Antioxidant activity of dulse (Palmaria palmata) extract evaluated in vitro

Palmaria palmata (dulse) is traditionally consumed as a snack food and garnish; but, little is known about its potential as a source of antioxidants. A 1-butanol soluble fraction extracted from dulse exhibited OH scavenging activity ± EDTA (non-site and site specific activity) in a deoxyribose assay. EC₅₀ concentrations of dulse extract to quench DPPH and ABTS⁺ free radicals were 12.5 and 29.5 mg/ml. Dulse extract inhibited (p < 0.05) conjugated diene production in a linoleic acid emulsion at 24, 48 and 52 h, 38 °C; and inhibited (p = 0.044) thiobarbituric acid reactive substances (TBARS) production at 52 h. One milligram dulse extract exhibited reducing activity = 9.68 μg l-ascorbic acid and total polyphenol content = 10.3 μg gallic acid; the dulse extract did not chelate transition metal ions. The antioxidant activity of the dulse extract was associated with aqueous/alcohol-soluble compounds characterized by phenolic functional groups with reducing activity.     

Retention of Physicochemical and Antioxidant Properties of Dehydrated Bael (Aegle Marmelos) and Palmyra (Borassus Flabellifer) Fruit Powders

Present study was carried out to evaluate the effect of various dehydration techniques such as sun drying, solar drying, drying after freezing (Freeze for one hour followed by mechanical drying at 55 °C), vacuum drying and drying using lab scale air oven on proximate composition and retention of antioxidants in different fruit powder prepared from Bael (Aegle marmelos) and Palmyra (Borassus flabellifer). Moisture content, Total Ash, Crude fiber %, Fat %, Crude protein %, total phenolic content,β –Carotene and antioxidant activity were tested. The antioxidant activity was measured based on the ability of fruit extract to scavenge 1, 1- diphenyl-2-picrylhydrazyl (DPPH). Among different drying treatments the highest fat percentage recorded by the solar dried palmyra fruit powder and there is no significant difference (α= 0.05) between sun drying and vacuumed drying. Higher concentration of β -Carotene and total phenolic content were recorded in vacuum dried samples both in bael and Palmyra fruit powders and it significantly different (α= 0.05) from other treatments. The scavenging activity of bael fruit powder in vacuum drying was ranged from 65.36% to 81.33% of the concentration 200 μg/ml to1000 μg/ml and the palmyra fruit powder was recorded 57.32% to 83.25% of the concentration 200 μg/ml to1000 μg/ml. Vacuum dried fruit powders of palmyra and bael were given highest radical scavenging activity and the scavenging activity of palmyra fruit powder is higher than the bael. Therefore vacuum drying can be recommended as the most effective drying method to protect chemical characteristics and retention of antioxidant properties of fruit powders.     

Evaluation of the antioxidant,antiproliferative and antimutagenic potential of araçá-boi fruit (Eugenia stipitata Mc Vaugh — Myrtaceae) of the Brazilian Amazon Forest

Eugenia stipitata is a fruit from Amazonia rich in terpene, volatile compounds, fiber, and vitamin C. The fruit is recognized for its high antioxidant activity and has attracted much attention due to their potential health benefits to humans. The total polyphenols, antioxidant, antiproliferative, antimutagenic and antigenotoxic activities of E. stipitata ethanolic extract were investigated. Total polyphenols were determined by the Folin–Ciocalteu method and showed 184.05 ± 8.25 mg GAE/100 g. The radical scavenging activity was DPPH _IC50 0.69 ± 0.23 μg/mL and TAC-ORAC_FL 371.98 μmol.TE/100 g. The extract was evaluated for its ability to inhibit the growth of tumor cell lines and had not complete cystostatic effect against any of the tested cell lines. Antimutagenic and antigenotoxic activities were investigated by micronucleus test and comet assay in mice, respectively. Ethanolic extract of E. stipitata showed higher antimutagenic and antigenotoxic properties at the highest concentration tested (300 mg/kg of body weight). In conclusion, these results suggest that this fruit could be used as a preventive agent against cancer.     

