of amyloid-β protein (Aβ) aggregation. The results showed that both WW7 (10.38 ± 0.22 μmol TE per μmol) and WW4 (6.32 ± 0.77 μmol TE per μmol) possessed a significant oxygen radical absorption capacity (ORAC) and strong 1,1-diphenyl-2-picrylhydrazyl (DPPH˙) scavenging capacity (WW7, IC50 0.05 ± 0.002; WW4, 1.06 ± 0.07). Interestingly, WW7 exhibited relatively higher antioxidant activity than WW4. In addition, both WW4 and WW7 showed high cell membrane penetrance characteristics in HEK293 cells. To measure the metabolic stability of WW4 and WW7 in cells, we labelled the peptides with FITC and then analyze the co-localization with lysosomes by imaging Flow-cytometry. We found that WW7 had a lower co-localization rate (1.39%) than WW4 (8.44%), indicating that WW7 was more stable than WW4. In vivo imaging assay demonstrated that WW7 presented higher metabolic stability with a much longer stability time (2687.33 ± 54.01 min) in BALB-c nude mice than WW4 (148 ± 26.85 min), which was consistent with the in vitro result. To illustrate the potential function of antioxidant capacity, an Aβ aggregation cell model was applied to examine anti-Aβ aggregation ability of WW4 and WW7. Surprisingly, WW7 (23.04 ± 13.64%) had stronger anti-Aβ aggregation ability but WW4 did not show obvious potential, which was due to their structure difference. The present work would offer novel insight into the activity of antioxidants and anti-Aβ aggregation, and uncover the under-appreciated function of peptides in effective application in AD therapy.

A fast and efficient method for purification of dihydromyricetin (3,5,7,3',4',5'-six hydroxy-2,3-dihydro flavonol; DMY) from Ampelopsis grossedentata was created by crystallization eight times at 25°C, and a purity of 98% was finally achieved. The purified DMY exhibited high oxygen radical absorbance capacity (ORAC) (30.21 μmol Trolox equiv/mg) and strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (half-maximal inhibitory concentration [IC50]=0.235 μg/mL). The addition of DMY could also effectively attenuate 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced human erythrocyte hemolysis and cupric chloride (CuCl2)-induced human plasma lipid peroxidation via inhibition of intracellular reactive oxygen species (ROS) generation. It was also found that DMY (>12 μg/mL) treatment significantly inhibited intracellular malondialdehyde (MDA) formation. Meanwhile, DMY treatment significantly inhibited the obvious increase of anti-oxidant enzymes levels (superoxide dismutase [SOD]; glutathione peroxidase [GPX], and catalase [CAT]) induced by AAPH radicals, suggesting that stress defense mechanisms are associated with protection of DMY against intracellular oxidation.

The intracellular antioxidant activities of diosmetin were evaluated by cellular antioxidant activity (CAA) assay, 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced erythrocyte hemolysis assay and cupric chloride (CuCl2)-induced plasma oxidation assay. The results showed that diosmetin exhibits strong cellular antioxidant activity (EC50 = 7.98 μmol, CAA value = 58 μmol QE/100 μmol). It was also found that diosmetin treatment could effectively attenuate AAPH-induced erythrocyte hemolysis (91.0% inhibition at 100 μg/mL) and CuCl2-induced plasma oxidation through inhibition of intracellular reactive oxygen species (ROS) generation. Diosmetin could significantly restore AAPH-induced increase of intracelluar antioxidant enzyme (SOD, GPx, and CAT) activities to normal levels, as well as inhibit intracellular malondialdehyde (MDA) formation. Thus, the intracellular antioxidant detoxifying mechanism of diosmetin is associated with both nonenzymatic and enzymatic defense systems.

