Antioxidant Capacity Of Extracts Research Articles

Binary ethanol–water solvents affect phenolic profile and antioxidant capacity of flaxseed extracts

Flaxseed extracts are in focus because of their potential application as a food ingredient. Ethanol–water mixtures are recommended for preparation of plant extracts due to their acceptability for human consumption. However, there is a lack of comprehensive studies concerning solvent effect on phenolic profile (phenolic composition and content) and its impact on flaxseed extract antioxidant capacity. This study investigated the effect of ethanol concentration in ethanol–water extraction solvent on the changes in phenolic profile (HPLC analysis after alkaline or alkaline-acid hydrolysis) and the antioxidant activity (DPPH· and ORAC_FL assays) of flaxseed extracts; various ethanol concentrations were investigated to prepare a suitable extract that could be safely introduced into food. The results showed relationships between the tested factors, i.e. the ethanol concentration and the phenolic content or the antioxidant capacity of flaxseed extracts. The content of phenolic compounds in extracts, including secoisolariciresinol diglucoside, phenolic acids and their glucosides, decreased with increasing concentration of the ethanol from 60 to 90 % in extraction solvent (total phenolics after alkaline hydrolysis were 106.5 and 7.7 mg g−1, respectively). On the contrary, the content of phenolic acid esters was the highest in the 90 % ethanol flaxseed extract. Changes in the phenolic profile with ethanol increase in extraction solvent impacted negatively the radical scavenging activity of the extracts. This study indicates that the mixture of ethanol and water in proportion of 60:40 (v/v) is the most suitable to obtain flaxseed extract with the high content of phenolic compounds and antioxidant activity.

Total Antioxidant Capacity of Labdane and Pimarane Diterpenoids of Juniperus phoenicea L

Although Juniperus phoenicea L is a widely distributed wild tree in the south of Saudi Arabia, but its phytochemical and physiological evaluation is still poor. The chromatographic separation of the CH2Cl2/MeOH, 1:1 extract of J, phoenicea L. fruits gave β-sitosterol, stigmasterol, four labdane and two pimarane diterpenoids, including new labdane diterpenoid. Additionally, the volatile compounds of the main petroleum ether extract, as well as the steam-volatile constituents were identified by GC/MS. The separated compounds were identified by spectral tools. The new diterpenoid was identified as 5,9,10 -triepicupressic acid. A previous false identification of sandracopimaric acid, from the fruits of Juniperus phoenicea L. grown in Egypt, was detected and declared to be revised. Total antioxidant capacity of extracts was estimated using total antioxidant capacity kit of Biodiagnostic, based on Koracevic et al., for biological fluids, with slight modification to suit extracts. Ascorbic acid was used as a reference antioxidant compound. Reasonable results were obtained by applying the modified method on petroleum ether extract, methylene chloride extract and ethyl acetate extract of Juniperus phoenicea L.

Supercritical fluid extraction vs conventional extraction of myrtle leaves and berries: Comparison of antioxidant activity and identification of bioactive compounds

In this work, the antioxidant capacity of extracts of Portuguese myrtle (Myrtus communis L.) is being studied over a period of three years. The samples were leaves of myrtle collected at the flowering stage and berries sampled at an early ripened stage. Supercritical fluid extraction (SFE) extracts were obtained at 23MPa, 45°C and a CO2 flow of 0.3kgh−1 using ethanol as co-solvent with a flow rate of 0.09kgh−1. Hydrodistillation was carried out in a Clevenger type apparatus and the aqueous phase was extracted with diisopropylether having obtained what is hereby designated as liquid phase extract (LPE).The antioxidant capacity of all the extracts was determined by using three different methods: the Folin–Ciocalteu, the Trolox Equivalent Antioxidant Capacity (TEAC) and the Oxygen Radical Absorbance Capacity (ORAC). The results show that the SFE extracts present a significantly higher antioxidant capacity. The extracts were characterized and quantified by HPLC-DAD-MS/MS methods. The bioactive compounds identified in all the extracts were phenolic acids (only in the LPE extracts), flavonoids and anthocyanins (only in the SFE extracts). The results indicate that the higher antioxidant capacity of the SFE myrtle extracts is mainly correlated with the concentration of flavonol glycosides, the myricetin-O-glycosides.

