High Levels Of Antioxidant Activity Research Articles

In vitro antioxidant activities and phenolic content in crop residues of Tunisian globe artichoke

The phenolic content and in vitro antioxidant activity of the bracts, leaves and floral stems of two Tunisian globe artichoke cultivars (‘Violet d’Hyéres’ and ‘Blanc d’Oran’) were assessed; the tests used to assay antioxidant activity were based on ABTS [2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid] and DPPH [2,2-diphenyl-l-picrylhydrazyl]. In addition reducing power was measured and the phosphomolybdenum total antioxidant activity assay was included. The bracts of ‘Violet d’Hyéres’ possessed, on average, twice the quantity of phenolic compounds than those of ‘Blanc d’Oran’. They also had a higher content of 3,5-O-dicaffeoylquinic acid. The bracts and floral stems contained high levels of total caffeoylquinic acid, whereas the leaves provided a potentially exploitable source of luteolin. Ethanolic extracts of both cultivars exhibited a high level of antioxidant activity. The ABTS EC50 value was high in extracts from the leaves of both cultivars, whereas the DPPH test showed no variation between the bracts, floral stems and leaves. The bracts were associated with strong reducing power and total antioxidant activity. Overall, the leaves were associated with more antioxidant activity than the bracts or the floral stems. The implication is that globe artichoke crop residues could provide a useful source of antioxidant compounds.

Quality parameters of olive oil from stoned and nonstoned Koroneiki and Megaritiki Greek olive varieties at different maturity levels

Virgin olive oil is a natural functional food and its beneficial role in health as an integral ingredient of the Mediterranean diet is universally recognized. The effects of olive pitting, degree of ripeness and variety (Greek varieties Koroneiki and Megaritiki) were investigated on the physicochemical characteristics, antioxidant constituent contents and capacity and on the fatty acid profile of olive oil. Ripeness resulted in a decrease ( P P < 0.05) monounsaturated/polyunsaturated fatty acid ratios, which are particularly important for the stability of the oil against oxidation. It was concluded that olive oil from pitted olives maintains a high content in bioactive compounds and a high level of antioxidant activity.

Evaluation of heavy metals, cytotoxicity, and antioxidant activity of tomatoes grown in toxic muddy soils.

This research studies tomatoes grown in polluted soils to ascertain their phytochemical and nutritive features. Pulp and seeds from tomatoes grown in muddy soils were analyzed for their antioxidant power and their toxicity because of the possibility that heavy metals were present in the soils. An antioxidant assay on methanol extracts was made by using DDPH, while an ABTS [2,2'-Azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid)] assay was used to evaluate the antioxidant activity of lipophilic fractions. Results of the antioxidant assay showed that the tomatoes maintained a high level of antioxidant activity especially in the lipophilic fractions which contain the most representative compounds. Cytotoxic activity was performed on HeLa, PDAC, and A375 cell lines by [3-(4,5-dimethylthiazol-2-yl)-2,5-phenyl-2H-tetrazolium bromide] (MTT) assay. Results showed that neither the seeds, nor the pulp, of the extracts was cytotoxic. The presence of heavy metals was evaluated by using spectroscopy of atomic absorption with a graphite oven. Test results show the absence of heavy metals and these results have an interesting scientific role because they provide useful information for promoting food safety.

국내 자생 식물추출물의 DPPH radical 소거활성 및 항균성 스크리닝

This study was conducted to determine the antioxidant potentials of some available plants to source alternate antioxidants and antibiotics. The antioxidant activity was evaluated by determining the antioxidant activity reducing powers and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities of extracts from some local edible native plants. The DPPH radical scavenging activity of the extracts was found to have been 0.41-94.84%. The Elsholtziasplendens NAKAI extract (85ºC, ethanol, accelerated solvent extraction) showed the highest level of antioxidant activity. Eight samples of plant extracts were evaluated for their antimicrobial activities against three microflora (Bacillus subtilis, Escherichia coli, and Candida albicans) using disc diffusion assay. Two samples (Geranium krameri FR. Et SAV. and Cleyera japonica Thunb.) had much more intensive antimicrobial activities than the control. However, their DPPH free radical scavenging activity levels were only 14.50 and 13.85, respectively. It is suggested that they could be used as natural preservatives against bacterial contamination in cosmetics and foods, in place of the common synthetic preservatives currently used.