Effect of blanching on the antioxidant properties of some tropical green leafy vegetables

Eight popularly consumed green leafy vegetables in Nigeria namely: Structium sparejanophora, Amarantus cruentus, Telfairia occidentalis, Baselia alba, Solanum macrocarpon, Corchorus olitorus, Vernonia amygdalina, and Ocimum gratissimum were blanched in hot water for 5 mins. The antioxidant properties of the fresh and blanched green leafy vegetables were subsequently determined. The total phenol, ascorbic acid and the antioxidant potentials as typified by reducing property and free radical scavenging activity was also determined. The results of the study revealed that blanching cause a significant (P<0.05) increase in the total phenol [fresh (0.1–0.3 g/100 g), blanched (0.2–0.6 g/100 g)] content of the green leafy vegetables except in Amarantus cruentus and Vernonia amygdalina where there was no change. Conversely, there was a significant (P<0.05) decrease in the vitamin C [fresh (43.5–148.0 mg/100 g), blanched (15.8–27.3 mg/100 g)], reducing property [fresh (0.5–1.5 absorbance), blanched (0.1–0.6 absorbance)] and free radical scavenging ability [fresh (20.0–51.4%), blanched (16.4–47.1%)] of the blanched green leafy vegetables except in Structium sparejanophora, where there was no change in the reducing property (0.6 absorbance) and free radical scavenging ability (59.8%) of the blanched vegetable. In view of this it could be concluded that blanching of vegetables though makes green leafy vegetables more palatable and less toxic, however it reduces their antioxidant properties drastically.     

Air-dried capsicum annuum var. acuminatum medium and big: Determination of bioactive constituents,antioxidant activity and carbohydrate-hydrolyzing enzymes inhibition

In the present study the total phenols, flavonoids, carotenoids and capsaicinoids content, the in vitro antioxidant and hypoglycemic activities of extracts of air-dried fruits from two Capsicum annuum cultivars were investigated. A different composition between the two cultivars was evidenced. C. annuum var. acuminatum medium extract presented a major content of phenols, carotenoids, capsaicin and dihydrocapsaicin while C. annuum var. acuminatum big extract is characterized by the highest quercetin, luteolin and kaempferol content with 68.0, 87.6 and 29.7 μg/g dried weight, respectively, analyzed by HPLC. Medium pepper showed the highest radical scavenging activity in DPPH assay (IC₅₀ of 85.3 μg/ml) while big pepper have an interesting activity in ABTS assay (IC₅₀ of 16.4 μg/ml) and the highest inhibition of linoleic acid oxidation with an IC₅₀ value of 1.2 μg/ml after 30 min of incubation. A selective inhibitory activity against α-amylase was demonstrated for C. annuum var. acuminatum big lipophilic fraction (IC₅₀ values of 8.7 μg/ml). The obtained results suggest that C. annuum cultivars could be used as valuable flavor with functional properties for foods.     

Phenolic composition,antioxidant and antimicrobial activities of free and bound phenolic extracts of Moringa oleifera seed flour

Phenolic compounds, antioxidant and antibacterial activities of defatted Moringa oleifera seed flour (DMF) were investigated. The total phenolic and flavonoid contents were measured using colorimetric methods. Free phenolic acid and flavonoid profiles were analyzed by high performance liquid chromatography, while antioxidant capacities were evaluated using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH), ferric reducing antioxidant power and total antioxidant capacity. The results showed that extractability of phenolic compounds was significantly higher (p < 0.05) in bound phenolic extract (4173.00 ± 32.22 mg gallic acid equivalents (GAE)/100 g) than in free phenolic extract (780.00 ± 14.2 mg GAE/100 g) and it showed higher antioxidant and antimicrobial activities. The IC₅₀ value for DPPH radical scavenging activity was 0.9 ± 0.05 and 14.9 ± 0.07 mg/mL for bound phenolic and free phenolic extracts, respectively. Bound phenolic extract was more effective (minimum inhibitory concentration (MIC), 0.06–0.157%) than free phenolic extract (MIC, 0.117–0.191%) against tested bacteria. Ten phenolic compounds (gallic acid, p-coumaric acid, ferulic acid, caffeic acid, protocatechuic acid, cinnamic acid, catechin, epicatechin, vanillin and quercetin) were identified and quantified in both extracts. These natural plant phenolics from Moringa seeds could be a good source of antioxidants and antibacterials for food and pharmaceutical industries.     

