Assessments of phenolic compounds and flavonoids contents in rice seeds for screening of Thai rice varieties (Oryza sativa L.)

Abstract

The variation of secondary metabolites in rice seeds are affected by environmental cultivation and rice varieties. This research used six varieties of Thai rice seeds from Pathumthani, Ubon Ratchathani and Roiet Rice Research Center. Three varieties of non-pigmented rice (Hahng Yi71, Chai Nat1 and RD49) and three varieties of pigmented rice (Glutinous rice Ubon, Khum Ubon and Khum Udon) were investigated for their total phenolic compound and total flavonoids profiles. The high contents of total phenolic compound and total flavonoids were also observed in pigmented rice seeds which more than in non-pigmented rice seeds. Glutinous rice Ubon variety presented the highest levels of total phenolic compound and total flavonoids (670 mg Gallic/g and 380 mg Catechin/g, respectively) followed by Khum Ubon and Khum Udon varities. Moreover, these rice extracts were evaluated for their antioxidant capacities by ABTS and DPPH assay. The rice extracts from Glutinous rice Ubon variety presented the highest antioxidant activities both ABTS (14 µM Trolox/g) and DPPH (6 µL) assay as well as total phenolic compound and total flavonoids contents. The quantitative total phenolic compound, total flavonoids and antioxidant capacities profiles of rice seeds can be useful to value-added and nutrient enrichment in Thai rice varieties.