Cent. Eur. J. Biol. • 4(4) • 2009 • 499–506 DOI: 10.2478/s11535-009-0041-1

Central European Journal of Biology

Comparison of antioxidant capacity and phenolic compounds of berries, chokecherry and seabuckthorn

Research Article

Wende Li1, Arnold W. Hydamaka 1, Lynda Lowry2, Trust Beta1,3*

1Department of Food Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada

2Food Development Centre, Portage la Prairie, Manitoba R1N 3J9, Canada

3Richardson Centre for Functional Foods & Nutraceuticals, Smartpark, University of Manitoba, Winnipeg, Manitoba R3T 6C5, Canada

Received 9 June 2009; Accepted 21 July 2009

Abstract: Antioxidant capacity and phenolic compounds (phenolic acids and anthocyanins) of four berry fruits (strawberry, Saskatoon berry, raspberry and wild blueberry), chokecherry and seabuckthorn were compared in the present study. Total phenolic content and total anthocyanin content ranged from 22.83 to 131.88 g/kg and 3.51 to 13.13 g/kg, respectively. 2,2-Diphenyl-1-picryhydrazyl free radical scavenging activity ranged from 29.97 to 78.86%. Chokecherry had the highest antioxidant capacity when compared with berry fruits and seabuckthorn. The highest , gallic acid and trans- levels were found in chokecherry (6455 mg/kg), raspberry (1129 mg/kg) and strawberry (566 mg/kg), respectively. Caffeic acid was also the major in Saskatoon berry (2088 mg/kg) and wild blueberry (1473 mg/kg). The findings that chokecherry has very high antioxidant capacity and caffeic acid levels, are useful for developing novel value-added antioxidant products and also provide evidence essential for breeding novel cultivars of fruit plants with strong natural antioxidants. Keywords: Berry fruits • Chokecherry • Antioxidant capacity • Radical scavenging • Phenolic compounds • Anthocyanin • Phenolic acids © Versita Warsaw and Springer-Verlag Berlin Heidelberg.

1. Introduction in black currant berries [11] and raspberry [12] have been reported. The benefit of these in promoting health is believed to be achieved through Many epidemiological studies show that consumption of possible mechanisms of directly reacting with and fruits and vegetables is able to reduce the risk for some quenching free radicals, chelating transition metals, major human chronic diseases such as age-related reducing peroxides, and stimulating the antioxidative degenerative diseases, cancer and cardiovascular defense enzyme system [13]. Anticancer effects of berry diseases [1-3]. Beneficial effects of promoting health fruit bioactives have been confirmed, such as strawberry and preventing diseases are due to an enrichment of extracts inhibiting the growth of human oral, colon and phytochemicals present in various fruits and vegetables prostate cancer cells [10], cranberry proanthocyanidin [4,5]. The presence of phytochemicals including vitamin extract inhibiting the viability and proliferation of human C and tocopherols in seabuckthorn berries [6], phenolic esophageal adenocarcinoma cells [14]. Anticancer compounds in strawberry fruits [7-10], and anthocyanins impact of berry bioactives is believed to be achieved

* E-mail: [email protected] 499 W. Li et al.

