Evaluation of antioxidant capacity and total phenolic content of different fractions of selected microalgae

In order to identify new sources of safe and inexpensive antioxidants, the antioxidant capacity and total phenolic content of different fractions of 23 microalgae were evaluated, using Trolox equivalent antioxidant capacity assay and the Folin–Ciocalteu method, respectively. The microalgae were extracted using hexane, ethyl acetate and water by a three-step sequential extraction procedure. Most of these microalgae were evaluated for the first time for their antioxidant activities. It was found that the microalgae Synechococcus sp. FACHB 283, Chlamydomonas nivalis and Nostoc ellipsosporum CCAP 1453/17 possessed the highest antioxidant capacities and thus could be potential rich sources of natural antioxidants. In addition, the correlation coefficients between the antioxidant capacities and the phenolic contents were very small in hexane (R² = 0.0075), ethyl acetate (R² = 0.5851) and water (R² = 0.3599) fractions. Thus, phenolic compounds were not a major contributor to the antioxidant capacities of these microalgae. This was very different from many other plant species like fruits, vegetables and medicinal plants. The microalgae could contain different antioxidant compounds from other plants.     

Antioxidant capacities and total phenolic contents of 62 fruits

In order to supply new information on the antioxidant function of selected fruits for nutritionists and the general public, antioxidant activities and total phenolic contents of 62 fruits were evaluated using ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays as well as the Folin–Ciocalteu method, respectively. The correlations between the FRAP value and the TEAC value as well as total phenolic content were also assessed. The results showed that different fruits had diverse antioxidant capacities and the variation was very large, and seven fruits, Chinese date, pomegranate, guava, sweetsop, persimmon, Chinese wampee and plum, possessed the highest antioxidant capacities and total phenolic contents among tested fruits, and could be important dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress.     

Systematic evaluation of natural phenolic antioxidants from 133 Indian medicinal plants

Total antioxidant capacities of 133 Indian medicinal plant species sampled from 64 families were assessed by ABTS, DPPH and FRAP assays, and their total phenolic contents measured by Folin–Ciocalteu assay. These species exhibited a broad range of antioxidant activities, varying from 0.16 to 500.70 mmol TEAC/100 g DW in the ABTS assay. The antioxidant activity values similarly varied with the DPPH and FRAP assays. Significant and positive linear correlations were found between total antioxidant capacities and phenolic contents (R = 0.89–0.97), indicating that phenolics were the dominant antioxidant constituents in the tested medicinal plants. Preliminary identification of the major phenolic compounds from 83 selected medicinal plants by reversed-phase HPLC revealed phenolic acids, tannins, flavonoids, curcuminoids, coumarins, lignans, and quinines. The fruit of Terminalia chebula, pericarp of Punica granatum and gall of Rhus succedanea showed very high levels of hydrolysable tannins, and the gum of Acacia catechu presented very high levels of catechin and epicatechin in addition to tannins. Major phenolics in many of the medicinal plants were identified for the first time (e.g., Euphorbia lathyrus, Ipomoea turpethum, and Picrorrhiza kurroa). This systematic investigation of a large number of Indian medicinal plants proved important for understanding their chemical constituents and functionality in Ayurvedic medicine, and contributes to the search for natural sources of potent antioxidants.     

Total phenol,flavonoid, proanthocyanidin and vitamin C levels and antioxidant activities of Mauritian vegetables

Ten Mauritian vegetables, broccoli, cauliflower, white cabbage, lettuce, Chinese cabbage, mugwort, carrot, onion, tomato and chilli pepper, were analysed for their total phenol, flavonoid, proanthocyanidin and vitamin C contents and antioxidant capacity. Antioxidant activities of the vegetables ranged from 0.43 to 3.68 µmol g^?1 fresh weight Trolox equivalent antioxidant capacity (TEAC) and from 0.60 to 8.47 µmol g^?1 fresh weight ferric reducing antioxidant power (FRAP). Levels of total phenols in the vegetables varied between 132 and 1189 µg g^?1 fresh weight and those of total flavonoids between 45 and 944 µg g^?1 fresh weight, while proanthocyanidins were detected at very low levels in only a few vegetables. Vitamin C contents varied between 25 and 748 µg g^?1 fresh weight. Quercetin was the dominant flavonoid aglycone in the hydrolysed vegetable extracts, with values in the range of 15–390 µg g^?1 fresh weight. There were strong correlations between antioxidant capacity and total phenols (TEAC, r = 0.91; FRAP, r = 0.83) and total flavonoids (TEAC, r = 0.89; FRAP, r = 0.82). Vitamin C contents showed poor correlation with TEAC values (r = 0.33), while no correlation was observed with FRAP values. Highest antioxidant capacities were observed in Chinese cabbage (Brassica chinensis L), onion (Allium cepa L), mugwort (Artemisia vulgaris Cantley) and broccoli (Brassica oleracea L var botrytis L subvar cymosa). Mauritian vegetables therefore represent a significant source of phenolic antioxidants, with quercetin derivatives being most abundant, and this may contribute to their potential health benefits. Copyright © 2004 Society of Chemical Industry     

