Oxidative stability of soybean oil enriched with ethyl acetate extract of olive by-products

In this study, oxidative stability of soybean oil (SBO) enriched with ethyl ecetate extracts of olive by-products was investigated. Total phenolic contents, phenolic profiles and antioxidant activities of olive wastewater (OMWW) and olive pomace (OP) extracts were also determined. Total phenolic contents of extracts obtained from OMWW and OP were 134.45 and 281.43 mg gallic acid equivalent (GAE)/g extract, respectively. While antioxidant activities of OMWW extracts in the linoleic acid emulsion were in the range of 85.79 % and 88.54 %, OP extracts had 83.30 % and 90.09 % at different concentrations (0.5, 1, 2 ve 3 mg/mL) after incubation at 37 °C. β-carotene bleaching activities of the extracts at 50 °C were found as 26.80-66.63% in OMWW extracts and 18.76-53.32% in OP extracts, respectively. 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of OP extracts were higher than those of OMWW extracts and ranged from 30.6% to 87.7% in OP extracts and 16.6% to 54.1% in OMWW extracts at these concentrations. Both the antioxidant and antiradical activities of extracts significantly increased with increased concentration (p

Simultaneous Study of Anti-Ferroptosis and Antioxidant Mechanisms of Butein and (S)-Butin

To elucidate the mechanism of anti-ferroptosis and examine structural optimization in natural phenolics, cellular and chemical assays were performed with 2′-hydroxy chalcone butein and dihydroflavone (S)-butin. C11-BODIPY staining and flow cytometric assays suggest that butein more effectively inhibits ferroptosis in erastin-treated bone marrow-derived mesenchymal stem cells than (S)-butin. Butein also exhibited higher antioxidant percentages than (S)-butin in five antioxidant assays: linoleic acid emulsion assay, Fe3+-reducing antioxidant power assay, Cu2+-reducing antioxidant power assay, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide radical (PTIO•)-trapping assay, and α,α-diphenyl-β-picrylhydrazyl radical (DPPH•)-trapping assay. Their reaction products with DPPH• were further analyzed using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-Q-TOF-MS). Butein and (S)-butin produced a butein 5,5-dimer (m/z 542, 271, 253, 225, 135, and 91) and a (S)-butin 5′,5′-dimer (m/z 542, 389, 269, 253, and 151), respectively. Interestingly, butein forms a cross dimer with (S)-butin (m/z 542, 523, 433, 419, 415, 406, and 375). Therefore, we conclude that butein and (S)-butin exert anti-ferroptotic action via an antioxidant pathway (especially the hydrogen atom transfer pathway). Following this pathway, butein and (S)-butin yield both self-dimers and cross dimers. Butein displays superior antioxidant or anti-ferroptosis action to (S)-butin. This can be attributed the decrease in π-π conjugation in butein due to saturation of its α,β-double bond and loss of its 2′-hydroxy group upon biocatalytical isomerization.

Antioxidant Potential and Stabilization Studies of Sunflower Oil Using Sorbaria tomentosa Extract and its Cu(II)/Zn(II) Chelates

Sorbaria tomentosa,, commonly known as “Berre” is native to Himalaya and Hindukush range in Pakistan. Qualitative phytochemical screening as well as quantitative antioxidant potential of its ethanolic extract was evaluated. Antioxidant potential of the extract was determined using standard methods like DPPH, FRAP, total phenolics, total flavonoids, ABTS radical cation scavenging assay and β-carotene linoleic acid emulsion system. Cu(II) and Zn(II) chelates of ,,Sorbaria tomentosa,, were also prepared and their antioxidant potential was compared with the extract as well as with synthetic antioxidants (BHT and BHA). It was observed that ,,Sorbaria tomentosa,, is a good source of natural antioxidant that worked efficiently compared to respective chelates. Keeping in view less efficiency of chelated extracts, stabilization studies of sunflower oil were conducted with ethanolic extract (250, 500, 1000 ppm) of ,,Sorbaria tomentosa,,. Various parameters like PV, FFA and IV were estimated to evaluate stabilization of oil. ,,Sorbaria tomentosa,, extract (1000 ppm) showed almost same role during stabilization like BHA at ambient condition during a storage period of 45 days. Keywords: Sorbaria tomentosa, phytochemicals, antioxidant potential, chelation, stabilization

Development of a Method Suitable for High-Throughput Screening to Measure Antioxidant Activity in a Linoleic Acid Emulsion

An improved system for measuring antioxidant activity via thiobarbituric acid reactive substances and ferric thiocyanate assays is reported, on the basis of oxidation of a linoleic acid (LA) emulsion. Oxidation times were reduced from 20 h to 5 h by increasing the reaction temperature from 37 °C to 50 °C and with an acceptable precision of <10% coefficient of variation (CV). Antioxidants varying in polarity and chemical class—250 µM Trolox, quercetin, ascorbic acid and gallic acid—were used for method optimisation. Further reductions in reaction time were investigated through the addition of catalysts, oxygen initiators or increasing temperature to 60 °C; however, antioxidant activity varied from that established at 37 °C and 20 h reaction time—the method validation conditions. Further validation of the method was achieved with catechin, epicatechin, caffeic acid and α-tocopherol, with results at 50 °C and 5 h comparable to those at 37 °C and 20 h. The improved assay has the potential to rapidly screen antioxidants of various polarities, thus making it useful in studies where large numbers of plant extracts require testing. Furthermore, as this assay involves protection of a lipid, the assay is likely to provide complementary information to well-established tests, such as the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay.

