UV-B induced changes of phenol composition and antioxidant activity in black currant fruit (Ribes nigrum L.)*

Transcription

1 Journl of Applied Botny nd Food Qulity 81, (2007) 1, 2 Humoldt-Universität zu Berlin, Institute for Hortiulturl Sienes, Setion Qulity Dynmis/Posthrvest Physiology nd Setion Fruit Siene, Berlin, Germny 3 Tehnil University of Berlin, Institute for Food Tehnology nd Food Chemistry, Berlin, Germny UV-B indued hnges of phenol omposition nd ntioxidnt tivity in lk urrnt fruit (Ries nigrum L.)* S. Huyskens-Keil 1, I. Eihholz 2, L.W. Kroh 3, S. Rohn 3 (Reeived July 6, 2007) Summry Informtion on UV-B eliitor medited hnges on phenoli omposition nd ntioxidnt tivity of lk urrnt (Ries nigrum L.) re snty. In the present study physiologil ripe lk urrnt fruits were hrvested nd exposed to UV-B rdition with different exposure nd dpttion times. The influene of UV-B on phenoli profile nd quntittive omposition s well s on the orresponding ntioxidnt tivity ws investigted. Antioxidnt tivity ws sreened with eletron spin resonne spetrometry (ESR), while phenoli ompound omposition ws onduted y HPLC nlysis. Totl phenol ontent nd phenoli omposition (flvonols, nthoynins, hydroxyinnmi nd hydroxyenzoi ids) inresed to lrge extent during UV-B tretment, irrespetive of the dpttion time. Anthoynins re onluded to sor UV rdition within short time, menwhile flvonols nd phenoli ids re ssumed to hve n impt on ntioxidnt protetion of UV-B medited tissue dmge. Moreover, ntioxidnt tivity signifintly orrelted with different phenoli ompounds nd inresed to similr extent y UV-B exposure. Introdution Polyphenols elong to the seondry plnt metolites nd re present in wide rnge of fruits nd vegetles. Bsed on the hemil struture phenoli ompounds re mrked y rod spetrum of helth-promoting funtions suh s ntioxidnt, ntimutgeni nd ntinerogeni properties (HALLIWELL, 1996). There is ler evidene for n ssoition etween the free-rdil inding hrter of phenols nd the prevention of degenertive diseses, e.g. ner nd rdiovsulr diseses (WORLD CANCER RESEARCH FUND, 1997; BAZZANO et l., 2002). Berry fruits suh s lk urrnt (Ries nigrum L.) re rih soure of phenoli ompounds (KÄHKÖNEN et l., 2001; BENVENUTI et l., 2004). The ntioxidnt tivity of lk urrnt fruits is sed on the high ontent of flvonols (myrietin nd queretin derivtives) (ANTTONNEN nd KARJALAINEN, 2006) nd nthoynins (delphindin nd ynidin derivtives) (SLIMESTAD nd SOLHEIM, 2002). Moreover, hydroxyinnmi ids (ffei id nd oumri id) nd hydroxyenzoi id (glli id nd hydroenzoi id) lso ontriute to the ntioxidnt tivity, ut to smller extent (HÄKKINEN et l, 1999; KÄHKÖNEN et l., 2001; MÄTTÄÄ et l., 2003). Up to now, reserh on ntioxidnt phenoli plnt ompounds in lk urrnt ws minly foused on the effet of ultivrs, sesonl timing nd ultivtion prties (KÄHKÖNEN et l., 2001; MIKKONEN et l., 2001; MOYER et l., 2002; ANTTONNEN nd KARJALAINEN, 2006; TAB- ART et l., 2006). However, informtion on hnges in phenoli omposition nd ntioxidnt tivity in lk urrnt s ffeted y ultrviolet-b (UV-B) rdition is snty. In reent yers, inresed UV-B rdition ( nm) y ir pollution-indued ozone depletion hs rised wreness of the effets of UV-B on the eosystem. Though only smll portion of the totl * This pper ws presented t the 42 th meeting of the Deutshe Gesellshft für Qulitätsforshung (Pflnzlihe Nhrungsmittel) DGQ e.v. solr spetrum, UV-B hs lrge photoiologil effet (KERR et l., 2003). There re mny reports on potentil onsequenes of n inrese in UV-B rdition on plnts, however, rther limited understnding the effet on seondry plnt metolites is present. The inresing exposure of plnts to UV-B uses protetive mehnisms in plnt response to this nthropogeni soure of stress. Additionlly