A novel antioxidant and antimicrobial peptide from hen egg white lysozyme hydrolysates

Hen egg white lysozyme (HEWL) was hydrolyzed with papain, trypsin and a combination of the two to isolate antioxidant peptides. The prepared hydrolysates were evaluated for antioxidant activity using DPPH and ABTS radical scavenging, metal ion chelation and lipid peroxidation inhibition. The obtained hydrolysate by a combination of the two enzymes exhibited the highest antioxidant activity compared to other hydrolysates and elected for isolation of antioxidant peptides by reverse-phase high-performance liquid chromatography (RP-HPLC). A most potent fraction namely F2 fraction, identified to be NTDGSTDYGILQINSR (MW: 1753.98 ± 0.5 Da) using tandem mass spectrometry. The antimicrobial activity of the F2 peptide was tested using radial diffusion assay (RDA). Our results showed that this peptide has inhibitory effects on both Gram-negative and Gram-positive bacteria. Minimum inhibition concentration (MIC) values of the F2 peptide against Escherichia coli and Leuconostoc mesenteroides bacteria were 355.64 (±2.2) and 442.25 (±2.8) μg/ml, respectively.     

Antioxidant properties and components of some commercially available varieties of rice bran in Pakistan

The antioxidant activity of five indigenous rice bran varieties, i.e. Rice bran-Super kernel (RB-kr), Rice bran-Super 2000 (RB-s2), Rice bran-Super Basmati (RB-bm), Rice bran-Super-386 (RB-86) and Rice bran-Super fine (RB-sf), collected from the same agricultural plots, was evaluated. The order of antioxidant activity was evaluated by measurement of total phenolic content, antioxidant activity in linoleic acid system, reducing power, metal chelating ability, scavenging capacity by DPPH radical and ABTS cation radical and conjugated dienes. Determination of major antioxidant components reported in rice bran, i.e. tocopherols, tocotrienols and γ-oryzanol, was made using reverse phase HPLC. However, for comparison of tocopherol content, quantification was also done by voltammetry. The overall order of antioxidant activity was RB-kr > RB-s2 > RB-bm > RB-86 > RB-sf. However, according to the chelating activity and conjugated dienes assays the antioxidant efficacy of RB-sf was higher than RB-bm and RB-86. Antioxidant power was correlated with growth period and irrigation water demand by a particular variety. A strong correlation of these two parameters with antioxidant activity was observed. RB-kr has the longest growth period and takes the least amount of water out of the series and exhibits highest antioxidant activity. Strongly reverse behavior was observed in case of RB-sf.     

Identification and characterization of papain-generated antioxidant peptides from palm kernel cake proteins

Novel peptides with antioxidant activity were isolated and identified from papain generated palm kernel cake (PKC) proteolysate. The proteolysate was fractionated into individual peptides based on hydrophobicity and isoelectric point using reversed-phase high-performance liquid chromatography and isoelectric focusing techniques. The individual peptides were identified by tandem mass spectrometry and their respective antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and metal chelating activity assays. Peptide sequences, AWFS, WAF, and LPWRPATNVF showed the highest radical scavenging activities of 71%, 56%, and 50%, respectively, while peptide sequences GGIF, YGIKVGYAIP and YLLLK showed the highest metal chelating activities of 56%, 53%, and 50%, respectively. However, the best IC₅₀ values of peptides measured by DPPH assay were displayed by GIFE, GVQEGAGHYALL and GGIF at 0.02 μM, 0.09 μM and 0.35 μM, respectively, while the best half maximal inhibitory concentration values measured using metal chelating activity were shown by LPWRPATNVF, AWFS and YGIKVGYAIP at 0.001 μM, 0.002 μM and 0.087 μM, respectively. It can be concluded that the peptides derived from PKC proteolysate were more potent and distinctive compared to those previously reported from other plant protein sources.     

NMR-based quantification of rosmarinic and carnosic acids,GC–MS profile and bioactivity relevant to neurodegenerative disorders of Rosmarinus officinalis L. extracts

A comparative study of phytochemicals content and biological properties of eight Rosmarinus officinalis (rosemary) populations (RO1–RO8) collected in different areas of Tunisia was carried out. Two of the main rosemary constituents, rosmarinic and carnosic acids, were quantified by an NMR technique. Carnosic acid content was higher than that of rosmarinic acid. The non-polar constituents were examined by GC and GC–MS. Total phenols and flavonoids content were also determined in order to discuss the possible correlation between these phytochemicals and bioactivity. Antioxidant activity was investigated through different in vitro assays. Sample RO3 from a sub-humid area showed the highest potency in 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay (IC₅₀ of 6.74 μg/mL) while RO5 from arid area exhibited the highest radical 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) scavenging activity (IC₅₀ of 5.92 μg/mL). The most active sample in Ferric Reducing Antioxidant Power (FRAP) assay was RO4 (62.21 μM Fe(II)/g), followed by RO1–RO3 and RO8 harvested in sub-humid areas with values in the range 49.61–58.72 μM Fe(II)/g. Extracts were able to inhibit acethylcholinesterase (AChE) and butyrylcholinesterase (BChE). Sample RO5 exhibited a promising AChE inhibitory activity (IC₅₀ of 4.47 μg/mL). Thus, we suggest rosemary extracts as a functional food ingredient for preventing AD.     