Assessment of selenium compounds use in limitation of petroleum impact on antioxidant capacity in sandy soil / Ocena wykorzystania związków selenu w ograniczeniu oddziaływania substancji ropopochodnych na pojemność antyoksydacyjną gleby lekkiej

Abstract The aim of this study is to assess the selenium (on two oxidation states +IV and +VI) effect on antioxidant capacity in light soil contaminated with gasoline and diesel fuel. The soil used in experiment is characterised by granulometric composition of loamy sand with organic carbon content of 8.7 g·kg−1. Different combinations of gasoline or diesel fuel in dosage 1 or 5%, and H2SeO3 and H2SeO4 in dosage 0.05 mmol Se·kg−1 were added into soil. In the period of 35 days at weekly intervals, antioxidant capacity of the soil in methanol and alkali extracts was determined. Soil contamination with petroleum caused the decrease in antioxidant capacity. Selenium application increased in antioxidant capacity in extracts. In the case of uncontaminated soil, this effect was higher for selenium on the oxidation state +VI, and in soil that contained petroleum for selenium on the oxidation state +IV.

Antioxidant activity of different parts of Pistacia khinjuk Stocks fruit and its correlation to phenolic composition

The fruits of Pistacia khinjuk Stocks were collected from Ilam province, Iran. The aim of this study was to analyse antioxidant capacity and phenolic composition of different parts of P. khinjuk fruit. The antioxidant capacity of extracts was measured using different assays: ferric reducing ability of plasma, 2,2-diphenyl-1-picrylhydrazyl and nitric oxide radical scavenging. The phenolic composition of P. khinjuk fruit is reported for the first time. Amongst different parts of the fruit analysed in this study, hull extract contained the highest total phenolic and flavonoid contents. We observed a high correlation between different antioxidant activity and total phenolic and flavonoid contents. Therefore, antioxidant capacity can be related to total phenolic and flavonoid contents. A correlation analysis revealed that ascorbic acid, gallic acid, rutin, caffeic acid, ferulic acid and sinapic acid were the phenolic compounds mainly responsible for antioxidant power of the fruit extracts.

Interspecies variation of chemical constituents and antioxidant capacity of extracts from Jasminum sambac and Jasminum multiflorum grown in Malaysia

The chemical constituents from various process of extraction of Jasminum sambac and Jasminum multiflorum were identified by gas chromatography–mass spectrometry to depict their interspecies differences. Major compounds identified from methanol extract of J. sambac were β-farnesene (52.52%), nerolidol (19.85%) and benzyl alcohol (17.56%) whereas, headspace solid phase microextraction (HS-SPME) showed linalool (35.92%), benzaldehyde (17.92%) and benzyl alcohol (10.87%) while hydrodistillation yielded β-farnesene (45.13%), α-cadinol (26.21%) and linalool (9.96%). The methanol extract of J. multiflorum yielded nerolidol (42.44%), benzyl benzoate (39.00%) and jasmolactone (12.02%) whereas, HS-SPME eluted nerolidol (76.56%), jasmone (15.31%) and hexyl benzoate (4.40%) while hydrodistillation yielded hexenyl benzoate (35.89%), β-farnesene (24.62%) and α-cadinol (14.30%). The methanol extracts of both J. sambac (0.48%) and J. multiflorum (1.38%) showed DPPH free radicals scavenging activities with an IC50 value of 208μg/mL and 81μ/mL respectively. The antioxidant properties of Jasminum provided a natural preservative ingredient for food and pharmaceutical products.

Comparative phytochemical analysis of Gentiana cruciata L. roots and aerial parts, and their biological activities

The purpose of this study was to evaluate the antioxidant potential of methanol extracts of Gentiana cruciata L. aerial parts and roots, as well as the stability of the phenolic compounds and antioxidant capacity of extracts during heating, at different pHs and after an in vitro digestion procedure. Also, their genotoxicity and antigenotoxicity against carbon tetrachloride in the liver of albino Wistar rats using the comet assay were evaluated. Three secoiridoid glycosides (swertiamarin, gentiopicrin, and sweroside) and four phenolic compounds (orientin, vitexin and two isovitexin-glucosides) were identified as the major constituents in aerial parts and roots of G. cruciata, using UHPLC-DAD/±HESI-MS/MS analysis. The results of antioxidant assays showed that aerial parts displayed higher antioxidant activity compared to the roots, which could be related to higher phenolics content, especially flavonoids. In general, extracts showed pH and thermal stability, while duodenal condition had more influence on total phenolic condition and antioxidant activity of extracts. Both extracts showed a protective effect against CCl4 in comet assays. The roots extract showed no genotoxic activity, while aerial parts extract showed slight genotoxicity at concentrations of 400mg/kg b.w.

