Characterization of the bioactive composition of ground ivy (Glechoma hederacea L.) using fractionation of poylphenolic compounds

Dobričica (Glechoma hederacea L.) je ljekovita biljka s dugom tradicijom primjene u narodnoj medicini. Biološki aktivne komponente dobričice odgovorne za njezina ljekovita svojstva su polifenolni spojevi. U svrhu detaljnije karakterizacije polifenolnog sastava dobričice, cilj rada bio je primjenom postupka frakcioniranja izdvojiti i analizirati četiri frakcije: slobodni topljivi, esterificirani, glikozilirani i netopljivi vezani polifenolni spojevi. Dobivene frakcije analizirane su primjenom spektrofotometrije (udjel ukupnih polifenola i antioksidacijski kapacitet) te HPLC-DAD (pojedinačni polifenolni spojevi) metodologije. U dobričici su polifenoli većinski prisutni kao esteri kafeinske kiseline - ružmarinska (6,64 mg g-1s.tv.) i klorogenska kiselina (1,11 mg g-1s.tv.) te kao flavonoid rutin (1,87 mg g-1s.tv.). U frakciji glikoziliranih polifenolnih spojeva identificiran je kvercetin što potvrđuje da je rutin dominantan glikozid u izvornom ekstraktu. Prisutnost sinapinske kiseline u frakciji esterificiranih polifenolnih spojeva upućuje na moguće postojanje složenijih esterificiranih konjugata. Vezani polifenolni spojevi nemaju izražen doprinos na polifenolni sastav dobričice. Najveći antioksidacijski kapacitet, prema ABTS i DPPH metodi, određen je u frakciji slobodnih topljivih polifenolnih spojeva (80,15 μmol Trolox-a g-1s.t.v. ABTS; 70,25 μmol Trolox-a g-1s.t.v. DPPH). Dobričica se može smatrati dobrim izvorom polifenola izraženog antioksidacijskog kapaciteta.Ground ivy (Glechoma hederacea L.) is a medicinal plant which has been widely used in folk medicine. Biologically active compounds responsible for its medicinal properties are polyphenols. For the purpose of more detailed characterization of the polyphenolic composition of ground ivy, the aim of this study was to isolate and analyse four fractions using fractionation: free soluble, esterified, glycosylated and insoluble bound polyphenols. The obtained fractions were analysed using spectrophotometry (total polyphenol content and antioxidant capacity) and HPLC-DAD methodology (individual polyphenolic compounds). In ground ivy, polyphenols were mostly present as esters of caffeic acid – rosmarinic (6.64 mg g-1dmb.) and chlorogenic acid (1.11 mg g-1dmb.), as well as, flavonoid rutin (1.87 mg g-1dmb.). Quercetin was detected in glycosylated phenolic fraction confirming rutin as dominant gylcoside in the intial extract. Presence of sinapic acid in esterified phenolic fraction implies possible existence of more complex esterified conjugates. Insoluble bound phenolics do not contribute significantly to the polyphenol composition of ground ivy. The highest antioxidant capacity, according to ABTS and DPPH assays, was determined in free soluble phenolic fraction (80.15 μmol Trolox-a g-1dmb. ABTS; 70.25 μmol Trolox-a g-1dmb. DPPH). Ground ivy can be considered as a relatively good source of polyphenols with a potent antioxidant capacity