The discovery of 2,5-dialkylcyclohexan-1,3-diones as a new class of natural products.

Orchids employing sexual deceit attract males of their pollinator species through specific volatile signals that mimic female-released sex pheromones. One of these signals proved to be 2-ethyl-5-propylcyclohexan-1,3-dione (chiloglottone1), a new natural product that was shown to be most important in the relations between orchids of the genus Chiloglottis, native to Australia, and corresponding pollinator species. Systematic investigations on the mass spectrometric fragmentation pattern of 2,5-dialkylcyclohexan-1,3-diones identified key ions providing information about the structures of the substituents at positions 2 and 5. Results enabled us to identify 2-ethyl-5-pentylcyclohexan-1,3-dione (chiloglottone2) and 2-butyl-5-methylcyclohexan-1,3-dione (chiloglottone3) as new natural products that play a decisive role in the pollination syndrome of some Chiloglottis species. During field bioassays, pure synthetic samples of chiloglottone1-3 or mixtures thereof proved to be attractive to the corresponding orchid pollinators. Because of their likely biogenesis from ubiquitous fatty acid precursors, 2,5-dialkylcyclohexan-1,3-diones may represent a hitherto overlooked, widespread class of natural products.

Fertility signals in the bumblebee Bombus terrestris (Hymenoptera: Apidae).

In eusocial Hymenoptera, queen control over workers is probably inseparable from the mechanism of queen recognition. In primitively eusocial bumblebees (Bombus), worker reproduction is controlled not only by the presence or absence of a dominant queen but also by other dominant workers. Furthermore, it was shown that the queen dominance is maintained by pheromonal cues. We investigated whether there is a similar odor signal released by egg-laying queens and workers that may have a function as a fertility signal. We collected cuticular surface extracts from nest-searching and breeding Bombus terrestris queens and workers that were characterized by their ovarian stages. In chemical analyses, we identified 61 compounds consisting of aldehydes, alkanes, alkenes, and fatty acid esters. Nest-searching queens and all groups of breeding females differed significantly in their odor bouquets. Furthermore, workers before the competition point (time point of colony development where workers start to develop ovaries and lay eggs) differed largely from queens and all other groups of workers. Breeding queens showed a unique bouquet of chemical compounds and certain queen-specific compounds, and the differences toward workers decrease with an increasing development of the workers' ovaries, hinting the presence of a reliable fertility signal. Among the worker groups, the smallest differences were found after the competition point. Egg-laying females contained higher total amounts of chemical compounds and of relative proportions of wax-type esters and aldehydes than nest-searching queens and workers before the competition point. Therefore, these compounds may have a function as a fertility signal present in queens and workers.

[Pesticides]. / Pestizide.

This review introduces the most important groups of pesticides. The necessary application of pesticides involves advantages as well as risks for man and environment.

2-Mercapto-1-methyl-5-methylmercapto-imidazole: a new metabolite of thiamazole.

2-Mercapto-1-methyl-5-methylmercapto-imidazole (13) was found in urine samples of man and rat after intake of thiamazole (1). It is assumed that the metabolite is produced via a N-oxidation intermediate enabling a nucleophilic attack at carbon-5 in the thiazole ring.

[Identification of chlorzoxazone metabolites in human urine (author's transl)]. / Identifizierung von Chlorzoxazon-Metaboliten im menschlichen Urin.

Besides 6-hydroxychlorzoxazon II, the main metabolite of 5-chlorobenzoxazolin-2-one (chlorzoxazone I, Paraflex) two other compounds were found to be metabolites of chlorzoxazone: 5-chloro-2,4-dihydroxyacetanilide XXII is produced from 6-hydroxychlorzoxazone II by ring cleavage and acetylation of the nitrogen. More interesting is the formation of the 6-hydroxybenzoxazolone XX. This compound is formally produced by substitution of Cl for hydrogen and hydroxylation of a neighbour ring-carbon atom.