title: Study on total phenolic contents and their antioxidant activities of Thai white, red and black rice bran extracts.
abstract: In this study, different brans of Thai rice cultivars which were divided into 3 groups: white color (Hom mali 105, Supan, Saohai, Hom chaiya and Hom jun), red color (3256, GS 18003, 21606, 21699 and 5718) and black color (96041-20, 96051-37, 96004-49, 96023-35 and 96065-42) were investigated their Total Phenolic Content (TPC) and antioxidant activities. The rice brans were firstly extracted using methanol. The extracts were analyzed using Folin-Ciocalteau method for total phenolic content while thiocyanate method and 1,1-diphenyl-2-picrylhydrasyl (DPPH) free radical-scavenging assay were used for antioxidant activities determination. The results indicated that the total phenolic content of white, red and black rice bran extract were in the range of 0.8931-0.9884, 1.0103-1.0494 and 1.0810-1.2239 mg gallic acid equivalent (GAE mg(-1)), respectively. With thiocyanate method, percentage inhibition were in the range of 10.15-20.68, 30.64-38.80 and 25.52-26.28 for white, red and black rice bran extract, respectively. With DPPH radical-scavenging assay, methanolic extract of 5718 showed the highest (IC50=0.0057 mg mL(-1)) while Homchaiya showed the lowest (IC50=0.2582 mg mL(-1)) activities. All of extracts showed lower activity than BHA (IC50=0.0012 mg mL(-1)). However, the antioxidant activity of all rice bran extracts indicated high antioxidant efficiency in the following order: red>black>white color rice brans. It is a promising that Thai rice bran are potential antioxidant sources.
authors.affiliation: The Center of Excellence for Innovation in Chemistry, Department of Chemistry, Faculty of Science, Mahasarakham University, Mahasarakham 44150, Thailand.
authors.forename: N
authors.initials: N
authors.lastname: Muntana
authors.forename: S
authors.initials: S
authors.lastname: Prasong
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism*; D001713:Biphenyl Compounds / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry; D012275:Oryza / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism; D013785:Thailand; D013861:Thiocyanates / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D005609:Free Radicals; D007202:Indicators and Reagents; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; D013861:Thiocyanates; C004931:1,1-diphenyl-2-picrylhydrazyl