Evaluation and comparison of the content of total polyphenols and antioxidant activity in onion, garlic and leek

ArticleinPotravinarstvo 8(1) · November 2014with 55 Reads
Cite this publication
Abstract
Onion, leek and garlic as onion family are a great source of freely available health-promoting and chemoprotective compounds (polyphenols, flavonoids, fructooligosaccharides, thiosulfinates and other sulfur compounds, vitamins). Chemoprotective compounds belong between natural components. Onion, garlic and leek have high nutritional value. They are an important component of our human diet and we used them as a preventive factor for many diseases of civilization (cancer, coronary heart diseases, and atherosclerosis). In this work we watched and evaluated content of total polyphenols and antioxidant activity in onion, garlic and leek. Samples of plant material (onion, garlic and leek) we collected at the stage of full maturity in the area of Pružina. Pružina is area without negative influences and emission sources. Samples of fresh onion, garlic and leek were homogenized and were prepared an extract: 25 g cut onion, garlic and leek extracted by 50 ml 80% ethanol accourding sixteen hours. These extracts were used for analyses. The content of the total polyphenols was determined by using the Folin-Ciocalteu reagent (FCR). Antioxidant activity was measured by using a compound DPPH˙ (2.2-diphenyl-1-picrylhydrazyl). In the present experiment it was detected, that total polyphenols content in samples ranges from 210.67 mg/kg (leek) - 429.58 mg/kg (onion). Statistically significant highest value of total polyphenols was recorded in onion (389.64 to 429.58 mg/kg). Statistically significant the lowest content of total polyphenols was recorded in leek (210.67-254.80 mg/kg). Another indicator that has been evaluated and compared was the antioxidant activity of onion, garlic and leek. Statistically significant highest value of antioxidant activity was recorded in onion (20.22-25.76%). Statistically significant the lowest value of antioxidant activity was recorded in garlic (4.05-5.07%). Based on the measured values of AOA in onion, garlic and leek samples can be classified as follows: onion (20.22-25.76%) > leek (8.55-12.92%) > garlic (4.05-5.07%).

Do you want to read the rest of this article?

Request Full-text Paper PDF
  • Article
    Full-text available
    Objective This study was conducted to investigate the effect of dietary onion (Allium cepa) extract (OE) supplementation on growth performance, apparent total tract retention (ATTR), blood profile, carcass characteristics and meat quality in broilers. Methods Four hundred male broiler chicks (Ross 308, 3-d old) were randomly allocated to four dietary treatments for 28 d feeding trial. Each treatment has five replications with 20 birds each. Four dietary treatments were designated according to the OE supplementation levels (0 as control, 5, 7.5, and 10 g of OE per kg of basal diet respectively). On d 28, a total of 20 birds from each treatment were subjected for ATTR, serum biochemical assay, carcass characteristic and organ weight measurement. Results Overall weight gain of OE 7.5 g/kg group was higher (p = 0.04) than control group. The ATTRs of dietary energy (p<0.01) and ether extract (p = 0.04) linearly increased with increasing levels of dietary OE. However, no difference in ATTR of dry matter and crude protein was evident. Furthermore, serum IgG concentration increased linearly (p<0.01) and quadratically (p = 0.03) with increasing OE supplementation. No differences in carcass dressing weight and amount of abdominal fat by treatments were observed. Also, the weight of organ including immune organ was not different among the treatments. The TBARS values of 10 d stored breast meat decreased linearly (p<0.01) and quadratically (p<0.01) with increasing dietary OE levels. The meat color was also affected, with lower (p<0.01) redness score in meats from OE supplemented groups. This study showed that dietary OE improved broiler weight gain presumably by increasing feed intake and ATTR of both energy and ether extract. The dietary OE increased serum IgG level and meat anti-oxidation capacity. Conclusion This study implies that the recommended level of dietary OE supplementation could be beneficial for improving broiler performance and meat quality.
