Seasonal variation in the phenol content of Eugenia uniflora L. leaves / Variação sazonal nos teores de fenóis de folhas de Eugenia uniflora L

Hydrolysable tannins, total phenols and flavonoids in Eugenia uniflora leaves were monthly analysed for one year. The results were correlated with climate conditions (rainfall, humidity, cloudiness and mean temperature) through chemometric methods. Principal component analysis revealed high levels of hydrolysable tannins in the rainy season, whereas flavonoids were mainly produced in the dry season. These facts suggest that climatic changes may be one of the factors affecting phenol levels in Eugenia uniflora.

Taninos hidrolisáveis, fenóis totais e flavonóides presentes em folhas de Eugenia uniflora foram quantificados mensalmente durante um ano. Os resultados foram correlacionados com as condições climáticas (pluviosidade, umidade, nebulosidade e temperatura média) através de métodos quimiométricos. Análise de componentes principais revelou a ocorrência de altos teores de taninos hidrolisáveis durante a estação de chuvas, enquanto os flavonóides foram produzidos principalmente na estação seca. Estes fatos sugerem que mudanças climáticas podem ser um dos fatores que afetam os níveis de fenóis em Eugenia uniflora.

[Investigation of the best method for extraction of phenolic compounds from echinaceae purpurea L. [moench]]

Echinacea spp. Have been used in traditional medicine for many years. Recently, many investigations have been done on this plant and they showed that the plant is an immunostimulant agent. The plant contains different components such as flavonoids, phenolic compounds and isobutylamides. Phenolics are one of the most important agents in immunostimulant effects of the plant; therefore, determination of a method for the best extraction of these compounds from the plant is important. In this research, the effects of solvent, extraction procedure, plant particle size and plant: solvent ratio on extraction of phenolic compounds of Echinacea purpurea [L.] Moench have been investigated. Different polar and non-polar solvents from hexane to acidic water were used in order to determine the best solvent for phenolics extraction. Moreover, the methods of maceration, sonification, perculation, digestion and continuous extraction [by use of soxhelet apparatus], different particle sizes of the plant powder and various plant: solvent ratios were examined as well. The results showed that the best method for extraction of phenolics is methanol: water 80:20 as solvent, method of digestion [2h, 50[degree sign] C], particle size of 300 micro m for the plant powder and plant :solvent ratio of 1:200. It can be concluded that in order to efficient extraction of phenolic compounds from Echinacea purpurea aerial parts, special condition should be considered