Analysis of Phenolic Content and Antioxidant Properties of Selected Cowpea Varieties Tested in Bovine Peripheral Blood

Cowpea is an important grain legume with a dual purpose function as a food and feed resource. Cowpea contains phenolic compounds that are beneficial to human and animal health. We evaluated the phenolic content, condensed tannin content and antioxidant capacities of methanol extracts of seed and leaf of seven varieties commonly used in food and animal feed. The total phenolic content and condensed tannins were quantified using the Folin-Ciocalteu and Vanillin-HCL method respectively. The effects of cowpea phenolic extract on total antioxidant capacity, glutathione peroxidase and superoxide dismutase activity was evaluated in vitro in bovine blood. Overall, the methanol extracts of the leaves contained high concentrations (p<0.0001) of total phenolic content (290.51±38.02 mg GAE/g) compared to seed extracts (118.10±71.96 mg GAE/g), although high antioxidant capacity was observed in both extracts. In addition, a positive correlation was found between total phenol and tannins content and antioxidant capacity of the extracts. Treatment with cowpea phenolic extract increased (p<0.0001) the total antioxidant capacity in cow blood (5.33±0.27 mM UAE) relative to controls (1.62±0.10 mM UAE). The enzymatic activities of GSH-Px and SOD were also increased. Our findings, suggest the potential of cowpea polyphenols to reduce oxidative stress in livestock production. Results of the present study showed that leaf and seeds of cowpea possess rich amounts of natural antioxidants and can be further explored for their possible use as a natural additive in food or use in pharmaceutical industries and in animal feed.

Antioxidant activity and total phenolic content of Boerhavia elegans (choisy) grown in Baluchestan, Iran.

Boerhaavia elegans L. (Nyctaginaceae) is a medicinal plant used for the treatment of kidney disorders, urinary tract disorders and blood purification in Baluch tribe. The aim of present study is to evaluate the antioxidant property of B. elegans species for the first time. Different parts (leaf, stem and fruit) of the plant were extracted by using various solvents (water, methanol, chloroform and ethyl acetate) and evaluated for their antioxidant activity using DPPH (2, 2-diphenyl-1 picryl hydrazyl) and FRAP (ferric reducing antioxidant power) methods. In addition, total phenolic content was determined by Folin-Ciocalteu reagent. Antioxidant results were expressed as IC50. The antioxidant power in DPPH and FRAP assay were evaluated as shown in decreasing order: Methanolic extract > Aqueous extract > Ethyl acetate extract > Chloroform extract, for all parts of the plant. In both methods of antioxidant assay and Folin-Ciocalteu method, methanolic extract of leaf exhibited the highest activity and the most phenolic content IC50= 6.85 ppm and 16.41 mg GA/g d w respectively. Total phenolic content had a positive relationship with antioxidant capacity in extracts and there was a high correlation (r=1.00, p<0.01) between antioxidant activities as determined by both antioxidant assays for various parts. The results of the experiments showed that B. elegans extract had significant antioxidant effects. This high antioxidant activity may be linked to phenolic contents of the plant but complementary investigations are suggested in order to determine active elements.

Extraction Techniques for Bioactive Compounds and Antioxidant Capacity Determination of Chilean Papaya (Vasconcellea pubescens) Fruit

The aim of this work was to assess and compare different extraction methods by using high hydrostatic pressure (HHPE), ultrasound (UE), agitation (AE), and their combinations for the extraction of bioactive compounds of Chilean papaya. Extract antioxidant capacity was evaluated by three methods (i.e., DPPH, FRAP, and Voltammetry) and phenolic compounds and vitamin C were determined by HPLC. Papaya sample extraction was performed by HHPE at 500 MPa for 10 min and UE and AE for 30 min, respectively. The combined-extractions: HHPE-UE and HHPE-AE, were carried out for 5 min and 15 min, respectively. The highest values found were total phenolic 129.1 mg GAE/100 g FW, antioxidant capacity by DPPH 20.6 mM TE/100 g FW, and voltammetry 141.0 mM TE/100 g FW for HHPE-UE method in free compound extraction. Regarding vitamin C content, its highest value was found by HHPE-UE (74 mg/100 g FW) a combined extraction method. The phenolic compounds rutin andp-coumaric acid were found in all the extracts, both in free and bound forms, respectively. Besides, the combined techniques improved the extraction of bioactive compounds.