  • Article
    Full-text available
    Garlic (Allium sativum L.) is one of the most valuable plants in the world because it contains important substances with protective and healing effects on human health. Its health-promoting effects have been already known in ancient Egypt, China, Greece and also the Romans used it. Many studies have shown that garlic can help from colds, coughs, flu, pulmonary diseases, clean blood vessels, lowers blood pressure and cholesterol and has antibacterial, antiviral, anti-carcinogenic, anti-mutagenic and antioxidant properties. Garlic contains antioxidant that support the body´s defense mechanism against oxidative damage. The physiological effect of garlic can be affected by sulphur – containing compounds as well as other biologically active compounds such as polyphenols (mainly flavonoids), minerals (Ca, Fe, I, K, Mg, Na, Zn) and vitamins (A, B1, B2, B6, C). The main sulphur compound in garlic is alliin, converted to allicin by the enzyme alliinase, which results in a characteristic garlic aroma and taste.
  • Article
    The process of breeding to enhance nutrients, such as vitamins and minerals, in food crops through biofortification is a sustainable, eco-friendly and powerful strategy to overcome micronutrient deficiency. Therefore, the aim of the present investigation was to increase selenium content in edible parts of garlic (Allium sativum L.) supplied with either 20g/ha or 50g/ha aqueous solution of anhydrous sodium selenate. This was done either through foliar spray or soil flood application under open-field conditions. Results indicated that the 50g/ha concentration of sodium selenate application in the form of foliar spray significantly enhanced the selenium content in garlic bulb (3.23±0.16mgSe/Kg) and vegetative part (15.46±0.71mgSe/Kg) that is, a 12.52 and 7.8 fold increase was observed respectively, as compared to control. A significant increase in total phenolic content (4.72±1.79GAE/100g), total flavonoid content (18.50±1.82 mgQE/100g) and total antioxidant capacity (IC 50 of 0.81mg/ml determined through DPPH radical scavenging assay) was also observed in the bulbous part of garlic. The results suggested that the consumption of 16g of dried garlic bulb, biofortified with 50g Se/ha, could cover the daily recommended dose of selenium for human beings. Selenium biofortified garlic crop can hold a market value as selenium functional food and can be used as an alternative to synthetic selenium supplements to overcome selenium deficiency.
  • Article
    Full-text available
    Allium ampeloprasum var. porrum has been recognized as a rich source of secondary metabolites, including phenolic acids, flavonoids and flavonoid polymers (proanthocyanidins or condensed tannins), with related health benefits. Both parts of Allium ampeloprasum var. porrum (white bulb and pseudostem) are traditionally consumed either as a vegetable or as a condiment in many Mediterranean countries. The aim of the present study was to optimize the extraction conditions of polyphenols from white leek stem and green leek leaf by implementing a Box-Behnken design (BBD). The optimization considered basic factors affecting extraction efficiency, including extraction time, solvent to plant material ratio and solvent mixture composition. Maximum polyphenol yield was achieved at an extraction time of 80 and 100 min for white leek stem and green leek leaf extracts respectively, solvent to plant material ratio of 5:1 (v/w) and methanol to water ratio of 40:60 (v/v), for both leek extracts. Interestingly, higher total phenolic content was found in green leek leaf extracts compared to white leek stem extracts, due to a possible relationship between polyphenol production and sunlight radiation. High correlation values were also observed between total phenolic content and antioxidant-antiradical activity of optimized leek extracts.