through their ability to counteract, reduce, and repair ambient temperature in a rotary shaker (Fermentation damage resulting from oxidative stress and inflammation, Design Inc., Allentown, PA) set at 300 rpm. The mixture and also through regulating carcinogen and xenobiotic was then centrifuged at 7,800 x g (10,000 rpm, SS-34 metabolizing enzymes, various transcription and growth Rotors, RC5C Sorvall Instruments) at 5°C for 15 min. factors, inflammatory cytokines, and subcellular signaling The supernatant fluid was kept at -20°C in the dark until pathways of cancer cell proliferation, apoptosis, and further analysis for DPPH• scavenging activity, and TPC. tumor angiogenesis [15]. Various fruits and vegetables Extraction of each sample was carried out in duplicate. are an important part of our daily diets. Hence, fruits Fruit samples were subjected to alkaline hydrolysis and vegetables with a high level of antioxidant capacity for determination of their phenolic acid composition by should have potential for disease prevention and health HPLC according to our previous method with some promotion. modification [16]. The hydrolysis procedure was as Four berry fruits, chokecherry and seabuckthorn follows. Ground sample (2 g) was hydrolyzed using were selected for comparison of their antioxidant 2 M NaOH (60 mL) containing ascorbic acid (1% w/v) capacity and phenolic compounds in this study. The main and ethylenediaminetetraacetic acid (10 mM) for 2 h objective was to obtain an in-depth understanding of at 25oC in a rotary shaker (MaxQ 5000, BI Barnstead/ their antioxidant activity and phenolic acid composition. Lab-Line) set at 280 rpm. The hydrolyzed mixture was Antioxidant-enriched fruits have potential in value-added adjusted to pH 1.5-2.5 using ice-cold 6 M HCl and then applications in addition to their health benefits. centrifuged at 7,800 x g (10,000 rpm, RC5C, Sorvall Instruments, DuPont, Wilmington, DE) at 5oC for 20 min. The supernatant was extracted with hexane to remove 2. Experimental Procedures lipids. The final solution was extracted three times with ethyl acetate. The combined ethyl acetate fraction was 2.1 Chemicals evaporated to dryness at 35oC by using a rotary vacuum Folin-Ciocalteau reagent, 2,2-diphenyl-1- evaporator (RotaVapor R-205, BÜCHI Labortechnik AG, picryhydrazyl free radical (DPPH•), 2,2΄-azobis(2- Switzerland). The residue was dissolved in 5 mL of 50% methylpropionamidine) dihydrochloride (AAPH), and methanol, filtered through a 0.45 µm nylon filter, and 16 phenolic acid standards such as gallic, gentisic, analyzed by HPLC to obtain phenolic acid composition. p-coumaric, m-coumaric, caffeic, sinapic, ferulic, syringic, Hydrolysis of each sample was carried out in duplicate. o-coumaric, vanillic, protocatechuic, chlorogenic, isoferulic, ellagic, trans-cinnamic, and p-hydroxybenzoic 2.3 TPC determination acids were from Sigma-Aldrich (St. Louis, MO). All other TPCs were determined by using modified procedures chemicals and solvents were of the highest commercial of the Folin-Ciocalteau method [17]. The extract grade and used without further purification. (200 µL) was added to 1.9 mL of freshly diluted 10-fold Folin-Ciocalteau reagent. Sodium carbonate solution 2.2 Sample preparation (1.9 mL) (60 g/L) was then added to the mixture. After Four berry fruits (strawberry, Saskatoon berry, raspberry, 120 min of reaction at ambient temperature, the wild blueberry), chokecherry and seabuckthorn were absorbance of the mixture was measured at 725 nm selected for comparison of their antioxidant capacity and against a blank of distilled water. was used phenolic compounds. Each of the fruit samples came as a standard and results expressed as ferulic acid from one variety. Each variety was randomly picked at equivalents. All analyses were performed in duplicate. the peak of their ripeness from several trees in orchards surrounding Winnipeg (Manitoba, Canada) and then 2.4 TAC determination combined. All fruits were first freeze-dried using Genesis TACs were determined according to the pH-differential 25 Freeze Dryer (SP Industries, Gardiner, NY) and then method [18]. Briefly, the extract (1 mL) was placed into a ground to powder prior to analyses. The stone seed 25 mL volumetric flask, made up to final volume with pH (stone) present in fresh chokecherry and seabuckthorn 1.0 buffer (1.49 g of KCl/100 mL water and 0.2 N HCl, was removed prior to freeze-drying. Their antioxidant with a ratio of 25:67), and mixed. Another 1 mL of extract components were extracted using ethanol (95%)/1N was also placed into a 25 ml volumetric flask, made up HCl (85:15, v/v) for analysis of total phenolic content to final volume with pH 4.5 buffer (1.64 g of sodium (TPC), total anthocyanin content (TAC), and DPPH• acetate/100 mL of water), and mixed. Absorbance was scavenging activity. The extraction procedure involved measured at 510 nm and at 700 nm. Absorbance was adding 15 mL of solvent to 1.0 g of ground sample in calculated as: D 50-mL brown bottles and shaking the sample for 6 h at A = (A510nm – A700nm)pH1.0 – (A510nm – A700nm)pH4.5.