Oxidative stability of ghee as affected by natural antioxidants extracted from food processing wastes

In this research, bioactive compounds found in peanut skins (PS), pomegranate peels (PP) and olive pomace (OP) were extracted using ethanol (80%), ethyl acetate and n-hexane. Ethanol extract showed slightly better antioxidant characteristics compared with ethyl acetate and hexane extracts. Extracts showed varying degrees of antioxidant potential in different test systems in a dose-dependent manner, whereas, antioxidant capacity of extracts was found to be in parallel with their higher phenolic contents. Total phenolic compounds (as gallic acid equivalent) ranged between 0.89 and 16.6, 1.83 and 261, and 1.56 and 124mg gallic acid/g extract for OP, PS and PP, respectively. Ethanol extracts of different by-products were added to ghee at concentrations of 200, 400 and 600ppm, respectively. BHA was also added to ghee at a concentration of 200ppm for comparison. All samples were incubated at 63°C for 21days. Ethanol extracts of PS, OP and PP gave good antioxidant activity during accelerated oxidative incubation of ghee. The results revealed that ethanolic extracts under study, at a concentration of 200ppm, could be used to retard fat auto-oxidation.

Polyphenol content and antioxidant capacity in organically and conventionally grown vegetables

Objective: To evaluate the polyphenol content and antioxidant capacity of ethanol extracts of some organically and conventionally grown leafy vegetables. Methods: The ethanol extracts of kailan (Brassica alboglabra), bayam (Amaranthus spp.) and sawi (Brassica parachinensis) were tested for total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC) and the antioxidant capacity of the extracts measured using 2,2-diphenyl-1-picrylhydrazyl assay. Results: In TPC test, sawi extract showed the highest phenolic content while bayam contained the least phenolic content for both organically and conventionally grown types. In TFC test, organically grown sawi extract showed the highest flavonoid content, while organically grown kailan extract showed the least flavonoid content among all types of vegetables. The flavonoid content of the conventionally grown types of vegetable extracts was the highest in kalian and the least in sawi. For 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, the activity increased with the increasing concentration of each extract. All conventionally grown vegetable extracts showed higher antioxidant activity compared to their organically grown counterparts. Extracts of conventionally grown sawi showed the highest percentage inhibition followed by conventionally grown kailan and organically grown sawi. There were no correlation between TPC, TFC, TAC and IC25 of both organically and conventionally grown vegetables. However, there was a correlation between TAC and IC25 of conventionally grown vegetable extracts. The results showed relatively similar polyphenol content between organically and conventionally grown vegetable extracts. However, the conventionally grown vegetables extracts generally have higher antioxidant activity compared to the organically grown extracts. Conclusions: These results suggested that the different types of agricultural practice had a significant contribution to the polyphenol content and antioxidant activity in the vegetables.

Subcritical water extraction and antioxidant activity evaluation with on-line HPLC-ABTS(·+) assay of phenolic compounds from marigold (Tagetes erecta L.) flower residues.

Subcritical water extraction (SWE) of phenolics was investigated from marigold (Tagetes erecta L.) flower residues. The total phenolics content (TPC), total flavonoids content (TFC) and antioxidant capacities of extracts were determined, furthermore, antioxidant activities of individual compounds were evaluated with on-line HPLC-ABTS(•+) system. The optimum SWE time was 45min, solid-to-liquid ratio was 1:50, and the highest TPC and TFC were obtained at 220°C respectively. The effect of SWE temperature on TPC and TFC was significant (p < 0.05), and TPC was ranged from 28.42 ± 0.94 to 124.27 ± 1.94 (mg GAE/g), and TFC ranged from 34.21 ± 0.36 to 133.22 ± 1.57 (mg GAE/g) between 80 and 220°C. On-line HPLC-ABTS(•+) profiles revealed that quercetagetin from SWE at 200°C had nearly twofold radical scavenging activities than that by leaching extraction.