Antioxidant activities of aqueous extracts of selected plants

The antioxidant properties of 25 edible tropical plants, expressed as Trolox equivalent antioxidant capacity (TEAC), were studied using DPPH (1,1-diphenyl-2-picrylhydrazyl free radical) scavenging and reducing ferric ion antioxidant potential (FRAP) assays. Their cupric ion chelating activities (CCA) and total polyphenol contents (TPC) were also determined. A strong correlation between TEAC values obtained for the DPPH assay (TEAC_DPPH) and those for the FRAP assay (TEAC_FRAP) implied that compounds in the extracts were capable of scavenging the DPPH free radical and reducing ferric ions. A satisfactory correlation of TPC with TEAC_DPPH and TEAC_FRAP suggested that polyphenols in the extracts were partly responsible for the antioxidant activities while its correlation with CCA was poor, indicating that polyphenols might not be the main cupric ion chelators. Principal component analysis (PCA) indicated that TEAC_DPPH, TEAC_FRAP and TPC contributed to the total variation in the antioxidant activities of the plants.     

A systematic survey of antioxidant activity of 30 Chinese medicinal plants using the ferric reducing antioxidant power assay

The antioxidant activities and total phenolic contents of 30 Chinese medicinal plants were evaluated using the ferric reducing antioxidant power assay and the Folin–Ciocalteu method, respectively. The Chinese medicinal plants were extracted by the traditional method, boiling in water and also in 80% methanol. A significant and linear correlation coefficient between the antioxidant activity and the total phenolic content was found in both aqueous (R² = 0.7917) and methanol (R² = 0.7584) extracts. Phenolic compounds are thus a major contributor of antioxidant activity. Comparing the extraction efficiency of the two methods, the boiling water method extracted phenolic compounds more efficiently, and antioxidant activity of the extract was higher. It was found that the Chinese medicinal plants Rhodiola sacra Fu, the stem of Polygonum multiflorum Thunb. and the root of P. multiflorum Thunb. possessed the highest antioxidant activities and thus could be potential rich sources of natural antioxidants.     

A comprehensive study of polyphenols contents and antioxidant potential of 39 widely used spices and food condiments

Spices and condiments are rich sources of potent antioxidants. In the present investigation, total equivalent antioxidant capacities (TEAC) of 39 spices were studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) scavenging, and cupric reducing antioxidant capacity (CUPRAC) assays. Their total phenolic contents (TPC) and total flavonoid contents (TFC) were also determined. TEAC, TPC, and TFC varied significantly (P?<?0.05) among these spices. ABTS, DPPH, and CUPRAC assay values of studied spices ranged from 1.42 to 112.94 mg ascorbic acid equivalents (AAE)/g, 1.14 to 91.09 mg Trolox equivalents (TE)/g, and 0.52 to 54.47 mg TE/g, respectively (dry weight basis; DW). Based on Folin–Ciocalteu assay, TPC ranged from 2.93 to 160.55 mg of gallic acid equivalents (GAE)/g DW. Strong correlations between TPC and TEAC values (R?=?0.966, 0.825, and 0.954 for ABTS, DPPH, and CUPRAC, respectively) were found. This indicates that phenolic compounds are potent antioxidants in these spices. Principal component analysis (PCA) indicated that cloves (flower buds of Syzygium aromaticum) had the most distinct and potent antioxidant capacity, followed by allspice (fruits of Pimenta dioica) and cinnamon (bark of Cinnamomum verum). Results of the present study provide adequate evidence that polyphenols are responsible for their compelling antioxidant capacities of studied spices. Thus, consumption of antioxidant-rich spices such as cloves, allspice, and cinnamon can significantly prevent oxidative stress in the human body.     

