Methodology Optimization for Quantification of Total Phenolics and Individual Phenolic Acids in Sweetpotato (Ipomoea batatas L.) Roots

Abstract

Phenolic acids are one of the several classes of naturally occurring antioxidant compounds found in sweetpotatoes. Simplified, robust, and rapid methodologies were optimized to quantify total and individual phenolic acids in sweetpotato roots. Total phenolic acid content was quantified spectrophotometrically using both Folin-Denis and Folin-Ciocalteu reagents. The Folin-Ciocalteu reagent gave an overestimation of total phenolic acids due to the absorbance of interfering compounds (that is, reducing sugars and ascorbic acid). Individual phenolic acids were quantified by high-performance liquid chromatography (HPLC) using the latest in column technology. Four reversed-phase C18 analytical columns with different properties (dimensions, particle size, particle shape, pore size, and carbon load) were compared. Three different mobile phases using isocratic conditions were also evaluated. A column (4.6 x 150 mm) packed with 5-microm spherical silica particles of pore size 110 A combined with 14% carbon load provided the best and fast separation of individual phenolic acids (that is, chlorogenic acid, caffeic acid, and 3 isomers of dicaffeoylquinic acid) with a total analysis time of less than 7 min. Among the 3 mobile phases tested, a mobile phase consisting of 1% (v/v) formic acid aqueous solution: acetonitrile: 2-propanol, pH 2.5 (70:22:8, v/v/v) gave adequate separation. Among the solvents tested, aqueous mixtures (80:20, solvent:water) of methanol and ethanol provided higher phenolic acid extraction efficiency than the aqueous mixture of acetone.

The Content and Antioxidant Activity of Phenolic Compounds in Cold‐pressed Plant Oils

“…The presence of ascorbic acid or other very easily oxidized substances, not considered as phenolic compounds, may also result in the (Singleton et al 1999;Shahidi and Naczk 2004). It has been argued that Folin reagents may be inappropriate for plant extracts with high levels of other easily oxidizable substances (Padda and Picha 2007).…”

The Anti-angiogenic Effect of Chlorogenic Acid on Choroidal Neovascularization

“…Many potential beneficial nutritional effects on retinal diseases are still insufficiently understood. Chlorogenic acid is particularly abundant in coffee, but it is also the principal phenolic acid found in common foods such as sweet potatoes and apples [15,16]. Chlorogenic acid has been shown to have biological activities, including anti-oxidant, anti-inflammatory, and anticarcinogenic effects.…”

Effect of Home-Cooking Methods on Phenolic Composition and Antioxidant Activity of Sweetpotato (<i>Ipomoea batatas</i> (L.) Lam.) Cultivars Grown in Egypt

“…Isolation and quantification of individual phenolic acids were obtained using a reversed-phase HPLC method described by Padda and Picha [28]. The phenolic extracts were analyzed using an Agilent 1200 Series HPLC System equipped with a UV/Vis Detector at 320 nm.…”