Antioxidant properties and polyphenolics composition of common hedge hyssop (Gratiola officinalis L.)

The antioxidant potential of Gratiola officinalis was evaluated by the off-line and on-line HPLC/UV/DPPH radical scavenging assays, phytochemical composition was analyzed by LC/MS. On-line method was validated by using reference antioxidants and linear dependence was found between their concentration and radical scavenging peak area. Radical scavenging capacity (RSC) of methanol and acetone extracts expressed in their concentration required to scavenge 50% of DPPH^? was 0.10% and 0.13%, respectively; the RSC in ABTS^?+ assay was 1093 ± 104 and 746 ± 18 μM of trolox equivalents in 1 g, respectively. Good correlation was observed between total amount of phenolic compounds and RSC. Preliminary HPLC/UV/MS analysis revealed that the main compounds possessing antioxidant activity in the extracts might be phenylpropanoid glycosides; UPLC/UV/ESI-QTOF-MS analysis suggested 15 structures: 2,5-dihydroxy-p-benzenediacetic and caffeic acids, apigenin 6,8-di-C-β-d-glucopyranoside (vicenin-2), apigenin 8-C-α-l-arabinoside 6-C-β-d-glucoside, (shaftoside), forsythoside B, arenarioside, verbascoside (acteoside), amioside, quercetin-6-O-(2-O-acetyl-glucopyranosyl)-glucopyranoside, isoverbascoside, quercetin glucuronide, linariifolioside, methoxy luteolin-7-O-(6-O-acetyl-glucopyranosyl)-glucopyranoside, methoxy luteolin-glucuronide and luteolin glucuronide.     

Quinone reductase inducing and antioxidant activities of aqueous isolates of green bean (Phaseolus vulgaris L.)

Aqueous extracts of green bean (Phaseolus vulgaris L.) were examined for antioxidant functions in terms of total reducing power (TRP), peroxyl radical quenching (PRAC), total antioxidant activity (TAA), and the ability to induce quinone reductase (QR) as a biomarker for phase II detoxification enzymes in Murine hepatoma (Hepa) cells. In terms of Trolox equivalents (TE), crude aqueous extracts exhibited 71 μmol TE/g dry weight (gdw) for TRP, 29 μmol TE/gdw for PRAC, and 8.5 μmol TE/gdw for TAA. Aqueous extractable QR-inducing activity was fractionated by Sephadex LH-20 chromatography with several resulting fractions capable of doubling QR specific activity in the Hepa bioassay. Of 10 recovered fractions, the first and most polar fraction doubled QR at a level of 39 μg/ml (CD value), while the ninth fraction exhibited a similar CD value of 35 μg/ml. Semi-preparative LC and UV spectral analysis of fraction 9 indicated the presence of quercetin and kaempferol glycosides, and simple phenolics among the enriched QR-inducing isolates.     

Antioxidant activity of peanut seed testa and its antioxidative component,ethyl protocatechuate

The antioxidant activity of ethanolic extracts of peanut seed testa (EEPST) and its antioxidative component, ethyl protocatechuate (EP), was examined. It was found that EEPST and EP showed a dose-dependent activity on the inhibition of liposome peroxidation. EEPST and EP in the range of 50–500 mg/l were effective in protecting protein against oxidative damage. EEPST and EP at 100 mg/l showed 92.6% and 84.6% scavenging effect, respectively, on α,α-diphenyl-β-picrylhydrazyl radical, indicating that they act as a primary antioxidant. In addition, EEPST and EP, at a dose of 200 mg/l, showed 70.6% and 67.7% scavenging effect, respectively, on the hydroxyl radical. EEPST also exhibited a metal-binding ability, while EP did not. The inhibitory effect of EEPST on linoleic peroxidation correlated with their polyphenolic content. These results suggest that the antioxidant mechanism, for both EEPST and EP, could possibly be due to their scavenging effect on free radical and hydroxyl radical. In addition, its metal binding ability may contribute to antioxidant activity of EEPST.     

