Obtenção de taninos a partir do extrato hidroalcoólico de folhas e flores de Lippia alba

Abstract

The Lippia alba plant is an aromatic shrub commonly known as lemon balm or Melissa and it is widely studied of the genus Lippia due to its medicinal properties. The main reason for studying the chemistry metabolism of the plant is because of the vast amount of chemical structures found in their organic constituents. Among the secondary metabolites that occur after the growth phase are flavonoids, polyphenolic compounds that aggregate various classes of metabolites, including tannins. Tannins are compounds largely distributed amongst plants and known for have bitter taste and molecular weight between 500 and 3000 a.m.u. These compounds are vastly used in tanning leather, pharmaceutical, and other industries. The extracts can also be used as flocculants or coagulants. Due to their chemical structure, the tannins are classified as hydrolysable - having ester bonds liable of undergoing hydrolysis, while condensed tannins are more resistant to fragmentation of molecules and have polymeric structure. With purpose to obtainment tannins from leaves and flowers of Lippia alba, qualitative experiments were performed using different solvents and concentrations in order to determine which was the best solvent to obtain significant results. After performing the qualitative tests, the quantitatives were initiated, in which the methods used were based on the reaction of Stiasny described by Trugilhoet al. (2003) and also others Stiasny methods described by Brazilian Society of Pharmacognosy (2009). The results obtained from the extraction and use of different methodologies of quantification were identified as significant results, with the best response was obtained with the 6:4 solvent system of the sheet. The best yield level of condensed tannin was achieved at the first day, using both Trugilho et al. (2003) and to the Brazilian Society of Pharmacognosy (2009).