Effect of methyl jasmonate on the anthocyanin content and antioxidant activity of blueberries during cold storage.

The effects of postharvest methyl jasmonate (MeJA) fumigation on total soluble solids (TSS), titratable acidity (TA), ascorbic acid, total phenolic content (TPC), total monomeric anthocyanins (TMAs), individual anthocyanins and antioxidant activity of blueberries stored at 1 °C for 28 days were evaluated. Prior to storage, the blueberries were fumigated with 0.05 mmol L(-1) MeJA for 12 h. Control blueberries were subjected to the same conditions but were not exposed to MeJA. MeJA treatment had no adverse effect on TSS and TA and inhibited the decrease in ascorbic acid during storage. MeJA treatment induced an enhancement in TPC on day 21; TPC decreased thereafter. Similarly, a significant increase in TMAs and individual anthocyanins was observed 21 days after MeJA treatment. TPC, TMAs and individual anthocyanins increased in control fruits on day 7 and decreased thereafter. Moreover, MeJA treatment maintained higher levels of antioxidant activity during the entire storage period. These results suggest that cold storage enhances TPC, TMAs and individual anthocyanin content during short-term storage. However, postharvest application of MeJA to blueberries enhances TPC, TMAs and individual anthocyanin content during long-term storage.

Chilling injury and phytochemical composition of peach fruits as affected by high carbon dioxide treatment before cold storage

A chilling-sensitive peach (Prunus persica ‘Mibaekdo’) was pre-treated with 30% CO2, stored at 7°C for 4 weeks, followed by 3 days of subsequent ripening at room temperature. Significant reductions in both chilling injuries and softening were observed during the cold storage and also the subsequent ripening period. The high CO2 pre-treatment inhibited the decreases of antioxidant activity and the total phenolics. The beneficial effects of high CO2 were clearly apparent after three days at room temperature after cold storage, and the CO2 treatment had a strong effect on the high phytochemical content in peaches. Our results indicated that high levels of antioxidant activity, total phenolics, and ascorbic acid in the CO2-treated peach fruits might be directly responsible for reducing chilling injury in peach fruits under a high CO2 condition, which efficiently protects cells from free radicals induced by chilling stress.

Evaluation of Several Romanian Honeys Based on their Palynological and Biochemical Profiles

In this work, different types of honey were characterized based on their palynological and biochemical characteristics. A mellisopalynological analysis was performed to authenticate the botanical origin of the honey samples. According to this method, the honey types were classified in: acacia (n = 10), linden (n = 10), and rape (n = 10). This article also reports the phenols content, the flavonoids content, and the antioxidant activity of honey samples. The highest level of antioxidant activity was recorded for linden honeys and the lowest for acacia honeys. The multivariate analysis demonstrated to be an important tool in classification and discrimination between different honeys concerning the palynological and biochemical properties.

Evaluation of the in vivo antioxidative activity of redox nanoparticles by using a developing chicken egg as an alternative animal model

