Intermediates with biosynthetic implications in de novo production of phenyl-phenalenone-type phytoalexins by Musa acuminata revised structure of emenolone

Synthesis and Antifungal Activity of Musa Phytoalexins and Structural Analogs

“…Previously, we have used this reaction to unambiguously confirm the structure of 4´-methoxyirenolone, a natural phytoalexin [5]; in addition, aryl Grignard reagents have also been used for the synthesis of extended phenalenones [6]. Other compounds such as irenolone [4-(4'-hydroxy)phenylphenalenone)], and 4-phenylphenalenone were obtained from natural sources, as described elsewhere [1,5].…”

The biosynthesis of 8-phenylphenalenones from involves a putative aryl migration step

“…The structure 0031-9422/$ -see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.phytochem.2004.10.019 of emenolone (Luis et al, 1993), originally supposed to be a 5-phenylphenalenone, has been revised to a 9-phenylphenalenone (Luis et al, 1995).…”

“…The occurrence of putative phenylphenalenone-derived phenylphenalenes (Greca et al, 1992) and phenylnaphthalenedicarboxylic acids (Greca et al, 1993) in E. crassipes prompted us to reinvestigate this plant with respect to the typical phenylphenalenones, which are polycyclic natural products of the Haemodoraceae (Cooke and Edwards, 1980), Musaceae (Luis et al, 1993;Hirai et al, 1994), and Strelitziaceae (Hö lscher and Schneider, 2000). Phenylphenalenones are implicated in the complex defense mechanism of plants and their role as phytoalexins and phytoanticipins in Musa is documented (Luis et al, 1995;Binks et al, 1997;Kamo et al, 2000;Otálvaro et al, 2002). As known from biosynthetic studies of phenylphenalenones in Haemodoraceae and Musaceae, the polyphenolic skeleton is formed by condensing two phenylpropanoic acid units (Thomas, 1971;Harmon et al, 1977;Hö lscher and Schneider, 1995a;Kamo et al, 2000) and C-2 of acetate or malonate (Edwards et al, 1972;Hölscher and Schneider, 1995b).…”

Phenylphenalenone phytoalexins, will they be a new type of fungicide?

“…Phenylphenalenones are biosynthesized from two units of phenylalanine and one carbon atom from acetate, (Beecher et al 1983;Luis et al 1995b;Otalvaro et al 2002a;Kamo et al 2000), through a Diels-Alder cicloaddition (Weiss 1984;Hölscher and Schneider 1995a) to yield a diarylheptanoid intermediate (Hölscher and Schneider 1995b). A biosynthetic exper- iment to understand the production of phytoalexins in plants was carried out using methyl jasmonate as inductor and applying acetate, phenylalanine and SAM (S-adenosylmethionine) 13 C-labeled.…”