Gil Garzón, Maritza AndreaRojano, Benjamín AlbertoGuerrero, Carlos Andrés2012-04-122012-04-122012-04-12978-958-8406-14-5http://hdl.handle.net/10567/148Abstract Introduction. Looking for new sources of natural compounds with anti-oxidant activity, a great variety of phenolic plants have been being found. They have a high protective power on the enzymatic browning, responsible for undesired color changes in fresh fruits and vegetables. Objective. In this work, enzymatic browning inhibition of polyphenol oxidase, PPO, extracted from Giant Cavendish bananas (export type) is studied, by the use of the dopamine substratum. Methodology. The inhibitors used were: Isoespintanol (a metabolite extracted from Oxandra cf. xylopioides (Annonaceae) and two of its analogs: 2-isopropyl-4 -bromo-3 ,6-dimethoxy-5-methylphenol and 3-isopropyl-6-methyl-1, 2,4-trihydroxybenzene, which were simultaneously obtained by the use of the bromination method with dimethylsulphonium bromide in a (75:25) relation, respectively. Also, ascorbic acid was used as a reference anti-oxidant. The compounds synthesized were characterized by performing a magnetic resonance spectroscopy and a chromatography coupled to masses and its anti-oxidant capability was evaluated with the ABTS, FRAP and DPPH methods. PPO´s activity, partially purified, was analyzed on the enzymatic extract, spectrophotometrically, at 30°C before the anti-oxidants at 500, 1000 and 1500 ppm. Results and analysis. Isoespintanol had the best response under the three anti-oxidant capability techniques, while the bromination had the best reduction capability under the FRAP method and the demethylated had a better performance in the methanolic medium. PPO´s activity was 102.3 activity units, this means that thee was a reduction between 72.5 and 92% with al of the compounds. The highest inhibition was achieved at 1500 ppm of ascorbic acid (92%). With the inhibition of the enzymatic activity for the brominated and the demethylated compound there were no significant differences, (P>0.05) at 500 ppm (84.8 – 84.53%), 1000 ppm (73.87 - 72.53%) and 1500 ppm (84 – 82.4%), respectively. The opposite took place for the isoespintanol concerning its two analogs, at 1000 ppm (42.4%), which obtained significant statistic differences (P>0.05). The inhibition type was studied for isoespintanol, which had a competitive inhibition (KI=0.015M y KM=0.026M).esBanano (Cavendish Gigante)Corporación Universitaria LasallistaAntioxidantesPardeamiento enzimáticoIndustria alimenticiaIndustria agrícolaFrutas - CalidadIsoespintanoBook chapter