Natural Antioxidants in Purple Sprouting Broccoli under Mediterranean Climate

Phenolic compounds and antioxidant activities of 70% ethanol extracts of the peels from two Pakistani citrus mandarin cultivars, namely, Feutrell's Early and Kinnow, were investigated. Results were compared with synthetic antioxidants and also with Chinese Ponkan mandarin peel to see the varietal and geographical effects. The cultivars showed the significant differences in total polyphenols, flavonoids and phenolic acids. Ferulic acid ranging from 1193.84 to 1640.87 µg/g dry weight was the dominant phenolic acid in all cultivars. The antioxidant activity of extracts as determined by β-carotene bleaching assay ranged from 28.40 to 43.78% and was in the following order: Kinnow < Feutrell's Early < Ponkan. A strong positive correlation was observed among the analyzed phenolic compounds and the antioxidant capacities. Results reveal that citrus peels under study might be used as an economical source of natural antioxidants, and both cultivars and geographical factors affect the bioactive composition in citrus mandarin peel. PRACTICAL APPLICATIONS Foods from plant origin usually contain natural antioxidants that can scavenge free radical and may contribute to reduce human diseases. Therefore, many studies have been undertaken to find the new sources of antioxidant compounds. Citrus mandarin (Citrus reticulata Blanco) peels are the source of bioactive compounds with enhanced antioxidant activity. Feutrell's Early and Kinnow peels contain a high amount of polyphenols, flavonoids and phenolic acids, and, therefore, can be the basis for food ingredient designed for functional food applications. The varietal and geographical conditions affect the antioxidant potential of citrus cultivars, and Feutrell's Early seems to be a promising one, for its raw material usage in the food and the pharmaceutical industry as a potential natural antioxidant and a functional ingredient.

Spent coffee grounds (SCG) were extracted with an environmentally friendly procedure and analyzed to evaluate the recovery of relevant natural antioxidants for use as nutritional supplements, foods, or cosmetic additives. SCG were characterized in terms of their total phenolic content by the Folin-Ciocalteu procedure and antioxidant activity by the DPPH scavenging assay. Flavonoid content was also determined by a colorimetric assay. The total phenolic content was strongly correlated with the DPPH scavenging activity, suggesting that phenolic compounds are mainly responsible for the antioxidant activity of SCG. An UHPLC-PDA-TOF-MS system was used to separate, identify, and quantify phenolic and nonphenolic compounds in the SCG extracts. Important amounts of chlorogenic acids (CGA) and related compounds as well as caffeine (CAF) evidenced the high potential of SCG, a waste material that is widely available in the world, as a source of natural phenolic antioxidants.

Known as carrageenan, Kappaphycus alvarezii is a popular species of red edible seaweed which is mainly cultivated for its hydrocolloids. K. alvarezii is a good source of phenolics which are considered to be natural antioxidants that promote myriads of health benefits. Extraction of phenolic compounds using conventional solvent extraction may result in hazards and toxicological effect and low yield of bound phenolics. Therefore, this study was conducted to increase the release of bound phenolics through solid substrate fermentation. In the present study, three different varieties of K. alvarezii were fermented with Aspergillus oryzae through solid substrate fermentation (SSF) at 30 ℃ for 2 to 6 days. The changes of total phenolic content and antioxidant activity due to the effects of SSF were investigated. Results obtained revealed that the highest total phenolic content for green (10.022 mg GAE/g) and purple (4.037 mg GAE/g) varieties of K.alvarezii were on the fourth day of fermentation while for yellow (4.479 mg GAE/g) variety was on the sixth day of fermentation. A remarkable enhancement of antioxidant activity was discovered through DPPH radical scavenging activity on the fourth day of fermentation for all varieties of K. alvarezii tested. Total phenolic content also showed a significant correlation with antioxidant activity of fermented seaweed. Cellulase, xylanase, and β-glucosidase enzymes produced by A.oryzae during SSF were also investigated to see the relationship with the release of phenolic compounds after fermentation. The highest cellulase activity was observed on the fourth day of fermentation. The similar observation was also found for xylanase enzyme in yellow and purple varieties of K. alvarezii , except for green variety where the highest xylanase activity was on the sixth day of fermentation. The maximum β-glucosidase activity in yellow and green varieties was observed on the fourth day of fermentation while purple variety exhibited the maximum β-glucosidase activity on the sixth day. There are positive correlation between the enzymes studied and the polyphenols content in all varieties of K. alvarezii . This study demonstrated that fermented K. alvarezii contained more phenolic content compared to non-fermented seaweed.

