Peroxidation In Linoleic Acid System Research Articles

Chemical Composition, Antioxidant, and Antimicrobial Activities of Rosmarinus officinalis Essential Oil From Moroccan Middle Atlas

This study was designed to evaluate antioxidant and antibacterial activities of essential oils from Rosmarinus officinalis obtained by three different extraction methods: DA: Artisanal distillation; the essential oils were obtained directly from small cooperatives using a very traditional (nonindustrial) method and based on the technique of Steam distillation; DI: Industrial distillation which is also based on steam distillation; and DC: hydrodistillation through Clevenger apparatus laboratory. The chemical analyses were carried out with gas chromatography/mass spectrometry (GC/MS); they identified 16 components representing more than 99.89% of the essential oil and indicate that the chemotype is 1,8-Cineole and varies according to the method used (DI: 49.09%, DA: 42.12%, and DC: 53.21%). The antioxidant activity was evaluated by the β-carotene bleaching test measuring percent inhibition of peroxidation in linoleic acid system. The disc diffusion and modified resazurin microtiter-plate assays were used, respectively, to evaluate the inhibition zones (IZ) and minimum inhibitory concentration (MIC) of Rosmarinus officinalis essential oil. In general, Rosmarinus officinalis L. essential oil showed a lower antioxidant and antimicrobial activity than 1,8-Cineole the major component of the essential oil.

Chemical composition, antioxidant and antimicrobial potential of essential oils from different parts of Daphne mucronata Royle

This research work was executed to determine chemical composition, anti-oxidant and anti-microbial potential of the essential oils extracted from the leaves and stem of Daphne mucronata Royle. From leaves and stem oils fifty-one different constituents were identified through GC/MS examination. The antioxidant potential evaluated through DPPH free radical scavenging activity and %-inhibition of peroxidation in linoleic acid system. The stem’s essential oil showed the good antioxidant activity as compared to leaves essential oil. Results of Antimicrobial activity revealed that both stem and leaves oils showed strong activity against Candida albicans with large inhibition zone (22.2 ± 0.01, 18.9 ± 0.20 mm) and lowest MIC values (0.98 ± 0.005, 2.44 ± 0.002 mg/mL) respectively. Leaves essential was also active against Escherichia coli with inhibition zone of 8.88 ± 0.01 mm and MIC values of 11.2 ± 0.40 mg/mL. These results suggested that the plant’s essential oils would be a potential cradle for the natural product based antimicrobial as well as antioxidant agents.

Compositional studies and Biological activities of Perovskia abrotanoides Kar. oils.

BackgroundCurrent study has been designed to evaluate the chemical composition of essential and fixed oils from stem and leaves of Perovskia abrotanoides and antioxidant and antimicrobial activities of these oils.ResultsGC-MS analysis of essential oil identified 19 compounds with (E)-9-dodecenal being the major component in stem and hexadecanoic acid in leaves. In contrast, GC-MS analysis of fixed oil showed 40 constituents with α-amyrin the major component in stem and α-copaene in leaves. The antioxidant activity showed the highest value of 76.7% in essential oil from leaves in comparison with fixed oil from stem (45.9%) through inhibition of peroxidation in linoleic acid system. The antimicrobial assay tested on different microorganisms (e.g. E. coli, S. aureus, B. cereus, Nitrospira, S. epidermis, A. niger, A. flavus and C. albicans) showed the higher inhibition zone at essential oil from leaves (15.2 mm on B. cereus) as compared to fixed oil from stem (8.34 mm on S. aureus) and leaves (11.2 mm on S. aureus).ConclusionsThe present study revealed the fact that essential oil analyzed from Perovskia abrotanoides stem and leaves could be a promising source of natural products with potential antioxidant and antimicrobial activities, as compared to fixed oil.