In vitro determination of the lipophilic and hydrophilic antioxidant capacity of unroasted coffee bean extracts and their synergistic and antagonistic effects

The yield extraction, basic compositional analysis, individual antioxidant capacity and synergistic/antagonistic antioxidant interactions of unroasted coffee bean extracts with different degree of polarity from different locations and species were studied and compared. The beans were extracted with hexane followed by methanol to obtain lipophilic and hydrophilic extracts, respectively. Furthermore, an autoclave extraction was conducted as a simple representative approach to obtain an antioxidant rich powder for industrial application. The antioxidant capacity of all extracts and their synergistic/antagonistic responses was determined by using different but complementary well-known kinetic methods of β-carotene and crocin bleaching assays, which are representative of lipidic and hydrophilic oxidation processes. The results of this study indicated that the yield distribution and antioxidant capacity of the hydrophilic extract were much greater than the lipophilic ones, but similar to the industrial approach. The potential equivalent capacity of the industrial approach indicated that raw coffee beans possess a high content of antioxidants, offering an alternative source of nutraceuticals as well as preservatives in food formulations. Finally, statistically consistent synergistic and antagonistic values were found between the extracted coffee residues and some commercial antioxidants of well-known degree of polarity. Interestingly, it was found that the extracted residues with an equivalent degree of polarity act similar to the additive mode of interaction between single chemical entities, and as an independent interaction mode when their degree of polarity varies. The results if transferable to more realistic food matrices in the food industry, may guide the development and evaluation of food products and processes, underlying different phenomena that may affect the quality of products.

English

The chemical diversity of antioxidants in complex matrices makes it difficult to separate and quantify them in natural form. Therefore, it is enviable to establish methods that can measure the total antioxidant capacity of extracts. In the present study, the different assays, especially most widely used: deoxyribose, reducing, chelating power, lipid peroxidation and DNA nicking assays have been used to assess the antioxidant capacity of acetone extract/fractions of Terminalia chebula. The extract was prepared by maceration method and further fractionated with ethyl acetate and water. It was observed that the radical scavenging activity of fractions was comparatively more as compared to crude extract, and ethyl acetate fraction showed maximum effect in all assays. The percent inhibition with ethyl acetate fraction of acetone extract was observed to be 79.2, 85.9, 90.1 and 88.9% in chelating power, lipid peroxidation, site specific and non-site specific deoxyribose scavenging assays, respectively at maximum concentration tested. The results of present work indicate that ethyl acetate fraction (EAF) might be the potential antioxidant for application in food products. &nbsp; Key words: Terminalia chebula, antioxidants, lipid peroxidation assay, DNA nicking assay, reducing power assay.&nbsp

Optimization of antioxidants extraction from coffee silverskin, a roasting by-product, having in view a sustainable process

Coffee silverskin is a major roasting by-product that could be valued as a source of antioxidant compounds. The effect of the major variables (solvent polarity, temperature and extraction time) affecting the extraction yields of bioactive compounds and antioxidant activity of silverskin extracts was evaluated. The extracts composition varied significantly with the extraction conditions used. A factorial experimental design showed that the use of a hydroalcoholic solvent (50%:50%) at 40°C for 60min is a sustainable option to maximize the extraction yield of bioactive compounds and the antioxidant capacity of extracts. Using this set of conditions it was possible to obtain extracts containing total phenolics (302.5±7.1mgGAE/L), tannins (0.43±0.06mgTAE/L), and flavonoids (83.0±1.4mgECE/L), exhibiting DPPH scavenging activity (326.0±5.7mgTE/L) and ferric reducing antioxidant power (1791.9±126.3mgSFE/L). These conditions allowed, in comparison with other “more effective” for some individual parameters, a cost reduction, saving time and energy.

Rosehip extraction: Process optimization and antioxidant capacity of extracts

Abstract This article examines the extraction of rosehip to study the recovery of a number of compounds with antioxidant properties (polyphenols, flavonoids, and β-carotene). Two varieties of rosehip, cultivated and wild are used as raw material. A detailed study of the process kinetics at different operating conditions is carried out in order to determine appropriate processing parameters, which results in extracts with higher content of target compounds and higher antioxidant capacity. Data on the concentration of active components in the different parts of the fruit (skin, seeds, and pappi) are also obtained, which gives information about their distribution within the fruit. The comparison of wild and cultivated varieties demonstrates the better quality of the cultivated one. The results are useful for production of improved and enriched rosehip extracts with higher content of antioxidant substances that have proven beneficial effects on the human health.

