title: Plastochromanol-8: fifty years of research.
abstract: Plastochromanol-8 (PC-8) is an antioxidant that, together with tocopherols and tocotrienols, belongs to the group of tocochromanols. Plastochromanol-8 has been found to occur in several plant species, including mosses, and lichens. PC-8 is found in seeds, leaves and other organs of higher plants. In leaves, PC-8 is restricted to chloroplasts. The identification of tocopherol cyclase (VTE1) as the key enzyme in the biosynthesis of PC-8 suggests that plastoglobules are the primary site of its biosynthesis. Other enzymes related with PC-8 biosynthesis in plastoglobules include: NDC1 and the ABC1-like kinase ABC1K3. The antioxidant properties of PC-8 are similar to those of other chloroplastic antioxidants in polar solvents but considerably they are enhanced in hydrophobic environments, suggesting that the unsaturated side chain performs some quenching activity. As a result of a non-enzymatic reaction, singlet oxygen can oxidize any of the 8 double bonds in the side chain of PC-8, giving at least eight hydroxy-PC-8 isomers. This review summarizes current evidence of a widespread distribution of PC-8 in photosynthetic organisms, as well as the contribution of PC-8 to the pool of lipid-soluble antioxidants in both leaves and seeds.
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kruk
authors.affiliation: Department of Medical Physics and Biophysics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Reymonta 19, 30-059 Krakow, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Szymańska
authors.affiliation: Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain.
authors.forename: Jana
authors.initials: J
authors.lastname: Cela
authors.affiliation: Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain. Electronic address: smunne@ub.edu.
authors.forename: Sergi
authors.initials: S
authors.lastname: Munne-Bosch
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D002839:Chromans / Q000737:chemistry* / Q000378:metabolism; D028482:Hevea / Q000737:chemistry; D019751:Intramolecular Transferases / Q000378:metabolism; D015394:Molecular Structure; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry; D012639:Seeds / Q000737:chemistry; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; D002839:Chromans; D014810:Vitamin E; C013649:plastochromanol 8; D009247:NADH, NADPH Oxidoreductases; C561934:NDC1 protein, Arabidopsis; D019751:Intramolecular Transferases; C103397:tocopherol cyclase
keywords: Antioxidants; Plastochromanol-8; Tocochromanols; Tocopherols; Vitamin E