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 Fish protein hydrolysates from whole kilka, using alcalase enzyme (ratio 1: 100) under optimal temperature (55°C) and pH (8.5) was evaluated for its hydrolysis degree and antioxidant activity. Results of the hydrolysis degree recorded at time intervals of 1, 2, 3 and 4 hours indicated the hydrolysis degree increased with increase in the hydrolysis time. The evaluation of FPH antioxidant activity, using DPPH, ABTS and reducing power assay tests at 3 concentrations (1, 2 and 5 mg/ml indicated the highest inhibitory effect at 5 mg/ml was 74.4%, 72.3% and 1.8 absorbance in 700 nm for DPPH, ABTS and reducing power assay, respectively. Generally, the findings of this research confirmed the potential of kilka as a source of natural antioxidants for food applications.

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Effect of different temperature (30 to 90 °C), time (10 to 70 min) and pH (4 to 9) conditions were investigated on the extraction efficiency of polysaccharides from seaweed E. intestinalis. Results showed that the extraction temperature had the highest effect on the enhancement of polysaccharide content. The highest polysaccharide extraction yield was achieved at 90 °C, 30 min and pH 8. Therefore, antioxidant effects of polysaccharides obtained at temperatures 30, 70 and 90 °C, times 10, 30 and 50 min, and pH 4, 7 and 8 with significant yield differences were evaluated. DPPH radical scavenging activity, ferric reducing power and total antioxidant activity were employed in order to evaluate the antioxidant properties of polysaccharides. The maximum DPPH radical scavenging activity was obtained for polysaccharides of 30 °C (73.90%), 30 min (95.08%) and pH 7 (75.61%). The highest reducing power was achieved for polysaccharides of 70 °C (97.49%), 50 min (99.05%) and pH 8 (97.49%). The maximum total antioxidant activity was obtained for polysaccharides of 70 °C (49.97), 10 min (62.32) and pH 7 (59.11 mg ascorbic acid/ g dried seaweed powder?). Overall, findings of current study suggest that the polysaccharides from green seaweed E. intestinalis possess antioxidant capacity and that the use of high temperature, long time and acidic or basic pH in extraction process results in diminishing this antioxidant capacity.     

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  In this experiment, acetone was used to extract the phenolic compounds of grape pomace by colorimetric method (Folin-Ciocalteu). The phenolics extract levels of 50, 150, 250 and 350 ppm were used to assess their antioxidant activity in raw soybean oil. On day 0, 4, 8 and 12 the proxide value for soybean oil was estimated. Also, the TBA value for soybean oil on day 0, 5, 9 and 13 was estimated. The results showed that the phenolic compounds whose content in grape pomace is 64 g/kg DM has an antioxidant activity. The level of 150 ppm of tannin extract from grape pomace showed a desirable activity to prevent the oxidation of raw soybean oil. The antioxidant activity of this level was higher than those obtained by the level 200 ppm from synthetic antioxidants. Therefore, the use of phenolic compound in grape pomace as natural antioxidants can be recommended.  

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In this research, methanolic extraction of Salvia leriifolia leaves produced a higher yield and antioxidative activity than other organic solvents (ethanol, acetone, chloroform, n-hexane). ‏The methanolic extract was reserved about 24 hours in the refrigerator and its precipitates were then separated. The extract was separated into 12 fractions by thin-layer chromatography (TLC). The highest yields were found in fractions with Rf values of 0.29, 0.54, 0.11 and 0.38 at 16.24%, 12.48%, 8.81% and 7.60%, respectively. All fractions and also whole methanolic extract and precipitates of methanolic extract had more anti-oxidative activity than the control based on the thiocyanate method. Whole methanolic ex-tract, precipitates of methanolic extract and most separated fractions showed more anti-oxidative activity than –tocopherol. The fraction with Rf value of 0.29 at 16.24% yield and 85.61% antioxidative activity of synthetic antioxidant BHT based on thiocyanat method was chosen as the fraction with the highest yield and the highest antioxidative ac-tivity.