Antioxidant/prooxidant effects of α-tocopherol, quercetin and isorhamnetin on linoleic acid peroxidation induced by Cu(II) and H2O2

The peroxidation of linoleic acid (LA) in the presence of copper(II) (Cu(II)) ions alone and with α-tocopherol (α-TocH) was investigated in aerated and incubated emulsions at 37 °C and pH 7. Additionally, the effects of quercetin (QR) and its O-methylated derivative, isorhamnetin (IR), as potential antioxidant protectors were studied in the (Cu(II) + TocH)-induced LA peroxidation system. Cu(II)-induced LA peroxidation followed pseudo-first-order kinetics with respect to primary (hydroperoxides) and secondary (aldehydes- and ketones-like) oxidation products, which were determined by ferric thiocyanate and thiobarbituric acid-reactive substances methods, respectively. As opposed to the concentration-dependent (at 0.6 and 10.0 µM) prooxidative action of α-TocH in the absence of QR and IR, the latter two compounds showed antioxidant effect over TocH. The peroxidation of LA in the presence of Cu(II)−H2O2 combination alone and with TocH, QR and IR were also investigated in aerated and incubated emulsions, where the latter three compounds exhibited antioxidant effects.

Isolation and identification of antioxidant peptides derived from whey protein enzymatic hydrolysate by consecutive chromatography and Q-TOF MS

To isolate and identify antioxidant peptides from enzymatically hydrolysed whey protein, whey protein isolate was hydrolysed by different protease (trypsin, pepsin, alcalase 2·4L, promatex, flavourzyme, protease N). The hydrolysate generated by alcalase 2·4L had the highest antioxidant activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, superoxide radicals and in a linoleic acid peroxidation system induced by Fe2+. The IC50 values of DPPH and superoxide radical scavenging activities of the hydrolysate decreased significantly (6·89 and 38·88%, respectively) after treatment with macroporous adsorption resin. Seven different peptides showing strong antioxidant activities were isolated from the hydrolysate using consecutive chromatographic methods including gel filtration chromatography and high-performance liquid chromatography. The molecular mass and amino acids sequences of the purified peptides were determined using a Quadrupole time-of-flight mass spectrometer (Q-TOF MS). One of the antioxidative peptides, Trp-Tyr-Ser-Leu, displayed the highest DPPH radical scavenging activity (IC50=273·63 μm) and superoxide radical scavenging activity (IC50=558·42 μm). These results suggest that hydrolysates from whey proteins are good potential source of natural antioxidants.

Benzophenones fromHypericum eleganswith antioxidant and acetylcholinesterase inhibitory potential

Background:Hypericum elegans is used in Bulgarian folk medicine for treatment of wounds, depression, gastrointestinal and bacterial diseases.Objective:Recently, new natural benzophenones: Elegaphenone and O-glycosides: Hypericophenonoside, Neoannulatophenonoside and Elegaphenonoside as well as already known 7-Epiclusianone were isolated from the titled species. The aim of the present study was to evaluate the antioxidant and acetyl cholinesterase inhibitory potential of the isolated compounds.Materials and Methods:1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) di-ammonium salt (ABTS) free radicals, ferric reducing antioxidant power (FRAP) assay as well as inhibition of lipid peroxidation in linoleic acid system were used for determination of antioxidant activity. Modified Ellman's colorimetric method was carried out to assess the acetyl cholinesterase inhibition potential. Hyperoside and Galantamine hydrobromide were used as positive controls.Results:Hypericophenonoside was found to possess the strongest DPPH radical scavenging activity (IC50 = 181.85 ± 6.82 μM), while Neoannulatophenonoside showed the highest ABTS (IC50 = 0.25 ± 0.005 μM) and lipid peroxidation inhibitor activity. FRAP activity was demonstrated only by prenylated aglycones – Elegaphenone [942.16 ± 4.03 μM Trolox Equivalent (TE)] and 7-Epiclusianone (642.95 ± 3.95 μM TE) and was stronger compared to the control Hyperoside (421.75 ± 9.29 μM TE). Elegaphenone and 7-Epiclusianone were found to possess moderate acetyl cholinesterase inhibitory potential with IC50 values of 192.19 ± 3.54 μM and 142.97 ± 4.62 μM, respectively.Conclusion:The results obtained revealed that H. elegans is a potential natural source of bioactive compounds and benzophenones could be useful in therapy of free radical pathologies and neurodegenerative disorders.

