Noël Arpin

A new C40H56 carotene with a terminal methylene group

Abstract The structure of a new C 40 H 56 carotene isolated from the discomycete Caloscypha fulgens (Pers.) Boud. is shown by spectral methods to be β,γ-carotene (VII). This is the first demonstration of a naturally occurring carotenoid with a terminal methylene group.

10-Oxo-trans-8-decenoic acid (ODA): production, biological activities, and comparison with other hormone-like substances in Agaricus bisporus.

The few well-characterized fungal growth-regulating substances include 10-oxo-trans-8-decenoic acid (ODA) and hercynine. This report deals with production and tissue location of ODA. It also describes some biological activities of addition of ODA, hercynine, and cytokinins on growth and postharvest morphogenesis of Agaricus bisporus. Production of ODA in sporophore extracts was limited mainly by oxygen availability and the possible occurrence of a competitive metabolic pathway. Presumably synthesized within the stipe and skin tissues, ODA accumulated in the gills. Mycelium growth rate on a potato-based medium was significantly increased in the presence of ODA. Moreover, stipe lengthening was slightly stimulated by 10 or 100 µM ODA. Although these findings were similar to previous ones (Mau JL, Beelman RB, Ziegler GR. Phytochemistry 1992;31:4059-64), ODA appeared poorly active in our assays and mycelium growth on asparagine-glucose medium was strongly inhibited by 200 µM ODA. In contrast with cytokinins or hercynine, ODA did not speed up cap opening. Finally, tests carried out on animal cells suggested a dose-dependent cytotoxic effect of ODA.

Mycosporins from Ascochyta pisi, Cladosporium herbarum and Septoria nodorum

Abstract The chemical structure of the mycosporin isolated from Ascochyta pisi, Cladosporium herbarum and Septoria nodorum was established as mycosporin-2 glucoside.

Isolation of flavomannin-6,6′-dimethyl ether and one of its racemates from higher fungi

Abstract The main yellow pigment of Dermocybe cinnamomeolutea, D. uliginosa and D. palustris var. sphagneti has been shown to be flavomannin-6,6′-dimethyl ether (I). Tricholoma flavovirens (= T. equestre ) contains a racemate of the same pigment. Minor pigments in D. cinnamomeolutea are anhydroflavomannin-quinone-6,6′-dimethyl ether (VII), questin, dermolutein, dermorubin and traces of endocrocin.

Le fomentariol: Nouvelle benzotropolone isolée de Fomes fomentarius

Abstract The brown—red colour of the external layer of Fomes, fomentarius is basically due to three compounds. The main constituent, fomentariol, has the structure 7,4′-di(3-hydroxy-1-propenyl)-purpurogallin.

Open and ring forms of mycosporin-2 from the ascomycete Gnomonia leptostyla

Abstract The three reproductive forms of Gnomonia leptostyla synthesize mycosporin-2 ring and open forms. The chemical structures were determined from NMR and MS data.

Soluble uridine diphospho-D-glucose: mycosporin glucosyltransferase from spores of Ascochyta fabae Speg.

The enzyme properties of a soluble uridine 5′-diphosphate (UDP) glucose: mycosporin-2 glucosyltransferase from spores of Ascochyta fabae Speg. (Fungi imperfecti) were studied. The optimal conditions for the glucose transfer from UDP-glucose to the mycosporin-2 (the amide form being the best acceptor) were determined; for maximal activity the glucosyltransferase requires a pH of about 8.5 and the presence of divalent cations (Mn2+ being more efficient than Ca2+ or Mg2+). The reaction was not reversible in presence of large amounts of UDP.

In vitro formation of a dimer in the 4-aminophenol-melanin pathway

Abstract Incubation of 4-aminophenol with tyrosinase (EC 1.14.18.1) gives a brown-black precipitate. A transient yellow compound formed during this reaction has been isolated and identified as a dimer: 2-hydroxy-3-( p -hydroxyphenylamino)-4-imino-cyclohexa-2, 5-dien-1-one. Its involvement in the browning process of Agaricus bisporus should be now considered.