Ultrafiltration, ion-exchange chromatography, and gel filtration chromatography were used to purify anti-oxidant peptides from hydrolysates of soybean protein isolates. The <1-kD peptides were found to exhibit much higher anti-oxidant activity as compared to larger ones. Also, the alkaline peptide fractions were shown to have stronger anti-oxidant capacity than acidic and neutral peptides. Interestingly, an anti-oxidant tripeptide, Ser-Phe-Val (352.4 Da), was identified by reversed-phase high-performance liquid chromatography (RP-HPLC) connected online to electrospray ionization mass spectrometry. The tripeptide was further prepared by fluorenylmethoxycarbonyl (Fmoc) solid-phase synthesis and was found to have a dose-dependent protective effect against hydrogen peroxide (H2O2)-induced injuries in rat adrenal pheochromocytoma (PC12) cells.

Due to the poor protein solubility, hot-pressed peanut meal (HPM) has less value than cold-pressed peanut meal (CPM) in the food industry. The objective of this study was to determine whether the denatured proteins in HPM were suitable for hydrolysis by digestive enzymes. The hydrolysis characteristics and antioxidant activity of HPM and CPM during in vitro digestion were compared. The results showed that HPM was hydrolysed more extensively than CPM. There were more free amino acids and small peptides with MW<5 kDa in HPM hydrolysates. In addition, HPM hydrolysates displayed stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,20-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging activities, ORAC value and reducing power than CPM hydrolysates, which could be due to the higher content of small peptides, antioxidative amino acids and melanoidins in HPM hydrolysates. The above results indicated that HPM was a potential source of protein supplement for human consumption., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The anthocyanins in the fruits of Rhodomyrtus tomentosa (ACN) were extracted by 1% TFA in methanol, and then purified by X-5 resin column and C18 (SPE) cartridges. The purified anthocyanin extract (ART) from the fruits of R. tomentosa showed strong antioxidant activities, including DPPH radical-scavenging capacity, ABTS radical scavenging capacity, reducing power and oxygen radical absorbance capacity (ORAC). The purified anthocyanin extract was analyzed by high performance liquid chromatography (HPLC). The major anthocyanins were purified by semi-preparative HPLC and Sephadex LH-20 column chromatography, and were identified as cyanidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside, petunidin-3-O-glucoside, delphinidin-3-O-glucoside and pelargonidin-3-glucoside by HPLC-ESI/MS and nuclear magnetic resonance spectroscopy (NMR). Cyanidin-3-O-glucoside was considered as the most abundant anthocyanin, which was 29.4 mg/100 g dry weight of R. tomentosa fruits. Additionally, all the major anthocyanins were identified from R. tomentosa fruit for the first time., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In this study, polysaccharides from Tricholoma matsutake (TM-P) were purified using a DEAE-Sepharose fast flow column and three polysaccharide fractions (TM-P1, TM-P2 and TM-P3) were obtained. The chemical composition and structural characteristics of TM-P2 were quite different from those of TM-P1 and TM-P3. TM-P2 consisted of glucose, galactose and mannose with a molar ratio of 5.9:1.1:1.0. The glycosidic linkages were mainly composed of 1,6- and 1-linked glucose. Furthermore, TM-P2 showed the strongest in vitro antioxidant and antitumour activities. The oxygen radical absorbance capacity (ORAC) of TM-P2 was 2100.44 μmol Trolox/g. The antiproliferative activities of TM-P2 (4.0mg/ml) on the growth of HepG2 and A549 cells were 67.98% and 59.04%, respectively., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The antioxidant and antifatigue activities of two peptides of <5 kDa were determined, that is, loach peptide A (LPA, from a papain digestion) and loach peptide B (LPB, from a Flavorzyme digestion). Their degrees of hydrolysis were 21 ± 0.21 and 35 ± 0.32%, respectively. LPA fraction mainly possessed peptides of 1000 < MW < 3000 Da (65.41%), whereas LPB mainly possessed peptides of 500 < MW < 1000 Da (58.27%). LPA fraction contained 116.3 mg amino acid residues/g loach peptide powder of branched-chain amino acids, 1.42-fold that in LPB. LPA had stronger in vitro antioxidant activity than LPB. Compared with LPB, LPA increased swimming time more effectively and reduced blood urea nitrogen (BUN) and liver malonaldehyde (MDA) levels in mice, although both of them had significant antifatigue effects compared to the control (P < 0.05). Pearson correlation analysis showed that the antifatigue activity of loach peptide was highly correlated with its antioxidant activities.