Antioxidant and acetylcholinesterase inhibition properties of Amorpha fruticosa L. and Phytolacca americana L.

Background:Amorpha fruticosa L. and Phytolacca americana L. are native plants for North America, but invasive for Central Europe and the Mediterranean areas. Previous investigation reported DPPH radical scavenging activity of A. fruticosa seeds from Mississippi river basin and P. americana berries from Iran. The aim of the present study was to investigate methanol extracts from leaves and fruits of these invasive species growing in Bulgaria for radical scavenging and acetylcholinesterase inhibitory potential.Materials and Methods:Antioxidant activity was investigated using DPPH and ABTS free radicals; FRAP assay and inhibition of lipid peroxidation in linoleic acid system by FTC. Modified Ellman′s colorimetric method was carried out to quantify acetylcholinesterase inhibition potential. In addition, the quantities of total polyphenols, flavonoids, and hydroxycinnamic derivatives were determinated using Folin-Chiocalteu reagent, AlCl3, and Na2MoO4, respectively.Results:The highest concentrations of total polyphenols and flavonoids were found in A. fruticosa leaves (786.70±1.78 mg/g dry extract and 32.19±0.29 mg/g dry extract, respectively). A. fruticosa fruit was found to be the most enriched in total hydroxycinnamic derivatives (153.55±1.11 mg/g dry extract) and demonstrated the highest antioxidant activity: DPPH, IC50 9.83 μg/mL; ABTS, IC50 2.90 μg/mL; FRAP 642.95±3.95 μg TE/mg de, and acetylcholinesterase inhibitory activity, 48.86±0.55% (2 mg/mL).Conclusions:Phytolacca americana leaves and Amorpha fruticosa could be useful in therapy of free radical pathologies and neurodegenerative disorders.

Essential‐Oil and Fatty‐Acid Composition, and Antioxidant Activity of Extracts of Ficaria kochii

The essential-oil and fatty-acid composition of the aerial parts of Ficaria kochii (Ledeb.) Iranshahr & Rech.f. native to Iran, and the antioxidant activity of various extracts of this plant were examined. The study by GC-FID and GC/MS analysis of the essential oil resulted in the identification of 61 compounds, representing 86.01% of the total oil composition. Phytol (10.49%), farnesol (7.72%), methyl linoleate (5.57%), and α-farnesene (4.96%) were the main components. The fatty-acid composition of the aerial parts of F. kochii was also analyzed by GC/MS. The major components were palmitic acid (25.9%), linolenic acid (25.3%), and linoleic acid (17.5%). Polyunsaturated fatty acids (PUFAs) were found in higher amounts than saturated fatty acids. The possible antioxidant activity of various extracts (prepared by using solvents with different polarity) of the F. kochii aerial parts was evaluated by screening for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, Fe(III) -reducing power, total antioxidant activity, and inhibitory activity in the linoleic acid-peroxidation system. H(2) O proved to be the most efficient solvent for the extraction of antioxidants, as the H(2) O extract contained the highest amount of phenolic compounds (2.78±0.23 GAE/g dry matter) and also exhibited the strongest antioxidant capacity in all the assays used. The results of the present investigation demonstrated that the aerial parts of F. kochii can be used as natural and safe nutrition supplement in place of synthetic ones.

Variation in Antioxidant Attributes at Three Ripening Stages of Guava (Psidium guajava L.) Fruit from Different Geographical Regions of Pakistan

