Antioxidant Activity and Polyphenol Content of Some Brazilian Medicinal Plants Exploiting the Formation of the Fe(II)/2,2′-bipyridine Complexes

Abstract

Aqueous plant extracts contain polyphenols that reduce Fe 3+ to Fe 2+ , which in the presence of excess 2,2'-bipyridine (bipy) yield the Fe(bipy) 3 2+ complex (max = 521 nm). This reaction was used to quantify the total polyphenol content (TPC) of nineteen Brazilian medicinal species using pyrogallic acid (PA) as a standard. A calibration curve of absorbance values at 521 nm values vs. PA was linear from 0.378 to 3.03 mg L-1 (r = 0.998; n = 8) with a limit of detection 0.16 mg L-1. The TPC quantification using the proposed reaction was compared with values obtained with the Folin-Ciocalteu reagent, yielding good agreement (r = 0.965). For the same species the TPC obtained with the proposed method also resulted in good correlation (r = 0.773) with the antioxidant capacity values quantified using the 2,2-diphenyl-1-picrylhydrazyl method. It was also found that Fe(bipy) 3 2+ complexes can be used to calculate the reducing capability of polyphenols. The polyphenol structure, and the number and position of the hydroxyl group attached to the benzene ring modify this reductive capacity.

Polyphenolic Compounds and Antioxidant Activity of Cold‐Pressed Seed Oil from Finola Cultivar of Cannabis sativa L.

“…Since antioxidants terminate direct reactive oxygen species attacks and radical‐mediated oxidative reactions, appear to be of primary importance in the prevention of these diseases and health problems. Antioxidants have been detected in a number of plants and foods, including seed oils (Kalt et al ., ; Iauk et al ., ; Munro et al ., ; Santana et al ., ). Hemp seed oil shows excellent oxidative stability suggesting the possible presence of phenolic compounds that act as antioxidants in the cold‐pressed seed oil (Abuzaytoun and Shahidi, ).…”

A handy-assay procedure to measure simultaneously the polyphenol content and the antioxidant capacity in teas using the Folin Ciocalteu reagent

“…Several studies are found in the literature dealing with the determination of total polyphenol content (TPC) and the antioxidant capacity of Brazilian medicinal plant species (BLAINSKI; LOPES; MELLO, 2013;BRIGHENTE et al, 2007;HABERMANN et al, 2016;MANOEL;SANTANA;. Most of them investigated a unique part of the plant species (leaves, stem, seeds, etc.).…”

Comparative Evaluation of the Nutrients, Phytochemicals, and Antioxidant Activity of Two Hempseed Oils and Their Byproducts after Cold Pressing

“…Considering this, minimizing oxidative damage may be one of the most important approaches to the primary prevention of chronic diseases and ageing-associated health problems. Antioxidants have been detected in several plants and foods, including seed oils [ 14 , 15 ]. HSO shows excellent oxidative stability, suggesting the possible presence of secondary metabolites with strong antioxidant activity [ 6 , 16 ].…”