Comparative evaluation of the antioxidant potential of some Iranian medicinal plants

Medicinal plants are a source for a wide variety of natural antioxidants. In the study reported here, we have conducted a comparative study between five medicinal plants having the same geographic origin: the Hamadan region in the west of Iran and growing in the same natural conditions. The amount of total phenolics and total flavonoids for parts of these plants used in Iranian popular medicine were evaluated. Furthermore, antioxidant activities for these parts using vitamin C equivalent antioxidant capacity (VCEAC) test were also evaluated. The results show that the antioxidant activities varied greatly among the different plant parts used in this study and some plants are rich in natural antioxidants especially leaves of Lavandula officinalis and of Melissa officinalis. A positive correlation between total phenolic or flavonoid contents and VCEAC was found with a correlation coefficient of R² = 0.961 and R² = 0.817, respectively. These findings show that phenolics in these plants provide substantial antioxidant activity.     

Total phenolics and antioxidants profiles of commonly consumed edible flowers in China

Edible flowers are referred to the non-toxic flowers that can be consumed by human beings for their additional nutritional or medical properties. These flowers are rich source of natural antioxidants, thus exert specific positive health effects on chronic diseases and act as a potential function food. This research paper is focused on the determination of total phenolic content (TPC), total flavonoids content (TFC), and antioxidant capacities of different kinds of edible flowers in China and compared systematically. Sixty-five flower samples were collected from parks in Guangzhou and also purchased from Qingping Market. TPC, TFC, and three anti-oxidative assays (DPPH free radical scavenging activity, ABTS radical scavenging activity, and Ferric reducing antioxidant capacity (FRAP) assay) were conducted. Different flowers presented diverse range of antioxidant capacities, phenolic contents, and flavonoid contents. A high correlation between TPC and antioxidant activity (as accessed using three different methods) was reported. However, a low relationship was observed between TFC value and antioxidant capacities. This study revealed that five Rosa species exhibited strong antioxidant capacities among other samples, and these can be used as potential functional foods to counterbalance the effect of reactive oxygen species (ROS) and oxidative stress.     

Antioxidant properties of Cortex Fraxini and its simple coumarins

We present the antioxidant properties of crude extract, fractions and ingredients of Cortex Fraxini (CF) and compare the antioxidant capacities of coumarin ingredients of CF and known antioxidants, including catechin, quercetin, ascorbic acid, trolox and BHT. The IC₅₀ values for CF in the DPPH and TEAC methods were 406 and 39.3 μg/ml, respectively. Among all fractions the chloroform fraction is the most active fraction in scavenging DPPH, ABTS and hydroxyl radicals, and there is a significant relationship between the antioxidant activities and the contents of the antioxidant phenolic ingredients. The contents of esculetin and fraxetin in the chloroform fraction were 8.44% and 11.1%, respectively. Esculetin and fraxetin also had good radical-scavenging capacities, and esculetin was the best, among all test compounds, against the DPPH radical. Moreover, esculetin and fraxetin had selective scavenging activity upon hydroxyl radicals and hydrogen peroxide, and this potency was better than known antioxidants and equal to quercetin in scavenging hydrogen peroxide. These results show that CF, partitioned with chloroform, gave a phenolic coumarin-enriched fraction, and that this fraction had the best free radical-scavenging activity and inhibition of Fe²⁺/ascorbate-induced lipid peroxidation, mainly due to its reducing power.     

Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues

The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radical scavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radical scavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radical scavenging ability; reducing power and ABTS radical scavenging activity; and ABTS and DPPH radical scavenging abilities showed a high degree of correlation (r² = 0.85-0.91). However, r² of 0.36, 0.66, and 0.49 between TPC and DPPH radical scavenging activity; TPC and reducing power; and TPC and ABTS radical scavenging ability, respectively, indicated that some non-phenolic compounds also contributed to the total antioxidant activity in fruit residue extracts examined in this study. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, reducing power, and antioxidant activity for the six fruit residues. This study demonstrated that kinnow peel, litchi pericarp, litchi seeds, and grape seeds, can serve as potential sources of antioxidants for use in food and pharmaceutical industry.     