Antioxidants have been demonstrated to exert beneficial effects as pharmacotherapies for cardiovascular diseases. The in vitro systems generally employed to evaluate antioxidants, however, are limited by having no appreciable in vivo redox status of the antioxidants. Therefore, we used our developing chicken egg model to evaluate the in vivo antioxidative activity of a redox nanoparticle possessing 2,2,6,6-tetramethylpiperidine-1-oxyl (RNPO). The 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH) elicited strong oxidative stress and its LD50 value for chick embryos was 3.5±0.9mg/egg. The low molecular weight nitroxide compound, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), which is known to have the highest level of antioxidant activity, showed no significant protective effect against AAPH-induced embryo lethality. On the contrary, RNPO had potent protective effects against AAPH-induced embryo lethality. Moreover, RNPO could significantly suppress the production of lipid peroxides in chick serum induced by hydrocortisone. Since RNPO has a longer retention time in blood than TEMPOL, RNPO may protect the embryo against lethal oxidative stress by suppressing lipid peroxidation. The validity of in vivo experiments using developing chicken eggs was supported by our data, where RNPO was determined to elicit strong antioxidative activity in vivo, irrespective of the lack of a significant difference in the in vitro activity between low-molecular weight TEMPOL and RNPO. Our results support the use of the developing chicken egg model to evaluate the potential in vivo antioxidative activity of RNPO.

Contemporary Gathering Practice and Antioxidant Benefit of Wild Seaweeds in Hawai’i

Contemporary Gathering Practice and Antioxidant Benefit of Wild Seaweeds in Hawai’i. Wild-gathered seaweeds (limu) are a prominent component of Native Hawaiian diet and culture, but are understudied for their nutritional benefits and contemporary cultural use. This study uses a combination of ethnographic, pharmacological, and ecological approaches to document contemporary levels of wild seaweed gathering and consumption, and it explores the impact of cultivation and eutrophication on the disease-preventive benefits wild seaweeds may provide. Levels of gathering and consumption of seaweed were assessed with surveys of high school students and interviews with adult limu gatherers on O’ahu island, Hawai’i. Antioxidant activity was assessed with laboratory-based assays. Almost all students surveyed reported consuming cultivated seaweeds, one-third reported having consumed wild seaweeds, and one-fifth had gathered them, confirming that gathering practice and traditional diet have persisted in Hawai’i despite major social and environmental change. Wild gathering was three times as high and consumption 60% more prevalent among Native Hawaiians compared to non-Hawaiian students. Further, students with a parent who gathered limu were six times more likely to have gathered limu themselves, asserting the importance of within-family transmission to cultural continuity. A larger proportion of male than female Hawaiian students reported gathering wild seaweeds, indicating a cultural shift from pre-Contact Hawai’i, when women were the predominant gatherers and consumers of limu. The wild seaweeds assessed demonstrated higher levels of antioxidant activity than did cultivated seaweeds. Eutrophication was correlated with a decline in antioxidant activity, indicating that changing ocean conditions may alter the nutritional quality of this traditional food. Today, nearly all students are receiving some antioxidant benefits from seaweed, with Native Hawaiian youth from families that gather seaweed most likely to receive this health benefit. Conservation and restoration of near-shore environments to promote native edible seaweeds in pollution-free areas would provide greater opportunities for Native Hawaiian gathering practice and would support Native Hawaiian health.

ROS homeostasis in halophytes in the context of salinity stress tolerance

Halophytes are defined as plants that are adapted to live in soils containing high concentrations of salt and benefiting from it, and thus represent an ideal model to understand complex physiological and genetic mechanisms of salinity stress tolerance. It is also known that oxidative stress signalling and reactive oxygen species (ROS) detoxification are both essential components of salinity stress tolerance mechanisms. This paper comprehensively reviews the differences in ROS homeostasis between halophytes and glycophytes in an attempt to answer the questions of whether stress-induced ROS production is similar between halophytes and glycophytes; is the superior salinity tolerance in halophytes attributed to higher antioxidant activity; and is there something special about the specific 'pool' of enzymatic and non-enzymatic antioxidants in halophytes. We argue that truly salt-tolerant species possessing efficient mechanisms for Na(+) exclusion from the cytosol may not require a high level of antioxidant activity, as they simply do not allow excessive ROS production in the first instance. We also suggest that H2O2 'signatures' may operate in plant signalling networks, in addition to well-known cytosolic calcium 'signatures'. According to the suggested concept, the intrinsically higher superoxide dismutase (SOD) levels in halophytes are required for rapid induction of the H2O2 'signature', and to trigger a cascade of adaptive responses (both genetic and physiological), while the role of other enzymatic antioxidants may be in decreasing the basal levels of H2O2, once the signalling has been processed. Finally, we emphasize the importance of non-enzymatic antioxidants as the only effective means to prevent detrimental effects of hydroxyl radicals on cellular structures.

