10 th <str<strong>on</strong>g>Symposium</str<strong>on</strong>g> <strong>on</strong> <strong>the</strong> <strong>Flora</strong> <strong>of</strong> Sou<strong>the</strong>astern <strong>Serbia</strong> <strong>and</strong> Neighbouring regi<strong>on</strong>s,Vlasina 17 to 20 June 2010Antimikrobna aktivnost etarskih ulja nekih vrsta rodaSatureja L. protiv fitopatogene bakterije Erwinia amylovoraTatjana Mihajilov-Krstev 1 , Dragan Radnović 2 , Dušanka Kitić 31 Odsek za biologiju i ekologiju, Prirodno-matematiki fakultet, Univerzitet uNišu, Srbija2 Departman za biologiju i ekologiju, Prirodno-matematiki fakultet,Univerzitet u Novom Sadu, Srbija,3 Medicinski fakultet, Univerzitet u Nišu, Srbijanis_mikrobi@yahoo.comU ovom radu je ispitivana antimikrobna aktivnost etarskih ulja biljnih vrsta S.kitaibelii Wierzb. ex Heuff., S. m<strong>on</strong>tana ssp. m<strong>on</strong>tana L., S. adamovicii Čilić i S.fukarekii Čilić protiv fitopatogene bakterije Erwinia amylovora za koju se veruje dase je iz Severne Amerike raÅ¡irila po celom svetu (osim Australije i Japana). Onaizaziva sistemsku infekciju jabuka i drugih Rosaceae koja je poznata kao"plamenjača" (firebligh). Ispitivanje je vršeno uz pomoć dve metode: disk-difuzi<strong>on</strong>ei mikrodiluci<strong>on</strong>e. Rezultati su pokazali da je ova bakterija veoma osetljiva nadelovanje ispitivanih ulja. Najveće z<strong>on</strong>e inhibicije su izmerene kod etarskog uljavrste S. m<strong>on</strong>tana ssp. m<strong>on</strong>tana (25 mm), a najniže vrednosti za minimalnuinhibitornu i baktericidnu k<strong>on</strong>centraciju su dobijene za ulje vrste S. adamovicii(MIC=MBC=0,09 μl/ml). Kod svih ispitivanih ulja vrednosti za MIC su bilejednake vrednostima za MBC, što znači da ulja, u veoma niskim k<strong>on</strong>centarcijama,deluju baktericidno i mogu pretstavljati prirodni izvor neškodljivih herbicida.Stability <strong>of</strong> flav<strong>on</strong>oids toward UV-irradiati<strong>on</strong> <strong>and</strong> inhibiti<strong>on</strong><strong>of</strong> lipid peroxidati<strong>on</strong>: correlati<strong>on</strong> <strong>of</strong> structure <strong>and</strong> functi<strong>on</strong>Cvetković, D., Marković, D.Faculty <strong>of</strong> Technology Leskovac, University <strong>of</strong> Niš, <strong>Serbia</strong>dejan_markovic57@yahoo.comStability <strong>of</strong> flav<strong>on</strong>oids toward UV-irradiati<strong>on</strong> <strong>and</strong> inhibiti<strong>on</strong> <strong>of</strong> lipidperoxidati<strong>on</strong>: correlati<strong>on</strong> <strong>of</strong> structure <strong>and</strong> functi<strong>on</strong> Dragan Cvetković <strong>and</strong> DejanMarković University <strong>of</strong> Nish, Faculty <strong>of</strong> Technology, Leskovac, <strong>Serbia</strong> Flav<strong>on</strong>oidsmake big class <strong>of</strong> natural polyphenol compounds <strong>of</strong> low molecular mass. They arewidely distributed in plant world, mostly in plants leafs (epidermal layer), seeds <strong>and</strong>flowers; so far about 4000 flav<strong>on</strong>oids have been isolated. Flav<strong>on</strong>oids act inbiological systems as antioxidants, enzyme inhibitors, photosensitizers, energy86