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Free radicals, having one or more unpaired electrons in the outer orbit, which are oxygen-centred free radicals, sometimes known as reactive oxygen species (ROS). The oxidative stress imposed by ROS plays an important role in many chronic and degenerative diseases. The aim of the present research was undertaken to study the antioxidant activity and polyphenolic content in the different extracts of sea urchin Echinometra mathaei. Different extracts (spine, shell, gonad and aristotol lantern) of sea urchin were isolated by three solvents (n- hexan, ethyl acetate, methanol). Antioxidant activity of extracts was assessed by measured reducing power, DPPH free radical scavenging activity and total antioxidant capacity assays, and compared with the synthetic antioxidant butylated hydroxytoluent (BHT) and Ascorbic acid. Total phenolic and flavonoid contents were measured spectrophotometrically. According to the results of the study, highest the reducing power and free radical-scavenging activity of the methanolic shell and methanolic spine, respectively. In total antioxidant capacity assay, the antioxidant activity of aristotol lantern ethyl acetate, spine and gonad n-hexan was higher as compared to that of the ascorbic acid. The highest total phenol and flavonoid compound content per gram of the methanolic spine were 0.0044±0.0003 mg gallic acid equivalents and 24.616±0.7167 mg quercetin equivalents, respectively. Significant differences were observed at P

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Nowadays, replacement of the synthetic antioxidants by natural ones has been noticed in the food industry. Seaweeds with rich sources of antioxidant compounds will be excellent choice for this purpose. In the study Effect of the use of water and different organic solvents such as acetone, ethanol and methanol 50% on the total polyphenol content and antioxidant activity was studied for two species of red algae Hypnea hamulosa and Gracilaria corticata of Persian Gulf. Extraction was performed using conventional solvent extraction method and the ratio of 1:20 algae: solvent. The results indicated that acetone extracts (50%) had the highest values in the total phenol contents (0.31 mg tannic acid / g algal powder), ferric reducing antioxidant power (0.06 mg tannic acid / g algal powder), DPPH radical scavenging activity 76.11% (p<0.05). Total antioxidant activity of this extract showed no significant difference with ethanolic extracts (50%) and aqueous extract (p> 0.05). Comparison of two algal species showed that in all factors except total antioxidant activity, algal species Gracilaria corticata had a higher antioxidant activity (p<0.05). Therefore conclude that solvents with different polarities have a significant effect on total phenolic content and antioxidant activity.

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Aims: Skipjack tuna has the highest level of catch rate among tuna all over the world. Its head contains about 64% protein. Many Protein Hydrolysates and peptides obtained from various marine sources have a high antioxidant power. The aim of this study was to investigate the antioxidant activity of Protein Hydrolysate in Skipjack tuna head.
Materials & Methods: In this experimental study, 30 Skipjack tunas were investigated. At first, the amount of different compounds (protein, fat, ash, and moisture) was evaluated in the raw material; then, the hydrolysis process was performed by Alcalase enzyme and the hydrolysis degree of the protein hydrolysate was evaluated at different times. The antioxidant activity of the protein hydrolysate mixture was measured by DPPH radical scavenging activity, iron revival power, and ABTS radical inhibitory activity. For data analysis, the analytical tests were used.
Findings: The main part of the fish head was protein and it had high levels of ash. The degree of hydrolysis increased with increasing time and was it significant at 15, 60, and 120 minutes (p<0.05), but not significant at 120 and 240 minutes (p<0.05). DPPH radical scavenging activity increased with increasing hydrolysis time and there was a significant difference in all samples obtained from different times (p<0.05). The iron reduction capacity of the protein hydrolysate samples increased with increasing the hydrolysis time, and the highest amount was at 240 minute. The samples obtained from different times had a significant difference in iron reduction capacity (p<0.05). Increasing the concentration of protein hydrolysate increased inhibitory activity (p<0.05).
Conclusion: Protein hydrolysate in Skipjack tuna head has a high antioxidant activity and can be used in food products to increase oxidation stability.