500 Comparison of antioxidant capacity and phenolic compounds of berries, chokecherry and seabuckthorn

Results were calculated using the following equation 2.7 Statistical analysis and expressed as equivalents of cyanidin 3-glucoside: Data were subjected to one-way analysis of variance Total anthocyanin content (mg/kg) = (DA/εL) × MW for comparison of means, and significant differences × D × (V/G) × 1,000 were calculated according to Duncan’s multiple range where DA is absorbance, ε is cyanidin 3-glucoside molar test at the 5% level. Data were reported as means absorbance (26900), L is cell path length (1 cm), MW ± standard deviation. Differences at P<0.05 were is the molecular weight of cyanidin 3-glucoside (449.2), considered statistically significant. Quantitative results D is a dilution factor, V is the final volume (mL), G is were expressed on a dry weight basis (dwb). the sample weight (g), 1,000 is a conversion factor from gram to kilogram. All determinations were carried out at least in duplicate. 3. Results 2.5 DPPH• scavenging activity assay 3.1 TPC DPPH• scavenging activity was measured according to a The TPC, expressed as ferulic acid equivalents, of fruit method previously reported [19] with some modification. extracts are shown in Table 1. Significant differences in Briefly, a 60 µm DPPH• solution was freshly made in TPC were found between chokecherry and seabuckthorn, 95% ethanol solution. The extracts (200 µL) were between chokecherry and four berry fruits (strawberry, reacted with 3.8 mL of the DPPH• solution for 60 min. Saskatoon berry, raspberry and wild blueberry) and The absorbance (A) at 515 nm was measured against a between seabuckthorn and four berry fruits (strawberry, blank of pure 95% ethanol at t = 0, 5, 10, 20, 30, 40, 50, Saskatoon berry, raspberry and wild blueberry). and 60 min. The chemical kinetics of antioxidant activity Chokecherry had the highest TPC (131.88 g/kg) among of fruit extracts was also recorded. Antioxidant activity the six fruits. The TPC decreased in the following order: was calculated as follows: chokecherry without stone (CCWS) > Saskatoon berry

% DPPH• scavenging activity = (1 - [Asample t/Acontrol t=0]) × (SKB, 37.91 g/kg) > wild blueberry (WBB, 37.76 g/kg) 100. > raspberry (RB, 36.81 g/kg) > strawberry (SB, DPPH tests were all carried out in duplicate. 33.74 g/kg) > seabuckthorn without stone (SWS, 22.83 g/kg). However, significant differences were not found 2.6 Determination of phenolic acid among the berry fruits (SB, SKB, RB and WBB). composition HPLC analysis for phenolic acid compositions of fruit hydrolysate was performed on a Waters model 2695 Name Equivalent of ferulic acid (g/kg) chromatograph instrument (Waters, Mississauga, ON, Strawberry 33.74 ± 1.86b Canada) equipped with a Waters 2996 photodiode array b detector. Phenolic acids were separated on a reverse- Saskatoon berry 37.91 ± 0.61 phase Phenomenex C18 column (150 mm × 4.6 mm) Raspberry 36.81 ± 0.95b with a gradient of solvent A (water containing 1% (v/v) Wild blueberry 37.76 ± 0.93b formic acid) and solvent B (methanol containing 0.1% Chokecherry without stone 131.88 ± 8.09a (v/v) formic acid) for 72 min at a flow rate of 0.7 mL/min. c The column temperature was set at 30oC. The solvent Seabuckthorn without stone 22.83 ± 1.40 gradient was programmed as follows: at 0 min 15% Table 1. Total phenolic content of extracts from Manitoba fruitsa. B, 7 min 20% B, at 8 to 20 min 15% B, 21 to 33 min a Values are mean ± standard deviation. Values with the same letter 24% B, 34 to 36 min 13% B, 37 to 45 min 20% B, 46 to are not statistically different at the 5% level (Duncan’s multiple range 62 min 42% B, 63 to 68 min 100% B, and 69 to 72 min test). 15% B. Phenolic acids in the eluants were monitored at 270 and 325 nm synchronously. Identification of 3.2 TAC the phenolic acids was accomplished by comparing The TAC, expressed as cyanidin 3-glucoside equivalents, the retention times of peaks in samples to those of 16 of fruit extracts are shown in Table 2. The colour of phenolic acid standards. The HPLC profile of 16 phenolic extracts from berry fruits (SB, SKB, RB and WBB) and acid standards is shown in Figure 2A. was CCWS was red in acidic media. The red colour indicates used as the internal standard. The HPLC analyses were the presence of anthocyanin compounds in fruits. carried out in duplicate. However, anthocyanins in SWS were not detectable. CCWS had a higher TAC (13.13 g/kg) than other berry fruits (SB, SKB, RB and WBB). The TAC decreased in

