Possible dual roles of an allelopathic compound, cis-dehydromatricaria ester
The aqueous extract of the root ofSolidago altissima was lethal to nematodes. The major compound isolated from the toxic fraction wascis-dehydromatricaria ester (methyl 2-decene-4,6,8-triynoate), which is already known as an allelopathic compound of a composite showing growth-inhibition to a rice seedling. This compound showed high toxicity to plant-parasite nematodes. A composite exudes one defending substance against both competitive plants and plant-parasite nematodes.
Allelopathy and Allelochemicals of Solidago canadensis L. and S. altissima L. for Their Naturalization
Solidago canadensis L. and Solidago altissima L. are native to North America and have naturalized many other continents including Europa and Asia. Their species is an aggressive colonizer and forms thick monospecific stands. The evidence of the allelopathy for S. canadensis and S. altissima has accumulated in the literature since the late 20th century. The root exudates, extracts, essential oil and rhizosphere soil of S. canadensis suppressed the germination, growth and the arbuscular mycorrhizal colonization of several plants, including native plant species. Allelochemicals such as fatty acids, terpenes, flavonoids, polyphenols and their related compounds were identified in the extracts and essential oil of S. canadensis. The concentrations of total phenolics, total flavonoids and total saponins in the rhizosphere soil of S. canadensis obtained from the invasive ranges were greater than those from the native ranges. Allelochemicals such as terpenes, flavonoids, polyacetylene and phenols were also identified in the extracts, essential oil and the rhizosphere soil in S. altissima. Among the identified allelochemicals of S. altissima, the cis-dehydromatricaria ester may be involved in the allelopathy considering its growth inhibitory activity and its concentration in the rhizosphere soil. Therefore, the allelopathy of S. canadensis and S. altissima may support their invasiveness, naturalization and formation of thick monospecific stands. This is the first review article focusing on the allelopathy of both of S. canadensis and S. altissima.
Synthesis of 10-Hydroxy-cis-8-decene-4,6-diynoic and 9-Hydroxy-cis-7-nonene-3,5-diynoic Acids
In the previous paper1) we reported the simple pre paration of 1-acetoxy-cis-2-penten-4-yne (I) applying the selective hydrogenation to the conjugated trimethyl silyl-diyne system. Here we describe the first synthesis of two natural acetylenes using I as the starting material. 10-Hydroxy-cis-8-decene-4, 6-diynoic acid (Va) and 9-hydroxy-cis-7-nonene-3, 5-diynoic acid (VIa) were found from the culture of the fungus Fistulina pallida2) with their corresponding trans-isomers. The latters were synthesized and identified directly as their methyl esters, however, the structure of cis-isomers were estimated from the spectrometric data and by comparing them to their trans-isomers. As shown in the schema, Va was easily obtained by Chodkiewicz coupling3) between I and 5-bromo-4pentynoic acid (III).4) As described before cis-2penten-4-ynol is unstable in the basic media, however, the acetyl derivative I coupled with the bromoacetylene to give exclusively the cis-acid Va in good yield (70 based on I). Therefore it seems reasonable to assume that the protective group was hydrolysed after the coupling reaction. Moreover I was converted to the 1-bromoacetylene derivative H which was capable of using as the halo genated coupling fraction in Chodkiewicz reaction.3) Direct bromination by sodium hypobromite in aqueous solution is more satisfactory than the known method using ether-water mixture. The brominated product II was also easily coupled with 3-butynoic acid (IV)2) under the usual Chodkiewicz coupling condition in good yield (60 % based on II). These two hydroxyacetylenic acids were esterified with diazomethane and their spectrometric data were identical to those in the original report.2)