Avaliação das atividades antiproliferativa e antioxidante em frutos de Campomanesia pubescens

Chemical investigation on the bioactive extracts from fruits of Campomanesia pubescens (Myrtaceae) resulted in the isolation of two chalcones. The isolated compounds were identified by means of spectroscopic analysis (1H, 13C and 2D NMR), and by comparing with the data reported in the specific literature. Antioxidant capacity of extracts and fractions was determined using the oxygen radical absorbance capacity (ORAC-FL) and DPPH assays; and the total soluble phenolic contents were measured by using Folin-Ciocalteau reagent. The anti-proliferative effects of the extracts and of the chalcone isolates 1 and 2 were determined in vitro against human cancer cells lineages U251 (glioma), UACC-62 (melanoma), MCF-7 (breast), NC1-ADR/RES (ovarian-resistant), 786.0 (kidney), NCI-H460 (lung), PC-3 (prostate), OVCAR-3 (ovarian), HT-29 (colon) and K562 (leukemia), and against non-cancerous cell line VERO. Hexanic extract and chalcone isolated compounds 1 and 2 showed potent antiproliferative effect against cancer cell lineages with lower total growth inhibition (TGI) values than those found in control cell line. The highest activity of the chalcones 1 and 2 was observed against the MCF-7, PC-3 and HT-29 cell lines.

Chemical composition and antioxidant activity of ultrasound-assisted extract of the endemic plant Haberlea rhodopensis Friv.

The antioxidant capacity of extracts from leaves of Haberlea rhodopensis Friv. obtained by a highly efficient and simple method of the ultrasound-assisted extraction was investigated. The total polyphenolic content was determined spectrophotometrically using the Folin - Ciocalteu's phenol reagent and the polyphenols composition was analyzed by HPLC method. Antioxidant activity of the extract was evaluated as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis-3 ethyl benxothiazoline-6-sulphonic acid (ABTS) cation decolorization activity assays and the ferric reducing/antioxidant power method (FRAP). The total phenolics of the extract were determined to be 148.71 ± 5.33mg GAE on a dry weight basis. The HPLC analysis showed a large number of flavonoids and phenolic acids present in the ultrasound ethanol extract of H. rhodopensis. Results also revealed that the major flavonoids were luteolin (2730.18μg/g DW), hesperidin (928.56μg/g DW) and kaempferol (578.52μg/g DW), whereas the most abundant phenolic acids identified in the extract were ferulic acid (630.48μg/g DW) and sinapic acid (580.80μg/g DW). DPPH(•) and ABTS(•+) values were 0.803 ± 0.007 and 0.769 ± 0.040mmol TE/g DW, respectively and FRAP values were 1.362 ± 0.05mmol TE/g DW.

Differential induction of antioxidant stilbenoids in hairy roots of Vitis rotundifolia treated with methyl jasmonate and hydrogen peroxide

Stilbenoids are polyphenolic phytoalexins that exhibit potential health applications in humans. Hairy root cultures of muscadine grape (Vitis rotundifolia Michx.) were used to study the biochemical and molecular regulation of stilbenoid biosynthesis upon treatment with 100 μM methyl jasmonate (MeJA) or 10 mM hydrogen peroxide (H2O2) over a 96-h period. Resveratrol, piceid, and ε-viniferin were identified in higher concentrations in the tissue whereas resveratrol was the most abundant stilbenoid in the medium under either treatment. An earlier increase in resveratrol accumulation was observed for the MeJA-treated group showing a maximum at 12 h in the tissue and 18 h in the medium. Furthermore, the antioxidant capacity of extracts from the tissue and medium was determined by the 2,2′-azinobis[3-ethylbenzthiazoline sulfonic acid] (ABTS) and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays showing correlation with the stilbenoid content. Fourteen candidate reference genes for qPCR were tested under the described experimental conditions and resulted in the selection of 5 reference genes. Quantitative analyses of transcripts for phenylalanine ammonia-lyase (PAL), resveratrol synthase (RS), and two stilbene synthases (STS and STS2) showed the highest RNA level induction at 3 h for both treatments with a higher induction for the MeJA treatment. In contrast, the flavonoid-related chalcone synthase (CHS) transcripts showed induction and a decrease in expression for MeJA and H2O2 treatments, respectively. The observed responses could be related to an oxidative burst triggered by the exposure to abiotic stressor compounds with signaling function such as MeJA and H2O2 which have been previously related to the synthesis of secondary metabolites.