501 W. Li et al.

the order CCWS > SKB (10.79 g/kg) > WBB (9.97 g/kg) Name DPPH• scavenging (%) > RB (6.62 g/kg) > SB (3.51 g/kg). The TAC levels in c CCWS were 20 to 270% higher in comparison to the Strawberry 40.33 ± 0.96 berry fruits (SB, SKB, RB and WBB) studied. Significant Saskatoon berry 36.59 ± 0.67d differences in TAC were found among CCWS and berry Raspberry 51.23 ± 0.38b fruits (SKB, WBB, RB and SB). The results indicated that Wild blueberry 34.13 ± 1.20e anthocyanins present in fruits were significantly affected Chokecherry without stone 78.86 ± 0.54a by the varieties or genotypes of fruits. A significant correlation (r=0.6739) was found between TAC and TPC Seabuckthorn without stone 29.97 ± 0.51f at P<0.05. Table 3. DPPH• scavenging activity after 60 min reaction timea.

a Values are mean ± standard deviation. Values with the same letter are not statistically different at the 5% level (Duncan’s multiple range Name Equivalent of cyanidian-3-glucoside (g/kg) test). DPPH radical scavenging (%) was determined at 60-fold dilution for extracts of 1 g (dwb) powder. Strawberry 3.51 ± 0.01e Saskatoon berry 10.79 ± 0.18b

Raspberry 6.62 ± 0.25d

Wild blueberry 9.97 ± 0.45c

Chokecherry without stone 13.13 ± 0.03a

Seabuckthorn without stone nd Table 2. Total anthocyanin content of extracts from Manitoba fruitsa.

a Values are mean ± standard deviation. Values with the same letter are not statistically different at the 5% level (Duncan’s multiple range test). nd, not detectable.