不同可食阶段蚕豆结合酚抗氧化活性的研究

本文研究了五个蚕豆品种（凤豆6号、13号、15号、17号和18号）在三个可食阶段S1（138 DAS）、S2（156 DAS）、S3（173 DAS）（DAS,days after seeding,播种后的天数）种皮和胚结合酚提取物的抗氧化活性。采用Folin-酚法、亚硝酸钠-氯化铝法和香草甲醇法分别测定总酚、黄酮和缩合单宁含量,并通过DPPH自由基清除能力、Trolox等量抗氧化活性（TEAC）和铁还原抗氧化能力（FRAP）评价抗氧化活性,同时对酚类化合物含量和抗氧化活性进行相关性分析。结果显示,种皮总酚、黄酮、缩合单宁含量和抗氧化活性均高于胚;S2采收的凤豆18号酚含量和抗氧化活性在种皮和胚中均最高,S1采收的凤豆17号酚含量和抗氧化活性在种皮中最低,S3采收的在胚中最低;不同品种在整个采收过程中酚含量和抗氧化活性存在差异;在种皮中,总酚含量（TPC）和黄酮含量（FC）与DPPH、FRAP呈极显著相关（P<0.01）,缩合单宁含量（CTC）与DPPH、TEAC、FRAP呈极显著相关（P<0.01）,在胚中,TPC和FC与DPPH、TEAC、FRAP均呈极显著相关（P<0.01）。     

5 种梅干菜的酚类化合物及抗氧化能力比较分析

以市售5 种梅干菜为研究对象,测定梅干菜酚类化合物的含量,用高效液相色谱-串联质谱（high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS）法鉴定梅干菜酚类化合物的种类,并用4 种抗氧化能力评价方法评价梅干菜。结果表明,市售5?种梅干菜所含的酚类化合物含量和各酚类化合物所占的比例及其抗氧化能力差异显著。其中咕咕鲜牌梅干菜（GGX）的总酚含量为14.18?mg?GAE/g,总黄酮含量为7.10?mg?RE/g,2,2’-联氮-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonate),ABTS）法、铁离子还原（ferric reducing antioxidant power,FRAP）法、1,1-二苯基-2-三硝基苯肼法和氧自由基吸收能力（oxygen radical absorbance capacity,ORAC）法测得的抗氧化能力分别为28.09、32.88、31.72?μmol?TE/g和445.55?μmol?TE/g,显著高于其他4?种梅干菜。其次,利用HPLC-MS/MS法分析鉴定出梅干菜中共含有17?种酚类化合物,包括9?种类黄酮和8?种酚酸。其中,梅干菜中的类黄酮主要有野漆树苷、山柰酚、异鼠李素、柚皮素等;酚酸主要有阿魏酸、香豆酸和肉桂酸等。此外,4?种抗氧化能力评价方法中,ABTS与FRAP相关性最高,相关系数为0.967;ORAC法测得的梅干菜抗氧化能力显著高于其他3?种方法;而ABTS法与梅干菜的抗氧化剂相关性最高,最适合评价梅干菜的总抗氧化能力。综上所述,不同种类市售梅干菜的酚类化合物含量和抗氧化能力均不同,其中,GGX总酚含量最高、抗氧化能力最强。     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.     

Evaluation of antioxidant activities of rosehip ethanol extracts in different test systems

