Determinación del potencial inhibitorio de la fracción alcaloidal de Psychotria viridis sobre xantina oxidasa y radical superóxido mediante autografía.

Abstract

The objective of this investigation was to determine the inhibitory potential of the isolated alkaloid fraction of Psychotria viridis in the enzyme xanthine oxidase (XO) and the superoxide radical by autograph. To evaluate the enzyme inhibition, different concentrations of the alkaloid fraction (1, 10, 50, 100 ug) dissolved in a mixture of phosphate solution after pH 7.9 and dimethylsulfoxide were used as a solubility improver (0.25%), and XO. Similarly, two methods were used to determine the ability to capture capacity superoxide radicals; the first consists of riboflavin (B2), nitro blue tetrazolium (NBT) and light system, and the second consists of nicotin adenine in dinucleotide reduced (NADH) tetrazolium nitro blue (NBT) and phenazine methosulfate (PMS). The tests were carried out on thin layer chromatography plates, in which the samples were seeded by the dot blot technique. Once positive results were obtained in the previous autographic tests, experiments were carried out on 96-well microplates and a microelisa reader, for the determination of the mean inhibitory concentration (IC50) of the alkaloidal fraction and suitable comparison standards (ascorbic acid, acid gallic acid and allopurinol) both for the enzyme inhibition test, and for the superoxide radical uptake tests. It was established that the alkaloidal fraction of Psychotria viridis does not exhibit a significant inhibitory capacity on XO at the concentrations tested (4-32 ug/mL); however, it shows a very appreciable superoxide radical scavenging capacity, with IC50 values of 0.94±0.064 ug/mL and 16.01±0.14 ug/mL in the B2 / LUZ / NBT and NADH / PMS / NBT systems, respectively; even exceeding the controls tested, ascorbic acid IC50 2.03±0.026 ug/mL and gallic acid IC50 22.6±0.78 ug/mL. The above creates many expectations for further research in the field of the antioxidant potential of the molecules present in the alkaloidal fraction of Psychotria viridis. It is recommended to continue with the studies of structural elucidation.