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Microorganisms and plants have high potential for reducing the metal (biosynthesis of nanoparticles) through their metabolic pathways. Apart from the environmental benefits of biosynthesis of nanoparticles, there is the opportunity for production of nanomaterial with new properties in this method. In this study, the fruit aqueous extract of Capparis spinosa L. was used for synthesis of nanoparticles. To evaluate the reducing potential of plant, total phenolic content and antioxidant activities of both aqueous and ethanolic extracts were measured by DPPH and FRAP methods. The aqueous extract showed a lower antioxidant activity than the ethanolic extract; however, it had high potential to reduce the free radicals and metal ions. After preparing the extract, for phytosynthesis of silver nanoparticles, 2 ml of extract was added to 4 ml of 1 mM silver nitrate. The extract was used as a reducing and stabilizing agents of the nanoparticles. The effect of determining parameters for optimizing synthesis of nanoparticles such as: pH of reaction, the amount of extract, concentration of metal ion and time of reaction were evaluated using Ultraviolent-Visible (UV-Vis) spectroscopy and Transmission Electron Microscopy (TEM) .The spectrum of Surface Plasmon Resonance (SPR) of silver nanoparticles showed the maximum absorbance at 415 nm. Fourier Transform Infrared (FT-IR) spectroscopy was used to identify the possible functional groups involved in the synthesis of silver nanoparticles. The Results showed that the nanoparticles were spherical shape and the size of them were about 8-12 nm.

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  In the present study the effects of extract from the peels of Ramus potato variety as a natural antioxidant in refined soybean oil were investigated using the Schaal oven and Rancimat methods. Phenolic antioxidants of potato peels were extracted by two different solvent extraction methods (Solvent with methanol and ultrasound-assisted method with different solvents including methanol, ethanol, hexane, acetone and water ). The total phenolic compounds were determined according to the Folin–Ciocalteu method. Maximum amount of extract was obtained with water, followed by methanol and ethanol but maximum amount of phenolics was obtained                                                            with methanol, followed by water and ethanol by ultrasound method. Sonication improved the total phenolic compounds of the potato peel extract and shortened the extraction times.                                                                                                   After 16 days storage at 63°C,soy bean oil containing 200, 800, 1600, and 2400 ppm of  methanolic extract of potato peels, attained lower peroxide values (PV , 42.67 , 37.35 , 24.65 and 19.09 meq/kg, respectively) than the control sample (PV , 64.08 meq/kg ) indicating strong antioxidant activity. Oils treated with 200 ppm of BHA, BHT and TBHQ attaind PVs of 33.20 , 28.88 and 9.96 meq/kg, respectively, after 16 days storage at 63°C. Also, results Rancimat (at 90,120,150°C) showed that potato peel extract, at concentrations of 1600 and 2400 ppm exhibited strong antioxidant activity which was almost equal to synthetic antioxidants (BHA & BHT).                                                                                                                                                     

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  Phenolic compounds, especially those of plants origin, are an essential part of the human diet, and are of considerable interest due to their antioxidant properties. The total phenolics content (TPC) and antioxidant and antimicrobial activities of pistachio green hull methanolic extracts of five different cultivars (Fandoghi, Kaleghochi, Ahmadaghai, Forotani and Seyed ali aghai) were studied. TPC ranged from 15.3 mg/g of GAE (cv. Kaleghochi) to 31.1 mg/g of GAE (cv. Ahmadaghai). The antioxidant capacity of extracts was assessed through DPPH and ABTS methods. A concentration-dependent antioxidative capacity was verified in both methods for all the cultivars. Antioxidant activity of Ahmadaghai cultivar in both methods was more than the other cultivars. The antimicrobial capacity was screened against Gram positive and Gram negative bacteria, and fungi. All the extracts inhibited the growth of Gram positive bacteria of Bacillus cereus and Staphylococcus aureus. Bacillus cereus was more susceptible than Staphylococcus aureus for all the extracts. The results obtained in this study showed that pistachio green hull can be used as a cheap and easily accessible source of natural bioactive compounds.