The present investigation was carried out to appraise the levels of total phenols and vitamin C as well as antioxidant potential at three different ripening stages (un-ripe, semi-ripe and fully-ripe) of guava (Psidium guajava L.) fruit collected from three different geographical regions of Pakistan (Islamabad, Faisalabad and Bhakkar). The antioxidant potential of guava fruit extracts was assessed by means of different in-vitro antioxidant assays, namely inhibition of peroxidation in linoleic acid system, reducing power and radical scavenging capability. Overall, fruit at the un-ripe stage (G1) exhibited the highest levels of TPC, TFC, reducing power and DPPH radical scavenging activity, followed by the semi-ripe (G2) and fully-ripe (G3) stages. On the other hand, vitamin C content increased as the fruit maturity progressed, with highest value seen at the fully-ripe stage (G3) followed by the semi-ripe (G2) and un-ripe stage (G1). The concentration of vitamin C in fruits varied as: Faisalabad (136.4–247.9 mg 100 g−1), Islamabad (89.7–149.7 mg 100 g−1) and Bhakkar (73.1–129.5 mg 100 g−1). The results showed that different stages of maturation and geographical locations had profound effects on the antioxidant activity and vitamin C contents of guava fruit.

Benzophenones and flavonoids from Hypericum maculatum and their antioxidant activities

The occurrence of three known benzophenones, namely annulatophenonoside, acetylannulatophenonoside and annulatophenone as well as a flavonol O-glycoside guajaverin in the aerial parts of Hypericum maculatum Crantz was established. In addition, hyperoside, isoquercitrin and miquelianin were isolated from this plant, as well. Radical scavenging and antioxidant activities of the isolated compounds were examined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) free radicals, ferric reducing antioxidant power (FRAP) assay and inhibition of lipid peroxidation in linoleic acid system by the ferric thiocyanate method. Isoquercitrin demonstrates the highest DPPH radical scavenging (96.6 ± 0.3%), FRAP (23.8 ± 0.2 Trolox equivalent, TE mol−1) and antioxidant activity in linoleic acid system. Guajaverin and acetylannulatophenonoside show significantly strong ABTS radical scavenging activity (93.9 ± 0.4% and 93.4 ± 0.6%, respectively), which is comparable to that of ascorbic acid (96.2 ± 0.4%).

Antioxidant Activity of Some Carduus Species Growing in Bulgaria

Background: Species of genus Carduus are traditionally used in Bulgarian folk medicine as diuretic, cardiotonic and antihemorroidal remedies. C. candicans ssp. globifer and C. kerneri ssp. austro-orientalis are Balkan endemic, whereas C. acanthoides, C. nutans, C. thoermeri C. are invasive alien weeds in the Americas, Australia and New Zealand, and causes major economic losses. The aim of the present study was to screen some Carduus spesies growing in Bulgaria for radical scavenging and inhibitition of lipid peroxidation in order to discover new natural sources of antioxidants for further investigation. Methods: Antioxidant activity of Carduus species were investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2´-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) di-ammonium salt (ABTS) free radicals; ferric reducing antioxidant power (FRAP) assay and inhibition of lipid peroxidation in linoleic acid system by the ferric thiocyanate method (FTC). Butylated hydroxytoluene (BHT) and ascorbic acid were used as positive controls. In addition, the quantification of total water soluble polyphenols and flavanoids were determinate by Folin-Chiocalteu reagent and AlCl3, respectively. Results: The highest concentrations of total water soluble polyphenols and flavonoids were found in C. thoermeri (2.06 ± 0.03 g /100 g dw and 3.31 ± 0.12 g /100 g dw, respectively), followed by C. nutans (1.88 ± 0.01 g/100 g dw; 2.60 ± 0.09 g /100 g dw, respectively) and C. candicans ssp. globifer (1.85 ± 0.04 g/100 g dw). Conclusions: All tested extracts demonstrate significant antioxidant activity moreover C. thoermeri, C. nutans and C. candicans ssp. globifer were found to be the most potent and can be a good new source of natural antioxidants.

Antioxidant Activity in Some In vitro Oxidative Systems of the Essential Oils from the Fruit and the Leaves of Platycladus orientalis

The antioxidant effects of the essential oils from the fruit and leaves of Platycladus orientalis Franco (Cupressacae) were studied. Accordingly, their ability to inhibit (i) LDL oxidation, (ii) red blood cells hemolysis, (iii) insulin and hemoglobin glycosylation, and (iv) linoleic acid peroxidation were assessed. The results showed that (a) the antioxidant effect of the leaf oil was significantly higher than the fruit oil in all oxidative systems employed in the present investigation, except LDL oxidation, (b) a greater effect was observed in glycosylation system with more than 60% antioxidant properties, and (c) in linoleic acid peroxidation system, a greater antioxidant effect was observed after 2 h incubation (about 45%).

