PubMed · 13438206
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B DENIS. 1957-05-10. [Panaris].. https://pubmed.ncbi.nlm.nih.gov/13438206/
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The isolation and structural elucidation of three novel-type naphthylisoquinoline alkaloids, ancistrocladinium A and B (the latter along with its atropisomer), from a Congolese Ancistrocladus species collected in the habitat Yeteto is reported. Their structures, including all stereochemical features, were elucidated by spectroscopic, chemical, and chiroptical methods. Ancistrocladinium A and B are the first N,C-coupled naphthyldihydroisoquinoline alkaloids found in nature, i.e., with an iminium-aryl axis. Although ancistrocladinium A, which is N,8'-coupled, is configurationally stable at this axis, ancistrocladinum B and its rotational isomer are based on a hitherto unprecedented N,6'-coupling type, with a slow rotation about the hetero biaryl axis at room temperature; they thus occur as a 46:54 mixture of two configurationally semistable atropo-diastereomers. For the isomerization of (P)-ancistrocladinium B to its (M)-diastereomer and for the opposite direction, the Gibbs free energies of activation were determined to be DeltaG double dagger1 = 105.8 kJ mol-1 and DeltaG double dagger2 = 105.7 kJ mol-1, respectively. In addition, the compounds were shown to have promising antileishmanial activities.
Plants of the carnivorous genus Nepenthes efficiently trap insects in leaf pitchers, mostly employing epicuticular wax crystals on the pitcher walls to make them slippery for the prey. In the present study, the compositions and micromorphologies of the wax crystals of five Nepenthes species and hybrids were analysed in order to test whether the chemical principles underlying this ecological function are widespread within the genus. Three wax layers could be distinguished within the Nepenthes pitcher cuticles: (1) the outermost part of the crystals forming the platelets visible in standard scanning electron microscopy, (2) the bottom portion of the epicuticular wax crystals, and (3) an intracuticular wax layer. The composition of the intracuticular wax differed significantly from that of the neighbouring epicuticular layer. The compositions of corresponding wax mixtures from all five Nepenthes species and hybrids were very similar, with almost equal amounts of very long chain aldehydes and primary alcohols. While triacontanal (C(30) aldehyde) was prevailing in the epicuticular crystals of Nepenthes albomarginata and Nepenthes x intermedia, Nepenthes x superba and Nepenthes x henriana were found to have especially high percentages of dotriacontanal (C(32) aldehyde). Nepenthes "khasiana" had an intermediate aldehyde composition with almost equal amounts of both chain lengths.
The mode of inheritance of six enzyme markers in the octoploid alpine plant Cerastium alpinum was analyzed. Offspring from crosses between heterozygotes showed fixed heterozygosity at malate dehydrogenase-2, phosphoglucoisomerase-2, triosephosphate isomerase-2, and triosephosphate isomerase-3. Phosphoglucomutase-1 also showed fixed heterozygosity except in offspring from one cross. Fixed heterozygosity in five enzyme systems suggests that C. alpinum has originated through at least some allopolyploidization. Offspring from plants heterozygous for two alleles at the menadione reductase-1 (Mr-1) locus did not deviate significantly from a 1:2:1 ratio. The large proportion of homozygotes suggests disomic inheritance because any kind of polysomic inheritance would result in a substantially increased proportion of heterozygotes relative to disomic inheritance. Assuming a diploid model for Mr-1, this locus was used to analyze the population genetic structure within C. alpinum populations. Inbreeding was found in many alpine populations. This may help explain the large genetic distances found among alpine populations in a previous study. The analysis is only based on one segregating locus, and the results should therefore be treated with caution. However, by establishing the mode of inheritance through crosses, we have been able to use a codominant marker in population genetic analysis of an octoploid plant.