Phenolic compounds in plants

Fenolni spojevi u biljkama su mnogobrojni i pripadaju sekundarnim tvarima u biljnom organizmu. S kemijskog aspekta, to je grupa spojeva koja ima fenolnu odnosno hidroksilnu skupinu na aromatskom prstenu. Postoje različiti načini sinteze fenolnih spojeva. Najvažnija dva puta biosinteze su put šikiminske kiseline i put jabučne kiseline. Biljke proizvode širok spektar sekundarnih metabolita koji pokrivaju različite funkcije, kao na primjer obrana biljke od herbivornih organizama, mehanička potpora biljke, privlačenje oprašivača i rasprostranjivača plodova ili inhibiciji rasta susjednih biljaka. Najčešće zastupljena skupina fenolnih spojeva su flavonoidi. Flavonoidi se sintetiziraju putem fenilpropanoida i služe kao UV zaštitnici u obrani patogena, za komunikaciju biljaka i mikroorganizama i regulaciju reaktivnih vrsta kisika. U svijetu postoji veliko zanimanje za fitokemikalije kao bioaktivne komponente hrane. Konzumacija voća i povrća u prehrani ljudi može prevenirati neke bolesti zahvaljujući visokoj antioksidacijskoj aktivnosti istih. Slobodni radikali imaju važnu ulogu u procesima kvarenja hrane, razgradnji kemijskih materijala i također doprinose više od stotinu poremećaja kod ljudi. Posljednjih godina postoji povećan interes za upotrebu antioksidanta u medicinske svrhe, a veliku pozornost privlače klijanci žitarica i mahunarki zbog svojih jakih antioksidacijskih svojstava. Postoje mnoge metode detekcije fenolnih spojeva i izračuna ukupne antioksidacijske aktivnosti. U grubo su podijeljene u dvije skupine: in vitro metode i in vivo metode. Neke od in vitro metoda su DPPH, TEAC, FRAP, SOD, ORAC i mnoge druge, a od in vivo metoda to su GSH, GSHPx, CAT, GGT itd.Phenolic compounds in plants are numerous and belong to secondary metabolites of the plant organism. From a chemical point of view, it is a group of compounds having a phenolic or hydroxyl group on the aromatic ring. There are various ways of synthesis of phenolic compounds. The most important two pathways of biosynthesis are the shikimic acid pathway and the malic acid pathway. Plants produce a wide range of secondary metabolites that cover a variety of functions, such as defending a plant against herbivorous organisms, mechanically supporting the plant, attracting pollinators and fruit spreaders, or inhibiting the growth of other plants. The most commonly represented group of phenolic compounds are flavonoids. Flavonoids are synthesized via phenylpropanoids pathway and serve as UV protectors and in pathogen defense, for plant and microorganism communication and for the regulation of reactive oxygen species. There is great interest in the world for phytochemicals as bioactive food components. Consumption of fruits and vegetables in human diet can prevent some diseases due to their high antioxidant activity. Free radicals play an important role in the processes of food deterioration, the degradation of chemical materials and also contribute to more than one hundred disorders in humans. In recent years, there has been an increased interest in the use of antioxidants for medical purposes, and a great deal of attention has been paid to cereals and legumes because of their strong antioxidant properties. There are many methods of detecting phenolic compounds and calculating total antioxidant activity. They are roughly divided into two groups: in vitro methods and in vivo methods. Some of the in vitro methods are DPPH, TEAC, FRAP, SOD, ORAC and many others, and in vivo methods are GSH, GSHPx, CAT, GGT, etc