Runa Berg Østby

• Nagy, Nina Elisabeth; Norli, Hans Ragnar; Fongen, Monica; Østby, Runa Berg; Heldal, Inger & Davik, Jahn [Show all 7 contributors for this article] (2022). Patterns and roles of lignan and terpenoid accumulation in the reaction zone compartmentalizing pathogen-infected heartwood of Norway spruce. Planta. ISSN 0032-0935. 255(3). doi: 10.1007/s00425-022-03842-1. Full text in Research Archive Show summary

  Tree defense against xylem pathogens involves both constitutive and induced phenylpropanoids and terpenoids. The induced defenses include compartmentalization of compromised wood with a reaction zone (RZ) characterized by polyphenol deposition, whereas the role of terpenoids has remained poorly understood. To further elucidate the tree–pathogen interaction, we profiled spatial patterns in lignan (low-molecular-weight polyphenols) and terpenoid content in Norway spruce (Picea abies) trees showing heartwood colonization by the pathogenic white-rot fungus Heterobasidion parviporum. There was pronounced variation in the amount and composition of lignans between different xylem tissue zones of diseased and healthy trees. Intact RZ at basal stem regions, where colonization is the oldest, showed the highest level and diversity of these compounds. The antioxidant properties of lignans obviously hinder oxidative degradation of wood: RZ with lignans removed by extraction showed significantly higher mass loss than unextracted RZ when subjected to Fenton degradation. The reduced diversity and amount of lignans in pathogen-compromised RZ and decaying heartwood in comparison to intact RZ and healthy heartwood suggest that α-conindendrin isomer is an intermediate metabolite in lignan decomposition by H. parviporum. Diterpenes and diterpene alcohols constituted above 90% of the terpenes detected in sapwood of healthy and diseased trees. A significant finding was that traumatic resin canals, predominated by monoterpenes, were commonly associated with RZ. The findings clarify the roles and fate of lignan during wood decay and raise questions about the potential roles of terpenoids in signal transduction, synthesis, and translocation of defense compounds upon wood compartmentalization against decay fungi.

• Østby, Runa Berg; Didriksen, Terje; Antonsen, Simen Gjelseth; Nicolaisen, Steinar Sollien & Stenstrøm, Yngve H. (2020). Two-phase dibromocyclopropanation of unsaturated alcohols using flow chemistry. Molecules. ISSN 1431-5157. 25(10). doi: 10.3390/molecules25102364. Full text in Research Archive Show summary

  Dibromocyclopropanations are conventionally done by addition of dibromocarbene to alkenes under phase-transfer conditions in batch reactions using a strong base (50% NaOH (aq)), vigorous stirring and long reaction times. We have shown that cyclopropanation of unsaturated alcohols can be done under ambient conditions using continuous flow chemistry with 40% (w/w) NaOH (aq) as the base. The reactions were generally rapid; the yields were comparable to yields reported in the literature for the conventional batch reaction

• Østby, Runa Berg; Stenstrøm, Yngve H. & Didriksen, Terje (2015). The use of flow chemistry for two-phase dibromocyclopropanation of alkenes. Journal of Flow Chemistry. ISSN 2062-249X. 5(2), p. 69–73. doi: 10.1556/JFC-D-14-00041. Show summary

  Conventional batch dibromocyclopropanations by reaction of bromoform and alkenes under phase-transfer conditions require strong base (50% NaOH (aq)), vigorous stirring, and often long reaction times. Using flow chemistry in a microreactor, the reactions were found to be smooth, rapid, and high-yielding under ambient conditions when 40% (w/w) NaOH was used as the base. The reaction has been tested with a representative selection of alkenes, displaying a variety of structural features.

• Østby, Runa Berg & Stenstrøm, Yngve (2014). Syntheses of bicyclo[3.3.0]octanes and bicyclo[4.3.0]nonanes by ring expansion of isopropylidenecyclobutanes. ARKIVOC. ISSN 1551-7004. p. 266–284. doi: 10.3998/ark.5550190.p008.383. Show summary

  When subjected to HBr/HOAc in polar solvents like acetic acid, 6-(1-methylethylidene)- bicyclo[3.2.0]heptanes undergo a ring expansion reaction yielding 2-bromo-3,3- dimethylbicyclo[3.3.0]octane and 3-bromo-2,2-dimethylbicyclo[3.3.0]octane. Several other isopropylidenecyclobutanes have been found to undergo the same reaction with high stereoselectivity and moderate regioselectivity. In less polar solvents like diethyl ether the ring expansion reaction is suppressed, and bromides resulting from addition of HBr to the isopropylidene double bond are obtained.

View all works in Cristin

• Antonsen, Simen Gjelseth; Østby, Runa Berg & Stenstrøm, Yngve H. (2018). Naturally Occurring Cyclobutanes, their Biological Significance and Synthesis. Elsevier. ISBN 9780444640574. 41 p.

View all works in Cristin

• Østby, Runa Berg; Didriksen, Terje; Antonsen, Simen Gjelseth; Nolsøe, Jens Mortansson Jelstrup; Stenstrøm, Yngve H. & Monsen, Erling Berge (2019). Two-phase Dibromocyclopropanation of Unsaturated Alcohols Using Flow Chemistry.
• Østby, Runa Berg; Antonsen, Simen Gjelseth; Stenstrøm, Yngve & Westerås, Stephen (2015). Synthesis of cyclobutanes by microwave assisted [2+2] intramolecular allene-ene reactions.
• Stenstrøm, Yngve H.; Hansen, Trond Vidar & Østby, Runa Berg (2015). Syntheses of 3-, 4- and 5-Membered Carbocycles - New Methodology on Old Methods. SiÅs, NMBU,Ås. ISSN 978-82-575-1329-0.

View all works in Cristin