to morphologil hnges the protetive stress response triggers distint hnges in the plnt s seondry metolism resulting in n umultion of vrious phytohemils (e.g. phenoli ompounds) nd their ntioxidtive tivity (SCHREINER nd HUYSKENS-KEIL, 2003; EICHHOLZ et l., 2005; HUYSKENS-KEIL et l., 2006; SCHREINER nd HUYSKENS-KEIL, 2006). ). Anthoynins nd flvonoids hve vrious physiologil funtions (i.e. ntioxidtive nd ntitumor tivity) nd revel UV protetive effets (HIGASHIO et l., 2001; INDORF, 2001; KOLB et l, 2001; HIGASHIO, 2005). In generl, the synthesis of phenoli ompounds n lso e stimulted y UV exposure in posthrvest s it ws reported for exmple for queretin in onion nd strwerry, flvonoids in rokkoli nd lk urrnt (HIGASHIO et l., 2005; COSTA et l., 2006; HUYSKENS-KEIL et l., 2006). However, UV stress medited hnges in phenol profile nd ntioxidnt tivity re dependent on the durtion of stress, dpttion time of plnts to UV stress nd physiologil sttus of the plnt t the time of UV exposure. This study ontriutes to n ssessment of short-term UV-B stress indued impt on the dynmis of seondry plnt metolites in posthrvest, exemplrily demonstrted on phenoli omposition nd ntioxidnt tivity of lk urrnt. Furthermore, the effet of trgeted UV pplition in posthrvest for inresing helth-promoting phytohemil ompounds nd thus, nutritionl vlue of fruits nd vegetle produts is foused. Mteril nd methods Plnt mteril nd Experimentl setup Three yers old plnts of Ries nigrum L. v Titni (n=120) were ultivted in 10 L ontiners with Compo Sn rose sustrte, (COMPO GmH & Co. KG, Münster) nd Mnn Lin M fertilizer (Wilhelm Hug GmH & Co. KG, Ammeruh, Germny). Fruits were hrvested t fully developed ripening stge (ording to the mturity index s desried elow) in July Speil ttention ws pid on piking erries of the pproprite mturity stge ording to fruit firmness nd mturity index (sugr-id-rtio) onsidering smple olletion from ll setions of the ush. After piking, one prt of fruit smples (250 g PE-trys) ws sujeted to UV-B rdition for 60, 90 or 120 min using n UV-B fluoresene light soure (FL 20SE, nm) with n verge flueny rte of 8.2 Ws m -2 t distne of 30 m to fruits. After n dpttion time of 2 or 22 h fruits were shok-frozen in liquid nitrogen nd kept t -25 C efore freeze drying (Christ Alph 1-4, Christ; Osterode, Germny). Dried smples were grinded for susequent extrtion nd nlysis of totl phenoli ontent nd phenoli omposition, i.e. flvonoid sulsses (flvonols, nthoynins, hydroxyinnmi nd hydroxyenzoi ids). The experiment ws onduted with three

2 Phenol Composition nd Antioxidnt Ativity in Blk Currnt Fruit 141 replites per UV-B tretment nd dpttion time. Non-treted fruits (250 g with three repetitions) were used s ontrol. Mturity index Solule solids of 150 g fruit per tretment with three replitions were determined using hnd refrtometer (Leo Küler GmH, Germny). For the determintion of titrtle idity fruits were homogenized (Ultr-Turrx T25, Ik-Lortehnik, Stufen, Germny). Therefter, 2.5 grms of the homogente were dissolved with 2.5 ml of distilled wter. Titrtle idity ws determined y titrtion with 0.1 N NOH until ph 8.1 nd expressed s perent totl orgni id on sis of itri id eing the min id omponent in lk urrnt fruits. T. 1: Anlysis of phenoli ompounds using HPLC-DAD grdient Time (min) Eluent B (%) Phenoli ompounds Anlysis of phenoli ompounds For the nlysis of phenoli ompounds, extrtion ws onduted following the method desried y KÄHKÖNEN et l. (2001) nd CONNOR et l. (2002) using idified methnol (0.1% hydrohlori id). An liquot of 0.5 g grinded smple ws mixed vigorously with 3 ml of idified methnol (0.1% hydrohlori id) nd entrifuged for 15 minutes t 3000 rpm. The superntnt ws olleted in 10 ml volumetri