  • Article
    Full-text available
    Moringa oleifera and Thymus vulgaris are well known and widely used herbs, which contains several interesting bioactive constituents and possesses health promoting properties. The aim of the present study is to evaluate and compare thein vitro anti-inflammatory effects of ethanol extracts of Moringa oleifera and Thymus vulgaris and a 1:1 blend of the two extracts against the denaturation of proteins. The test extracts and the reference drug of varying concentrations were incubated with egg albumin under controlled experimental conditions and subjected to determination of absorbance to assess the anti-inflammatory property. A standard anti-inflammatory drug, Ibuprofen, was used as reference drug. The results obtained showed a concentration-dependent inhibition of protein (albumin) denaturation by both extracts, including the 1:1 blend of the extractsas well as the reference drug. The extract concentrationas well as the reference drugfor 50% inhibition (EC 50) was determined by the dose-response curve using GraphPad Prism 6.01 software package and were as follows: Moringa oleifera (EC 50 = 215.9±29.8 μg/mL); Thymus vulgaris (EC 50 = 144.9±1.1 μg/mL); the extracts blend (EC 50 = 441.6±8.6 μg/mL) and ibuprofen (EC 50 = 1599±337 μg/mL), respectively. These findings showed that both Moringa oleifera and Thymus vulgaris possessed marked in vitro anti-inflammatory effect against the denaturation of protein when compared with the standard anti-inflammatory drug, ibuprofen. Thymus vulgaris extractwas found to be more active than Moringa oleifera, possibly due to the higher flavonoids and/or organic acid contents.
  • Article
    Full-text available
    The green pea is ranged between the crops with high antioxidant potential. This potential is connected with phytochemical components mainly with polyphenols. All these bioactive chemicals have disease-fighting properties. In real human diet there is no usually possibility of fresh garden pea consumption during the whole year. The total polyphenol content is significantly changed among other things by processing methods. Focus on variety, bio-fortification and other specific agricultural inputs, could be the right method of total polyphenol contents and total antioxidant capacity increasing. The main objective of the present work was to consider the changes of total polyphenols content in dependence on variety and to evaluate an antioxidant potential six garden pea varieties arranged by the ripening point of view. Variety 'Exzeleus' belongs to very early type, 'Premium' is early maturing, 'Flavora' is middle ripening variety and the last three varieties 'Utrio', 'Jumbo' and 'Ambassador' are middle late types of varieties. Every variety was grown in four replications, i.e. on 24 m2 total plot in Botanical garden of Slovak University of Agriculture in Nitra during 2013. Total polyphenols were determined by the Lachman's method and expressed as mg of gallic acid equivalent per kg fresh mater. Total antioxidant capacity was measured by the Brand-Williams method using a compound DPPH (2.2-diphenyl-1-pikrylhydrazyl)). The highest value was reached in case of variety 'Jumbo' 1179.995 ±28.081 mg/kg, the lowest value in case of 'Premium' 674.505 ±26.541 mg/kg. When evaluating an antioxidant capacity in chosen varieties of garden pea, the interval estimated by our trail ranged from 0.523 ±0.206% ('Exzeleus') to 6.844 ±0.591% ('Flavora'). Following the both observed parameters, TPC and TAC, variety 'Flavora' (as a member of middle ripening varieties) seems to be the most optimal from the human nutrition point of view. The various varieties had significant influence on TPC and TAC according to used statistical analyzes. Within the all observed varieties, when they were arranged by ripening, there was estimated significant difference only in case of garden pea varieties 'early - middle late'. Other couples didn't show any statistical important differences in total polyphenol content.
  • Article
    Antioxidant activities of different fruits (apple, quince, grape, pear and pomegranate) and vegetables (potato, onion, spring onion, red radish and red cabbage) were determined. In addition, total phenolic and flavonoid contents of those samples were assessed. Among fruits, pomegranate had the highest (62.7%) antioxidant activity, followed by quince (60.4%), grape (26.6%), apple (25.7%) and pear (13.7%). The antioxidant activity of vegetables ranged from 40.8% (red cabbage) to 12.5% (onion). Total phenolic and flavonoid contents in fruits varied from 326 to 4306 mg of catechin kg-1 and from 282 to 2115 mg of catechin kg-1, respectively. Those in vegetables ranged between 536 and 2166 mg of catechin kg-1 and between 153 and 842 mg of catechin kg-1 respectively. A high and significant correlation between antioxidant activity and total phenolic content was determined in fruits (r2 = 0.9307, P < 0.01) and vegetables (r2 = 0.9361 P < 0.05). However, flavonoid content was not significantly correlated with antioxidant activity in vegetables, while it was significantly related in fruits (r2 = 0.8316, P < 0.01). It was observed that total phenolic content is the major contributor to the antioxidant activity of fruits and vegetables.
