A Novel Insight into Screening for Antioxidant Peptides from Hazelnut Protein: Based on the Properties of Amino Acid Residues

This study used the properties of amino acid residues to screen antioxidant peptides from hazelnut protein. It was confirmed that the type and position of amino acid residues, grand average of hydropathy, and molecular weight of a peptide could be comprehensively applied to obtain desirable antioxidants after analyzing the information of synthesized dipeptides and BIOPEP database. As a result, six peptides, FSEY, QIESW, SEGFEW, IDLGTTY, GEGFFEM, and NLNQCQRYM were identified from hazelnut protein hydrolysates with higher antioxidant capacity than reduced Glutathione (GSH) against linoleic acid oxidation. The peptides having Tyr residue at C-terminal were found to prohibit the oxidation of linoleic acid better than others. Among them, peptide FSEY inhibited the rancidity of hazelnut oil very well in an oil-in-water emulsion. Additionally, quantum chemical parameters proved Tyr-residue to act as the active site of FSEY are responsible for its antioxidation. This is the first presentation of a novel approach to excavating desired antioxidant peptides against lipid oxidation from hazelnut protein via the properties of amino acid residues.

Synthesis, Characterization, Antioxidant Activity, and Toxicity Properties of Tripolyphosphate Crosslinked Chitosan

Chitosan is biopolymer obtained from chitin deacetylation reaction. Chitin is a constituent of shrimps’ outer shell. Chitosan modification using crosslinker agent could increase the active groups and stabilize the physical character. One of non-toxic crosslink agents was tripolyphosphate. This study aimed at synthesizing tripolyphosphate crosslinked chitosan (TPP-Cs) to test the antioxidant and toxicity. Synthesizing tripolyphosphate chitosan was conducted using ionic gelation method. The antioxidant activity test was studied from DPPH radicals scavenging and the ability to inhibit linoleic acid oxidation. The toxicity test was using BSLT (Brine Shrimp Lethality Test) method and Artemia salina leach nauplii. The study showed that TPP-Cs could be synthesized from pink shrimp and showed antioxidant activity. The activity was due to amino and hydroxyl groups. The BSLT method showed that TPP-Cs had the potential to be applied for antibacterial, antivirus, or anticancer products.

Natural Cinnamic Acid Derivatives: A Comprehensive Study on Structural, Anti/Pro-Oxidant, and Environmental Impacts

Cinnamic acid (CA), p-coumaric acid (4-hydroxycinnamic acid, 4-HCA), caffeic acid (3,4vdihydroxycinnamic acid, 3,4-dHCA), and 3,4,5-trihydroxycinnamic acid (3,4,5-tHCA) were studied for their structural, anti-/pro-oxidant properties and biodegradability. The FT-IR, FT-Raman, UV/Vis, 1H and 13C NMR, and quantum chemical calculations in B3LYP/6-311++G** were performed to study the effect on number and position of hydroxyl group in the ring on the molecular structure of molecules. The antioxidant properties of the derivatives were examined using DPPH● and HO● radicals scavenging assays, ferric ion reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), inhibition of linoleic acid oxidation, as well as the biological antioxidant assay with Saccharomyces cerevisiae. Moreover, the pro-oxidant activity of compounds in Trolox oxidation assay was estimated. The effect of the derivatives on environment on the basis of increasing the carbon and nitrogen compounds transformation processes occurring in biological wastewater treatment was studied.

Antioxidant activities of pomegranate peel methanolic and water extracts by in vitro methods

In this study, the antioxidant activities of pomegranate (Punica granatum) peel extracts were investigated using different antioxidant activity methods. The antioxidant activities of extracts prepared at different concentrations (100-1000 μg/ml) were compared with α-tocopherol, ascorbic acid, BHT, and BHA standards. The methanol extract of peels had the highest yield (45.5%). Chelating activities (Fe2+) of methanol extract at 100-1000 μg/ml concentrations ranged between 16.63 and 46.45%. However, the chelating activities of all test extracts were lower than the standards. The reducing power of all extracts increased concentration-dependent. DPPH˙˙ radical scavenging activity of methanol extract varied in the range of 18.53 to 88.75%. The highest percentage inhibition of linoleic acid oxidation was found in 250 μg/ml concentrations. Trolox equivalent (TEs) antioxidant capacity values of methanol extract ranged from 3.09 to 15.27 µM TEs 10 g-1. It was determined that methanol extract showed a dose-dependent inhibition of the antioxidant activities.

Fertilizer micro-dosing and harvesting time of indigenous leafy vegetables affect in vitro antioxidant activities

Plant nutrient management can influence the type and level of polyphenolic compounds within leafy vegetables. Therefore, we investigated the effects of fertilizer micro-dosing and harvest time on antioxidant activities of aqueous polyphenolic extracts from Amaranthus cruentus, Ocimum gratissimum and Solanum macrocarpon. Plants were cultivated using urea alone or combined with cattle manure for three staggered harvest periods. Polyphenolics profile (RP-HPLC), DPPH, hydroxyl and superoxide radical scavenging activities, ferric ion reducing power, ferrous ion chelation and inhibition of linoleic acid oxidation were determined. Polyphenolic contents of A. cruentus (caffeic acid, myricetin, quercetin and rutin) and O. gratissimum (catechin and gallic acid) as well as antioxidant activities of the vegetables extracts (except hydroxyl radical scavenging by A. cruentus) were fertilizer micro-dose and harvest time-dependent. Thus, combination of both factors highlighted the screening of optimal farming conditions for these vegetables in order to get leaf extracts possessing higher polyphenolic contents and antioxidant activities.

Fertilizer micro-dosing and harvesting time of indigenous leafy vegetables affect in vitro antioxidant activities

Plant nutrient management can influence the type and level of polyphenolic compounds within leafy vegetables. Therefore, we investigated the effects of fertilizer micro-dosing and harvest time on antioxidant activities of aqueous polyphenolic extracts from Amaranthus cruentus, Ocimum gratissimum and Solanum macrocarpon. Plants were cultivated using urea alone or combined with cattle manure for three staggered harvest periods. Polyphenolics profile (RP-HPLC), DPPH, hydroxyl and superoxide radical scavenging activities, ferric ion reducing power, ferrous ion chelation and inhibition of linoleic acid oxidation were determined. Polyphenolic contents of A. cruentus (caffeic acid, myricetin, quercetin and rutin) and O. gratissimum (catechin and gallic acid) as well as antioxidant activities of the vegetables extracts (except hydroxyl radical scavenging by A. cruentus) were fertilizer micro-dose and harvest timedependent. Thus, combination of both factors highlighted the screening of optimal farming conditions for these vegetables in order to get leaf extracts possessing higher polyphenolic contents and antioxidant activities.