Rosmarinus officinalis essential oil: antiproliferative, antioxidant and antibacterial activities

The aim of this work was to investigate and compare the antiproliferative, antioxidant and antibacterial activities of Rosmarinus officinalis essential oil, native to Pakistan. The essential oil content from the leaves of R. officinalis was 0.93 g 100g-1. The GC and GC-MS analysis revealed that the major components determined in R. officinalis essential oil were 1,8-cineol (38.5%), camphor (17.1%), α-pinene (12.3%), limonene (6.23%), camphene (6.00%) and linalool (5.70%). The antiproliferative activity was tested against two cancer (MCF-7 and LNCaP) and one fibroblast cell line (NIH-3T3) using the MTT assay, while, the antioxidant activity was evaluated by the reduction of 2, 2-diphenyl-1-picryl hydrazyl (DPPH) and measuring percent inhibition of peroxidation in linoleic acid system. The disc diffusion and modified resazurin microtitre-plate assays were used to evaluate the inhibition zones (IZ) and minimum inhibitory concentration (MIC) of R. officinalis essential oil, respectively. It is concluded from the results that Rosmarinus officinalis essential oil exhibited antiproliferative, antioxidant and antibacterial activities.

ENZYMATIC HYDROLYSIS OF SILK SERICIN BY PROTEASES AND ANTIOXIDANT ACTIVITIES OF THE HYDROLYSATES

ABSTRACT This study was conducted to investigate the free radical-scavenging activity and antioxidant activity of silk sericin hydrolysates (SSH). SSH were obtained by hydrolysis of silk sericin with alcalase, trypsin, neutrase, bromelin, papain and flavourzyme. Its ability to scavenge 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS) cation radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was determined by ultraviolet spectrophotometry. The antioxidant activities of the SSH, including lipid peroxidation in linoleic acid system, reducing power and ferrous ion chelating ability, were evaluated. The results showed that different protease hydrolysates possessed different ability to quench the ABTS cation radicals and DPPH radicals. Among those tested, alcalase hydrolysate exhibits the highest scavenging activity than other proteases (P < 0.05). Alcalase hydrolysate exerted the highest peroxidation inhibition than other proteases (P < 0.05). The reducing power and ferrous ion chelating ability of six SSH were significant. These results indicated that six SSH were natural antioxidants with potent antioxidative activity. PRACTICAL APPLICATIONS Most of silk sericin must be removed during raw silk production at the reeling mill and the other stages of silk processing. At present, silk sericin is mostly discarded in the silk processing wastewater. If silk sericin was recovered and recycled, it could represent a significant economic and social benefit. Silk sericin is a natural macromolecular protein derived from silkworm Bombyx mori. Silk sericin is useful because of its antioxidant activity. Silk sericin can be cross-linked, copolymerized and blended with other macromolecular materials, especially artificial polymers, to produce materials with improved properties. The protein is also used as an improving reagent or a coating material for natural and artificial fibers, fabrics and articles. The materials modified with silk sericin and sericin composites are useful as degradable biomaterials, biomedical materials and functional membranes.

Rosmarinus officinalis essential oil: antiproliferative, antioxidant and antibacterial activities.

The aim of this work was to investigate and compare the antiproliferative, antioxidant and antibacterial activities of Rosmarinus officinalis essential oil, native to Pakistan. The essential oil content from the leaves of R. officinalis was 0.93 g 100g-1. The GC and GC-MS analysis revealed that the major components determined in R. officinalis essential oil were 1,8-cineol (38.5%), camphor (17.1%), α-pinene (12.3%), limonene (6.23%), camphene (6.00%) and linalool (5.70%). The antiproliferative activity was tested against two cancer (MCF-7 and LNCaP) and one fibroblast cell line (NIH-3T3) using the MTT assay, while, the antioxidant activity was evaluated by the reduction of 2, 2-diphenyl-1-picryl hydrazyl (DPPH) and measuring percent inhibition of peroxidation in linoleic acid system. The disc diffusion and modified resazurin microtitre-plate assays were used to evaluate the inhibition zones (IZ) and minimum inhibitory concentration (MIC) of R. officinalis essential oil, respectively. It is concluded from the results that Rosmarinus officinalis essential oil exhibited antiproliferative, antioxidant and antibacterial activities.