Genotype-Related Differences in the Phenolic Compound Profile and Antioxidant Activity of Extracts from Olive (Olea europaea L.) Leaves

The phenolic compound contents and antioxidant activities of the leaf extracts of nine olive genotypes were determined, and the obtained data were analysed using chemometric techniques. In the crude extracts, 12 compounds belonging to the secoiridoids, phenylethanoids, and flavonoids were identified. Oleuropein was the primary component for all genotypes, exhibiting a content of 21.0 to 98.0 mg/g extract. Hydroxytyrosol, verbascoside, luteolin 7-O-glucoside, and luteolin 4′-O-glucoside were also present in noticeable quantities. Genotypes differed to the greatest extent in the content of verbascoside (0.45–21.07 mg/g extract). The content of hydroxytyrosol ranged from 1.33 to 4.03 mg/g extract, and the aforementioned luteolin glucosides were present at 1.58–8.67 mg/g extract. The total phenolic content (TPC), DPPH• and ABTS•+ scavenging activities, ferric reducing antioxidant power (FRAP), and ability to inhibit the oxidation of -carotene-linoleic acid emulsion also varied significantly among genotypes. A hierarchical cluster analysis enabled the division of genotypes into three clusters with similarity above 60% in each group. GGE biplot analysis showed olive genotypes variability with respect to phenolic compound contents and antioxidant activities. Significant correlations among TPC, FRAP, the values of both radical scavenging assays, and the content of oleuropein were found. The contents of 7-O-glucoside and 4′-O-glucoside correlated with TPC, TEAC, FRAP, and the results of the emulsion oxidation assay.

Proximate Compositions and Biological Activities of Caulerpa lentillifera

Caulerpa lentillifera is an edible and functional seaweed due to its high nutritional compositions and its biological activities. In this study, C. lentillifera was evaluated for its proximate compositions (moisture, ash, protein, lipid and fiber contents) and its biological activities (antimicrobial, anti-oxidant, and toxicity). Moisture content, crude lipid, crude protein, and crude fiber were determined using oven method, soxhlet extraction, semi-micro Kjeldhal, and hydrolysis, respectively. Fresh C. lentillifera of Natuna Island, Indonesia, showed its higher level content of ash, crude lipid, and crude fiber compared to that of fresh C. lentillifera of Penghu, Taiwan. For its biological activity assays, the extracts were prepared from fresh and dry C. lentillifera (FC and DC). Both of the extracts showed the broad spectrum of weak antimicrobial using well-diffusion agar tests and antioxidant activities using a modified linoleic acid emulsion system. The toxicity for both extracts was determined using brine shrimp lethality test. DC extract showed its very low toxicity level and there was no toxicity for FC. Hemolytic activity was determined using red blood assay. Both extracts showed their low hemolytic activities (about 5-13%) for the concentration of 100 and 150 μg/mL, but the activity increased sharply (about 96%) on the concentration of 200 μg/mL. It was concluded that C. lentillifera has a potency as a functional food due to containing secondary metabolites with various biological activities.

Inhibition of Formation of Conjugated Dienes in Linseed Oil

Oxidation of fats and oils reduces the nutritional value of food and causes various health problems. The addition of antioxidants prevents the oxidation of fats in the food. The antioxidant activity of antioxidants represents the ability to inhibit the process of oxidation. The antioxidant activity of herbal extracts has usually been assessed in a linoleic acid emulsion system. The aim of the present study was to evaluate inhibition of conjugated diene formation in Latvian linseed oil. Ethanol extract of the calyx of Hibiscus sabdariffa L., vanillin, α-tocopherol and 2,6-di-tert-butyl-4-methylphenol as additives were compared for their antioxidative activity. The samples of linseed oil with additives were incubated for 24 h at 60 °C and then analysed using UV spectrophotometry (λ = 234 nm). The antioxidant activity of additives was characterised by the percentage of formation of conjugated dienes. The ability of additives to inhibit oxidation in linseed oil decreases as follows: vanillin, 2,6-di-tert-butyl-4-methylphenol and α-tocopherol. Our results indicate that linseed oil can be used to test antioxidative activity of substances.

Antioxidant activity, phenolic and flavonoid contents of snake gourd (Trichosanthes anguina) extract

Marsetya YR, Mudjijono, Hastuti S. 2009. Antioxidant activity, phenolic and flavonoid contents of snake gourd (Trichosanthes anguina) extract. Biofarmasi 7: 77-86. This research was carried out to evaluate the antioxidant activity and the relationship between antioxidant activity with phenolic and flavonoid contents in snake gourd extract. The extract was prepared by a maceration using methanol, and then continued by an extraction using solvent with increasing polarity. Extract obtained was analyzed to determine the antioxidant activity, and they were compared to the synthetic antioxidant, BHT (Butylated Hidroxytoluene) and PG (Propyl Gallate). The antioxidant activity was determined using the modification of β-carotene-linoleic acid emulsion system. Phenolic content was measured by Folin-Ciocalteu method and the flavonoid content was determined using AlCl3 reagent. The result of this research showed that the antioxidant activity of methanol extract (29.566%) was higher than BHT (16.268%), and it was not significantly different from PG (29.452%). Chloroform extract had the highest antioxidant activity (36.384%), followed by water, hexane, butanol, and ethyl acetate extract, respectively. Phenolic contents of each extract (methanol, chloroform, ethyl acetate, butanol, and water) were 1.904, 3.547, 2.553, 3.114, and 1.776 g GAE (Gallic Acid Equivalent)/100 g extract, and the flavonoid contents were 4.072, 4.162, 1.751, 2.944, and 1.392 g QE (Quercetin Equivalent)/100 g extract, respectively. A positive relationship was found in this research, the chloroform extract that had the highest antioxidant activity contained the highest amount of phenolic and flavonoid. This study showed that snake gourd could be used as a source of natural antioxidant.