Gypsum habitats represent a stressful environment for plants, combining aridity, limited nutrients and salt toxicity in the soil. Si nce different abiotic stress conditions cause oxida tive stress by generation of 'reactive oxygen species' ( ROS), the activation of antioxidant systems is considered as one of the general mechanisms of resp onse to stress in plants. The levels of total phenolic compounds and total flavonoids, well-known antioxidants, were determined in several species from a gypsum area in Valencia, SE Spain, t o study their possible role as biochemical markers of stress responses. Plant samples were collected f rom three selected experimental plots, located on a hill slope and showing different levels of environm ental stress, regarding dryness and gypsum content in the soil. Samplings were repeated three times al ong the year 2009, in spring, summer and autumn. The measured levels of total phenolics and flavonoi ds were very variable among taxa, precluding a direct comparison of different species, but in gene ral most of them showed higher contents of these compounds in summer, which is the most stressful period in the Mediterranean climate, with higher temperatures and practically no rainfall. The patte rns of phenolics and flavonoids accumulation in plants, according to spatial gradients in the exper imental area, also suggested a correlation with wat er stress, but not so much with the toxicity of the su bstrate.

In this study, the polyphenols composition and antioxidant properties of 12 blue highland barley varieties planted on the Qinghai-Tibet Plateau area were measured. The contents of the free, bound and total phenolic acids varied between 166.20–237.60, 170.10–240.75 and 336.29–453.94 mg of gallic acid equivalents per 100 g of dry weight (DW) blue highland barley grains, while the free and bound phenolic acids accounted for 50.09% and 49.91% of the total phenolic acids, respectively. The contents of the free, bound and total flavones varied among 20.61–25.59, 14.91–22.38 and 37.91–47.98 mg of catechin equivalents per 100 g of dry weight (DW) of blue highland barley grains, while the free and bound flavones accounted for 55.90% and 44.10% of the total flavones, respectively. The prominent phenolic compounds in the blue hulless barley grains were gallic acid, benzoic acid, syringic acid, 4-coumaric acid, naringenin, hesperidin, rutin, (+)-catechin and quercetin. Among these, protocatechuic acid, chlorogenic acid and (+)-catechin were the major phenolic compounds in the free phenolics extract. The most abundant bound phenolics were gallic acid, benzoic acid, syringic acid, 4-coumaric acid, benzoic acid, dimethoxybenzoic acid, naringenin, hesperidin, quercetin and rutin. The average contribution of the bound phenolic extract to the DPPH• free radical scavenging capacity was higher than 86%, that of free phenolic extract to the ABTS•+ free radical scavenging capacity was higher than 79%, and that of free phenolic (53%) to the FRAP antioxidant activity was equivalent to that of the bound phenol extract (47%). In addition, the planting environment exerts a very important influence on the polyphenol composition, content and antioxidant activity of blue highland barley. The correlation analysis showed that 2,4-hydroxybenzoic acid and protocatechuic acid were the main contributors to the DPPH• and ABTS•+ free radical scavenging capacity in the free phenolic extract, while chlorogenic acid, vanillic acid, ferulic acid and quercetin were the main contributors to the free radical scavenging capacity in the bound phenol extract. The study results show that the blue highland barley grains have rich phenolic compounds and high antioxidant activity, as well as significant varietal differences. The free and bound phenolic extracts in the blue hulless barley grains have an equivalent proportion in the total phenol, and co-exist in two forms. They can be used as a potential valuable source of natural antioxidants, and can aid in enhancing the development and daily consumption of foods relating to blue highland barley.

