Inhibición de la polifenoloxidasa extraída del banano (cavendish) por medio de algunos derivados del isoespintanol
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Date
2012-04-12
Journal Title
Journal ISSN
Volume Title
Publisher
Corporación Universitaria Lasallista
Abstract
Abstract
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).
Description
Keywords
Banano (Cavendish Gigante), Corporación Universitaria Lasallista, Antioxidantes, Pardeamiento enzimático, Industria alimenticia, Industria agrícola, Frutas - Calidad, Isoespintano