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In this study, gelatin was first extracted by alkaline and acidic treatment including 0.19 N NaOH and 0.12 N acetic acid solution by ratio of skin of rainbow trout (Oncorhynchus mykiss (to solution of 1 to 7 and then heat treatment in 50 °C. Then, hydrolysed by alcalase enzyme for 4 hours with the ratio of enzyme to the substrate 1 to 100 and the degree of hydrolysis were measured after 4 hours. DPPH and ABTS free radical scavenging activity, as well as reducing power assay of gelatin hydrolysate were measured. The results showed that the degree of hydrolysis after 4 hours was 46/7%. Also the highest DPPH and ABTS free radical scavenging and reducing power at concentration of 10 mg/ml were 39/8%, 50/7%, and 0/123, respectively. The skin from fish filleting can be a suitable raw material for extraction of peptides with biological activities. The results showed that peptides derived from rainbow trout fish skin gelatin can be considered as a natural antioxidant.

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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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Zebrafish is considered as a useful laboratory model due to its diverse characteristics, including self-renewal. The embryo of this fish has unique characteristics in the early stages of development, and its effects were observed in various studies. The differentiating factors present in stem cells isolated from zebrafish embryos are effective in improving the functional status of patients, and exposure to zebrafish embryo extracts in the early stages of development may increase the expression of multipotent stem cells and exert positive effects.  In this study, we investigated the antioxidant properties of the zebrafish embryo extract in different embryonic stages of development.The Zebrafish egg extract was prepared in different embryonic stages. Its effect in concentrations of 0.5, 1, 1.5 and 2 mg/ml on DPPH free radical scavenging activity, ABTS radical inhibitory activity and iron reducing power (FRAP) were investigated. The studied groups included protein extracts in morula, blastula and gastrula stages. According to the obtained results, the amount of protein varied in different embryonic stages and the amount of protein increased with the progress of fetal growth and the amount of fat decreased.The protein extract in the gastrula stage showed the highest level of DPPH inhibition and iron ion reduction at a concentration of 2 mg/ml compared to the morula and blastula groups (P<0.05). Also, the protein extract in the embryonic stage of blastula had the highest inhibition of ABTS at a concentration of 2 mg/ml compared to other groups (P<0.05).

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The antioxidant capacity of wheat germ protein hydrolyzed by Alcalase was optimized using Response Surface Methodology (RSM). The optimum hydrolyzing parameters were found at temperature of 52.28°C, time 233 minutes, and E/S 1.46 %. The amino acids profiles of intact and hydrolyzed proteins showed that Wheat Germ Protein Hydrolysate (WGPH) had higher percentage of hydrophobic amino acids than that of intact protein. WGPH prepared in optimum condition was fractionated by RP-HPLC. The obtained fractions were subjected to ABTS assay for antioxidant capacity evaluation. The fraction with higher antioxidant value was then exposed to further analysis by LC-ESI/MS/MS. The sequences of the peptides were found to be TVGGAPAGRIVME (1257.66 Da) and GNPIPREPGQVPAY (1494.77 Da).

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In the last decades, an increasing interest has been granted to halophytes due to their high phenolic content, which have therapeutic potential in the treatment and/or management of human health. Therefore, it is important to measure the halophyte total polyphenol content correctly and to valorize their antioxidant capacity. Ethanol extracts from thirty halophytes were analyzed to evaluate the Total Phenol Content (TPC). We employed three testing methods to prove their antioxidant potentialities, including DPPH^• (1-DiPhenyl-2-PicrylHydrazyl), ABTS^•+ (2,20-Azino-Bis-3-ethylbenzoThiazoline-6-Sulfonic acid) and IRP (Iron Reducing Power) assays. Results showed that plants exhibited different TPC, which varied significantly from 411.5 mg GAE g^-1 DW in Cynomorium coccineum to 6.02 mg GAE g^-1 DW in Ammophila arenaria. Concerning antioxidant activities, data revealed that Cynomorium coccineum (IC₅₀= 3.82 µg ml^-1 versus ABTS^•+) and Euphorbia paralias had the highest antiradical capacity (IC₅₀= 0.12 µg ml^-1 against DPPH^•) and exhibited the best efficient concentration with an EC₅₀ value= 9.57 µg mL^-1 for the IRP. Considering correlation between phenols and antioxidant tests, three groups were distinguished with a higher correlation coefficient between 0.78 and 0.98 for the first group. These data suggest the promising potentialities of the Mediterranean medicinal halophytes as valuable source of powerful antioxidants of industries, especially for Cynomorium coccineum, Carpobrotus edulis, Reaumuria vermiculata, Tamarix gallica, and Euphorbia paralias regarding their strong phenol content.