INVESTIGATION OF PHYTOCHEMICAL COMPOSITION AND IN VITRO ANTIOXIDANT POTENTIAL OF DIFFERENT EXTRACTS AND GYROPHORIC ACID DERIVED FROM THE LICHEN UMBILICARIA GRISEA GROWING IN SERBIA

This study investigates the chemical composition, total phenolic and flavonoid content and antioxidant activity of acetone, methanol and ethanolic extracts of the poorly researched lichen Umbilicaria grisea and its major secondary metabolite, gyrophoric acid.The phytochemical composition was determined by high-performance liquid chromatography (HPLC-UV).In addition to gyrophoric, lecanoric and umbilicaric acid, the examined extracts also contain depsidone norstictic acid and depside atranorin, which were identified for the first time in this species.The study assessed the phenolic and flavonoid content of different solvent extracts from U. grisea, revealing that the methanolic extract exhibited the highest phenolic content (67.128 0.222 mg GAE/g Dry Extract), followed by acetonic (56.615 0.385) and ethanol (44.821 0.801) extracts.Total flavonoid content, expressed as rutin and quercetin equivalents, varied significantly among extracts, with acetone demonstrating the highest efficiency for flavonoid extraction from U. grisea.The antioxidant activity of tested extracts was estimated spectrophotometrically by determining the ability to scavenge DPPH and ABTS radicals.The acetone extract showed slightly enhanceds antioxidant activity compared to the other two extracts in both tests.Also, gyrophoric acid shows significantly better antioxidant activity compared to all extracts, but weaker compared to ascorbic acid and Trolox.These findings indicate the potential of extracts from U. grisea as sources of natural antioxidants. RezumatAcest studiu evalueaz compoziia chimic, coninutul total fenolic i flavonoidic, precum i activitatea antioxidant a extractelor obinute n aceton, metanol i etanol din lichenul Umbilicaria grisea, i ale metabolitului su secundar principal, acidul giroforic.Compoziia fitochimic a fost determinat prin HPLC-UV.Pe lng acizii giroforic, lecanoric i ombilicaric, extractele examinate mai conin acid depsidon-norstictic i depsid-atranorin, care au fost identificate pentru prima dat la aceast specie.Studiul a evaluat coninutul fenolic i flavonoidic al diferitelor extracte n solveni diferii din U. grisea, evideniind c extractul metanolic a prezentat cel mai mare coninut fenolic (67,128 0,222 mg GAE/g extract uscat), urmat de extractul acetonic (56,615 0,385) i cel etanolic (44,821 0,801).Coninutul total de flavonoide, exprimat ca echivaleni de rutin i quercetin, a variat semnificativ ntre extracte, cel obinut n aceton demonstrnd cea mai mare eficacitate pentru extracia de flavonoide din U. grisea.Activitatea antioxidant a extractelor testate a fost estimat prin determinarea capacitii de a chelata radicalii DPPH i ABTS.Extractul acetonic a artat o activitate antioxidant superioar celorlalte dou extracte, prin ambele teste efectuate.De asemenea, acidul giroforic prezint o activitate antioxidant semnificativ mai bun n comparaie cu toate extractele, dar redus comparativ cu acidul ascorbic i Trolox.Aceste rezultate indic potenialul extractelor din U. grisea ca surse de antioxidani naturali.