  • Article
    Full-text available
    Polyphenolic antioxidant compounds were studied in three onion varieties (red - cv. Karmen, yellow - cv. Všetana and white - cv. Ala) regarding their total content and qualitative composition of flavonoid complex. The effects of temperature and storage period during onion storage were also studied. The total content of polyphenols was estimated spectrophotometrically with Folin-Ciocalteau's phenolic reagent and individual flavonoid components by HPLC method using Waters TM chromatograph on Watrex 250 × 4 mm Sepharon SGX C18 7μm column with gradient elution. The highest amount of polyphenolic compounds was found in red variety Karmen (108,300 mg/kg DM), the lowest amount in white variety Ala (26,445 mg/kg DM) while the yellow variety Všetana had average content of total polyphenolic compounds 65,210 mg/kg DM. An increase in total polyphenols during storage was found in red and yellow varieties, esp. during storage at a laboratory temperature (22°C). Among the flavonoid and polyphenolic compounds as major constituents spiraeoside (quercetin-4´-O-β-D-glucoside), rutin and quercetin and three other not identified compounds were found. Significant varietal differences were found. The compound with the highest content was spiraeoside (32,234 mg/kg DM in red cv. Karmen, 23,283 mg/kg DM in yellow cv. Všetana and 265 mg/kg DM in white cv. Ala). Rutin ranged from 15 mg/kg DM in cv. Ala to 157 mg/kg DM in cv. Karmen and similarly quercetin from 1 mg/kg DM in cv. Ala to 163 mg/kg DM in cv. Karmen. During storage an increase in flavonoids could be observed, esp. at a laboratory temperature compared to storage at a lower temperature.
  • Article
    Onions (Allium cepa L.) are an important source of bioactive compounds including flavonoids, fructo-oligosaccharides (FOS), thiosulfinates and other sulfur compounds, and many of these compounds have potential beneficial properties for human health. Onion metabolites have traditionally been analyzed separately using high-performance liquid chromatography (HPLC) and mass spectrometry (MS). However, it has recently been found that nuclear magnetic resonance (NMR) spectroscopy represents a powerful tool for the simultaneous analysis of a large number of compounds from plants. Although the NMR quantification method provides excellent quantification of compounds with separated spectral lines, the method often produces overlapping signals, and an improved quantification method is needed. Here, we used a constrained total-line-shape (CTLS) approach to quantify overlapping metabolites from onion proton nuclear magnetic resonance (1H NMR) spectra. This method permitted the identification and quantification of amino acids, organic acids, and sugars; however, aromatic compounds excluding aromatic amino acids were difficult to analyze by NMR spectroscopy because of the small signal intensities produced by flavonols and their sugar derivatives. Metabolites present at low concentrations were successfully analyzed using the developed mass spectrometry method operating in the positive mode. The 1H NMR method developed here is an efficient technique for use in simultaneously analyzing compounds in a food matrix.
  • Article
    Four (red, violet, white and green) varieties of Allium cepa were studied for their total phenolic contents (TPC), antioxidant (AOA) and free radical scavenging activities (FRSA). The TPC varied from 4.6 to 74.1 mg/g GAE, AOA varied from 13.6% to 84.1% and FRSA showed wide range in terms of IC50 (inhibitory concentration) from 0.1 to 15.2 mg/ml, EC50 (efficient concentration) from 4.3 to 660.8 mg/mg and ARP (antiradical power) from 0.15 to 23.2. The outer dry layers of red and violet varieties showed better inhibition of lipid peroxidation assayed by ammonium thiocyanate than α-tocopherol. The non-site-specific inhibition of hydroxyl radical induced deoxyribose degradation was also higher in the outer dry layers of red and violet varieties than in their middle and inner layers. The outer layers were also potential inhibitors of nitroblue tetrazolium chloride (NBT) reduction caused by superoxide anions. On the other hand the ferrous ion chelating capacity of the red and violet varieties was highest in the inner layers. Specific phenolic composition performed through HPLC and LC–MS/MS showed the presence of gallic acid, ferulic acid, protocatechuic acid, quercetin, and kaempferol. The unutilised outer layers of the red variety were a rich source of quercetin (5110 μg/g) with high AOA, FRSA and also showed significant protection of DNA damage caused by free radicals.