Medicago spp. extracts as promising ingredients for skin care products

Agro-industrial by-products have the potential to be used with different purposes thus providing economical advantage to otherwise disposable residues. In particular, the field of skin care products and cosmetics may benefit from these remaining materials. Hydro-alcoholic extracts of seven species of Medicago (M. minima, M. tornata, M. truncatula, M. rigidula, M. scutelata, M. segitalis and M. sativa) were screened for antioxidant, cytotoxicity and antimicrobial activities aiming at their application as functional ingredient in skin formulations. Antioxidant activity was evaluated by standard methods such as DPPH· and FRAP. In both methods the antioxidant activity of M. segitalis displayed the highest antioxidant activity (214.49±6.69μmol Trolox equivalent per g db for DPPH; 120.84±1.86μmol/mg db for FRAP). For DPPH M. rigidula showed the lowest antioxidant activity (127.18±1.96μmol Trolox equivalent per g db) and for FRAP M. minima showed the lowest one (58.05±6.09μmol per mg db). Also, the total phenolic and total flavonoid contents (TPC and TFC, respectively) were evaluated. The TPC of the different extracts varied from 21.96mg to 36.41mg GAE/g db sample, being the highest TPC obtained for M. minima and the lowest for the M. scutelata. TFC varied from 5.54 to 11.67mg CEQ/gdb sample. Linear negative correlations were established between the total phenol contents and for both the antioxidant activity methods. The extracts were also screened for cytotoxicity using MTS and LDH assays in two different skin cell lines (HaCaT and HFF-1) and showed low cytotoxicity. Preliminary assays for antimicrobial potential showed that extracts from Medicago display antibacterial activity, with MIC values of 31.3μg/mL and 125μg/mL for some Gram-positive and Gram-negative bacteria, respectively. Taken together, the results suggested that Medicago hydro-alcoholic extracts are a potential source of natural compounds with high levels of antioxidant activity, low cytotoxicity for skin cells and the ability to potentially prevent microbial infections of the skin due to its antimicrobial effect, as well as contribute as a natural preservative in cosmetic products. All referred above justify their possible uses in skin care products.

Antioxidant activity and ultrastructural changes in gastric cancer cell lines induced by Northeastern Thai edible folk plant extracts

BackgroundPhytochemical products have a critical role in the drug discovery process. This promising possibility, however, necessitates the need to confirm their scientific verification before use. Hence, this study aims to evaluate (1) the antioxidant activity, (2) cytotoxicity potential, and (3) the effect on ultrastructural alteration in gastric cancer cell lines through exposure to fractions of three local Northeastern Thai edible plants.MethodsPlants, Syzygium gratum, Justicia gangetica and Limnocharis flava were extracted with ethyl acetate, and each crude extract analysed for their total phenolics content by Folin-Ciocalteu method. Their antioxidant activity was assessed using the ABTS system. The extracts were then assayed for cytotoxicity on two gastric cancer cell lines Kato-III and NUGC-4, and compared with Hs27 fibroblasts as a control using the MTT assay. The cell viability (%), IC50 values, as well as the ultrastructural alterations were evaluated after treatment with one way analysis of variance (ANOVA).ResultsThe total phenolic values of the ethyl acetate extracts were well correlated with the antioxidant capacity, with extracted product of S. gratum displaying the highest level of antioxidant activity (a 10-fold greater response) over J. gangetica and L. flava respectively. Exposure of S. gratum and J. gangetica extracts to normal cell lines (Hs27) resulted in marginal cytotoxicity effects. However, through a dose-dependent assay S. gratum and J. gangetica extracts produced cytotoxicological effects in just over 75 percent of Kato-III and NUGC-4 cell lines. In addition, apoptotic characteristic was shown under TEM in both cancer cell lines with these two extracts, whereas characteristics of autophagy was found in cell lines after post exposure to extracts from L. flava.ConclusionsFrom these three plants, S. gratum had the highest contents of phenolic compounds and antioxidant capacity. All of them found to contain compound(s) with cytotoxicity in vitro on cancer cells but not on normal cell lines as resolved in tissue culture and ultrastructural analysis. This is the first report to show the effect on cellular alteration as apoptosis of an ethyl acetate extract of S. gratum and J. gangetica. Further studies are now focused on individual isolates and their function, prioritizing on S. gratum and J. gangetica for the development of novel therapeutics and combatants against cancer.