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g-oryzanol is an unsaponifiable component of rice bran oil, composed of several kinds and has antioxidant activity similar to tocopherols. In order to separate g-oryzanol, four varieties of rice from north part of  Iran have been selected. These varieties include "local Tarom", "Fajr", "Shirudi" and "Neda". rice bran oil was subjected to oil extraction after thermal stabilization. Column and HPTLC chromatography followed by GC/MS were employed for separation, purification and identification of g-oryzanol. The antioxidant activity of the isolated concentrates were determined  0.01, 0.05 and  0.1 percent on tallow, a substrate suitable to evaluate antioxidant activity due to the lack of natural antioxidants. The results indicated that "Neda" variety had  the  highest content of oil  and g-oryzanol but the obtained g-oryzanol from "local Tarom"variety showed the highest antioxidant activity.

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Antioxidant properties of plant extracts are apparently related to the content of their phenolic compounds. In this study, phenolic compounds from two acorns varieties namely Q.branti var persica (Q.b) and Q.castaneifolia var castaneifolia (Q.c) were extracted with methanol (80%). After evaporation with rotary evaporator, extracts were dried with freeze drier. The concentrations of phenolic compounds in the extracts were determined according to the Folin-Ciocalteu method, and results were expressed as tannic acid equivalents per gram of dried extract (TAE/g d.e). Castaneifolia variety had the highest phenolic content with 217.65 (TAE/g d.e). Antioxidant activity of methanolic extracts were studied in sunflower oil and compared with synthetic antioxidants, by measuring their peroxide and thiobarbituric acid values during accelerated storage. Methanolic extracts of acorns at three different concentrations (250,500 and 1000 ppm) and synthetic antioxidant at two concentrations were added to sunflower oil. Both extracts retarded the oxidation of sunflower oil at 70°c more efficiently than BHA and BHT. The peroxide and thiobarbitoric acid values of control samles were raised to 328.88 (meq peroxide/ kg oil) and 0.58 (mg malon aldehyde/kg oil) after tewelve days storage while this values were 176.36 and 0.332 for oil sample contain 1000 ppm methanilic extract of Q.c  and 183.2 and for Q.b were 0.374, respectively.

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In this study, phenolic compounds of acorns (Q.castaneifolia var castaneifolia) were extracted with water and ethanol (70%). Total phenolic content of water and ethanolic (Et) extracts were 238.85 and 142.18 mg TAE/gr dried extracts, respectively. Antioxidant activity was evaluated using three different methods: including scavenging effect on DPPH radicals, reducing power of Fe⁺³ and total antioxidant capacity. The results were compared with synthetic antioxidant, BHA and BHT. In all the methods, the antioxidant activity was concentration dependent. Ethanolic extract of Q.castaneifolia was the highest in DPPH assay (EC50=34.28 µg/ml). In the reducing power and total antioxidant capacity, BHT obtained the best results followed by ethanolic extract , BHA and water extract. Also, the protective effect of ethanolic extract in stabilizing sunflower oil was tested. Ethanolic extract of acorn at three different concentrations, i.e. 250 (Et-250), 500 (ET-500) and 1000 ppm (Et-1000) was added to sunflower oil. BHA and BHT at 100 and 200 ppm were chosed as standards along with the control. All samples were incubated in open beakers at 70°C in the dark for 12 days. The peroxide and tiobarbitoric acid values of the samples were determined at definite time intervals of 0, 2, 4, 6, 8, 10 and 12 days. Results showed that ethanolic extract at all concentration retarded the retarded the oil oxidation. Et-1000ppm and Et-500 ppm  exhibited stronger antioxidant activity compared to BHT-200 and Et-250 was better than BHA-100.

