| Abstract | Antioksidansi su spojevi koji pokazuju veliku aktivnost u sprječavanju štetnog djelovanja slobodnih radikala. Za mjerenje antioksidativne aktivnosti spojeva služe nam različite metode među koje ubrajamo spektrometrijske, elektrokemijske i kromatografske metode. Kao ostale metode opisane su biosenzorska metoda, fluorimetrija i elektronska spinska rezonancija. U spektrometrijskim metodama, antioksidans donira vodik radikalu ili radikalskom kationu, te na taj način reagira s njim. U ovom radu objašnjene su DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)), FRAP (ferric reducing antioxidant power), ORAC (oxygen radical absorption capacity), HORAC (hydroxyl radical averting capacity), TRAP (total peroxyl radical trapping antioxidant parameter), PERAP (potassium ferricyanide reducing power) i CUPRAC (cupric reducing antioxidant power) (2,2-difenil-l-pikirhidrazil) spektrometrijske metode. Elektrokemijske metode se temelje na mjerenju intenziteta struje i potencijala radne elektrode. Ciklička voltametrija, amperometrija i biamperometrija opisane su kao najznačajnije elektrokemijske metode. Kromatografske metode temelje se na razdvajanju spojeva između stacionarne i mobilne faze iz smjese spojeva, nakon čega se antioksidativni kapacitet spojeva određuje spektrofotometrijskom metodom. U ovom radu objašnjene su plinska i tekućinska kromatografija visoke djelotvornosti (HPLC). Biosenzori se primjenjuju za određivanje antioksidansa u čijem istraživanju je uključeno praćenje superoksidnog radikala, dušikovog oksida, glutationa, urične kiseline, askorbinske kiseline ili fenolnih spojeva, a za mjerenje ukupne antioksidativne aktivnosti koriste se DNA biosenzori. Fluorometrija je metoda koja se temelji na fluorescenciji, a antioksidativni kapacitet spojeva se određuje mjerenjem fluorescencijskog i emisijskog spektra pomoću spektrofotometra. Elektronska spinska rezonancija je metoda koja se koristi za proučavanje slobodnih radikala i paramagnetskih metala u kemijskim i biološkim tkivima. |
| Abstract (english) | Antioxidants are compounds that show great activity in preventing the harmful effects of free radicals. To measure the antioxidant activity of the compounds, different methods are used, which are spectrometric, electrochemical and chromatographic ones. As other methods, the biosensor method, fluorimetry and electron spin resonance are described. In spectrometric methods, the antioxidant donates hydrogen to the radical or radical cation and thus react with it. This paper explains DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS ( 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)), FRAP (ferric reducing antioxidant power), ORAC (oxygen radical absorption capacity), HORAC (hydroxyl radical averting capacity), TRAP (total peroxyl radical trapping antioxidant parameter), PERAP (potassium ferricyanide reducing power) and CUPRAC (cupric reducing antioxidant power) spectrometric methods. Electrochemical methods are based on measuring the intensity of the current and the potential of the working electrode. Cyclic voltammetry, amperometry and biamperometry are described as the most important electrochemical methods. Chromatographic methods are based on the separation of the compounds between the stationary and the mobile phase from the mixture of compounds, after which the antioxidant capacity of the compounds is determined by spectrophotometric method. This paper describes high-resolution gas and liquid chromatography (HPLC). Biosensors are used to determine the antioxidants in which a superoxide radical, nitrogen oxide, glutathione, uric acid, ascorbic acid or phenolic compounds is monitored, and DNA biosensors are used to measure total antioxidant activity. Fluorimetry is a method based on fluorescence, and the antioxidant capacity of the compounds is determined by measuring the fluorescence and emission spectra by spectrophotometers. Electron spin resonance is a method used to study free radicals and paramagnetic metals in chemical and biological tissues. |