Evaluation of antioxidant activity, colour and some nutritional characteristics of pomegranate (Punica granatum L.) juice and its sour concentrate processed by conventional evaporation

In this study the antioxidant activity, colour and some nutritional characteristics of pomegranate juice (PJ) and its traditional sour concentrate (CPJ), produced in Denizli, Turkey, were analysed. The total anthocyanin content of PJ was found to be 492.9 mg/l but it was not determined in CPJ. The total phenolics were also found to be 3,246 and 9,870 µg/ml in PJ and CPJ, respectively. The antioxidant activity (percentage of inhibition of on peroxidation in linoleic acid system) of CPJ was determined to be higher (85.91%) than that of PJ (79.06%). During the concentration process, the reducing sugars, glucose and fructose level of CPJ showed an increase to 46.46%, 23.89%, and 22.53%, respectively. In CPJ the amounts of sodium, iron, zinc, copper and lead were found lower than those of PJ. On the other hand, potassium and magnesium mineral contents increased during concentration. Among the various elements, cadmium, mercury, manganese, cobalt and boron were also analysed for determination of metallic contamination, but they were not found in PJ juice and CPJ. 5-Hydroxymethyl furfural was determined to be at a significant level in CPJ as a result of the heat process.

Comparison of hot air‐drying and freeze‐drying on the physicochemical properties and antioxidant activities of pumpkin (Cucurbita moschata Duch.) flours

SummaryFreeze‐drying and hot air‐drying were applied in the preparation of pumpkin flours to investigate the effects of drying methods on the antioxidant activities and physicochemical properties. The antioxidant activities of methanol extracts from pumpkin flours were studied in terms of total antioxidant activity, reducing power, free radical scavenging, superoxide anion radical scavenging and metal chelating activities. Hot air‐dried pumpkin flour showed stronger antioxidant activities than freeze‐dried flour. The percentage inhibition of peroxidation in linoleic acid system by 15 mg mL−1 extracts from hot air‐dried and freeze‐dried pumpkin flours was found to be 92.4% and 86.1% after 120 h of incubation, respectively. Hot air‐dried pumpkin flour exhibited higher reducing power, free radical scavenging and metal chelating activities than freeze‐dried flour. This study also indicated that freeze‐drying significantly reduced the browning and preserved the redness of pumpkin flours. Hot air‐drying reduced the oil absorption capacity, water absorption and porosity of pumpkin flours, while it markedly increased the water solubility and bulk density.

Autolysis-assisted production of fish protein hydrolysates with antioxidant properties from Pacific hake ( Merluccius productus)

Fish protein hydrolysates (FPH) with antioxidative properties were prepared using Pacific hake fish with high endogenous proteolytic activity from Kudoa paniformis parasitic infection. Infection level of ∼10 7 K. paniformis spores/g fish mince or higher yielded FPH with high antioxidant potential by autolysis and/or Validase ® BNP or Flavourzyme ® 500L. Autolyzing fish mince containing 30 × 10 6 spores/g for 1 h at 52 °C and pH 5.50 produced FPH (named E-1h) with Trolox equivalent antioxidant capacity (TEAC) in the 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) radical assay of 262 ± 2 μmol/g and oxygen radical absorbing capacity (ORAC) of 225 ± 17 μmol Trolox equivalents/g freeze-dried sample. E-1h FPH also exhibited a marked concentration-dependent scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radical. Antioxidant activity of E-1h FPH was higher ( p < 0.05) than BHA and α-tocopherol in a linoleic acid peroxidation system over prolonged storage (∼162 h). Antioxidative FPH from Pacific hake may be useful ingredients in food and nutraceutical applications.