Flavonoids can provide antioxidant effects by preventing the formation of ROS, directly capture ROS, protect lipophilic antioxidants and stimulate the increase of enzymatic antioxidants. Flavonoids are phenolic compounds that are widely found in medicinal plants, one of which is Gyrinops versteegii leaves. In this research to determine the potential of flavonoids in water extract Gyrinop versteegii as one source of natural antioxidants was investigated. This research begins with maceration of Gyrinops versteegii leaves with some solvents such as ethyl acetate, ethanol, methanol and water. Each of the extracts obtained measured the total content of Phenol. The extract, which had the highest total phenol content, measured the total flavonoid content and antioxidant capacity. The active extract as antioxidant was further isolated and identified its flavonoid content. Flavonoids obtained measured antioxidant capacity in vitro. Total phenol (mg GAE/100 g) of ethyl acetate extract = 443, ethanol extract =1.510, methanol extract = 6.069 and water extract = 14.979, total flavonoid contens = 2298, 977 mg QE/100 gram, containing phenol, flavonoid, tannin, alkaloid and steroid compounds. Antioxidant capacity with IC50 = 3,45 ppm (5 min.) and 3,05 (60 min.). Identification of isolates with UV-Vis spectroscopy showed 2 absorption bands namely band I at 352 nm and band II at 256 nm. Addition of AlCl3 / HCl shear reagent showed band I undergoing a 2 nm batochromic shift. These results indicate that the resulting flavonoid is suspected to be a flavonoid group of flavonol substituted -OH group at C-5 or 5-hydroxy-flavonol. and its antioxidant capacity or IC50 = 17,14 ppm. These results indicate that the isolated flavonoid has very strong antioxidant activity and is potentially developed as a natural antioxidant.

Many studies show the antioxidant ability of the parasite plant. This study aims to determine the capacity of Dendrophthoe pentandra (L.) Miq and Scurrula ferruginea stem from Syzygium aqueum to use as a natural antioxidant source. The sample was taken from the host Syzygium aqueum. The sampels were exraction with ethanol using maceration. The parameters determined spectrophotometrically using specific reagents that were antioxidant capacity using 1,1-diphenyl-2-picrylhydrazyl, phenolics compounds using Folin-Ciocalteu, flavonoids using AlCl3, ascorbic acid using sulfosalicylic acid, while chlorophyll and carotenoid using dimethyl sulfoxide. The result of D. pentandra (L.) Miq and S. ferruginea extract showed that IC50 were 15.09±1.02 and 20.53±1.77 mg/ml, content of phenolics compounds were 557.45±19.77 and 433.99±20.89 mg GAE/ml extract, flavonoids were 9.72±0.23 and 3.02±0.71 mg QE/ml extract, chlorophylls-a were 2.67± 0.15 and 2.77±0,08 mg/g extract, chlorophylls-b were 3.34±0.06 and 3.44±0.04 mg/g extract, total chlorophylls were 6.01±0.21 mg/g extract, carotenoids were 1.71±0.01 and 2.10±0.01 mg/g extract respectively. The stems of both D. pentandra (L.) Miq and S. ferruginea from Syzygium aqueum have very strong antioxidant abilities so that they are potential to use as a source of natural antioxidants. The compounds support the antioxidant activity were phenolic, flavonoids, and ascorbic acids. The results of this study will open up opportunities to obtain new sources of antioxidants that can be utilized in human health management.

This study aimed at investigating the potential of microalgae species grown on industrial waste water as a new source of natural antioxidants. Six microalgae from different classes, including Phaeodactylum sp. (Bacillariophyceae), Nannochloropsis sp. (Eustigmatophyceae), Chlorella sp., Dunaniella sp., and Desmodesmus sp. (Chlorophyta), were screened for their antioxidant properties using different in vitro assays. Natural antioxidants, including pigments, phenolics, and tocopherols, were measured in methanolic extracts of microalgae biomass. Highest and lowest concentrations of pigments, phenolic compounds, and tocopherols were found in Desmodesmus sp. and Phaeodactylum tricornuotom microalgae species, respectively. The results of each assay were correlated to the content of natural antioxidants in microalgae biomass. Phenolic compounds were found as major contributors to the antioxidant activity in all antioxidant tests while carotenoids were found to contribute to the 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activity, ferrous reduction power (FRAP), and ABTS-radical scavenging capacity activity. Desmodesmus sp. biomass represented a potentially rich source of natural antioxidants, such as carotenoids (lutein), tocopherols, and phenolic compounds when cultivated on industrial waste water as the main nutrient source.

