title: A critical study of use of the Fe(II)/3-hydroxy-4-nitroso-2,7-naphthalenedisulfonic acid complexes in the quantification of polyphenols in medicinal plants.
abstract: A critical study of the use of the Fe(III)/3-hydroxy-4-nitroso-2,7-naphthalenedisulfonic acid (NRS) complexes on the quantification of the polyphenols content in aqueous extracts of plants, expressed as pyrogallic acid, [PA], is presented. The reaction used is based on the reduction of Fe(III) to Fe(II) by [PA] in the presence of NRS in a buffered medium (Tris; pH 8.0) with formation of Fe(II)/NRS complexes. A calibration curve of absorbance (at 730 nm) vs. [PA] is linear (r=0.998; n=7) from 1.0 to 7.0 μmolL(-1) [PA]. LD and RSD were 0.5 μmolL(-1) and 2.5% (6.0 μmolL(-1) [PA], n=10), respectively. The influence of pH, type of buffer solution and interfering species possibly present in the samples were evaluated. Aqueous extracts of twelve medicinal plants used in the Brazilian folk medicine were analysed by using both Fe(III)/NRS complexes and the Folin-Ciocalteu reagent.
authors: CEPES (Centro de Estudos, Pesquisa, Prevenção e Tratamento em Saúde), CEP 09060-650, Santo André, SP, Brazil.
authors: Diego Xavier
authors: DX
authors: da Silva
authors: Maryane Woth
authors: MW
authors: de Souza
authors: Camila Dos Santos
authors: Cdos S
authors: Corrêa
authors: Horacio Dorigan
authors: HD
authors: Moya
mesh_terms: D001938:Brazil; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D005296:Ferrous Compounds / Q000737:chemistry*; D009282:Naphthalenesulfonates / Q000737:chemistry*; D010936:Plant Extracts / Q000032:analysis*; D010946:Plants, Medicinal / Q000737:chemistry*; D059808:Polyphenols / Q000032:analysis*
chemical_list: D005296:Ferrous Compounds; D009282:Naphthalenesulfonates; D010936:Plant Extracts; D059808:Polyphenols