flsk. The residue ws treted gin twie with 3 ml idified methnol nd 15 minutes entrifugtion. Superntnts were olleted nd stndrdised to finl volume of 10 ml. The extrts otined were used for the determintion of the phenol ontent, omposition, nd ntioxidnt tivity. Determintion of the totl phenol ontent Totl phenol ontent in the fruit extrts were determined using the Folin-Ciolteu method with results expressed s milligrms glli id equivlents (GAE) per grm of dry mtter. Asorne ws mesured t 765 nm (LKB-Novspek II, Phrmi, Freiurg, Germny). Approprite dilutions of extrts were prepred y duplite with distilled wter (1+29; v,v). The mixture develops drk lue olor nd ws left to ret for one hour. Duplite leture of smples were mesured spetrophotometrilly t 765 nm. Anlysis of the phenoli ompounds using HPLC-DAD In the present study, the onentrtions of two mjor flvonoid sulsses, flvonols nd nthoynins, nd two phenoli id groups, hydroxyinnmi nd hydroxenzoi ids, were determined y HPLC-DAD. An nlytil Hewlett Pkrd 1100 series HPLC instrument equipped with n utosmpler, quternry HPLC pump nd diode rry detetor ws used. Anlytil seprtion of the phenoli ompounds ws rried out on 250 mm x 4.6 mm, 5 µm, Fluofix 120E olumn (Wko Pure Chemil Industries, Osk, Jpn) with two solvent moile phse (eluent A = wter/eti id/etonitrile ( ; v,v,v); eluent B = eti id/etonitrile (5 + 95; v,v). The eluent grdient used for ll extrts is desried in T. 1. The identifition of phenoli ompounds on the sis of the ompound group s hrteristi sorption wvelength ws onduted ording to KÄHKÖNEN et l. (2001). Two milliliter liquots of the extrt (50 mg DM ml -1 ) were onentrted y drying with nitrogen nd then re-dissolved to volume of 500 µl with HPLC grde methnol. The injetion volume ws 20 µl, nd the flow rte 1 ml min -1. Contents of nthoynin (detetion wvelength 520 nm), flvonol (365 nm), nd hydroxyinnmi id (320 nm) were quntified s ynidin-3- gluoside, rutin, nd hlorogeni id equivlents, respetively. Totl onentrtion of eh representtive sulss ws lulted from the onentrtion otined from 1 mm stndrd solution of the ompounds mentioned ove. Results were expressed s milligrms per grm dry mtter (DM). Determintion of the ntioxidnt tivity y Eletron Spin Resonne Spetrometry (ESR) The degrdtion of stle syntheti rdil, Fremy s slt (potssium nitrosodisulfonte), in presene of ntioxidnts in the lk urrnt extrts ws monitored with ESR s pplied y RÖSCH et l. (2003). Approprite extrt dilutions (1+29; v,v) were prepred nd 100 µl liquots were llowed to ret for 20 min with n equl volume of solution of Fremy s slt (1 mm in phosphte uffer, ph 7.4). ESR spetr of Fremy s rdil were otined with Minisope MS100 spetrometer (Mgnetteh GmH, Berlin, Germny). The ntioxidnt tivity expressed s mm Fremy s slt redued y 1 g dried smple (mm per g DM), ws lulted y omprison with ontrol retion with 100 µl Fremy s slt 1 mm nd 100 µl phosphte uffer. Sttistil nlysis All dt were sttistilly nlysed (ANOVA) with SPSS 13.0 (SPSS In., USA). Signifint differenes were determined y Tukey s test (p < 0.05). The men vriility ws indited y the stndrd devition. Results nd disussion Totl phenol ontent in the ripe lk urrnts studied were found to e slightly lower in omprison to the ontents reported in the literture, reveling mg/g DW nd mg/g DW, respetively (KÄH- KÖNEN et l., 2001). This might e due to geneti differenes of the plnt mteril, differenes in the physiologil ripening stge of the fruit t the time of hrvest nd/or environmentl onditions during plnt growth. The iosysnthesis of phenoli ompounds ws ffeted y UV-B rdition in posthrvest (Fig. 1). UV-B tretments resulted in ontinuous inrese of phenols showing pek t 90 minutes. However, dpttion times did