Infection with avirulent pathogens, tobacco mosaic virus (TMV) or Pseudomonas syringae pv. tabaci induced accumulation of polyisoprenoid alcohols, solanesol and a family of polyprenols [from polyprenol composed of 14 isoprene units (Pren-14) to -18, with Pren-16 dominating] in the leaves of resistant tobacco plants Nicotiana tabacum cv. Samsun NN. Upon TMV infection, solanesol content was increased seven- and eight-fold in the inoculated and upper leaves, respectively, while polyprenol content was increased 2.5- and 2-fold in the inoculated and upper leaves, respectively, on the seventh day post-infection. Accumulation of polyisoprenoid alcohols was also stimulated by exogenously applied hydrogen peroxide but not by exogenous salicylic acid (SA). On the contrary, neither inoculation of the leaves of susceptible tobacco plants nor wounding of tobacco leaves caused an increase in polyisoprenoid content. Taken together, these results indicate that polyisoprenoid alcohols might be involved in plant resistance against pathogens. A putative role of accumulated polyisoprenoids in plant response to pathogen attack is discussed. Similarly, the content of plastoquinone (PQ) was increased two-fold in TMV-inoculated and upper leaves of resistant plants. Accumulation of PQ was also stimulated by hydrogen peroxide, bacteria (P. syringae) and SA. The role of PQ in antioxidant defense in cellular membranous compartments is discussed in the context of the enzymatic antioxidant machinery activated in tobacco leaves subjected to viral infection. Elevated activity of several antioxidant enzymes (ascorbate peroxidase, guaiacol peroxidase, glutathione reductase and superoxide dismutase, especially the CuZn superoxide dismutase isoform) and high, but transient elevation of catalase was found in inoculated leaves of resistant tobacco plants but not in susceptible plants.

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N-acyl-dopamines are a novel class of biologically active lipids that have recently been identified in the brain and have the potential to interact with neural signaling pathways. This study seeks to determine the ability of N-oleoyl-dopamine, a synthetic amide of oleic acid and dopamine, to cross the blood brain barrier. We determined the tissue content of radioactivity in selected brain regions, in a shortrun study design, following injections of [ 3 H]N-oleoyl-dopamine (0.4 mCi) into the internal carotid artery in the rat. These results were compared with intracarotid injections of [ 3 H]dopamine and with intravenous injections of both radiolabeled compounds. The level of radioactivity was determined using liquid scintillation and was expressed as the percentage of its total dose injected per gram of tissue. We found that the 15-min brain uptake of radioactivity, with no distinct regional variations, amounted to about 6% following the intracarotid [ 3 H]N-oleoyl-dopamine, which was a significant 3-4-fold increase over that following similar administration of [ H]dopamine. Intravenous injections of [3 H]N-oleoyl-dopamine gave a much smaller yield of radioactivity in brain tissue samples which was still severalfold greater than that for intravenous [ 3 H]dopamine. Qualitative thin-layered chromatography screening showed the presence of unchanged N-oleoyl-dopamine in the brain following injections. We conclude that N-oleoyl-dopamine has an appreciable ability to cross the blood-brain barrier, which contrasts the limited transfer of dopamine alone. N-oleoyl-dopamine might exert physiological effects due to its known affinity for the central vanilloid receptors or to better satisfying the brain tissue demand for dopamine. The study suggests a potential pharmacological role for N-oleoyl-dopamine delivered exogenously in helping regulate the brain function. Drug Dev. Res. 60:217-224, 2003.