Two novel peptides, ECH (Glu-Cys-His) and YECG (Tyr-Glu-Cys-Gly), were designed based on glutathione (Glu-Cys-Gly, GSH) and their antioxidant activities were studied. Various chemical methods based on single-electron-transfer (SET) and hydrogen-atom-transfer (HAT) were applied to evaluate the antioxidant activities of the peptides. For SET-based assay, tripeptide ECH displayed the highest DPPH radical scavenging activity (80.16%) and the strongest reducing power (A(700)=0.378). Besides, ECH also exhibited the best inhibition activity toward linoleic acid peroxidation with inhibition rate 98.25% at 7th day, which is a HAT-based assay. However, for another two HAT-based assays, it was tetrapeptide YECG that showed extraordinary oxygen radical absorption capacity (ORAC value=2.42 μM Trolox/μM) and ABTS free radical scavenging ability (8.88 mM Trolox/mM). In vitro cultured PC12 cell model also suggested that YECG gave the best protection for PC12 cells to resist H(2)O(2)-treated necrosis. It was found that the discrepancy of antioxidant capacity between ECH and YECG was caused by the presence of antioxidant amino acids (His/Tyr) and their position in peptide chain. With His located at C-terminal position, ECH demonstrated good electrons donating capacity, while with Tyr at N-terminal position, YECG exhibited strong oxygen radical absorbance capacity., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The polyphenols (PF) from Platycladus Orientalis (L.) Franco leaves were purified by using 10 different macroporous adsorption resins. HPD‐722 resin showed the best adsorption and desorption capacities. The static and dynamic adsorption and desorption of PF on HPD‐722 resin were studied and the total polyphenols were separated into two fractions, PF‐A and PF‐B. PF‐A and PF‐B demonstrated similar scavenging activity of free radical (DPPH, ABTS, hydroxyl radical, superoxide anion). The scavenging activity of PF‐A and PF‐B on hydroxyl radical and superoxide anion radical reached the equal levels of vitamin C and gallic acid. The IC50 value of PF‐A for hydroxyl radical scavenging activity and superoxide anion radical scavenging activity were 0.50 and 0.56 mg/mL, while those of PF‐B were 0.61 and 0.64 mg/mL. PF‐A and PF‐B could reduce the overproduction of inflammatory cytokines (TNF‐α, Pro‐IL‐1β, and IL‐6) induced by lipopolysaccharide and their protein expression in THP‐1 cells. PF‐B exhibited better anti‐inflammatory effect than PF‐A in the dosage range of 1.0–4.0 µg/mL. Structural identification of PF‐A and PF‐B were conducted by HPLC‐MS/MS. Ten polyphenol compounds were identified in PF‐A and PF‐B, respectively, by HPLC‐MS/MS, including quercetin, apigenin, myricetin, and so on. Molecular docking studies indicated that apigenin, myricetin, luteolin, kaempferol, and quercetin effectively inhibit xanthine oxidase by forming hydrogen bonds with the amino acid residues and binding to the active site of the enzyme. The results might supply useful information for better understanding the chemical structure, antioxidant, and anti‐inflammatory activities of Platycladuso (L.) Franco leaves polyphenols. Practical Application: This study demonstrated that polyphenols from P. orientalis (L.) Franco leaves have the potential applications as functional food ingredient for the prevention and treatment of gout and inflammation, hyperuricemia and gout. [ABSTRACT FROM AUTHOR]

