Analytical Characterization of Pomegranate Peel Extract

The detailed procedure for preparing and analyzing PoPEx was published in our previous paper [27 (link)]. The powdered pomegranate peel was prepared from pomegranate fruits collected at a natural locality in southern Bosnia and Herzegovina. The peel was extracted with 50% ethanol, using 1:10 as a solid-to-solvent ratio. After filtration and evaporation, the extract was analyzed spectrophotometrically by the Folin–Ciocalteu method, where gallic acid was used to prepare the calibration curve. The results were expressed as mg of gallic acid equivalents per gram of dry weight. The pomegranate peel was deposited in the Botanical Garden “Jevremovac” University of Belgrade (voucher specimen No. BEOU 17742). HPLC analysis was performed on Agilent 1200 RR HPLC (Agilent, Waldbronn, Germany), equipped with a DAD detector, using reverse-phase analytical column Zorbax SB-C18 (Agilent, Waldbronn, Germany). Detection was performed at 260 and 320 nm. The quantity of analyzed compounds (punicalagin, punicalin, gallic acid, and ellagic acid) was calculated using calibration curves of authentic standards (Supplementary Figure S4). The results are expressed as mg per gram of dry weight. Experiments were repeated three times. Their mean content was as follows: punicalagin 67.26 ± 0.81 mg/g, punicalin 31.91 ± 0.22 mg/g, ellagic acid 25.11 ± 0.06 mg/g, and gallic acid 9.75 ± 0.05 mg/g.