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1999 (1)
1996 (1)
1Author    Sergi Munné-Bosch3, Karin Schwarz, Leonor Alegre3Requires cookie*
 Title    in Rosmarinus officinalis L. and Melissa officinalis L  
 Abstract    Summer diurnal variations of photosynthesis and a-tocopherol content were measured in relation to natural drought in field-grown rosemary (Rosmarinus officinalis L.) and lemon balm (Melissa officinalis L.) plants. During the summer relative water contents (RW C) of ca. 40% in Rosmarinus officinalis and ca. 30% in Melissa officinalis were attained, indicating severe drought. Both species showed similar diurnal patterns of net C 0 2 assimilation rates (A) with a wide plateau of maximum photosynthesis at midday in the absence of drought and one peak of maximum photosynthesis early in the morning under drought conditions. Net C 0 2 assimilation rates decreased by ca. 75% due to drought in both species. Melissa officinalis plants showed a significant decrease in the relative quantum efficiency of PSII photochemistry (4>psn), ratio of variable to maximum fluorescence yield (F J F m) and chloro­ phyll content of leaves by ca. 25% under drought conditions at midday. In contrast, cJ)pSI1, F J F m and chlorophyll content remained constant throughout the experiment in R. officinalis plants. Although the non-photochemical quenching of chlorophyll fluorescence increased from ca. 1.8 to 3 and the a-tocopherol content rose fifteen fold in both species in response to drought, only R. officinalis plants were able to avoid oxidative damage under drought conditions by the joint increase of carotenoids and a-tocopherol. 
  Reference    Z. Naturforsch. 54c, 698—7 (1999); received November 17 1998/March 20. 1999 
  Published    1999 
  Keywords    a-Tocopherol, Photosynthesis, Drought, Rosmarinus officinalis, Melissa officinalis 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0698.pdf 
 Identifier    ZNC-1999-54c-0698 
 Volume    54 
2Author    Werner Meyer, G.Erhard SpitellerRequires cookie*
 Title    Increase of Caryophyllene Oxide in Ageing Lemon Balm Leaves (Melissa officinalis L.) -A Consequence of Lipid Peroxidation?  
 Abstract    Oxidative processes, especially lipid peroxidation (LPO), are assumed to increase during ageing. In an attempt to provide experimental evidence for this assumption lemon balm plants (Melissa officinalis L.) of different age and location were analyzed for oxidatively caused changes in the etheric oil composition. The investigation revealed that the caryophyl­ lene oxide (CarO) content of lemon balm plants -a main constituent -depends on two factors: age and habitat. The content of CarO increased with age continuously up to a factor of 3. Poor nutritive conditions, as growth on unfertilized soil, also caused an increase in CarO content. Addition of Fe2+/ascorbate -enhancing oxidative processes -promoted the formation of CarO. Hydroperoxides of unsaturated fatty acids (L O O H s) in the lipid extract of lemon balm leaves were converted to corresponding hydroxy acids (LO H s) by sodium borohydride re­ duction. These were hydrogenated and subjected to GC/MS analysis after derivatisation. A surplus of 9-hydroxy-octadecanoic acid over the 13 isomer indicated at least in part enzymatic lipid peroxidation. Polarographie determination o f the oxygen consumption revealed a gen­ erally low but in ageing plants increased lipoxygenase activity. This indicates a contribution of lipid peroxidation in the epoxidation process of caryophyllene. 
  Reference    Z. Naturforsch. 51c, 651 (1996); received May 17/June 12 1996 
  Published    1996 
  Keywords    Melissa officinalis, Lemon Balm, Caryophyllene Oxide, Lipid Peroxidation, Lipoxygenase Activity, Ageing 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0651.pdf 
 Identifier    ZNC-1996-51c-0651 
 Volume    51