title: Improved antioxidant activity in transgenic Perilla frutescens plants via overexpression of the γ-tocopherol methyltransferase (γ-tmt) gene.
abstract: The main goal of this study was to generate transgenic Perilla frutescens with enhanced antioxidant properties by overexpressing the γ-tocopherol methyltransferase (γ-tmt) gene. In this study, the antioxidant activity of methanolic crude extracts of transgenic and non-transgenic control plants was investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method. Free radical scavenging activity was evaluated using α-tocopherol and butylated hydroxyl toluene as standard antioxidants. In general, the ethyl acetate fraction of transgenic P. frutescens showed stronger DPPH radical scavenging activity than the ethyl acetate fraction from non-transgenic control plants (IC50 2.00 ± 0.10 and 5.53 ± 0.40 μg ∙ ml(-1), respectively). High-performance liquid chromatography analysis of phenolic acids in leaf extracts confirmed increased levels of 16 individual phenolic compounds in two transgenic lines (pf47-5 and pf47-8) compared with control plants. Changes in the phenolic compound profile and α-tocopherol content were correlated with the antioxidant properties of transgenic plants, indicating that the introduction of transgene γ-tmt influenced the metabolism of phenolic compounds and subsequently produced biochemical changes in the transformants. There were no significant differences in photosynthetic rate in the transgenic plants as compared to the non-transgenic control plants, suggesting that the alteration of phenolic compounds and tocopherol composition had little impact on photosynthesis.
authors.affiliation: Department of Applied Bioscience, Konkuk University, Seoul, 143-701, South Korea.
authors.forename: Bimal Kumar
authors.initials: BK
authors.lastname: Ghimire
authors.forename: Eun Soo
authors.initials: ES
authors.lastname: Seong
authors.forename: Chan Ok
authors.initials: CO
authors.lastname: Lee
authors.forename: Jae Geun
authors.initials: JG
authors.lastname: Lee
authors.forename: Chang Yeon
authors.initials: CY
authors.lastname: Yu
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Ill Min
authors.initials: IM
authors.lastname: Chung
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics*; D001713:Biphenyl Compounds / Q000737:chemistry; D004790:Enzyme Induction; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000378:metabolism; D015870:Gene Expression; D008780:Methyltransferases / Q000235:genetics*; D031344:Perilla frutescens / Q000737:chemistry / Q000235:genetics*; D010636:Phenols / Q000378:metabolism; D010788:Photosynthesis; D010851:Picrates / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry*; D030821:Plants, Genetically Modified / Q000737:chemistry
chemical_list: D029681:Arabidopsis Proteins; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; C004931:1,1-diphenyl-2-picrylhydrazyl; D008780:Methyltransferases; C047259:gamma-tocopherol methyltransferase