Citharexylum solanaceum fruit extracts: Profiles of phenolic compounds and carotenoids and their relation with ROS and RNS scavenging capacities

Citharexylum solanaceum is a native fruit from Brazil, which both bioactive compounds and antioxidant potential were not yet investigated. Thus, the freeze-dried extracts of seed and pulp + skin of C. solanaceum fruits were obtained after solid-liquid extraction with ethanol and their bioactive compounds composition, namely phenolic compounds and carotenoids, were determined. The antioxidant capacity of both extracts against physiologically relevant reactive oxygen species (ROS) and reactive nitrogen species (RNS) was further investigated. Both C. solanaceum extracts showed high contents of phenolic compounds; however, pulp + skin extract presented 2.4-times more phenolic compounds (33.54 mg/g) than the seed extract (14.09 mg/g). Verbascoside (phenylpropanoid) was the major compound identified in both extracts (11–25 mg/g). Regarding the carotenoid composition, all-trans-lutein (14–42 μg/g) and all-trans-β-carotene (13–44 μg/g) were the major compounds in both extracts. The high content of phenolic compounds and carotenoids in pulp + skin extract might explain its higher scavenging capacity against all the ROS/RNS as compared to seed extract. In general, both extracts showed better scavenging capacity for the RNS than for the ROS. Our results indicate that C. solanaceum fruits can be explored as an important natural source of antioxidant compounds.     

Antioxidant and type II diabetes related enzyme inhibition properties of methanolic extract of an underutilized food legume,Canavalia ensiformis (L.) DC: Effect of traditional processing methods

The methanolic extract of Canavalia ensiformis (L.) DC (Jack bean) seed, an underutilized food legume collected from India was analyzed for antioxidant and health relevant functional properties. The raw seeds contained total free phenolic content of 12.98 ± 1.63 g catechin equivalent/100 g extract DM. The raw seed extract exhibited ferric reducing/antioxidant power (FRAP, 1218 mmol Fe[II]/mg extract), inhibition of β-carotene degradation (49.81%), radical scavenging activity against DPPH (56.78%) and superoxide (35.89%). In addition, 77.56% of α-amylase and 75.45% of α-glucosidase enzyme inhibition characteristics were found under in vitro starch digestion bioassay. Sprouting + oil-frying caused an apparent increase on the total free phenolic content with significant improvement on antioxidant and free-radical scavenging capacity, while soaking + cooking as well as open-pan roasting treatments showed diminishing effects. Inhibition of α-amylase and α-glucosidase enzyme activities were declined to 22.69 and 42.69%, respectively during sprouting + oil-frying treatment is more desirable for the dietary management of type II diabetic patients.     

Isolation of antioxidative and ACE inhibitory peptides from protein hydrolysate of skipjack (Katsuwana pelamis) roe

Bioactive peptides from protein hydrolysate of defatted skipjack (Katsuwonus pelamis) roe with 5% degree of hydrolysis (DH) prepared by Alcalase digestion were isolated and characterised. Two active fractions with ABTS radical scavenging activity (973.01–1497.53 μmol TE/mg sample) and chelating activity (0.05–0.07 μmol EE/mg sample) from consecutive purification steps including ultrafiltration, cation exchange column chromatography and reverse phase high performance liquid chromatography (RP-HPLC), were subjected to analysis of amino acid sequence by LC–MS/MS. Seven dominant peptides with 6–11 amino acid residues were identified as DWMKGQ, MLVFAV, MCYPAST, FVSACSVAG, LADGVAAPA, YVNDAATLLPR and DLDLRKDLYAN. These peptides were synthesised and analysed for ACE-inhibitory activity and antioxidative activities. MLVFAV exhibited the highest ACE inhibitory activity (IC₅₀ = 3.07 μM) (p < 0.05) with no antioxidative property, whilst DLDLRKDLYAN showed the highest metal chelating activity, ABTS radical and singlet oxygen scavenging activities. Therefore, peptides prepared from skipjack roe could be further employed as a functional food ingredient.     

Oxidative stability of virgin olive oil enriched with carnosic acid

The aim of this study was to evaluate the effect of the addition of carnosic acid on the oxidative stability of virgin olive oil. Two different amounts of carnosic acid (0.01 and 0.1 g/100 g oil) and two different temperatures (accelerated aging temperature, 60 °C; deep frying temperature, 180 °C) were considered. The influence of carnosic acid and heating time on the stability of the oils was studied by experimental design. The results obtained at 60 °C showed a dose dependent inhibition in the formation of primary and secondary oxidation products and a dose dependent enhancement of radical scavenging activity, which was only less significantly influenced by heating time. On the contrary, at 180 °C no protective effect against lipid oxidation was observed and the radical scavenging activity was practically zeroed by heating, probably as a consequence of a fast decomposition of carnosic acid.     

