Resazurin Method for Evaluation of Bioactive Compounds from Cranberry Extracts Using the Metabolic Activity of a Delta SOD1 Mutant of Saccharomyces cerevisiae Yeast Under Severe Osmotic Stress

摘要

Background: In addition to nutrients, plant raw materials for food production should also contain substances with beneficial biological properties, which unquestionably include antioxidant compounds. Among the numerous methods of determining the antioxidant properties of samples of plant material, biological methods that provide information about not only the in vivo antioxidant potential of samples but also their metabolism and bioavailability are increasingly valued. Objective: The aim of the study was to assess the antioxidant properties of extracts from large cranberry (Vaccinium macrocarpon) obtained from different producers. Methods: Biologically active compounds were extracted from cranberry fruits using water alone and ethyl alcohol-water in proportions of 1+1 and 4+1 (v/v) as solvents. The following were determined in the extracts: content of phenolic compounds and anthocyanins, total antioxidant capacity based on reduction of the ABTS(+center dot) [2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)] radical cation, and antioxidant properties as reflected by the growth of a Saccharomyces cerevisiae Delta sod1 mutant in a liquid hypertonic environment. The growth parameters of this Delta sod1 mutant, monitored by a method exploiting a color reaction with resazurin, reflected the antioxidant properties of the extracts. Results: The ethanol-water cranberry extracts showed higher content of polyphenols, anthocyanins, and total antioxidants expressed as Trolox equivalent, determined on the basis of ABTS(+center dot) reduction. Conclusions: The antioxidant properties determined by the bioassay did not respond strongly to the data obtained in the in vitro chemical and biochemical assays, because they were more closely associated with the batch of fruit than with the type of solvent used to extract phytochemicals.