Avaliação da qualidade de extratos de Stryphnodendron adstringens (Martius) Coville

Abstract

Barbatimão, Stryphnodendron adstringens (Martius) Coville, is a well-known medicinal plant in the Brazilian traditional medicine. It has been used as anti-inflammatory, astringent and wound healing since the 19th century. The high concentration of condensed tannins in thebark is responsible for its therapeutic effects. In the present work, barbatimão bark glicolic (GE) and dry ethanolic extracts (EE) were prepared, by percolation. An extractive-analytical method for determining tannins in barbatimão was developed and physical-chemical qualityof barks and extracts were assayed. The bark, GE and EE were characterized by the TLC. EE were purified by liquid-liquid partition presented greater concentration of markers in the organic fraction than in aqueous fraction. Totals tannins in the extracts was quantified byultraviolet spectrophotometry (UV, _ 272 nm) and by spectrophotometric pharmacopeial visible methods (Folin Denis, FD, _ 715 nm e Folin-Ciocalteau, FC, _ 760 nm). The pharmacopeial methods were checked regarding selectivity, linearity, and accuracy and compared to the UV method, by analysis of variance. A HPLC method using linear gradientmode in reverse phase (C18), UV detection at _ 210 nm, was developed and validated for quantification of gallocatechin (GC) and epigallocatechin gallate (EGCG) in extracts. The UV method presented linearity in the concentration range 5 to 30 ìg/mL with correlation coefficient r 0.9999 (EGCG). Intra-assay precision (RSD 2.06%) and inter-assay precision(RSD 4.68%) were satisfactory, meanwhile, the recovery percentage was 99.72% (RSD 2.69%); yielded limit of detection, LOD, of 0.23 ìg/mL and limit of quantification, LOQ, of 0.71 ìg/mL. The method showed to be selective and not robust. The HPLC method showed to be selective. Linearity was achieved in the range from 30 to 330 ng with r 0.9998 (GC),r 0.9986 (EGCG); intra-assay precision, RSD 1.86% (GC) and 1.10% (EGCG), and interassay precision, RSD 5.22% (GC) and 2.77% (EGCG) were satisfactory; accuracy presented 76.50% (RSD 4.53% for GC) and 104.98% (RSD 3.21% for EGCG) of recovery; LOD was 2.95 ng and LOQ was 8.94 ng for GC; for EGCG, LOD was 8.81 ng and LOQ was 26.69 ng.The method showed to be robust for GC and partially robust for GEGC. The organic fraction of S. adstringens EE showed an amount of 1.35% (GC) and 1.32% (EGCG), and S. obovatum EE presented an amount of 1.22% (GC) and 1.42% (EGCG), by HPLC. By determining 3-flavonol derivative markers in the fractions of the dry extracts it is possible tostandardize the intermediate products and to perform a better quality control for the finished products.