Antioxidant activity of some coumarins / Antioxidačná activita niektorých kumarínov

Abstract

Nineteen derivatives of coumarin were tested on the scavenging of 2,2-diphenyl-1-picrylhydrazyl, hydroxyl and superoxide anion radicals. It was found that antioxidant activity exhibits only such coumarins that contain hydroxyl groups. The derivatives without hydroxyl group showed very low antioxidant effectiveness or they were ineffective. On the other hand, the greatest antioxidant effectiveness was exhibited by coumarin derivatives that contained hydroxyl groups in 6 or 8 position, whereas the effectiveness of derivatives with one hydroxyl group in 4, 5 or 7 position was very low. Based on scavenging of the above-mentioned radicals, it was found that the most effective scavengers were 7,8-dihydroxy-4-methylcoumarin (i.e. compound that contains two hydroxyl groups in 7 and 8 positions), (7,8-dihydroxy-2-oxo-2H-chromen-4-yl)acetic acid (this compound contains in addition to two hydroxyl groups in 7 and 8 positions also one hydroxyl group in the acidic residue), esculetin (6,7-dihydroxycoumarin) and 6,7-dihydroxy-4-methylcoumarin.Otestovali sme devatnasť derivatov kumarinu, na vychytavanie DPPH, hydroxylovych, a superoxidovych anionovych radikalov. Ich antioxidačna učinnosť bola zavisla od počtu a lokalizacie hydroxylovych skupin. Derivaty, ktore nemali žiadnu hydroxylovu skupinu boli veľmi slabo učinne, alebo vobec neučinne. Najučinnejšie vychytavače radikalov boli tie derivaty kumarinu, ktore obsahovali hydoxylove skupiny v polohe 6 alebo 8. Na druhej strane derivaty, ktore mali iba jednu hydroxylovu skupinu v polohe 4, 5 alebo 7 boli veľmi slabo učinne. Najučinnejšie vychytavače vyššie spominanych radikalov boli 7,8-dihydroxy-4-metylkumarin (zlučenina, ktora obsahuje 2 hydroxylove skupiny na benzenovom jadre v polohe 7 a 8), 7,8-dihydroxykumarin-4-yl-octova kyselina (obsahuje okrem 2 hydroxylovych skupin na benzenovom jadre ma aj OH skupinu v kyselinovom zvyšku, eskuletin (6,7-dihydroxykumarin) a 6,7-dihydroxy-4-metylkumarin.