Plastid DNA fragments are often found in the plant nuclear genome, and DNA transfer from plastids to the nucleus is ongoing. However, successful gene transfer is rare. What happens to compensate for this? To address this question, we analyzed nuclear-localized plastid DNA (nupDNA) fragments throughout the rice (Oryza sativa ssp japonica) genome, with respect to their age, size, structure, and integration sites on chromosomes. The divergence of nupDNA sequences from the sequence of the present plastid genome strongly suggests that plastid DNA has been transferred repeatedly to the nucleus in rice. Age distribution profiles of the nupDNA population, together with the size and structural characteristics of each fragment, revealed that once plastid DNAs are integrated into the nuclear genome, they are rapidly fragmented and vigorously shuffled, and surprisingly, 80% of them are eliminated from the nuclear genome within a million years. Large nupDNA fragments preferentially localize to the pericentromeric region of the chromosomes, where integration and elimination frequencies are markedly higher. These data indicate that the plant nuclear genome is in equilibrium between frequent integration and rapid elimination of the chloroplast genome and that the pericentromeric regions play a significant role in facilitating the chloroplast-nuclear DNA flux.

Antioxidative compounds were isolated from the methanol extract of dry outer scales of onion (Allium cepa L.). Nine phenolic compounds (1 − 9) were finally obtained by reversed-phase high-performance liquid chromatography, and their structures were elucidated by NMR and mass spectrometry analyses. They were the six known compounds, protocatechuic acid (1), 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (2), quercetin 4‘-O-β-d-glucopyranoside (3), quercetin (5), 4‘-O-β-d-glucopyranoside of quercetin dimer (7), and quercetin dimer (8), and three novel compounds, condensation products of quercetin with protocatechuic acid (4), adduct of quercetin with quercetin 4‘-O-β-d-glucopyranoside (6), and quercetin trimer (9). These phenolic compounds were tested for their antioxidant properties using autoxidation of methyl linoleate in bulk phase or free radical initiated peroxidation of soybean phosphatidylcholine in liposomes. The flavonoid compounds having o-dihydroxy substituent in the B-ring were shown to be effective antioxidants against nonenzymic lipid peroxidation. Keywords: antioxidant; flavonoid; quercetin; lipid peroxidation; onion; Allium cepa

The antioxidant activity of vitamin E (a-tocopherol) during the peroxidation of unsaturated lipids has been reviewed based on its reaction products. Free-radical scavenging reactions of a-tocopherol take place via the a-tocopheroxyl radical as an intermediate. If a suitable free radical is present, a non-radical product can be formed from the coupling of the free radical with the a-tocopheroxyl radical. The reaction products of a-tocopherol with lipid-peroxyl radicals are 8a-(lipid-dioxy)-a-tocopherones which are hydrolyzed to a-tocopherylquinone. If the supply of oxygen is insufficient, a-tocopherol can trap the carbon-centered radicals of lipids to form 6-0-(lipidalkyl)-a-tocopherols. On the other hand, the dimer and trimer of a-tocopherol is formed by the bimolecular self-reaction of the a-tocopheroxyl radical in a reaction mixture containing a large amount of a-tocopherol. The other product-forming pathway yields isomeric epoxy-a-tocopherylquinones and their precursors, epoxyhydroperoxy-a-tocopherones, but the mechanism of this pathway remains unknown. The reaction products of other vitamin E compounds (7-and 6-tocopherols) during lipid peroxidation are almost the same as those formed from the a-tocopherol. The tocopheroxyl radicals of 7-and 6-tocopherols prefer to react with each other to form dimeric products that are still effective as antioxidants.