3.3 DPPH• scavenging activity DPPH• scavenging activity of fruit extracts is shown in Table 3. Significant differences in scavenging activity Figure 1. Kinetics of antioxidant activity of fruit extracts using the DPPH free radical. Notes: SB, strawberry; SKB, were found among six types of fruits. DPPH• scavenging Saskatoon berry; RB, Raspberry; WBB, Wild blueberry; activity (78.86%) of CCWS was the highest among the CCWS, Chokecherry without stone; SWS, Seabuckthorn fruit extracts. DPPH• scavenging activity decreased in without stone. DPPH radical scavenging (%) was determined at 60-fold dilution for extracts of 1 g (dwb) the order of CCWS > RB (51.23%) > SB (40.33%) > SKB powder. (36.59%) > WBB (34.13%) > SWS (29.97%). CCWS had 0.54 to 1.63 times greater scavenging activity than berry chromatogram of WBB is listed in Figure 2B. Nine fruits (SB, SKB, RB and WBB) and seabuckthorn. The types of phenolic acids were detected in SB and WBB, reaction kinetics of fruit extracts with DPPH• is shown eight types in RB, seven types in SKB, five types in in Figure 1. The kinetic curves clearly indicated that SWS and four types in CCWS. The major phenolic CCWS extract had high scavenging activity during the acid compounds (>100 mg/kg) were trans-cinnamic reaction period. CCWS extract still kept a high reaction (566 mg/kg), p-coumaric (213 mg/kg), gallic (212 mg/kg) rate after 10 min, however the reaction rate of berry and p-hydroxybenzoic (124 mg/kg) acids in SB, caffeic fruit and seabuckthorn extracts became progressively (2088 mg/kg) and protocatechuic (132 mg/kg) acids in slow and stable (Figure 1). A highly significant (P<0.05) SKB, gallic (1129 mg/kg) and protocatechuic (102 mg/kg) correlation (r=0.9362) was found between DPPH• acids in RB, caffeic (1473 mg/kg), syringic (286 mg/kg) scavenging activity and TPC. However, the correlation and gallic (190 mg/kg) acids in WBB, and caffeic (r=0.5909) between DPPH• scavenging activity and (6455 mg/kg), p-coumaric (953 mg/kg) and protocatechuic TAC was relatively low but significant (P<0.05). (214 mg/kg) acids in CCWS. Chokecherry showed very high levels of caffeic acid. Chokecherry had 2.1, 3.4 Phenolic acid composition 3.4, 188.9, 268.0 and 644.5 times higher caffeic acid The phenolic acid composition of berry fruits (SB, levels than the berry fruits (SKB, WBB, RB, SB) and SKB, RB and WBB), chokecherry and seabuckthorn is seabuckthorn, respectively. Chokecherry also contained shown in Table 4. The HPLC profile of a representative a high p-coumaric acid content with levels 3.5, 10.6, 12.2,

502 Comparison of antioxidant capacity and phenolic compounds of berries, chokecherry and seabuckthorn

Phenolic acids SB SKB RB WBB CCWS SWS

GA 212 ± 18b 22 ± 4c 1129 ± 62a 190 ± 3b nd 42 ± 10c

PA 34 ± 2d 132 ± 3b 102 ± 26c 76 ± 8c 214 ± 6a 42 ± 2d

p-HA 124 ± 5a 7 ± 4c 54 ± 9b nd nd nd

VA nd nd nd 56 ± 3 nd nd

CA 24 ± 2d 2088 ± 31b 34 ± 4d 1473 ± 6c 6456 ± 503a 10 ± 2d

SYA nd nd nd 286 ± 3 nd nd

p-CA 213 ± 2b 82 ± 4c 68 ± 7c 39 ± 2c 953 ± 43a 72 ± 3c

FA 14 ± 1c 50 ± 3a 35 ± 6b 41 ± 6ba 43 ± 5ba 15 ± 2c

SIA nd nd 18 ± 2 nd nd nd

o-CA 16 ± 2 nd nd nd nd nd

EA 20 ± 9b 20 ± 6b 52 ± 8a 24 ± 5b nd nd

trans-CA 566 ± 9a nd nd 9 ± 3b nd nd Table 4. Phenolic acid composition (mg/kg) of fruit hydrolysatesa. a Values are mean ± standard deviation. Values with the same letter in the rows are not statistically different at the 5% level (Duncan’s multiple range test). GA, gallic acid; PA, protocatechuic acid; p-HA, p-Hydroxybenzoic acid; VA, vanillic acid; CA, caffeic acid; SYA, ; p-CA, p-coumaric acid; FA, ferulic acid; SIA, ; o-CA, o-coumaric acid; EA, ellagic acid; trans-CA, trans-cinnamic acid. SB, strawberry; SKB, Saskatoon berry; RB, Raspberry; WBB, Wild blueberry; CCWS, Chokecherry without stone; SWS, Seabuckthorn without stone. nd, not detectable.

