TITLE:
A new method for quantification of total polyphenol content in medicinal plants based on the reduction of Fe(III)/1,10-phenanthroline complexes
AUTHORS:
Mônica Gabriela do Santo, Cecilia Veronica Nunez, Horacio Dorigan Moya
KEYWORDS:
Polyphenols; Medicinal Brazilian Plants; 1, 10-Phenanthroline; Iron (III); Antioxidant Activity
JOURNAL NAME:
Advances in Biological Chemistry,
Vol.3 No.6,
December
12,
2013
ABSTRACT: This paper proposes an
alternative analytical spectrophotometric method for the total polyphenol
quantification in the aqueous extract of plants. When these extracts are added
to solutions of Fe(III), in presence of 1,10-phenanthroline, the absorbance
values at 551 nm (A511nm) due to the complexes formed are proportional to the total polyphenol concentration
expressed as pyrogallic acid (PA). A typical
calibration graph of A511nm values vs. PA is linear from 0.16 to 0.64 mg L-1 (r = 0.994,
n = 6) with a limit of detection 0.041 mg L-1. The results of the polyphenol content of the aqueous
extracts of twenty medicinal Brazilian plants obtained with the proposed method
were compared with values using the Folin-Ciocalteu reagent. A paired t-test
revealed no statistically significant difference for the species analyzed. The total antioxidant capacity of the same twenty extracts was determined based on the scavenging of stable radical DPPH.