Introduction Definition of microencapsulationThe microencapsulation process is used to entrap small particles of liquids, solids, or gases in one or two polymers. As presented in Fig. 1, the particle component is referred as the core material , and polymers are called variously such as wall material , shell , coating , carrier , or encapsulant (Luzzi, 1970;Desai and Jin Park, 2005). The purpose of microencapsulation is to protect the core material from environmental factors (such as light, moisture, temperature, and oxygen), to extend shelf-life (Shahidi and Han, 1993;Gouin, 2004), and to improve the release properties of compounds (Müller et al., 2002). Microencapsulation has been applied in the design of new materials not only for the food industry but also for pharmaceuticals, cosmetics, and textiles, where the stability, efficiency, and bioactivity of compounds are required (Koo et al., 2014;Dias et al., 2015). Classification of microcapsulesThe selection of the core, wall material, and microencapsulation technique affects the properties of microcapsules, including morphology. Based on the various properties of the core, wall material, and microencapsulation technique, different types of particles (Fig. 2) can be obtained (Gharsallaoui et al., 2007). The morphology of microcapsules can be described as: mononuclear (Fig. 2a), poly/multinuclear (Fig. 2b), matrix (Fig. 2c), multi-wall (Fig. 2d), and irregular (Fig. 2e). Microencapsulation techniquesMicroencapsulation techniques are divided into three classes: chemical, physical, and physico-chemical methods (Jyothi et al., 2010). Chemical methods include in situ polymerization and use of liposomes; physical methods include spray-drying and fluidized bed coating, and physico-chemical methods include coacervation and sol-gel encapsulation (Gibbs, 1999;Gouin, 2004). The microcapsules produced by each method are different (Fang & Bhandari, 2010). Chemical methods In situ polymerizationThe in situ formation of a hydrogel has recently been recognized for its potential biomedical and biotechnological applications

Five major glycolipid classes (acylated steryl glucoside, steryl glucoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and glucocerebroside) from fruit pastes of red bell pepper were separated by silica gel column chromatography. The molecular species of each glycolipid were separated and characterized by reversed-phase high-performance liquid chromatography coupled with on-line mass spectrometry using atmospheric pressure chemical ionization. The molecular species of steryl glucoside were beta-sitosteryl and campesteryl glucosides, and those of the acylated steryl glucoside were their fatty acid esters. The dilinolenoyl species was predominant in monogalactosyldiacylglycerol in addition to small amounts of another five molecular species, whereas digalactosyldiacylglycerol consisted of seven molecular species varying in their degree of unsaturation. The glucocerebroside class contained at least seven molecular species, which were characterized by proton nuclear magnetic resonance spectroscopy.

Glycosidically bound compounds were isolated from the methanol extract of fresh rhizomes of smaller galanga (Alpinia officinarum Hance). Nine glycosides (1-9) were finally obtained by reversed-phase HPLC and their structures were elucidated by MS and NMR analyses. They were the three known glycosides, (1R,3S,4S)-trans-3-hydroxy-1,8-cineole beta-D-glucopyranoside (1), benzyl beta-D-glucopyranoside (3), and 1-O-beta-D-glucopyranosyl-4-allylbenzene (chavicol beta-D-glucopyranoside, 4); and the six novel glycosides, 3-methyl-but-2-en-1-yl beta-D-glucopyranoside (2), 1-hydroxy-2-O-beta-D-glucopyranosyl-4-allylbenzene (5), 1-O-beta-D-glucopyranosyl-2-hydroxy-4-allylbenzene (demethyleugenol beta-D-glucopyranoside, 6), 1-O-(6-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranosyl)-2-hydroxy-4-allylbenzene (demethyleugenol beta-rutinoside, 7), 1-O-(6-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranosyl)-4-allylbenzene (chavicol beta-rutinoside, 8), and 1,2-di-O-beta-D-glucopyranosyl-4-allylbenzene (9). Compounds 2-9 were detected for the first time as constituents of galanga rhizomes.

The reaction products of alpha-tocopherol and its model compound, 2,2,5,7,8-pentamethylchroman-6-ol, during the autoxidation of methyl linoleate at 37 C were investigated. Two isomeric trimers were obtained as the major reaction products of alpha-tocopherol, and a trimer was obtained as that of its model chroman. The structure of each trimer has been characterized by IR, UV, 1H and 13C NMR, and mass spectroscopy. The 13C NMR spectra showed the presence of a quaternary carbon atom and a carbon atom bearing two oxy substituents in the molecule. On methanolysis of each trimer, equimolar amounts of the 5-methoxymethyl compound and the dihydroxy dimer were formed, indicating the presence of a ketal group in the molecule. From these results, new trimeric structures are proposed. The reaction products of alpha-tocopherol could be well-separated by reverse-phase high performance liquid chromatography. When methyl linoleate was autoxidized in the presence of 1 mol% alpha-tocopherol, spirodiene dimer was the initial reaction product of alpha-tocopherol, and trimers were formed with the decrease of alpha-tocopherol.

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