Selection of Origanum vulgare plants for essential oil, carvacrol, total phenols and antioxidant potential

In the summer of 2005, individual plant selection was performed on different oregano populations started at Applied Plant Research (PPO-WUR) in Lelystad, The Netherlands. Selection was focused on erect growing, healthy, leafy but flowering, productive plants. Samples of these visually selected plants were analyzed for essential oil content and its main components (such as carvacrol). Some of the selected plants were also screened for phenolic components and antioxidant activity. This paper describes the selection process and presents the mean levels (from 79 selected plants with a complete data set) of the essential oil and its different components, the ethanol-soluble and cell wall-bound phenolic compounds, and the antioxidative activity of the extracts. The correlations between these parameters are presented. The results suggest that under the present experimental conditions, it is difficult to achieve the objective of single selection for high essential oil/carvacrol and high phenol content/antioxidant activit

Selection of Origanum vulgare plants for essential oil, carvacrol, total phenols and antioxidant potential

In the summer of 2005, individual plant selection was performed on different oregano populations started at Applied Plant Research (PPO-WUR) in Lelystad, The Netherlands. Selection was focused on erect growing, healthy, leafy but flowering, productive plants. Samples of these visually selected plants were analyzed for essential oil content and its main components (such as carvacrol). Some of the selected plants were also screened for phenolic components and antioxidant activity. This paper describes the selection process and presents the mean levels (from 79 selected plants with a complete data set) of the essential oil and its different components, the ethanol-soluble and cell wall-bound phenolic compounds, and the antioxidative activity of the extracts. The correlations between these parameters are presented. The results suggest that under the present experimental conditions, it is difficult to achieve the objective of single selection for high essential oil/carvacrol and high phenol content/antioxidant activit

A polymer of caffeyl alcohol in plant seeds

Lignins are complex phenylpropanoid polymers mostly associated with plant secondary cell walls. Lignins arise primarily via oxidative polymerization of the three monolignols, p-coumaryl, coniferyl, and sinapyl alcohols. Of the two hydroxycinnamyl alcohols that represent incompletely methylated biosynthetic products (and are not usually considered to be monolignols), 5-hydroxyconiferyl alcohol is now well established as incorporating into angiosperm lignins, but incorporation of caffeyl alcohol has not been shown. We report here the presence of a homopolymer of caffeyl alcohol in the seed coats of both monocot and dicot plants. This polymer (C-lignin) is deposited to high concentrations in the seed coat during the early stages of seed development in the vanilla orchid (Vanilla planifolia), and in several members of the Cactaceae. The lignin in other parts of the Vanilla plant is conventionally biosynthesized from coniferyl and sinapyl alcohols. Some species of cacti contain only C-lignin in their seeds, whereas others contain only classical guaiacyl/syringyl lignin (derived from coniferyl and sinapyl alcohols). NMR spectroscopic analysis revealed that the Vanilla seed-coat polymer was massively comprised of benzodioxane units and was structurally similar to the polymer synthesized in vitro by peroxidase-catalyzed polymerization of caffeyl alcohol. CD spectroscopy did not detect any optical activity in the seed polymer. These data support the contention that the C-lignin polymer is produced in vivo via combinatorial oxidative radical coupling that is under simple chemical control, a mechanism analogous to that theorized for classical lignin biosynthesis