Helminthosporium 77. siccans

In the course of biosynthetic studies on the antibiotic, siccanin (46), Nozoe et al. have not only isolated trans-y-monocyclofarnesol (47) from the mycelia of the fungus, Helminthosporium siccans, but they have also demonstrated that a cell-free enzymatic preparation from the fungi converts mevalonic acid lactone into (47) in high yield. A key intermediate in the synthesis of abscisic acid is (48), which... 

Siccanin (50) also contains a sesquiterpenoid portion. The immediate precursors of siccanin were shown to be siccanochromene-A (48) and -B (49). When a cell-free system of Helminthosporium siccans was used, monocyclo-farnesol (51) was labelled by [2- C]mevalonate. 

A monoprenylhydroquinone, siccayne (139 yellowish prisms extraction yeld 26 mg/ml), was identified from mycelia of the marine Basidimycotina Holocyphina villosa Kohlm. et Kohlm. (Corticiaceae). This fungus is found on mangrove roots and similar substrates in the vicinity of mussels and other marine organisms. Siccayne was formerly isolated from the terrestrial Deuteromycotina Helminthosporium siccans [140,141]. 

C22H30O3, Mr 342.48, pale yellow cryst., mp. 139-140°C, [a]u -136° (CHClj), soluble in organic solvents. A metabolite from cultures of the phytopath-ogenic fungus Helminthosporium siccans. The strac-ture of S. consists of a drimane sesquiterpene linked to orcinol. S. has broad antifungal activity, especially against Trichophyton species that cause skin infections. 

C, H,o02, Mr 174.20, yellowish prisms, mp. 115 -116°C. An antibiotic from cultures of Helminthosporium siccans (Deuteromycetes) and Halocy-phina villosa (Basidiomycetes). S. is cytotoxic and inhibits the growth of a series of plants and Gram-positive bacteria. Stmcturally related active compounds astasperpentyne ChHijOj.Mr 192.21,oil, [a][j-20° (acetone) and the phytotoxin eutypyne (dying-arm disease of grapevines, C, 2H,o02, Mr 186.21), see also mycenone. 

Helminthosporium siccans. Active against gram-positive bacteria and some fungi. Cryst. (C H ). Mp 115-116°. Di-Ac [22944-04-3]. 

The fungal metabolite siccanin (21) contains a sesquiterpenoid fragment and a fragment derived from orsellinic acid. Previous reports had described a cell-free system from Helminthosporium siccans for the synthesis of trans-y-mono-cyclofarnesol (22). The formation of siccanochromene-A (25) has now been studied by the incubation of cell-free systems from Helminthosporium siccans... 

Nocardia lurida Micromonospora sagamiensis Streptomyces albus Helminthosporium siccans Streptomyces sioyaensis Micromonospora inyoensis Streptomyces spectrabilis Streptomyces ambofaciens Streptomyces griseus... 

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