not signifintly ffet totl phenol ontent. The rpid physiologil response of phenols to UV rdition in posthrvest is lso reported for other hortiulturl produts, e.g. Brssi spp., Vinium spp. (HUYSKENS-KEIL et l., 2006). It is ssumed tht n UV stress medited inrese of phenyllnin mmoni-lyse tivity ourrs leding to n elertion of the iosynthesis of phenoli ompounds (PLUSKOTA et l., 2005). Anthoynin synthesis in lk urrnt ws promoted y inresing exposure time of UV-B (Fig. 2). The highest inrese of nthoynin (60%) ws found t 120 min UV tretment, irrespetively of the dp-

3 142 S. Huyskens-Keil, I. Eihholz, L.W. Kroh, S. Rohn ttion time. Similr results were reported for strwerries nd pehes, where UV medited inrese of nthoynins ws ssoited with n inrese in phenyllnin mmoni-lyse tivity (KATAOKA nd BEPPU, 2004; HIGASHIO et l., 2005). In ddition to phenyllnin mmoni-lyse indution, UV rdition inreses lso the tivity of other enzymes involved in flvonoid synthesis: hlon synthse, hlon isomerse, nd dihydroflvonol-4- redutse (TOMAS-BARBERAN nd ESPIN, 2001). In the present study lso flvonols were ffeted y the UV-B tretment (Fig. 3). With inresing UV-B exposure periods flvonol synthesis ws tivted Totl phenol ontent [mg/g DW] Anthoynin ontent [mmol/g DW] 25,0 2 15,0 1 Fig. 1: 7,0 6,0 5,0 4,0 3,0 2,0 1,0 Fig. 2: Flvonole ontent [mmol/g DW] Fig. 3: 5,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 d UV-B rdition (min)/dpttion time (h) UV-B rdition (min)/dpttion time (h) UV-B indued hnges of nthoynin ontent in lk urrnt fruits. Vertil rs indite signifint differenes P < 0.05 (Tukey Test). UV-B indued hnges of totl phenol ontent in lk urrnt fruits. Vertil rs indite signifint differenes P < 0.05 (Tukey Test). d UV-B rdition (min)/dpttion time (h) UV-B indued hnges of flvonol ontent in lk urrnt fruits. Vertil rs indite signifint differenes P < 0.05 (Tukey Test). reveling drsti inrese of 76% fter 120 minutes. The results demonstrte tht flvonols showed similr response to UV in omprison to nthoynins. Hydroxyinnmi nd hydroxyenzoi ids re iohemil preursors of flvonols nd nthoynins in the shikimte pthwy. Therefore, oth preursors showed n erly retion to UV exposure: hydroxyinnmi id inresed y 98% fter 60 min UV-B exposure, wheres the dominting hydroxyenzoi id only inresed y 35% (Fig. 4). Correltion etween totl phenol ontent nd phenoli ompounds reveled strong orreltion with hydroxyenzoi ids (r=0.71, p<0.01), nthoynins (r=0.75, p<0.01) nd flvonols (r=0.66, p<0.01). No orreltion ws found etween totl phenol ontent nd onentrtion of hydroxyinnmi id. Antioxidnt tivity in hrvested lk urrnt fruits ws signifintly indued (21%) y UV-B rdition, however only fter 120 min UV exposure with n dpttion time of 22 h (Fig. 5). Tendentiously, ntioxidnt tivity elerted with inresing dpttion times reveling longer iohemil retion time to UV medited stress. Fig. 4: mmol Fremys slt/ g DW Fig. 5: Phenoli ompounds [mmol/g DW] 0,40 0,35 0,30 0,25 0,20 0,15 0, ,5 2,0 1,5 1,0 0,5 Hydroxyinnmi id Hydroxyenzoi id B B B UV60 UV90 UV120 UV-B rdition [min] UV-B indued hnges of hydroxyinnmi nd hydroxyenzoi ids in lk urrnt fruit. Vertil rs indite signifint differenes P < 0.05 (Tukey Test). UV-B rdition (min)/dpttion time (h) A strong orreltion etween ntioxidnt tivity (ESR) nd the different phenoli ompounds were found: totl phenols (r=0.63, p<0.01), nthoynins (r=0.76, p<0.01); hydroxyenzoi ids (r=0.71, p<0.01) nd flvonols (r=0.70, p<0.01). No orreltion ws found etween ESR nd hydroxyinnmi id, presumly due to their low ontriution nd thus low ntioxidnt tivity. RICE-EVANS et l. (1995) lso A UV-B indued hnges of ntioxidnt tivity in lk urrnt fruit. Vertil rs indite signifint differenes P < 0.05 (Tukey Test).