Antioxidant potential of corncob extracts for stabilization of corn oil subjected to microwave heating

Antioxidant effectiveness of corncob extract with different polarity solvents ( n-hexane, ethyl acetate, acetone, ethanol, and methanol) was assessed for total phenolics content (TPC), DPPH radical scavenging activity and % inhibition of peroxidation in linoleic acid system. The yield of the extracts from corncob with different solvents ranged from 1.1 to 19.5 g/100 g of dry matter. TPC, DPPH radical scavenging and inhibition of linoleic acid oxidation for corncob extracts varied significantly ( P < 0.05) from 1.2 to 4.2, 16.0 to 42.1, and 37.3 to 89.9 g/100 g per dry matter, respectively. Methanolic extract offered the highest yield (19.5%), and also exhibited superior antioxidant activity. Corncob methanolic extract was added at concentrations of 500 and 1000 ppm to RBD (refined, bleached, deodorized) corn oil. BHT at 200 ppm served as standard beside the control. The stabilized corn oil samples subjected to microwave heating (0–21 min) were analyzed periodically. The magnitude of oxidative alterations was followed by the measurement of conjugated dienes (CD), conjugated trienes (CT), p-ansidine, and peroxide values. Results of different oxidation parameters revealed that methanolic extract at concentration of 1000 ppm was more effective than BHT and inhibited the rise in p-ansidine-, conjugated diene-, conjugated triene-, and peroxide-values up to 41.8%, 45.0%, 39.7%, and 65.0%, respectively, with respect to the control.However, at concentration of 500 ppm offered less efficient protection. The results of different antioxidant parameters investigated in the present study demonstrated that corncob is a potent source of natural antioxidants that might be explored to prevent oxidation of vegetable oils.

Determination of antioxidant activity and antioxidant compounds in wild edible mushrooms

The methanolic extracts of dried Agaricus bisporus, Polyporus squamosus, Pleurotus ostreatus, Lepista nuda, Russula delica, Boletus badius, and Verpa conica were analyzed for antioxidant activity in different systems including reducing power, free radical scavenging, superoxide anion radical scavenging, total antioxidant activity, and metal chelating activities. Those various antioxidant activities were compared to standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α-tocopherol. The percentage inhibition methanolic extracts of dried Russula delica, Boletus badius, Agaricus bisporus, Polyporus squamosus, Pleurotus ostreatus, Lepista nuda and Verpa conica at 100 μg/mL concentrations on peroxidation in linoleic acid system were 99.7%, 99.2%, 98.8%, 98.4%, 98.3%, 97.9% and 97.7%, respectively, and greater than those 400 μg/mL of α-tocopherol, BHA and BHT (77%, 85%, and 97%). Among methanolic extracts from seven wild edible mushrooms, the reducing power of Russula delica and Verpa conica were excellent, and were 1.32 and 1.22 at 200 μg/mL, respectively. Methanolic extract from Verpa conica, Boletus badius and Russula delica proved to be better at scavenging O 2 − than other mushroom species. The scavenging effects of methanolic extracts from mushroom species and standards on the DPPH radical decreased in the order of BHA> α-tocopherol> Lepista nuda> Russula delica> Polyporus squamosus> Pleurotus ostreatus> Agaricus bisporus> Verpa conica> Boletus badius and were, at the concentration of 180 μg/mL, 97.4, 95.4, 91.3, 86.1, 82.8, 81.3, 77.5, 75.7 and 68.7, respectively. The metal scavenging effect of extract of the mushroom species and standards decreased in the order of Verpa conica> Lepista nuda> Russula delica> Boletus badius> Polyporus squamosus>BHT> Pleurotus ostreatus> Agaricus bisporus>BHA> α-tocopherol. On the other hand, total phenolic compounds, α-tocopherol, and β-carotene were determined in the methanolic extracts of dried Agaricus bisporus, Polyporus squamosus, Pleurotus ostreatus, Lepista nuda, Russula delica, Boletus badius, and Verpa conica.