Differences in oxidative stress, antioxidant systems, and microscopic analysis between regenerating callus-derived protoplasts and recalcitrant leaf mesophyll-derived protoplasts of Citrus reticulata Blanco

It is known that protoplasts derived from either leaves or suspension cultures of a citrus genotype vary greatly in their regeneration capacities; however, the underlying physiological mechanisms are not well known. In this study, oxidative stress and antioxidant systems during in vitro culture of callus-derived protoplasts and leaf mesophyll-derived protoplasts of Ponkan (Citrus reticulata Blanco) were analyzed to gain insights into observed physiological differences. Morphological observations using light microscopy and scanning microscopy have shown that new cell wall materials appeared within 2–3 days, and the integrate cell walls were regenerated approximately after 6 days of culture of the callus protoplasts, whereas no cell wall formation was observed in the mesophyll protoplasts after culture. During the culture, higher levels of H2O2 and malondialdehyde were detected in the mesophyll protoplasts as compared with the callus ones. On the contrary, the callus protoplasts possessed higher activities of antioxidant enzymes (SOD, POD and CAT) and larger amount of glutathione and ascorbic acid (at one time point) than the mesophyll protoplasts during the culture process. The current data indicate that the mesophyll and callus protoplasts displayed remarkable difference in the degree of oxidative stress and the antioxidant systems, suggesting that high levels of antioxidant activities might play an important role in the regeneration of protoplasts.

Biological and functional properties of proteolytic enzyme‐modified egg protein by‐products

Enzymatic hydrolysis led to improve functional properties and biological activity of protein by-products, which can be further used as protein ingredients for food and feed applications. The effects of proteolytic enzyme modification of egg-yolk protein preparation (YP) and white protein preparation (WP), obtained as the by-products left during the course of lecithin, lysozyme, and cystatin isolation on their biological and functional properties, were evaluated by treating a commercial Neutrase. The antihypertensive and antioxidative properties of YP and WP hydrolysates were evaluated based on their angiotensin-converting enzyme (ACE)-inhibitory activity and radical scavenging (DPPH) capacity, ferric reducing power, and chelating of iron activity. The functionality of obtained hydrolysates was also determined. Neutrase caused a degree of hydrolysis (DH) of YP and WP by-products: 27.6% and 20.9%, respectively. In each of them, mixture of peptides with different molecular masses were also observed. YP hydrolysate showed high levels of antioxidant activity. The scavenging capacity, ferric reducing power, and chelating capacity were observed at the level: 0.44 μmol/L Trolox mg−1, 177.35 μg Fe2+ mg−1, and 549.87 μg Fe2+ mg−1, respectively. YP hydrolysate also exhibited significant ACE-inhibitory activity, in which the level was 59.2 μg. Protein solubility was significantly improved as the DH increased. WP hydrolysate showed high water-holding capacity of 43.2. This study indicated that YP and WP hydrolysates could be used in foods as natural antioxidants and functionality enhancers.