Free radical-scavenging capacity and HPLC-DAD screening of phenolic compounds from pulp and seed of Syzygium claviflorum fruit

Green leafy kale (Brassica oleracea var. sabellica) has huge scientific attention because of its health-promoting functionality. In the present study the impact of NPK, energen, biostim and humate on flavonoid, phenolic compounds, vitamin C, carotenoids, malondialdehyde (MDA), protein, proline and soluble sugar in kale was investigated. The mineral nutrients mostly increased but in some cases maintained the studied metabolites. The stimulatory effect of applied mineral nutrients on the phytochemicals analyzed varied with the different combinations of macro and microelements. Lipid peroxidation was minimized in leaves treated with mineral nutrients hence a reduction in MDA levels. Contrary to the correlation between nitrogen deficiency and increase in polyphenol and vitamin C content in plants, NPK and biostim did not reduce phenolic compound levels. The results of this study showed that NPK maximized the synthesis of vitamin C and proline; energen - phenolic compounds, carotenoids and sugar; biostim – phenolic compounds, proteins and sugar; humate – flavonoids and sugar in curly kale. Therefore, the type of macronutrient and micronutrients combination increases phytochemicals in differently. To enhance the synthesis of phenolic compounds and vitamins, the most promising additives are those containing humic acids (humate and energen), and biostim proved to be more effective for the synthesis of proteins. Background. The understanding of how diet affects the incidence or treatment of disease has led to a rise in consumer’s demand for functional foods as well as created the market for natural sources of health benefitting compounds rather than the synthetic sources. Curly kale has gained scientific attention as a functional food because it contains higher levels of phytochemicals than most vegetables. These phytochemicals have shown antioxidant, antimutagenic, cytotoxic, antifungal, and antiviral activities. However, the content levels of these metabolites are influenced by not only genetic but environmental factors. It was of interest to evaluate how various mineral nutrients can elicit the accumulation of these compounds that minimize the risk of chronic diseases or aid in their treatment. Purpose. Evaluate how the mineral nutrients, NPK, energen, biostim and humate affect the content of metabolites (proteins, sugars, flavonoids, phenolic compounds, vitamin C, carotenoids, MDA and proline) in curly kale (Brassica oleracea var. sabellica). Materials and methods. Sprouts from kale seed kept wet in a Petri dish for 7 days were transferred to the field. At 6 weeks old four mineral nutrients (NPK, energen, humate and biostim) were added to the soil. Control variants were treated with water. A week later, the leaves were harvested after which, the phenolic compound, flavonoid, protein, sugar, vitamin C, carotenoid, MDA and proline contents were determined using spectrophotometric methods. Results. It was shown that humate fertilizer elicited the highest accumulation of flavonoids. Kale plants fertilized with energen were observed to have the highest phenolic compound content. NPK, energen and humate caused a similarly positive effect on vitamin C content in leaves, unlike biostim whose effect did not significantly differ from control plants. Energen treated kale had the highest increment of carotenoids. A varied reduction of MDA levels in plants treated with all four mineral nutrients was observed in kale leaves. Plants fertilized with biostim accrued the highest protein content in leaves. Proline content increased under the influence of all fertilizers studied. Sugar levels for all kale plants treated with the studied mineral nutrients were enhanced equally Conclusion. Macro and microelements supplied by mineral nutrients differentially boost the biosynthesis of health-promoting metabolites in curly kale, thereby enhancing its quality.

In this study, Dipsacus asperoides was separately extracted in three solvents (water, methanol and acetone), and the antioxidant activities of each extract were investigated through assays of DPPH, ABTS, β-carotene/linoleic acid system and reducing power. The total phenolic acids, flavonoids and saponins in each solvent extract were calculated for a correlation analysis. The phenolic compounds in the extracts were identified by LC-ESI-QTOF-MS–MS. The results showed that the three extracts exhibited antioxidant effects in a concentration-dependent manner, and the water extracts exerted the highest antioxidant activity effect followed by the methanol and acetone extracts. The correlation analysis indicated that the total phenolic components presented the greatest contribution to the antioxidant activities. Fifteen main phenolic compounds were identified in the water extracts, and three of these compounds had not been previously identified in D. asperoides. The results suggest that water extraction of D. asperoides is a promising source of natural antioxidants.