Silkworm pupae protein (SPP) was pretreated by different processing (heat/alkali/pepsin) and then hydrolyzed by five proteases (trypsin/flavorzyme/papain/protamex/alcalase), respectively. It was found that the combination of heat pretreatment and alkali pretreatment followed by enzymatic hydrolysis with trypsin and flavorzyme could remarkably improve the protein recovery. The hydrolysates obtained from silkworm pupae protein hydrolyzed with trypsin and flavorzyme were stable at the pH range of 4.0-8.0, remaining 95 % of its original reducing power and 90 % of its OH • scavenging activity. However, they were susceptible to alkaline treatments (pH > 10.0) and lost >30 % of their antioxidant activities. Pasteurization (65 °C x 30 min) or autoclaving sterilization (121 °C x 20 min) did not show notable effects on the antioxidant activities. It was concluded that silkworm pupae protein hydrolysates (SPPH) were better to be applied in either neutral or acidic food system rather than in alkaline conditions. [ABSTRACT FROM AUTHOR]

Effect of antioxidants in oxidative stress-induced cell damage has been extensively studied, but its effects on cell macroscopic phenomena have rarely been explored. Cell morphology and motility are two interrelated cellular processes reflecting cellular function phenotype, and the real-time imaging technology is key for the study of these processes. In this study, we used two known antioxidants, pyrroloquinoline quinone (PQQ) and rutin, to explore the antioxidant effects on cell morphology and motility in rotenone-damaged NIH3T3 cells, as well as roles in their antioxidant function based on Cytation 7 Cell Imaging Multi-Mode Reader. First, NIH-3T3 cells were pretreated with PQQ and rutin for 4 h and then rotenone was used to induce oxidative damage. It was found that PQQ (2 μM) and rutin (300 μM) had similar protective effects on the proliferation activity of rotenone-damaged cells. Subsequently, the morphology and motility of the treated cells were quantified. Results showed that both PQQ and rutin could significantly inhibit morphological changes including cell shape index and cell surface of the damaged cells, however PQQ had a stronger effect on cell motility under the specific experimental concentrations. Using principal component analysis (PCA), we further demonstrated that the quantified cell morphology and motility were consistent with the cell proliferation activity. Consequently, quantification of cell morphology and motility as evaluation indices may serve as potential reference values for the evaluation of biological activity of antioxidants. [Display omitted] • Oxidative stress alters cell morphology and motility. • Rutin and PQQ relieve oxidation-damaged-induced cells morphology and mobility changes. • Cell tracking efficiently evaluates the biological activity of antioxidants. [ABSTRACT FROM AUTHOR]

Protein from pearl oyster (Pinctada fucata martensii) was purified and characterized. Results showed that the pearl muscle protein (PMP) was composed of a single polypeptide with a molecular weight of approximate 11.6 kDa and contained 95.1% of the protein and 4.92% of the carbohydrate of the oyster. The polypeptide appears to be a glycoprotein, since the Fourier transform infrared (FTIR) spectroscopy of the PMP shows the typical characteristics of protein and polysaccharides. The denaturation temperature of the PMP was 81.3°C by differential scanning calorimetry. Circular dichroism spectroscopy showed that the PMP has a highly ordered structure. The PMP (200μg/mL) showed a high oxygen radical absorbance activity (ORAC) of 6.57μmol Trolox/μmol protein. Its antioxidant activity was stable at temperatures from 30–80°C and pH 2–10. The antioxidant activity was significantly inhibited by Zn2+, Ca2+, and EDTA and enhanced by Mn2+. The results suggest that the PMP could be used as a potential natural antioxidant. [ABSTRACT FROM PUBLISHER]