Measurement of Antioxidant Activity in Selected Food Products and Nutraceuticals

Measurement of antioxidant activity using in vitro assays is paramount in the evaluation of various food products and nutraceuticals for determining antioxidant benefits. This relates to the fact that increased antioxidant levels can protect the human body from free radical damage. The objective of this study was to quantify the antioxidant activity of selected food products and nutraceuticals using a spectrophotometric assay. Using Efferdent tablets and isotonic saline diluent, antioxidant levels could be determined by the amount of FD & C Blue No. 2 remaining after incubation at 37°C for 25 minutes. The antioxidant activity of a 500 mg quantity of vitamin C (ascorbic acid) was used as standard. The results obtained indicated that agave nectar syrup and xylitol sweetener (in descending order) exhibited higher antioxidant properties than all the other commercial sweeteners tested. Grapefruit was found to have the highest antioxidant activity of those common citrus fruits tested. Popular contemporary antioxidant beverages, such as strawberry-kiwi blend tend to have very high antioxidant activity since they contain d-alpha tocopheryl acetate (a form of vitamin E). Among the herbal nutraceuticals tested, spirulina and red yeast rice exhibited abundant antioxidant activities, whereas graviola was found to have absolutely no antioxidant properties. Thieves’ oil was observed to have high antioxidant properties due to the synergism of the five oils in the preparation. Test results indicated a variable degree of antioxidant activity in foods and nutraceuticals compared to a standard antioxidant of 500 mg of vitamin C (ascorbic acid). Citrus fruits occupy the highest level of antioxidant activity overall, followed by antioxidant containing beverages and selected herbal products.

Redox properties of Abarema cochliacarpos (Gomes) Barneby & Grime (Fabaceae) stem bark ethanol extract and fractions

The redox properties of the hydroethanol extract (EE) and its ethyl acetate (EAF) and hydromethanol (HMF) fractions obtained from Abarema cochliacarpos (Gomes) Barneby & Grimes stem bark were evaluated. EAF had the highest total phenol content (848.62 ± 78.18 mg g−1), while EE showed the highest content of catechin (71.2 µg g−1). EE, EAF and HMF exhibited the highest levels of antioxidant activity at 100 and 1000 µg mL−1 when the non-enzymatic antioxidant potential was evaluated by the total reactive antioxidant potential, total antioxidant reactivity and nitric oxide scavenging assays. In addition, EAF and HMF showed SOD-like activity. The results for EE, EAF and HMF in this study showed that A. cochliacarpos (Gomes) Barneby & Grimes stem bark have redox properties and may be able to help the endogenous enzymatic and non-enzymatic systems to keep the redox balance.

Measuring hydrogen peroxide reduction using a robust, inexpensive, and sensitive method

Here, we report an improved method to analyze antioxidant activity using the europium tetracycline assay developed by Duerkop and Wolfbeis (J Fluor 15(5):755-761, 2005). The europium tetracycline hydrogen peroxide reduction assay (EHRA) accurately measures antioxidant activity based on hydrogen peroxide scavenging. Several known antioxidant compounds were assessed with the EHRA and a stoichiometric relationship between the number of oxidant molecules trapped per molecule of antioxidant was identified. Various extracts of hops were also tested to validate this method for use with natural extracts; water extraction yielded the highest level of antioxidant activity. Hop leaves were shown to be a better source of antioxidants relative to the traditional hop cones. The data also indicate that the EHRA may serve to breach the hydrophilic/lipophilic gap in antioxidant screening as the europium tetracycline probe is effective in many solvents. The EHRA thus provides a robust and inexpensive measure of antioxidant activity.