13.0 and 23.4 times higher in comparison with those found in SB, SKB, SWS, RB and WBB, respectively. Protocatechuic acid level contained in chokecherry was also the highest with 1.6, 2.1, 2.8, 5.1 and 6.3 times higher in comparison with those detected in SKB, RB, WBB, SWS and SB, respectively. The mapping of phenolic acid composition was achieved for berry fruits, chokecherry and seabuckthorn; that is, SB contained higher trans-cinnamic acid content and RB was richer in gallic acid in comparison to other fruits. Higher contents of caffeic acid were also present in WBB and SKB when compared to the levels in SB, RB and SWS.

4. Discussion

TPC was affected by fruit type [7,9]. High TPC is generally regarded as an indication of high total antioxidant capacity [20]. The very high TPC of chokecherry (Table 1), up three to six times greater than the other five fruits, Figure 2. (A) The HPLC profile of 16 standard phenolic acids. showed its potent potential as a source of natural (B) The HPLC profile of wild blueberry. Numbers in (A) indicate the following standard chemicals: 1, gallic acid; antioxidants. The benefits of phenolic-rich juice from 2, protocatechuic acid; 3, p-hydroxybenzoic acids; 4, grapes, some cherries and berries are to prevent cell gentisic acid; 5, ; 6, vanillic acid; 7, caffeic acid; 8, syringic acid; 9, p-coumaric acid; 10, death and DNA single-strand breakage against induced ferulic acid; 11, m-coumaric acid; 12, sinapic acid; 13, oxidative stress through an iron-chelating mechanism isoferulic acid; 14, o-coumaric acid; 15, ellagic acid; 16, trans-cinnamic acid. Numbers in (B) indicate the same [21]. Phenolic compound fractions from muscadine chemicals as in (A) and isoferulic acid was used as grapes and blueberries demonstrate inhibition effects internal standard in (B). Solid and dotted lines in (A) and on the growth of HepG2 liver cancer cell [22]. Phenolic (B) indicate 270 nm and 325 nm, respectively. compounds in fruits also contribute to the in vitro inhibition of tumour-cell proliferation [4].