Rosehip extracts of 18 samples representing six taxa in the genus Rosa were evaluated for antioxidant activities by use of different test systems. The ferric‐reducing antioxidant power (FRAP) and Trolox‐equivalent antioxidant capacity (TEAC) of the crude extracts ranged from 983.4 to 2187.1 µmol FRAP g⁻¹ dry matter and from 457.2 to 626.2 µmol TEAC g⁻¹ dry matter. The high antioxidant capacity was related to high contents of phytonutrients. The overall mean of antioxidants was 23.23 mg g⁻¹ total carotenoids and 76.26 mg g⁻¹ total phenolics. The phenolic component made a major contribution to the total antioxidant activities in both assays (overall mean was 90.5% and 75.7%), whereas the ascorbate made a minor contribution (8.6% and 16.9%) and the lipophilic component made an even smaller one (0.9% and 7.3%). However, the lipophilic component was the most effective when the comparison was based on the ratio of antioxidant activity to content of antioxidants. The crude extracts exhibited 50.9% (46.6–60.3%) inhibitory effect against the lipid peroxidation induced by 2,2′‐azobis(2,4‐dimethylvaleronitrile) (AMVN) and 85.0% (80.1–90.2%) inhibition in 2,2′‐azobis(2‐amidinopropane)hydrochloride (AAPH) assay at a concentration of 250 µg ml ⁻¹. Ascorbate acted as an antioxidant in both peroxy radical‐induced lipid peroxidations, but as a pro‐oxidant in the metal ion‐induced lipid peroxidation. The crude extracts showed a large inhibitory effect in the ferric ion‐induced lipid peroxidation and caused 83.7% inhibition at a concentration of 25 µg ml ⁻¹ dried rosehip powder. © 2000 Society of Chemical Industry     

Main nutrients,phenolics, antioxidant activity,DNA damage protective effect and microstructure of Sphallerocarpus gracilis root at different harvest time

Sphallerocarpus gracilis roots harvested at two different times (T1: 12-10-2009 and T2: 15-04-2010) were analysed for their main nutrients, phenolics, antioxidant activity, DNA damage protective effect and microstructure. Results revealed that higher amounts of starch were detected in T1 S. gracilis root, whereas higher levels of reducing sugar, protein, amino acids and phenolic compounds were determined in T2 S. gracilis root. The antioxidant activity was assessed by DPPH, FRAP and TEAC assay and T2 S. gracilis root was found to possess higher antioxidant activity. Also, results of the correlation analysis indicated that caffeic, p-coumaric and gallic acids contributed substantially to the antioxidant property and there was significant correlation between DPPH radicals scavenging capacity and FRAP and TEAC. The highest and lowest DNA damage protective effects were found of free phenolic extracts from T2 and T1 S. gracilis roots, respectively. The microstructure of S. gracilis root varied greatly with the harvest time.     

Antioxidant actions and phenolic and vitamin C contents of common Mauritian exotic fruits

Seventeen commonly consumed exotic fruits from Mauritius were analysed for their antioxidant capacity, total phenolics, proanthocyanidins, flavonoids and vitamin C content. Two independent methods were used to evaluate the antioxidant potential of total fruit extracts. The antioxidant activities of the fruits ranged from 1 to 47 µmol Trolox equivalent antioxidant capacity (TEAC) g^?1 fresh weight and from 0.3 to 34 micro/mol g fresh weight (FRAP) g^?1 fresh weight. Total phenolics in the fruits ranged from 118 to 5638 µg g^?1 fresh weight, proanthocyanidins from 7 to 2561 µg g^?1 fresh weight, flavonoids from 21 to 712 µg g^?1 fresh weight and vitamin C content from 8 to 1426 µg g^?1 fresh weight. There were strong correlations between antioxidant activity (assessed by both TEAC and FRAP) and total phenolics and proanthocyanidins. Flavonoids seemed to contribute less to the antioxidant potential of the fruits, while very poor correlations were observed between ascorbate content and antioxidant activity. The highest antioxidant capacities were observed in red and yellow Psidium cattleianum Sabine ‘Chinese guava’, sweet and acid Averrhoa carambola L ‘starfruit’, Syzygium cumini L Skeels ‘jamblon’ and white Psidium guajava L ‘guava’. These fruits were also characterised by high levels of total phenolics. Mauritian exotic fruits are thus a significant source of phenolic antioxidants, which may have potential beneficial effects on health. Copyright © 2003 Society of Chemical Industry     

Influence of heating on the polyphenolic content and antioxidant activity of grape seed flour