4 Phenol Composition nd Antioxidnt Ativity in Blk Currnt Fruit 143 reported low ntioxidnt tivity of ffei id in omprison to the high ntioxidnt tivity of nthoynins (delphinidin nd ynidin), flvonols (queretin nd myrietin) nd hydroxyenzoi ids (glli id) in lk urrnt. In onlusion, the results demonstrte tht the synthesis of phenoli ompounds nd ssoited ntioxidnt tivity of lk urrnt fruits is stimulted y short term UV-B rdition in posthrvest. Anthoynins re onluded to e le to sor UV rdition within short time nd thus hve UV-B protetive effet in lk urrnt s it is lso known for other fruits (JAAKOLA et l., 2004; YANG et l., 2005; HAGEN et l., 2007). Flvonoids hve vrious physiologil funtions suh s ntioxidnt or ntitumor tivity s well s UV protetive effets (HIGASHIO et l., 2001; KOLB et l, 2001; HIGASHIO, 2005). In the present study, flvonols nd phenoli ids re lso ssumed to hve n impt on the ntioxidnt protetion of UV-B medited tissue dmge in lk urrnt. Further studies on the dynmi of UV medited hnges in seondry plnt ompounds nd ntioxidnt tivity of lk urrnt will e onduted. Aknowledgements The uthors grtefully knowledge the lortory stff Inge Dressel of the Setion Qulity Dynmis/Posthrvest Physiology. Referenes ANTTONEN, M., KARJALAINEN, R.O., 2006: High-performne liquid hromtogrphy nlysis of lk urrnt (Ries nigrum L.) fruit phenolis grown either onventionlly or orgnlly. J. Agri. Food Chem. 54, BAZZANO, L., HE, J., OGDEN, G., VUPPUTURI, S., LORIA, C., MEYERS, L., WHELTON, P., 2002: Fruit nd vegetle intke nd risk of rdiovsulr disese in US dults: the first ntionl Helth nd nutrition exmintion survey epidemiologi follow-up study. Am. J. Clin. Nutr. 76, BENVENUTI, S., PELLATI, F., MELEGARI, M., BERTELLI, D., 2004: Polyphenols, nthoynins, sori id, nd rdil svenging tivity of ruus, ries, nd roni. J. Food Si. 69, CONNOR, A.M., LUBY, J.J., HANCOCK, J.F., BERKHEIMER, S., HANSON, E.J., 2002: Chnges in fruit ntioxidnt tivity mong lueerry ultivrs during old-temperture storge. J. Agri. Food Chem. 50, COSTA, L., VICENTE, A.R., CIVELLO, P.M., CHAVES, A.R., MARTINEZ, G.A., 2006: UV-C tretment delys posthrvest senesene in rooli florets. Posthrvest Biol. Tehnol. 39, EICHHOLZ, I., ROHN, S., KROH, L.W., HUYSKENS-KEIL, S., 2005: Influene of lotion nd fertiliztion on the ntioxidtive tivity of highush lueerries (Vinium orymosum L.). In: Eklund, T., Shwrz, M., Steinhrt, H., Their, H.P., Winterhlter, P. (eds.), Proeedings of the EURO FOOD CHEM XIII: Mromoleules nd their Degrdtion Produts in Food Physiologil, Anlytil nd Tehnologil Aspets, Vol. 2, Hmurg. ISBN HÄKKINEN, S., HEINONEN, M., KÄRENLAMPI, S., MYKKÄNEN, H., RUUSKANEN, J., TÖRROÖNEN, R., 1999: Sreening of seleted Flvonoids nd phenoli ids in 19 erries. Food Res. Intern. 