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Anthocyanins belong to a class of important vanillic acid (7.22 µmol Trolox equ.mg-1) and gallic acid antioxidants and are enriched in colorful fruits. They (6.97 µmol Trolox equ.mg-1) [30]. High antioxidant activity are quantitatively the most important type of fruit of protocatechuic and caffeic acids is possible to have compounds. Anthocyanin compounds, a positive relation with their two ortho hydroxyl groups such as pelargonidin-glucoside, pelargonidin-maloside- present in benzenic ring (2, 5 in Figure 2) according to glucoside, pelargonidin-rutinoside and cyanidin- established structure-activity relation from Villaño et al. glucoside, exist in different strawberry genotypes [9]. [30]. Antiradical efficiencies of caffeic acid, gallic acid, The benefits of anthocyanins in improving health and tannic acid, and ferulic acid were 2.75, 2.62, 0.57, and preventing disease have received great attention in 0.12, respectively [31]. In comparison with berry fruits recent years. Some berry and cherry fruits are rich (SKB, WBB, RB, SB) and seabuckthorn, rich caffeic (up sources of natural anthocyanins. Anthocyanins in grape to 6456 mg/kg) and high protocatechuic (214 mg/kg) juice had the ability to reduce in vitro oxidation of human acid levels found in chokecherry (Table 4) indicated low-density lipoprotein [23]. Anticancer and antitumour the potential of chokecherry as novel source of natural activities of anthocyanins from various sources have antioxidants because of protocatechuic and caffeic acids been demonstrated, such as inhibition of tumor with strong antioxidant capacity. The impact of some development and reduction in the proliferation of colon phenolic acids on health has been studied. Caffeic acid cancer cells [24], prevention of carcinogen-induced has novel and therapeutic effects on hepatocarcinoma colorectal cancer [25], and blocking of breast cell DNA cells [32] and protects WI-38 human lung fibroblast cells damage [26]. It was reported that anthocyanins from against H2O2 damage [33]. It was reported that caffeic, some fruit plants had inhibitory effects on the growth ellagic, chlorogenic and ferulic acids had inhibition of colonic cancer cell [27] and HepG2 liver cancer cell effect on 4-nitroquinoline-1-oxide-induced rat tongue [22]. carcinogenesis [34]. Ferulic acid may offer beneficial Free radicals may attack and damage important effects against cancer, cardiovascular disease, diabetes biological components in biological systems and lead to and Alzheimer’s disease [35]. p-Coumaric acid protects illnesses, such as cancers, heart diseases, and other the heart against doxorubicin-induced oxidative stress aging-associated health problems [28]. A diet rich in [36] and demonstrates good antiplatelet activity for the antioxidants will be an effective pathway for reducing prevention of vascular disease [37]. Protocatechuic acid the risk of these illnesses because antioxidants may has been shown to induce hepatocellular carcinoma cell terminate the attack of free radicals. Consumers prefer death [38]. It was reported that gallic acid had anticancer natural antioxidants as they are concerned about effects by inhibiting cancer cell proliferation through the safety of the synthetic antioxidants. In addition, inducing apoptosis in cancer cells, such as against antioxidants are important food additives to enhance the esophageal cancer cells [39], against stomach cancer quality, stability, and safety of food products [28]. Fruits and colon adenocarcinoma cells [40], and against lung with high free radical scavenging activity, especially cancer cells [41]. When trans-cinnamic acid was used chokecherry (Table 3) found in this study, have potential in combination with anti-tuberculosis drugs, synergistic as a source of novel natural antioxidants for disease activities against Mycobacterium tuberculosis were prevention and health promotion, and also as natural enhanced [42]. Because of the important benefist of food additives to improve the quality, stability, and safety phenolic acids in promoting health, it is valuable to of food products. fully understand phenolic acid composition of fruits as It is very useful to evaluate phenolic acid composition a novel source of natural antioxidants for developing in plants for application purposes. esters of functional food. p-coumaric and ellagic acids were found in strawberry extracts [10]. The antioxidant capacity of some phenolic acids decreased in the order protocatechuic acid > 5. Conclusion chlorogenic acid > caffeic acid > p-hydroxybenzoic acid > gentistic acid > ferulic acid > vanillic acid > syringic The study reported the antioxidant capacity of four berry acid > p-coumaric acid [29]. Oxygen radical absorbance fruits, chokecherry and seabuckthorn. Differences in capacity method also confirmed that protocatechuic antioxidant capacity were found among some of them. acid (18.61 µmol Trolox equ.mg-1), caffeic acid Antioxidant capacity was closely related to fruit type. (15.28 µmol Trolox equ.mg-1) and gentistic acid Chokecherry showed very high antioxidant capacity (13.85 µmol Trolox equ.mg-1) had high antioxidant capacity including its TPC, TAC, DPPH• scavenging activity and when compared with p-coumaric acid (10.16 µmol Trolox caffeic acid level in comparison with the four berry fruits equ.mg-1), ferulic acid (8.48 µmol Trolox equ.mg-1), and seabuckthorn studied. The findings on phenolic

504 Comparison of antioxidant capacity and phenolic compounds of berries, chokecherry and seabuckthorn

acid composition indicated that trans-cinnamic acid and Acknowledgements gallic acid were present at high levels in strawberry and raspberry, respectively. Although the highest caffeic We are grateful for the financial support provided acid levels were observed in chokecherry, Saskatoon by the Canada Foundation for Innovation (CFI New berry and wild blueberry also contained high caffeic Opportunities Fund), and Canada Research Chairs acid levels. The results provide evidence essential Program and the Manitoba Agri-Food Research and for breeding novel cultivars of fruit plants with strong Development Initiative (ARDI). We thank ARDI for natural antioxidants and developing new functional facilitating the provision of samples used for this study. food products. Further research is required to identify We are thankful for the technical assistance from Wan anthocyanin composition from the tested fruits and to Yuin (Alison) Ser of the Department of Food Science at investigate effect of phenolic acid composition on fruit University of Manitoba. quality and to demonstrate the inhibition effects of chokecherry antioxidants on cancer cells.

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