Abstract: The production of grape seed flour (GSF) from a waste product generated during winemaking, is of interest in product development applications due to its potential health benefits. However, before GSF can used in baking as a source of additional antioxidants, research on its heat stability is required. The overall objective of this study was to assess changes in phenolic content and antioxidant activity of GSF during heating. Merlot GSF was heated at 5 temperatures (120 to 240 °C) for 0 to 90 min. At each time/temperature combination, total phenolic content (TPC), total flavanoid content (TFC), Trolox equivalent antioxidant capacity (TEAC), 2,2 diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, and ferric ion reducing antioxidant power (FRAP) of the extracts were determined. Specific polyphenolic compounds, including catechin, gallocatechin, epicatechin, and gallic acid were also measured. Results showed that when Merlot GSF was heated to ≥180 °C, significant decreases in the TPC and antioxidant activity, measured using FRAP, DPPH, and TEAC, were observed. Longer heating times also caused a reduction in antioxidant capability. Catechin and epicatechin content decreased with increasing heating temperature while gallocatechin and gallic acid content increased. Both catechin and epicatechin content had strong positive correlations (r > 0.91) with TPC and TFC, as well with FRAP and TEAC, suggesting that the GSF antioxidant activity is related to the presence of these particular compounds. Overall, while a decrease in antioxidant content was observed during heating, this occurred at higher baking temperatures. Thus GSF may be suitable for use as an ingredient in baked goods to bolster antioxidant content. Practical Application: In order for Merlot grape seed flour (GSF) to be used in baking as a source of additional antioxidant compounds, the impact of heating on the polyphenolic compounds in the GSF needed to be examined. Thermal treatment of Merlot GSF caused significant decreases in the TPC, antioxidant power, and specific polyphenolic compounds when heated ≥180 °C. Thus while antioxidant content decreased with higher heating temperatures, this occurred at higher baking temperatures. Thus, GSF may be suitable for use as an ingredient in baked goods to bolster antioxidant content.     

ANTIOXIDANT ACTIVITY AND TOTAL PHENOLIC CONTENTS IN PEEL AND PULP OF CHINESE JUJUBE (ZIZIPHUS JUJUBA MILL) FRUITS

Total phenolic contents in peel and pulp of the fruits of three Chinese jujube cultivars ( Ziziphus jujuba cv. mayazao, Z. jujuba cv. dongzao and Z. jujuba cv. yuanzao) were determined. The antioxidant activities in peel and pulp of the jujube fruits were measured by different methods, including 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC). The total phenolic content in peel was five to six times higher than that in the pulp of all the three cultivars. The phenolics contents in the jujube were different with cultivars. The EC₅₀ ( Concentration of lyophilized samples needed to decrease the initial DPPH radical concentration by 50% ), FRAP and TEAC values of the peel and pulp were remarkably correlated to their total phenolic contents (R  = − 0.922, R  =  0.985 and R  =  0.997, respectively). The results indicated that the high capacity of antioxidant of Chinese jujube fruit could be attributed to the high phenolic contents in the fruit.

PRACTICAL APPLICATIONS

There was an expanding quest surrounding the use of antioxidant because they have the capacity to protect from the damage because of free radicals and reactive oxygen species. However, the safety of synthetic antioxidant was challenged. Much attention has been focused on the use of natural antioxidant. Interest in food phenolics had increased greatly because of their antioxidant and possible promoting-health role in human health. In this study, total phenolic contents and antioxidant capacities in vitro of Chinese jujube ( Ziziphus jujuba Mill) peel and pulp were researched. The work would help to explore a natural antioxidant for possible application in food and dietary supplemental products for health promotion.     

Chemical and antioxidant properties of pomegranate cultivars grown in the Mediterranean region of Turkey

Arils from six pomegranate (Punica granatum L.) cultivars obtained from various sites from the Mediterranean region of Turkey were evaluated for their chemical and antioxidant properties. These properties included total phenolics (TP), total monomeric anthocyanins (TMA), soluble solids (TSS), titratable acidity (TA), individual sugars and organic acids. Antioxidant capacities of arils were determined by both the ferric reducing antioxidant power (FRAP) and trolox equivalent antioxidant capacity (TEAC) assays. The antioxidant capacities averaged 5.60 and 7.35 mmol TE/l by the TEAC and FRAP methods. Variability among cultivars was greatest for TMA content (CV 132%); individuals ranged from 6.1 to 219 mg cy3-Gluc l⁻¹. TP means averaged 1507 mg GAE/l. Levels of FRAP, TEAC, TP, and TMA were strongly correlated (r = 0.82–0.96). The major sugars were fructose (6.4 g/100 ml) and glucose (6.8 g/100 ml), the major acids were citric (1.78 g/100 ml) and malic (0.12 g/100 ml).