Ambrosia species

Wollenweber, E. et al.. Exudate flavonoids in three Ambrosia species, Nat. Prod. Lett., 1,109,1995. 

E.2 Inhaled allergens Exposure to these commonly results in hay fever and asthma. The main sources are pollens and fungal (mould) spores. Pollens from grasses such as Timothy (Phleum pratensis) and perennial Rye (Lolium perenne) as well as those of Plantapfo and Ambrosia species are important in causing seasonal hay fever and possibly asthma. Spores from fungi such as Cladospo-rium and Sporobolomyces have been implicated in rhinitis and asthma. 

Mitchell JC, Fritig B, Singh B, Towers GHN (1970) Allergic contact dermatitis from Frullania and Compositae. The role of sesquiterpene lactones. J Invest Dermatol 54 233-239 Mitchell JC, Roy AK, Dupuis G, Towers GHN (1971) Allergic contact dermatitis from ragweeds Ambrosia species). The role of sesquiterpene lactones. Arch Dermatol 104 73-76 O Malley MA, Mathias CG (1988) Distribution of lost-work-time claims for skin disease in California agriculture 1978-1983. Am J Ind Med 14 715-720... 

Structure and absolute configuration of a new hydroxycostunolide (407) from Porella species 65) were elucidated mainly by comparison of its H-NMR spectrum with that of a co-metabolite, costunolide (406), and tamaulipin B ( = 3a-hydroxycostunolide) (413) from Ambrosia species (Compositae) 347). Acetylation of (407) gave novanin (412) with a 3 3-acetoxyl group. This was followed by cyclization with SOCI2 to afford cyclonovanin A (414) (i70), as shown in Scheme 50. Thus, the new germacranolide was formulated as (407). 

The next examples concern species of Ambrosia L. that are characterized, in the first, by a north-south variation, and in the second, an east-west one, with the added feature of different ploidy levels. The work is that of Seaman and Mabry (1979a, b). In the first example, we will look at A. ambrosioides (Cav.) Payne sampled from southern... 

As part of the same project a study of one of the most common weeds in some disturbed habitats from many regions in Los Tuxtlas (Veracruz) was carried out. Ambrosia cumanensls is found as an important species of the ruderal vegetation. It grows vigorously and in almost pure stands. We decided to assess its allelopathic potential in order to evaluate this phenomenom as a determining factor for the structure of the community as well as in the secondary succession process. 

Root and leaf aqueous leachates of Ambrosia cumanensls did indeed produce a strong inhibition on the growth of weed species. Aqueous extracts of soil collected under A.cumanensls in July (during its flowering) were strongly allelopathic to weed growth. Decomposition of leaves and roots in pots caused inhibition of some weeds also. Microorganisms have a major role in this process, as shown by results from sterile and nonsterile soils (17). 

Pheromones of insect species in the order Coleoptera are characterized by considerable structural diversity. Unlike the lepidopterous sex pheromones, which are nearly all tatty acid derivatives, coleopterous sex pheromone structures range in complexity from the relatively simple 3,5-tetradecadienoic acid of the black carpet beetle to the tricyclic terpenoid, lineatin, of the striped ambrosia beetle. While the sex pheromones of many beetles consist of mixtures of compounds that act synergistically to elicit a behavioral response, other Coleoptera species appear to use only a single compound for chemical communication between the sexes. In the latter case the compound usually has at least one chiral center and chirality plays a major role in determining pheromone specificity. 

The natural product (R)-sulcatol is a male-produced aggregation pheromone of the ambrosia beetle. This insect can devastate entire forests when its population is out of control.Various studies revealed that different species respond to the compound in different enantiomeric excess. The asymmetric synthesis of (R)-sulcatol was accomplished in the laboratory of S.G. Davies using a stereospecific [2,3]-Meisenheimer rearrangement as the key step. The treatment of the allylic amine substrate with mCPBA followed by the filtration of the reaction mixture through deactivated basic alumina afforded the desired hydroxylamine as a single diastereomer. 

Callus cultures of Bidens pilosa which normally produce no acetylenic compounds could be induced to do so by addition of culture filtrate from the fungus Pythium aphanider-matum cultures of this and other Bidens species that had been transformed with the Ti plasmid of Agrobacterium tu-mefaciens produced a root type profile of acetylenes (Ellis, 1988). Hairy root cultures of Ambrosia, Bidens, and Tagetes have similar content of acetylenes as those of normal plant roots (Flores et al., 1987, 1988). 

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