Aumento da fitorremediação do ácido 2,4-diclorofenoxiacético por Plectranthus neochilus, através de estimulos luminosos com diodos emissores de luz

Abstract

Plectranthus neochilus is a herbaceous and aromatic plant widely used in local medicine for the treatment of indigestion, diseases related to the digestive system, skin infections, respiratory diseases, liver failure, and dyspepsia. In addition, P. neochilus is a known phytoremediation agent of the herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D). The medicinal properties of tea are due to the functional properties of the plant's bioactive compounds. These compounds, in turn, are the result of secondary metabolism, mainly phenolic compounds and alkaloids, in species of the genus Plectranthus. These metabolites are responsible for the defense system of plants and have known antioxidant potential, arousing interest in their variety of pharmacological actions. These changes can contribute to the increase in phytoremediation of 2,4-D by bilberry, in view of the possible increase in tolerance to oxidative stress caused by pesticide poisoning. In this perspective, this dissertation aims to investigate the use of bilberry (P. neochilus) in two different biases, aiming to find the best way to prepare the infusion (best way to extract the bioactive phenolic compounds) by testing different conditions of infusion of the bilberry. And in another way, aiming to increase the phytoremediation potential of the boldo against the herbicide 2,4-D, using light stimuli through LEDs of different colors, in both cases validating the chromatographic methods by high performance liquid chromatography coupled to detector diode array (CLAE-DAD) for the quantification of 9 phenolic compounds in infusions of P. neochilus, and another method for the quantification of 2,4-D in phytoremediation waters. First, the infusions (10 mg / mL) were performed under the following conditions: 1) fresh whole leaves with and without agitation; 2) dry macerated leaves with and without agitation. The method used solid phase extraction (EFS) following analysis by HPLC-DAD for the quantification of phenolic compounds (rutin quercetin and 3-4-dihydroxybenzoic acids, rutin, caffeic, coumaric, chlorogenic, ferulic, synergic, and gallic). We investigated the levels of total phenolic compounds, soluble solids, and total antioxidant capacity (DPPH and reduction of phosphomolibdenum) in infusions. The influence of LEDs on the phytoremediation of 2,4-D by P. neochilus was evaluated with the following samples: natural light, white LED, blue LED and red LED with and without the plant for 28 days. Samples of 10 mL of water were taken every 7 days to monitor phytoremediation in all treatments. The chromatographic methods passed the following validation parameters: selectivity, linearity (r2), precision, limits of detection and quantification (LOD and LOQ), relative standard deviation (RSD), and recovery (only for the phenolic compounds method). Both chromatographic methods proved to be reliable and reproducible for the quantification of the compounds of interest, going through all the validation steps. Dry leaf infusions had a higher amount of phenolic compounds and soluble solids, and consequently greater antioxidant potential, as well as Rutin and caffeic acid were quantified only in these infusions. However, the stirred infusion provided greater extraction of phenolic compounds and soluble solids. The efficiency of the association of LEDs with P. neochilus in the 28 days occurred in the following sequence: ambient light + plant (47.0%); white + plant (37.10%); blue + plant (26.80%); red + plant (3.32%). The advantage of using LEDs in association with the plant was confirmed by the results obtained with their respective controls, which were between 40.0% and 55.0%. The results showed that infusions of P. neochilus with dry leaves prepared under constant agitation provided greater extraction of bioactive compounds and showed for the first time the increase in 2,4-D phytoremediation in water by P. neochilus, through light stimuli with LEDs.