Determination of Free and Bound Phenolic Acids, and Evaluation of Antioxidant Activities and Total Polyphenolic Contents in Selected Pearled Barley

• Published in: Food Science and Technology Research Vol. 16; no. 3; pp. 215 - 224
• Main Authors: Yoshida, Atsuko, Sonoda, Keisuke, Nogata, Yoichi, Nagamine, Takashi, Sato, Maki, Oki, Tomoyuki, Hashimoto, Shujiro, Ohta, Hideaki
• Format: Journal Article
• Language: English
• Published: Tsukuba Japanese Society for Food Science and Technology 2010; Japan Science and Technology Agency
• Subjects: antioxidant; antioxidant activity; barley; bound phenolic acid; bound phenolic acids; caffeic acid; chemical constituents of plants; cultivars; DPPH; ferulic acid; food composition; free phenolic acids; functional foods; genetic variation; geographical variation; Hordeum vulgare; insoluble; medicinal properties; ORAC; oxidative stress; p-coumaric acid; pearled barley; phenolic acids; polyphenols; quantitative analysis; seeds; sinapic acid; Canada; Sweden; Australia; Japan
• ISSN: 1344-6606; 1881-3984
• DOI: 10.3136/fstr.16.215

The content of insoluble bound phenolic acids in pearled barley was determined by an analytical system consisting of alkaline hydrolysis extraction, high-performance liquid chromatographic separation and electrochemical detection. Insoluble bound phenolic acids in five pearled cultivars and fifteen breeding lines of barley comprised ferulic acid (4.3-34.2mg/100 g dry matter), sinapic acid (0.025-0.445 mg/100 g), caffeic acid(0.002-0.016 mg/100 g). Soluble free polyphenols comprised procyanidins(12.2-80.3 mg/100 g), catechin (0.1-28.2 mg/100 g), and total pholyphenolcomprised 152.4-324.0 mg-gallic acid equivalents/100 g. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity for the barley samples ranged from 403 to 1501 μmol-Trolox equivalents/100 g whereas those of oxygen radical absorbance capacity (ORAC) ranged from 1050 to 3816 μmol-Trolox equivalents/100 g. High correlation (0.980, p<0.01) was found between the DPPH and ORAC assays. Total polyphenol contents positively correlated with the DPPH (0.875, p<0.01)and ORAC (0.881, p<0.01)assays. The correlation coefficient between insoluble bound phenolic acids and total polyphenol contents was higher than that between soluble free polyphenols and total poly-phenol contents. Taken together, the insoluble bound phenolic acids appear to greately contributed to the antioxidant activity in pearled barley.