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Cultures of Fusarium oxysporum Schl. emend. Sny. et Hans. f lycopersici (Sacc.) Sny. et Hans. grown on a liquid medium with glucose as the principal carbon source produce, among other products, the phytotoxin lycomarasmin. Acid hydrolysis of lycomarasmin results in the formation of aspartic acid, glycine, and pyruvic acid. Tracer studies showed that glycine-U-I4C, L-serine-U-14C, DL-aspartic acid-4-14C, DL-alanine-1-14C, and glucose-U-14C served as relatively efficient precursors of the lycomarasmin molecule. DL-Aspartic acid-4-I4C was incorporated into the 4-carbon fragment without label scrambling. Glycine was found to be the most efficient precursor of the 2-carbon fragment while glucose afforded the most efficient and direct route for the 3-carbon fragment.

Sexual reproduction in the aquatic fungus Achlya bisexualis is governed by antheridiol, a C 2 , sterol, secreted by the female plant and which initiates formation of antheridial hyphae on the male plant. Tracer studies showed that naturally occurring fucosterol supplied the necessary carbon skeleton for antheridiol. Labelling and trapping studies with a series of hypothetic sterol precursors have indicated the biological sequence involved in elaboration of the antheridiol side chain.La reproduction sexuelle chez le champignon aquatique Achlya bisesrralis est sous contrble d e l'antheridiol, un sterol en C , , , secrete par I'espece femelle et qui provoque la formation chez I'espece mile de I'anthkridial hyphae. Les etudes a I'aide de traceurs ont montre que le fucostCrol, un produit nature1 fournit le squelette carbone necessaire a I'antheridiol. Les etudes par marquage et par captage a l'aide d'une serie de precurseurs hypothetiques du type stir01 ont mis en evidence la sequence biologique ilnpliquee lors de I'elaboration de la chaine laterale de I'anthtridiol.[Traduit par le journal]Can.

The synthesis and characteristics of the 23-hydroxy-6-lactone isomer of antheridiol and (22S,23R) 3~-hydroxy-24-carbethoxyn1etl1ylene-cholest-5-cn-22,23-epoxide are described. The synthesis of the latter compound follows from the highly stereoselective epoxidation of 3P-acetoxy-cholesta-5,22-diene-24-one followed by a Wittig reaction to give (22S,23R) 3P-acetoxy-24-carbethoxymethylene-cholest-5-en-22,23-epoxide which upon treatment with perchloric acid gave exclusively the 6-lactone. Hematoporphyrin-sensitized photooxygenation followed by cupric acetate oxidation gave the required a,P-nnsaturated ketonic system in ring B. The 22R,23S stereochemical assignment of the final product is based on circular clichroism spectra. La photooxygenation sensibiliste de I'h6matoporphyrine par I'acttate cuivrique conduit au systeme cttonique a,P-insature requis pour le cycle B. L'attribution sttrtochimique 22R,23S du produit final est baste sur les spectres de dichroisme circulaire.[Traduit par le journal]Can. I . Chem.. 51. 1223 (1973) Continued refinement of analytical techniques has led to the discovery and characterization of a multitude of intermediate compounds involved in the biosynthetic pathways leading to major end products. Many postulated intermediates have been identified although present in only minute quantities. It is now quite obvious that in the course of the elaboration of the side chains of phytosterols, an extensive array of biogenetic intermediates is involved. The rather highly functionalized side chain of antheridiol (I), a mold sex hormone, is an example in which the hydrocarbon side chain of the most probable precursor, fucosterol, has been extensively modified. This steroidal hormone has been isolated, along with the biologically inactive 23-deoxyantheridiol (2), from culture liquids of the water mold, Achlyu bisexualis (1, 2). Both antheridiol (1) (in its natural 22S,23R configuration), and 23-deoxyantheridiol (2) (in its unnatural 22s configuration) have been chemically synthesized (2, 3). In this communication we describe a relatively efficient synthesis of the 23-hydroxy-&-lactonic isomer of antheridiol, 3a, having the 22R,23S configuration. We also describe the synthesis and characterization of 3P-hydroxy-24-carboxymethylene-cl1olest-5-en-22,23-epoxide (74.Our recent identification of fucosterol as the major sterol in Achlya bisexualis, and the occurCan. J. Chem. Downloaded from www.nrcresearchpress.com by 34.216.127.252 on 05/10/18For personal use only.