10 th <str<strong>on</strong>g>Symposium</str<strong>on</strong>g> <strong>on</strong> <strong>the</strong> <strong>Flora</strong> <strong>of</strong> Sou<strong>the</strong>astern <strong>Serbia</strong> <strong>and</strong> Neighbouring regi<strong>on</strong>s,Vlasina 17 to 20 June 2010transducers, expressing notable anti-cancer behaviour. The updated studiesc<strong>on</strong>nected flav<strong>on</strong>oids antioxidant activity with presence (or absence) <strong>of</strong> OH-group atC-ring 3-positi<strong>on</strong>, in combinati<strong>on</strong> with catechol B-ring structures. The importance <strong>of</strong>this positi<strong>on</strong> (wherever exists, like in flav<strong>on</strong>ols – represented by quercetin) may beestimated – am<strong>on</strong>g o<strong>the</strong>r ways – by comparing stabilities <strong>of</strong> quercetin <strong>and</strong> rutin(flav<strong>on</strong> representative – not having 3-OH group) toward an extternally indicedstress, like UV-irradiati<strong>on</strong>. The plant answer <strong>on</strong> <strong>the</strong> increased presence <strong>of</strong> highlyenergeticUV-B fracti<strong>on</strong> in sunlight spectrum is, am<strong>on</strong>g o<strong>the</strong>rs, an increasedsyn<strong>the</strong>sis <strong>of</strong> UV-B absorbing pigments, mostly flav<strong>on</strong>oids (flav<strong>on</strong>oids screeningaffect). The last fact was exploited in this work. Their chemical structures permit<strong>the</strong>m to be excellent UV-absorbers which enables <strong>the</strong>m to be (a) efficient preventiveantioxidants, because <strong>the</strong>y reduce initiati<strong>on</strong>, e.g. decrease producti<strong>on</strong> <strong>of</strong> free radicals(which is <strong>on</strong>e <strong>of</strong> <strong>the</strong> main c<strong>on</strong>sequences <strong>of</strong> c<strong>on</strong>tinuos UV-irradiati<strong>on</strong>). But, in <strong>the</strong>same time <strong>the</strong>y are (b) very effective chain-breaking antioxidants, acting asscavengers <strong>of</strong> <strong>the</strong> created radical species. Both (a) <strong>and</strong> (b) are especially importantfor inhibiti<strong>on</strong> <strong>of</strong> lipid peroxidati<strong>on</strong> (LP) process. There is undoubtfull correlati<strong>on</strong>between stability <strong>of</strong> flav<strong>on</strong>oids toward UV-irradiati<strong>on</strong> <strong>and</strong> degree <strong>of</strong> LP suppressi<strong>on</strong>(case (a)). This c<strong>on</strong>tributi<strong>on</strong> deals with studies <strong>of</strong> two selected flav<strong>on</strong>oids, quercetin<strong>and</strong> rutin, subjected to c<strong>on</strong>tinous, prol<strong>on</strong>ged irradiati<strong>on</strong> from three UV-sub-ranges:UV-A, 320-400 nm; UV-B, 290-320 nm; UV-C, 200-280 nm), in soluti<strong>on</strong>, in <strong>the</strong>presence or in <strong>the</strong> absence <strong>of</strong> „protective target“ soy bean lecithin. The change <strong>of</strong> <strong>the</strong>flav<strong>on</strong>oids stability was related to degree <strong>of</strong> <strong>the</strong> (UV-) induced lecithin peroxidati<strong>on</strong>,under <strong>the</strong> same irradiati<strong>on</strong> regime. The 3-OH group was found to play <strong>the</strong> crucialrole c<strong>on</strong>cerning <strong>the</strong> flav<strong>on</strong>oids photostability: <strong>the</strong> flav<strong>on</strong>oids with 3-OH in <strong>the</strong>structure are less resistent toward UV-irradiati<strong>on</strong> – in this case quercetin undergoesto faster destructi<strong>on</strong> (bleaching) than rutin, <strong>and</strong> <strong>the</strong> bleaching is energeticallydependent(following UV-C > UV-B > UV-A order). TBA-MDA test used to followchanges in <strong>the</strong> two flav<strong>on</strong>oids antioxidant activities – toward lecithin as <strong>the</strong>protective target – also expressed <strong>the</strong> same UV-energy-dependent order as <strong>the</strong>outcome. It was also found that rutin antioxidant activity is more influenced by UVeffectthan quercetin’s.87