Antioxidant and Anti-diabetic Properties of Caryota Urens (Kithul) Flour

Starch extracted from pith of Caryota urens L. (Family: Arecaceae) palm is known as “Kithul flour” and is claimed to have health benefits according to folklore and Ayurveda. Antioxidants are believed to possess numerous health benefits. However, as yet, health benefits of C. urens flour have not been scientifically investigated. Antioxidant properties of C. urens flour were tested using different in vitro assays namely, 2,2-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺), ferric reducing antioxidant power, oxygen radical absorbance capacity and ferrous ion chelating assays. Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) were also evaluated. Anti-diabetic properties were estimated using alpha amylase and alpha glucosidase enzyme inhibition assays. Dried methanolic extracts of both boiled and raw samples were used in all assays. Results of the study showed that C. urens flour possess free radical scavenging activity(raw 0.02± 0.01 and boiled 0.04±0.01 mg trolox equivalent (TE)/ g flour), electron donating reducing power (raw 0.10±0.03 and boiled 0.36±0.11 mg TE/g flour), oxygen radical absorbance capacity (raw 2.29± 0.71 and boiled 192.3 ± 57.71 mg TE/1 g flour) and metal ion chelating capacity (raw 0.03±0.01 and boiled 0.14±0.04 mg EDTA equivalents /g flour) exhibiting its antioxidant potential. TPC (raw 1.1±0.3 and boiled 5.12 ± 1.89 mg GAE/g flour) and TFC (raw 1.65 ± 0.47 and boiled 6.69 ± 1.27 μg QE/g flour) which are said to be contributed to antioxidant activities were also found. In addition, boiled flour which is generally consumed as a food has shown higher antioxidant activity. Caryota urens flour did not contain marked anti-diabetic properties. It is evident from results that Caryota urens flour has moderate antioxidant property which may associate with its traditional health claims.     

Alleviation of plasma,erythrocyte and liver lipidemic-oxidative stress by thymoquinone and limonene in atherogenic suspension fed rats

In the present study, the antioxidant efficacies of thymoquinone (TQ) and limonene (LMN), two main constituents of Nigella sativa seeds, were investigated in relation to plasma, erythrocyte and liver oxidative abnormalities in hyperlipidemic Wistar albino rats. Pretreatment with 10 mg TQ or 200 mg LMN in atherogenic suspension fed rats, effectively reduced the plasma lipid peroxidation markers, conjugated diene, lipid hydroperoxide, malondialdehyde, and replenished the plasma antioxidant capacity by increasing its ferric reducing ability and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid quenching to near normal levels and modulating the levels of reduced glutathione, enzymatic antioxidants superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, and erythrocyte membrane-linked ATPases to normalcy. These results demonstrate that radical scavenging/antiperoxidative efficacies of TQ were greater than LMN. Thus, these compounds, especially TQ, play an important and useful role in the preservation of plasma antioxidant status, cellular membrane structure and function of tissues, and may be used as chemopreventative food additives in the prooxidant state related disorders.     

Antiphotoaging effect and purification of an antioxidant peptide from tilapia (Oreochromis niloticus) gelatin peptides

In this study, the effect of tilapia gelatin peptides (TGP) on UV-induced damages to mice skin was evaluated. The antioxidant indicators, lipid, collagen and glycosaminoglycan of mice skin were determined and histological changes of the collagen were depicted. The results showed TGP could alleviate the UV-induced abnormal changes of antioxidant indicators, and the protective effect was in dose-dependent manners. TGP could protect skin lipid and collagen from the UV radiation damages, and the change of glycosaminoglycan was also recovered significantly. The action mechanisms of TGP mainly involved the antioxidant properties and the repairing to endogenous collagen synthesis. Therefore, the key antioxidant peptide was further purified from TGP. Finally, one antioxidant peptide was identified and the amino acid sequence was Leu-Ser-Gly-Tyr-Gly-Pro (592.26 Da). The IC₅₀ value of this peptide on hydroxyl radical scavenging activity was 22.47 μg/mL. TGP could be a novel antiphotoaging agent from natural resources.