고추 에탄올 추출물의 항산화 효과 및 생리활성에 관한 연구

고추(Capsicum annuum)의 항산화 효과 및 생리활성 측정을 통하여 기능성식품의 소재로 활용하기 위한 기초 연구를 진행하였다. 폴리페놀 함량은 과육보다는 씨에서 높게 나타났다. 그러나 플라보노이드 함량은 풋고추 과육에서 높은 함량을 보였다. DPPH radical 소거활성에서 SC50값은 홍고추 씨 1,935±162 ㎍ DM/mL, ABTS radical 소거활성에서는 SC50값이 풋고추 씨 3,354±76 ㎍ DM/mL로 과육에 비해 높았다. 최종당화산물(AGEs) 생성 억제활성은 풋고추와 홍고추 씨, 풋고추와 홍고추 과육 순으로, α-glucosidase 저해활성은 풋고추 과육, 홍고추 씨, 홍고추 과육, 풋고추씨 순이었다. Tyrosinase 억제활성은 홍고추와 풋고추 씨, 홍고추와 풋고추 과육 순이었다. 종합해보면 기능성식품 소재로서 홍고추 씨 및 풋고추 씨가 과육보다 활용도가 높은 것으로 결론지을 수 있다.

제조방법에 따른 딸기잼의 이화학적 품질 특성 비교

The objective of this study was to characterize three different commercial (A, B and C) and two handmade (HM-AP, atmospheric pressure; HM-RP, reduced pressure) strawberry jams in relation to soluble solids, pH, total acid, total polyphenol, anthocyanin, color values, texture properties, and sensory evaluation. The soluble solid contents varied from 62.33 to 68.33 , and the pH ranged from 3.59 to 3.70. The color L and a values were the highest in the HM-RP strawberry jam (p (HM-AP jam) to (jam B) dyne/, the jelly strength ranged from 40.08 (HM-AP jam) to 180.33 (jam B) dyne, and the strength ranged from 83.84 (jam C) to 302.93 (jam B) g. The sensory evaluation of the color, flavor, sweetness, sourness, viscosity and overall acceptability of the HM-RP jam showed higher values than those of the other jams. Especially, the highest value of the color score was found in the HM-RP jam. The electon donating abilities of jams A, B, and C and of the HM-AP and HM-RP jams were 44.27, 41.70, 53.06, 69.08, and 73.21%, respectively. These results indicated that the HM-RP strawberry jam prepared with reduced pressure using micro-oxygen technology was a good source of phenolic compounds, total polyphenols and anthocyanin, and had a high level of antioxidant activity.

Evaluation of Anti‐oxidant Activity and Identification of Major Polyphenolics of the Invasive Weed Oxalis pes‐caprae

Phytochemical analyses of weeds, many of which have been used in traditional medicine worldwide, could lead to the identification of secondary metabolites with significant biological activity. To perform an assessment of the chemical composition and exploitation potential of the invasive weed Oxalis pes-caprae. To evaluate the anti-oxidant activity of its extracts and isolate and characterise polyphenolic metabolites using LC-DAD-MS (ESI+) and NMR methods. Aerial parts of the invasive weed O. pes-caprae were extracted with solvents of increasing polarity and their major polyphenolic metabolites were identified by LC-DAD-MS (ESI+). The total phenolic content of the extracts was determined using the Folin-Ciocalteu method, while their anti-oxidant activity was evaluated on the basis of their ability to scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl and hydrogen peroxide. The major polyphenolic constituents of the extracts were tentatively characterised as chlorogenic acid, quinic ferulate, luteolin glucoside and cernuoside according to their MS and UV spectroscopic data. Cernuoside, an aureusidin glucoside, was isolated from the methanolic extract of the weed's flowers and its structure was unambiguously identified by 1D- and 2D-NMR spectroscopy. The butanol extract of O. pes-caprae displayed the highest anti-oxidant activity. The metabolic profile of O. pes-caprae was studied and the structures of the major polyphenolic metabolites based on their MS and UV-vis spectra were tentatively assigned. The aureusidin glucoside cernuoside was isolated and characterised for the first time from O. pes-caprae. The extracts exhibited high levels of anti-oxidant activity.