Obtaining and characterizing modified tannins by physical-chemical methods

• Published in: Central European journal of chemistry Vol. 12; no. 7; pp. 757 - 762
• Main Authors: Gonta, Alexandru, Lupascu, Tudor, Timbaliuc, Nina, Meghea, Aurelia
• Format: Journal Article
• Language: English
• Published: Heidelberg Versita 01.07.2014; De Gruyter
• Subjects: ABTS; Antioxidant; Antioxidants; Assaying; Biochemistry; Biological and Medical Physics; Biophysics; Chemiluminescence; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Geochemistry; Grapes; Oxidation; Polyphenols; Research Article; Seeds; Solubility; Tannins; Polyphenols; Tannins; Chemiluminescence; Antioxidant; ABTS
• ISSN: 1895-1066; 2391-5420; 1644-3624; 2391-5420
• DOI: 10.2478/s11532-014-0505-7

After oxidation of tannins (Tannins 1–3) extracted from grape seeds, Tanoxil compounds with increased solubility and enhanced antioxidant activities were synthesized. In this research, ABTS +· assay and a chemiluminescence method were used for antioxidant measurement of hydrophilic compounds (Tanoxils 1–3). It was observed that the antioxidant activity (AA, %) is very similar for the three samples, while at the same time AA is quite high (93.16%–96.48%). The percentage of inhibition by ABTS +· is higher for Tanoxil 2 (96.4%) as compared to Tannin 2 compound (14.34%). Moreover, the total content (T CF ) of carboxyl and phenolic groups was investigated. T CF values, determined for Tanoxil products, revealed a double (Tanoxil 1) or triple (Tanoxil 2) increase as compared to the value of the T CF of Tannin 1. Tanoxil products represent an interest for future research as they have a high AA (96.4%) and the content of acidic groups is significant (T CF , 0.191 meq g −1 ).