[3+2] Cycloaddition Synthesis of New Piperazine-Linked Bis(chromene) Hybrids Possessing Pyrazole Units as Potential Acetylcholinesterase Inhibitors

Two series of piperazine-linked bis(chromene) hybrids that are attached to pyrazole units were synthesized in the current study. Both series are attached to an acyl unit at pyrazole-C3, with one series attached to an acetyl unit and the other to an ethoxycarbonyl unit. A [3+2] cycloaddition protocol was conducted to produce the target hybrids with good yields by reacting the appropriate hydrazonoyl chlorides with chromene-based bis(enaminone) in dioxane containing triethylamine at reflux for 4 h. New hybrids were tested for acetylcholinesterase inhibitory activity at concentrations of 15 and 25 μM, as well as their ability to quench 2,2-diphenylpicrylhydrazyl (DPPH) free radicals at a concentration of 25 μg/mL. In general, the inhibitory activity is related to the electronic properties of the para-substituent that is attached to the arene unit at pyrazole-N1. Furthermore, the acyl unit attached to pyrazole-C3 has a significant effect on the new hybrids′ inhibitory activity. At the previous concentrations, the (3-acetylpyrazole)-linked hybrid attached to p-NO₂ units demonstrated the best acetylcholinesterase inhibitory activity, with inhibition percentages of 79.7 and 90.2. Furthermore, the previous hybrid demonstrated the most effective DPPH inhibitory activity, with an inhibition percentage of 87.5.     

Integrative taxonomy tests possible hybridisation between Central Asian cerambycids (Coleoptera)

Hybridisation can lead to the formation of new evolutionary lineages and some described insect species may in fact be first-generation hybrids of their parental species. Anoplistes forticornis and A. galusoi are two closely related cerambycid taxa endemic to Central Asia that exhibit a peculiar geographical distribution. Although the common diagnostic elytral pattern makes these beetles superficially easily distinguishable, there are marked resemblances in their morphology. By applying an integrative taxonomy approach, we verify the taxonomic status of A. forticornis and A. galusoi and test the possibility of hybridisation. The results of our comprehensive morphological examination and molecular analyses targeting mitochondrial (COI, 16S rRNA) and nuclear (arginine kinase, CAD, 28S rRNA) genes support the specific status of these taxa. In mtDNA, the putative hybrid specimen is more closely related to A. forticornis, which indicates that a female of this species bred with a male of A. galusoi. The supposed ecotypic variability (manifested in elytral pattern) is apparently not related to the topography or spatial structure of habitat. The phylogenetic hypothesis supports a peripatric scenario in which populations of the common ancestor had been separated for a significant period of time, first by the mountain ranges of Dzungarian Alatau (~11–10 Ma) and ultimately by the Ili River. The diverged taxa came into recent secondary contact following these isolation events. The methodology presented herein can be widely applied to identify first-generation hybridisation in Coleoptera.     

A taxonomic clarification of Petrorhagia section Kohlrauschia (Caryophyllaceae)

A taxonomic clarification of Petrorhagia section Kohlrauschia (Caryophyllaceae). The morphology of the inflorescence bracts and seeds in Petrorhagia glumacea and the large-flowered form of P. 'prolifera' is reported together with observations on some artificially produced hybrids. Petorhagia glumacea and large-flowered p. 'prolifera' can be distinguished on the basis of bract and seed morphology. The taxonomic status of large-flowered P. 'prolifera' is recognized as P. obcordata. Two groups of intermediate, natural populations are described from the Peloponnese and it is suggested that they are of hybrid origin. The seeds of P. obcordata are polytypic and show a geographical distribution pattern. Seed morphology, which is the most useful diagnostic character for identification, is described in P. prolifera, P. velutina and the tetraploid P. nanteuilii.     

