Antimutagenic and antioxidant activities of quebracho phenolics (Schinopsis balansae) recovered from tannery wastewaters

Quebracho extracts are used in tannery due to their high concentration of phenolics. The Mexican tannery industry uses around 450 kg/m3 of which, 150 kg/m3 remains in wastewaters and are discharged in drain pipe systems or rivers. The quebracho phenolics recovered from tannery wastewater (QPTW) was characterized by HPLC. The antimutagenic and antioxidant activities as well as the microbiological quality were evaluated. Total phenolic content of QPTW was 621 mg catechin equivalent/g sample. Gallic and protocatechuic acids were the major components characterized by HPLC. QPTW showed an inhibition range on aflatoxin B1 mutagenicity from 16 to 60% and was dose-dependent. Antioxidant activity (defined as β-carotene bleaching) of QPTW (64.4%) at a dose of 12.3 mg/mL was similar to that of BHT (68.7%) at a dose of 0.33 mg/mL, but lower than Trolox (90.8% at a dose of 2.5 mg/mL); meanwhile antiradical activity (measured as reduction of DPPH) (60.8%) was higher than that of BHT (50.8%) and Trolox (34.2%). Quebracho residues were demonstrated to be an outstanding source of phenolic acids and for research and industrial uses.