Chemical constituents and antioxidant potential of African Fruits

Seedlessness is an important economic trait relating to fruit quality, and gamma irradiation is a common technique used to obtain seedless citrus fruits. Herein, we report a study of new seedless ‘Murcott’ mandarin clones obtained by bud irradiation from the self-compatible not parthenocarpic ‘Murcott’ mandarin. All irradiated clones examined presented lower seed numbers (from 0.23 to 2.47 seeds per fruit) and reduced pollen germination (from 1.40% to 8.55%) whereas the wild-type ‘Murcott’ showed an average number of 9.03 seeds per fruit and a pollen germination value of 47.15%. Fruit quality and nutritional bio-components were affected differently; some clones presented no changes compared to the control ‘Murcott’ mandarin, while other clones showed significant differences. High-performance liquid chromatographic methods were used to identify and quantify of these compounds, using photodiode array, mass and refractive index detectors. Our results indicated high contents in natural antioxidants as vitamin C (from 20.13 to 25.73 mg/100 mL) and phenolic compounds, as flavonoids, in these citrus varieties cultived under the Mediterranean climate. Some of these clones, which ripen late in the season and whose fruit quality is maintained or improved, are in the process of registration. In conclusion, budwood irradiation is a suitable technique to improve cultivars, produce seedless cultivars, adjust ripening time or raise the content of health-promoting compounds. Also this study investigates the influence of temperature during flowering on the number of seeds formed. Findings indicate that low temperatures during flower formation decreased pollen germination and seed number.

An antioxidant may be roughly defined as a substance that when present at low concentrations, lower than the oxidizable compound to be protected, significantly delays or inhibits its oxidation. There are two basic categories of antioxidants, natural and synthetic, the second ones have been found to cause long-term toxicological effects, including carcinogenicity (1). Attentions have been paid to both natural and synthetic antioxidants. Antioxidants have been intensively studied over the past few decades. Antioxidants play a vital role against the deteriorating action of free radicals in the organisms. Deficiency of antioxidants in living organisms leads to oxidative stress. It has been found that antioxidant compounds present in food, and biological systems are fundamental to the protection of biomolecules from these free-radical redox reactions. There has been a great interest in phenolic compounds and their antioxidant activity among consumers and the scientific community in the past decade because of the epidemiological studies linking the consumption of diets rich in natural antioxidants with decreased risk of diseases associated with oxidative stress, such as cancer and cardiovascular disease (2). Phenolic compounds as bioactive substances are a large heterogeneous group of secondary plant metabolites that have been widely distributed in plants and are important constituents of human diet (3). The natural products rich in antioxidants are of great importance for scientists. For this reason antioxidant and antitumor activities of sulfated polysaccharide isolated from marine algae have been studied by many scientists. Marine resources have attracted a great attention in the search for bioactive substance to develop new drugs and healthy foods, because of their relatively low toxicity and high bioactivities (4). In particular, sulfated polysaccahrides from marine algae are known to exhibit various biological and physiological activities including antioxidant, anticoagulant, antiviral, antitumor, and anti-inflammatory activities. There is also an emerging interest in the use of naturally occurring antioxidants in foods. Honey a sweet natural product produced by honey bees form nectar, and other plant juices is also a good source of antioxidants. Antioxidant and antimicrobial properties of honey are due to presence of variety of compounds like phenolics, ascorbic acid, α-tocopherol, proline, vitamins, catalase and glucose oxidase. Extensive data is available for antioxidant properties of honeys from different origins of the world which evidenced that bioactivities of honeys vary from each other due to botanical and geographical variations (5). Due to importance of this class of compounds, assessment of antioxidant or radical-scavenging capacity has attracted increasing attention in a number of areas, which demands the availability of simple, convenient, rapid and reliable in vitro analytical methodologies. Many different methods are used to screen matrixes or to find specific antioxidants (6).

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review