Comparative analysis of photosynthetic characteristics and productivity in F2 hybrids of winter rye

Diversity of photosynthetic characteristics determined by plant genotypes provides the grounds for the increase in potential crop productivity by means of producing plant forms whose photosynthetic apparatus (PSA) has optimal size and functional efficiency. Parental forms of winter rye (Secale cereale L.) and their interline and intravarietal reciprocal F₂ hybrids were compared in terms of photosynthetic pigment (PSP) content, characteristics of chlorophyll a (Chl) fluorescence, some morphological traits, and grain productivity. At the booting and anthesis stages, significant divergence in chlorophyllous pigment content and Chl a fluorescence parameters was observed for winter rye inbred lines, rye varieties, and hybrids. The hybrids were revealed whose elevated grain productivity correlated with high PSP content and the highest photosystem II (PSII) activity. Analysis of correlations in reciprocal F₂ hybrids at booting and anthesis stages of rye development showed that accumulation of PSII is related to stem-forming capacity and to the flag leaf surface area. In reciprocal hybrids, the correlations between morphological traits, grain productivity, plastid pigments, and photochemical activity were subject to variations. The relationships between PSA parameters and grain productivity in winter rye F₂ hybrids varied depending on the developmental stage as well as on crossing combination; this relation was largely determined by the choice of pairs for hybridization, by direction of crosses, and by genetic features of parental forms.     

Genetic variation in resistance to Fusarium oxysporum f.sp. lilii in the genus Lilium

Genetic variation in Fusarium resistance in 82 Lilium genotypes was studied. A high level of resistance was found in the Asiatic hybrids (section Sinomartagon) and to a lesser extent in cultivars of L. longiflorum (section Leucolirion). The Oriental hybrids (section Archelirion) showed only moderate resistance. In the sections Sinomartagon, Leucolirion and Martagon species were detected with high levels of resistance. An accession of L. dauricum (section Sinomartagon) was the most resistant source. Possibilities for introgression of Fusarium resistance into cultivars by interspecific hybridisation, using the resistance found in Lilium genotypes, are discussed.     

The heathers of Europe and adjacent areas

McCLINTOCK, D., 1989. The heathers of Europe and adjacent areas. Andromeda polifolia, Bruckenthalia spiculifolia, Calluna vulgaris , two species of Daboecia , 19 of Erica with five subspecies and seven natural hybrids are discussed. Comment is chiefly given on E. andevalensis, E. maderensis and the group currently denominated: E. anthura, E. manipuliflora, E. multiflora and E. vagans. Two new combinations are made.     

Camalexin induction in intertribal somatic hybrids between Camelina sativa and rapid-cycling Brassica oleracea

  Camelina sativa, a wild relative of Brassica crops, is virtually immune to blackspot disease caused by Alternaria brassicicola. Intertribal somatic hybrids were produced between C. sativa and rapid-cycling Brassica oleracea as a step toward the transfer of resistance to this disease into Brassica vegetable crops. The plants recovered were confirmed as somatic hybrids by flow cytometry and RAPD analysis. All hybrids showed a morphology intermediate between the two parents. Rooted plants grew in soil up to 4–5 weeks, and some produced sterile flowers. Two of three hybrids tested showed a high level of resistance to  A. brassicicola. Resistance was correlated with the induction of high levels of the phytoalexin camalexin 48 h after inoculation, as in the resistant Camelina fusion partner. In contrast, susceptible somatic hybrids produced much lower levels of camalexin. Received: 2 April 1998 / Accepted: 14 July 1998     

Immunosuppressive Bibenzyl-phenylpropane Hybrids from Dendrobium devonianum

Two new bibenzyl-phenylpropane hybrids, dendrophenols A and B ( 1 and 2 ), along with nine known bibenzyls, were isolated from the aerial part of Dendrobium devonianum Paxt. Their structures were determined by extensive spectroscopic methods and methylation. Bioassays revealed that compounds 1–9 were specifically immunosuppressive to T lymphocytes with IC₅₀ values ranging from 0.41 to 9.4 μM, of which compounds 1 (IC₅₀=1.62 μM) and 2 (IC₅₀=0.41 μM) were promising immunosuppressive agents for T lymphocytes with the selectivity indices of 19.9 and 79.5, respectively.     

Hybridization of Cyprinus carpio and Carassius auratus,the first two exotic species in the lower Laurentian Great Lakes

Synopsis A preliminary comparison of Cyprinus carpio × Carassius auratus hybrids with the parent species is made by means of hybrid indices for 29 morphometric and 19 meristic characters. Of these 48 characters 29 were intermediate, seven were identical with one of the parents and 12 were extreme. Marked osteological differences in the crania of the parent species were noted as possible diagnostic characters for the identification of hybrids.Note