Although humic acids (HAs) from peat exhibit various therapeutic properties, there is\nlittle information available concerning their physicochemical and antioxidant properties. To address\nthis issue, nine different types of peat, including oligotrophic, mesotrophic, and minerotrophic peat\nsamples, were used for isolation ofHA fractions by basic (HAb) and pyrophosphate (HAp) extractions.\nPhysical parameters of the HAs were analyzed by UV-Vis, fluorescent, infrared (IR), and electron\nparamagnetic resonance (EPR) spectroscopy. AverageMr of the fractions ranged from 17.2 to 39.7 kDa,\nwhile their humification index (HIX) varied from 0.49 to 1.21. HAp fractions had a higher content of\naromatic structures compared to HAb fractions. Moreover, HAp fractions had a significantly higher\ncontent of phenolic OH groups (3.6 �± 0.5 mmol/g) versus HAb (3.1 �± 0.5 mmol/g). All HA fractions\nexhibited antioxidant activity in radical scavenging and electrochemical assays, and their EPR signal\nhad a single line with g = 2.0035, which is consistent with semiquinone type radicals. Furthermore,\nthe HIX was found to be important in determining the number of semiquinone-type free radicals\nin the HA structures. Overall, these data provide a molecular basis to explain at least part of the\nbeneficial therapeutic properties of peat-derived HAs.
Loading....