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Citrus peel is a natural source of antioxidants and the use of its natural extracts to improve the quality of fish is increasing. The effect of orange peel extract on the chemical and sensory properties of Huso huso fillet when refrigerated (4±1 °C) was investigated. In this study, fish fillets with aqueous solutions of ethanolic extract of orange peel (w / w 5%) or (5 ml of extract in 100 ml of solvent), orange peel extract (w / w 6%) and orange peel extract (w / w 7%) were tested as natural preservatives for 30 minutes. Control samples were immersed in distilled water for 30 minutes. Control and treated samples were packed with ethanolic extract of orange peel and stored for 15 days. Samples are then taken at regular intervals for chemical properties of pH, free fatty acid (FFA), peroxide (PV), thiobarbituric acid (TBA), total volatile nitrogen bases (TVB-N) and sensory evaluation (texture, color, odor and acceptance) were studied. Analysis of the results of chemical tests and sensory evaluation showed that orange peel extract maintains good quality characteristics and increases the shelf life of fish samples during storage at refrigerator temperature. 7% orange peel extract and then 6% and 5% orange peel extract significantly (P <0.01) delayed the oxidation and hydrolysis of fat in the samples that treated with the Orange peel extract.

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Tea and sesame seed oils extracted by different methods (including supercritical fluid extraction (SFE), at a pressure of 350 atm, a temperature of 60oC, a static extraction time of 20 minutes, a dynamic extraction time of 30 minutes and 150 g kg-1 of ethanol as a modifier). Solvent (SE) and ultrasound-assisted solvent extraction (UE)), as natural anti-oxidants, were evaluated during 15 days storage by monitoring their effects on refined sunflower oil at 60oC. The peroxide value (PV) and the thiobarbituric acid (TBA) value were used to assess the antioxidant activity of these extracted oils. The highest extraction yields were from SE and SFE, while UE gave a lower yield. Considering oil extraction yield and antioxidant activity, SE and SFE were the preferred methods. The results showed that tea seed oil had strong antioxidant activity, which was almost equal to sesame oil. Therefore, tea seed oil can be used in the same way as sesame seed oil in fat, oil and other food products as a natural antioxidant to suppress lipid oxidation.

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Diabetes mellitus is a major health problem in the worldwide. Inhibition of DPP-IV is one of the methods to control diabetes type 2. Inhibition of this enzyme may improve glycemic control in diabetics by preventing the rapid breakdown and there by prolonging the physiological action of incretin hormones. Furthermore, improving the antioxidant system in diabetic patients can prevent the occurrence of secondary disease caused by oxidative stress. Therefore, the head of skipjack tuna was hydrolyzed with alcalase enzyme (1/5% of raw material weight) for 4 hours, in order to produce a product with antidiabetic and antioxidant activities. The DPP-IV inhibition activity, DPPH radical scavenging activity and reducing power of hydrolysate were measured. The results showed that the skipjack tuna head protein hydrolysate possess bioactive properties in a concentration dependent manner and increasing the protein concentration leads to a significant increase in bioactive properties of hydrolyzed product (p≤0.05). The IC50 of protein hydrolysate in DPP-IV inhibition and DPPH radical scavenging activities were obtained 1.016±0.02 mg/ml and 0.297±0.015 mg/ml, respectively. Also the reducing power of hydrolysate was 0.176±0.002 in 2.5 mg/ml protein concentration. Overall, according to the obtained results, it can be concluded that protein hydrolysate of skipjack tuna head possess high antioxidant and antidiabetic activities in vitro, and can be used as a food additive to enhance health level if additional research be conducted.

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Pomegranate, a small tree with potential human health benefits, is grown mainly in Iran, India and USA as well as in most Near and Far East countries. It has been used extensively in folk medicine for a number of therapeutic purposes. In the present study, the ferric reducing/antioxidant power assay (FRAP) was employed and the FRAP value of the seed fraction of six different cultivars of pomegranate in Iran was determined in an attempt to compare their differing antioxidant acitivity. The antioxidant activity of seed fraction of six different cultivars of pomegranate in water extracts showed that the Sour white peel cultivar has the highest FRAP value (3.450.85 M) and the Agha Mohamad Ali cultivar has the lowest value (2.760.76 M); ethanolic extract of the seeds showed that Sour white peel and Black peel cultivars have the highest (3.881.31 M) and lowest (1.620.47 M) antioxidant activity, respectively. Results indicated that the extracts obtained from pomegranate seeds using various solvents exhibited various degrees of antioxidant activity. Further, it was cleared that Sour white peel had the highest potent antioxidant activity among different pomegranate seed cultivars and, so might be useful for its health benefits.