The antioxidant activities of the fermented wheat gluten hydrolysates with different fermentation times were investigated to elucidate the impact of lactic acid bacteria ( LAB) fermentation on the wheat gluten hydrolysates. Prior to LAB fermentation, wheat gluten was deamidated by hydrochloric acid and then hydrolysed by pancreatin to 12 and 24 h, respectively. Results showed that LAB fermentation had significant impacts on the enzymatic efficiency and antioxidant activities of wheat gluten. The degree of hydrolysis and protein recovery of hydrolysates gradually increased and then reached maximum values, respectively, when fermenting with LAB for 36 h. The hydrolysis degree and protein recovery of fermented pancreatin 24-h hydrolysates were larger than that of the fermented pancreatin 12-h hydrolysates during the whole fermentation. The antioxidant activity analysis revealed a marked increase and improvement in the scavenging activities of 1,1-Diphenyl-2-picrylhydrazyl·radicals, hydroxyl radicals and oxygen radical absorbance capacity, while the scavenging activities of ABTS+ radical decreased as the fermentation time extended. The antioxidant activities of pancreatin 24-h hydrolysates were higher than that of the pancreatin 12-h hydrolysates during the whole LAB fermentation. [ABSTRACT FROM AUTHOR]

Abstract: The sarcoplasmic protein was extracted from the muscle of grass carp, a Chinese freshwater carp, and was hydrolyzed with five proteases to produce antioxidant peptides. Papain hydrolysate was found to have the greatest activity against lipid peroxidation. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions (including enzyme to substrate ratio, time and temperature). The minimum EC50 value (317.25μg/mL) which signified the maximum antioxidant activity was obtained at an enzyme to substrate ratio of 0.79%, an incubation time of 5.69h and an incubation temperature of 52.15°C, which was in agreement with the predicted value (313.99μg/mL) estimated by RSM within a 95% confidence interval. Also, it was found that moderate denaturation of the sarcoplasmic protein and a modest increase in the degree of hydrolysis promoted the antioxidant activities of the hydrolysates. Oligopeptides (< 3kDa) contributed more to the antioxidant activity than polypeptides. [Copyright &y& Elsevier]

Abstract: Grass carp muscles were hydrolyzed with various proteases (papain, bovine pancreatin 6.0, bromelain, neutrase 1.5MG and alcalase 2.4L) to extract antioxidant peptides. The hydrolysates were assessed using methods of hydroxyl radical scavenging ability and lipid peroxidation inhibition activity. Hydrolysate prepared with alcalase 2.4L was found to have the highest antioxidant activity. It was purified using ultrafiltration and consecutive chromatographic methods including ion-exchange chromatography, multilayer coil high-speed counter-current chromatography, and gel filtration chromatography. The purified peptide, as a potent antioxidant, was identified as Pro-Ser-Lys-Tyr-Glu-Pro-Phe-Val (966.3Da) using RP-HPLC connected on-line to an electrospray ionization mass spectrometry. As well, it was found that basic peptides had greater capacity to scavenge hydroxyl radical than acidic or neutral peptides and that hydrophobic peptides contributed more to the antioxidant activities of hydrolysates than the hydrophilic peptides. In addition, the amino acid sequence of the peptide might play an important role on its antioxidant activity. [Copyright &y& Elsevier]

Abstract: Five peptide fractions isolated from peanut hydrolysate were purified by ultrafiltration and gel filtration chromatography. Their reaction degrees with glucose or lecithin in Maillard reaction were compared. Glucose consumption, oxygen radical absorbance capacity (ORAC) values and volatile compounds composition of peanut hydrolysate (PH) and its peptide fractions after thermal treatment and Maillard reaction were evaluated. Results revealed that the peptide fraction of 1–3kDa showed the highest antioxidant activity. The peptides with smaller molecular weight showed a higher reaction degree to increase antioxidant activity and to produce more volatile compounds through Maillard reaction. Analysis of molecular weight distribution showed that peptide degradation and cross-linking simultaneously occurred during the Maillard reaction. In addition, lecithin addition to peptide–glucose system caused a significant increase of antioxidant activity possibly due to more nitrogen-containing compounds formed. [Copyright &y& Elsevier]

