Caracterização fisiológica e produção de metabólitos secundários em Achillea millefolium L. após aplicação de quitosana

Elicitation with chitosan is a tool used to improve the responses of plant defense by inducing secondary metabolism routs. In addition, the adequate application of this elicitor on medicinal plants can promote the increase of major components in the composition of the oil. However, we lack information concerning which are the main physiological processes responsible for the changes in the composition of the oil. Thus, we aimed at evaluating the action of chitosan and determine an ideal concentration for optimizing the production of essential oil in Achillea millefolium L. and the changes in the physiological processes responsible for this increase. The research was conducted in greenhouse of the Plant Physiology sector of the Universidade Federal de Lavras (UFLA) with A. millefolium plants. The treatments consisted of control (water); acetic acid solvent (with no elicitor); and chitosan in the concentrations of 2, 4 and 6 g L -1 . The measurements of growth, gas exchange, enzyme activity of the antioxidant system and phenylalanine ammonia lyase (PAL), in addition to the production and composition of the essential oil. We verified that the application of chitosan promoted decrease in plant growth. However, the concentration of 4 g L -1 of chitosan induced an increase in the content and yield of the essential oil. In the oil, there was predominance of sesquiterpenic compounds, including the major compounds borneol, β-caryophyllene, β-cubebene, α-farnesene and chamazulene. The elicitation with chitosan at 4 g L -1 promoted an increase of the photosynthetic rate, activity of the antioxidant system and of PAL, however, this increase occurred in short-term, only in the first days after elicitation.

Síntese do complexo ferro (III) com ácido pirazina tetracarboxílico e aplicação como catalisador em reação fenton

The amount of waste generated by industries has increased gradually in recent years. The proper disposal of residues has been an area of study of many researchers. Several organic compounds are considered potential contaminants of natural waters due to their high toxicity, difficult natural degradation and long persistence in the environment. Ways of recovery and reutilization as well as concepts that minimize the generation of wastes have been increasing widely. Organometallic compound of pyrazine carboxylic acid has proven to be of great interest in many areas. Herein, we studied the use of pyrazine tetracarboxylic acid ligand for complex formation with iron (Fe). The binder (C 8H4N2O8) was synthetized with the addition of Fe (complex) and tested as a catalyst in oxidation reactions of the organic model compound methylene blue (MB). Tetramethyl pyrazine was used in the synthesis, which was oxidized with potassium permanganate in order to form the ligand. The ligand (C 8H4N2O8) was then characterized to validate its formation. For the complex solution, it was used (C 8H4N2O8) and Fe (NO3)3.9H2O 0,01molL-1. After preliminary tests, it was found that the best ratio of Fe and the ligand was 2: 1. Through the oxidation tests, it could be seen that the complex has great potential for the degradation of different concentrations of MB. During only 20 minutes of reaction, approximately 60% of MB 500 mgL -1 was oxidized. The use of the complex was found to be an attractive alternative for oxidation of effluents with high organic compounds levels and contributes to the minimization of organic contaminants hazards in the environment.

An alternative method for the simultaneous determination of copper and lead for quality control of sugar cane spirit using a nanotube-based sensor

The development of an electroanalytical method for simultaneous determination of copper and lead ions in sugar cane spirit (cachaça) using carbon paste electrode modified with ascorbic acid and carbon nanotubes (CPE-AaCNT) is described. Squarewave voltammetry (SWV) with anodic stripping was employed, and this technique was optimized with respect to the following parameters: frequency (50 Hz), amplitude (100 mV) and scan increment (9 mV). The analytical curves were linear in the range from 0.0900 to 7.00 mg L - 1 for lead and copper. The limits of detection were 48.5 and 23.9 µg L - 1 for lead and copper, respectively. The developed method was applied to the simultaneous determination of copper and lead in five commercial samples of sugar cane spirit. The results were in good agreement with those obtained by F AAS/GF AAS (flame atomic absorption spectrometry/graphite furnace atomic absorption spectrometry) and showed that CPE-AaCNT can be successfully employed in the simultaneous determination of these metals in real sugar cane spirit samples.