32, HAGEN, S.F., BORGE, G.I.A., BENGTSSON, G.B., BILGER, W., BERGE, A., HAFFNER, K., SOLHAUG, K.A., 2007: Phenoli ontents nd other helth nd sensory relted properties of pple fruit (Mlus domesti Borkh., v. Arom)- Effet of posthrvest UV-B irrdition. Posthrvest Biol. Tehnol. 45, HALLIWELL, B., 1996: Oxidtive stress, nutrition nd helth. Experimentl strtegies for optimiztion of nutritionl ntioxidnt intke in humns. Free Rdi. Res. 25, HIGASHIO, H., IPPOUSHI, K., ITO, H., AZUMA, K., 2001: Effet of UV irrdition on ontent of flvonoids in spini leves. At Hort. 553, HIGASHIO, H., HIROKANE, H., SATO, F., TOKUDA, S., URAGAMI, A., 2005: Effet of UV irrdition fter hrvest on the ontent of flvonoid in vegetles. At Hort. 682, HUYSKENS-KEIL, S., ULRICHS, CH., MEWIS, I., SCHREINER, M., 2006: Ultrviolet irrdition: Eliitor to promote the synthesis of phytohemils in vegetles in pre- nd posthrvest. At Hort. (in press). INDORF, A., 2001: Liht und UV-B-Wirkung uf die Bildung von Lignin, Flvonoiden und Tnninen in Keimlingen der Wldkiefer. PhD thesis, Alreht-Ludwigs-Universität Freiurg JAAKOLA, L., MÄÄTTÄ-RIIHINEN, K., KÄRENLAMPI, S., HOHTOLA, A., 2004: Ativtion of flvonoid iosynthesis y solr rdition in ilerry (Vinium myrtillus L.) leves. Plnt 218, KÄHKÖNEN, M.P., HOPIA, A.I., HEINONEN, M., 2001: Berry phenolis nd their ntioxidtive tivity. J. Agri. Food Chem. 49, KATAOKA, I., BEPPU, K., 2004: UV irrdine inreses development of red skin olor nd nthoynins in Hkuho peh. Hort. Si. 39, KERR, J.B., SECKMEYER, G., 2002: Surfe Ultrviolet Rdition: Pst nd Future. In: Sientifi Assessment of Ozone Depletion Glol Ozone Reserh nd Monitoring Projet Report No. 47. World Meteorologil Orgniztion, Genf. KOLB, C.A., KÄSER, M.A., KOPECKY, J., ZOTZ, G., RIEDERER, M., PFÜNDEL, E.E., 2001: Effets of nturl intensities of visile nd ultrviolett rdition on epiderml ultrviolett sreening nd photosynthesis in grpes leves. 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5 144 S. Huyskens-Keil, I. Eihholz, L.W. Kroh, S. Rohn Addresses of the uthors: Dr. Susnne Huyskens-Keil 1, Ines Eihholz 2, Humoldt-Universität zu Berlin, Institute for Hortiulturl Sienes, 1 Setion Qulity Dynmis/Posthrvest Physiology nd 2 Setion Fruit Siene, Lentzellee 75, D Berlin, Germny Prof. Dr. L.W. Kroh, Dr. Ssh Rohn, Tehnil University of Berlin, Institute for Food Tehnology nd Food Chemistry, TIB 4/3-1, Gustv-Meyer-Allee 25, D Berlin, Germny Corresponding uthor: Dr. Susnne Huyskens-Keil, emil: susnne.huyskens@grr.hu-erlin.de