Abstract: Phyllanthus emblica is a widely distributed tropical medicinal plant with good therapeutic properties. Gallic acid, ellagic acid, mucic acid 1,4-lactone 3-O-gallate, isocorilagin, chebulanin, chebulagic acid and mallotusinin were isolated and purified from this plant. The antioxidant activities of these compounds were evaluated by in vitro models of scavenging superoxide anion radicals, DPPH radicals and ABTS radicals, chelating ability of ferrous ion and inhibition capability of Fe (II)-induced lipid peroxidation, respectively. The results revealed that all the tested phenolics showed strong radical scavenging activity, good potency to chelate Fe2+ and good inhibition ability of lipid peroxidation. Amongst mallotusinin and mucic acid 1,4-lactone 3-O-gallate were reported for the first time to have antioxidant activity. In addition, the in vitro antiproliferative activities of those phenolics against MCF-7 breast cancer cell lines were assessed. Although the growth inhibition values induced by different phenolics on MCF-7 cell line yielded different effects, all the tested phenolics had apparent capacities of inhibiting the survival of MCF-7 human cancer cell line. [ABSTRACT FROM AUTHOR]

Abstract: The in vitro antioxidant activity and in vivo anti-fatigue activity of loach peptide (LP) were determined. Results showed that LP contained the amino acids, which were expected to contribute to its antioxidant and anti-fatigue activities. LP could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 17.0±0.54mg/ml) and hydroxyl radicals (IC50 2.64±0.29mg/ml). It could chelate cupric ion and inhibit the lipid peroxidation in a linoleic acid emulsion system. It also prolonged the swimming time to exhaustion of mice by 20–28% compared to the control. It increased the levels of blood glucose (28–42% increase) and liver glycogen (2.3–3.0-fold increase). It decreased the levels of lactic acid and blood urea nitrogen by 10.9–27.5% and 8.6–17.5%, respectively. It also improved the endogenous cellular antioxidant enzymes in mice by increasing the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). Therefore, LP can increase an endurance capacity and facilitate recovery from fatigue. [ABSTRACT FROM AUTHOR]

Abstract: A two-stage in vitro digestion model system (a pepsin treatment for 2h followed by a pancreatin treatment for 2h, both at 37°C) was used to simulate the process of human gastrointestinal (GI) digestion to determine the changes in antioxidant activities of loach peptide previously prepared by papain digestion. Results showed that the final GI digests contained 38.1% free amino acids, with short chain peptides (<500Da) making up the rest of the biomass. Enzymatic breakdown of the GI digests increased their hydroxyl (12% increase), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) (5% increase) radical scavenging activity, the reducing power (77% increase) and the chelating ability of Cu2+ (12% increase), compared to the blank. The results showed that the digestion by gastrointestinal proteases can be used to produce antioxidant peptides, with the advantage that the peptides formed will resist physiological digestion in GI tract. [Copyright &y& Elsevier]

Abstract: Loach protein was hydrolyzed by papain to obtain antioxidative peptides. The results showed that the loach protein hydrolysate (LPH) could scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC50 =17.0±0.54mg/mL) and hydroxyl radicals (IC50 =2.64±0.29mg/mL). It could chelate cupric ion and inhibit the lipid peroxidation in a linoleic acid emulsion system. The hydrolysate was isolated and purified by ultrafiltration and consecutive chromatographic methods including ion-exchange chromatography, gel filtration chromatography and a two-step reverse high-performance liquid chromatography (RP-HPLC). The purified antioxidant peptide was identified as Pro-Ser-Tyr-Val (464.2Da) using RP-HPLC connected on-line to an electrospray ionization (ESI) mass spectrometer. The purified peptide showed a 9.14-fold higher scavenging activity for hydroxyl radical compared with the crude LPH. Therefore, it is possible to produce natural antioxidative peptides from loach protein by enzymatic hydrolysis and purification. [Copyright &y& Elsevier]