  • Article
    Nine spice and aromatic herb samples (i.e., basil, bird pepper, black pepper, cinnamon, nutmeg, oregano, parsley, rosemary, and sage) were gamma-irradiated at a dose of 10 kGy according to commercial practices. The effects of the disinfection treatment on the content of organic radicals and some nutrients (namely, vitamin C and carotenoids) in the samples were investigated by chromatographic and spectroscopic techniques. Irradiation resulted in a general increase of quinone radical content in all of the investigated samples, as revealed by electron paramagnetic resonance spectroscopy. The fate of these radicals after storage for 3 months was also investigated. The cellulose radical was clearly observed in a few samples. Significant losses of total ascorbate were found for black pepper, cinnamon, nutmeg, oregano, and sage, whereas a significant decrease of carotenoids content was observed for cinnamon, oregano, parsley, rosemary, bird pepper, and sage.
  • Article
    Garlic [Allium sativum] is among the oldest of all cultivated plants. It has been used as a medicinal agent for thousands of years. It is a remarkable plant, which has multiple beneficial effects such as antimicrobial, antithrombotic, hypolipidemic, antiarthritic, hypoglycemic and antitumor activity. In this review, we will discuss particularly the largely preclinical use of this agent in the treatment and prevention of cancer. A number of studies have demonstrated the chemopreventive activity of garlic by using different garlic preparations including fresh garlic extract, aged garlic, garlic oil and a number of organosulfur compounds derived from garlic. The chemopreventive activity has been attributed to the presence of organosulfur compounds in garlic. How this is achieved is not fully understood, but several modes of action have been proposed. These include its effect on drug metabolizing enzymes, antioxidant properties and tumor growth inhibition. Most of these studies were carried out in the animal models. Also, recent research has focused on the antimutagenic activity of garlic. Recently, it has been observed that aged garlic extract, but not the fresh garlic extract, exhibited radical scavenging activity. The two major compounds in aged garlic, S-allylcysteine and S-allylmercapto-L-cysteine, had the highest radical scavenging activity. In addition, some organosulfur compounds derived from garlic, including S-allylcysteine, have been found to retard the growth of chemically induced and transplantable tumors in several animal models. Therefore, the consumption of garlic may provide some kind of protection from cancer development.
  • Article
    Full-text available
    Although garlic and onions have long been associated with putative cardiovascular health benefits, the effects of different commercially available onions and level of intake have not been studied. Therefore, the aim of the present study was to evaluate the potential health benefits of raw onions using the pig as a biomedical model. Twenty-five female (Large White x Landrace) pigs were used in a (2 x 2)+1 factorial experiment. Pigs were fed a standard grower diet supplemented with 100 g tallow/kg with the addition of Allium cepa var. cavalier or var. destiny at 0, 10 or 25 g/MJ digestible energy for 6 weeks. Overall, the consumption of onions resulted in significant reductions in plasma triacylglycerol; however, the reductions were most pronounced in pigs fed destiny onions (-26 %, P=0.042). Total plasma cholesterol and LDL:HDL ratios were not significantly different. Onion supplementation, regardless of the variety, resulted in dose-dependent reductions in erythrocyte counts and Hb levels, while the white blood cell concentrations, particularly lymphocytes, were increased in pigs that consumed onions. Furthermore, indices of blood clotting were largely unaffected by onion consumption. In conclusion, dietary supplementation with raw brown onions has moderate lipid-modulating and immunostimulatory properties. However, daily onion intake >25 g/MJ digestible energy could be detrimental to erythrocyte numbers.