Alternaric acid

A formal synthesis of the antifungal agent alternaric acid was realized in the Trost group.95 The skipped diene portion of the natural product was obtained via a ruthenium-catalyzed intermolecular Alder-ene reaction (Scheme 36). Several attempts to produce 162 from the protected fragment 161 gave low yields and unremarkable regioselectivity. The diol (R = H), however, performed satisfactorily, allowing the reaction to be carried out at room temperature. The product 162 was obtained in 51% isolated yield as an 8.9 1 mixture of branched to linear isomers. 

Another fungal pathogen Altemaria produces a variety of nonhost-selective phytotoxins291 such as aromatic polyketides (alternariol, zinniol) and reduced polyketides (alternaric acid, solanapyrones). Alternaric acid292 isolated from Altemaria solani shows unique physiological effects on the hypersensitive cell death of potato... 

Alternaria solani is a plant pathogen and the causitive agent of early blight in solanum species. It produces numerous polyke-tides, such as solanopyrone A 51 and alternaric acid 52, and it... 

Alternaria species are associated with several leaf-spot diseases of plants. Alternaric acid (8.10), produced by A. solani, which is the cause of early blight on potatoes and tomatoes, has a marked phytotoxic activity and may be responsible for many of the symptoms of the plant disease caused by the fungus. It also shows a specific anti-fungal activity. The branched chain structure is biosynthesized from nine acetate units and three Ci units derived from formate. The solanopyrones are another group of phytotoxic metabolites of A. solani. Solanopyrone A (8.11) induced necrotic lesions on the leaves of potatoes typical of this fungal infection. The structures of the solanopyrones were established by... 

Trost, B.M., Probst, G.D. and Schoop, A. (1998) Ruthenium-catalyzed Alder ene type reactions. A formal synthesis of alternaric acid. Journal of the American Chemical Society, 120, 9228-9236. 

Alternaric acid AUemaria aolani Inoculated unsterilized tomato fruits... 

Goodman (1959) discusses the phytotoxicity of streptomycin, cycloheximide, griseofulvin, polymyxin and tetracyclines. These are antibiotics that have been most used, or considered for use, in plant disease control. Other antibiotics that he mentions which have been observed to be phytotoxic are alternaric acid, glutinosin, mycophenolic acid and gliotoxin. 

Brian also calls attention to the fact that certain parasitic microorganisms within plant tissues can produce antibiotics that are toxic to their hosts. Among these are lyco-marasmin, fusarinic acid, alternaric acid and patulin. There appears to be considerable doubt as to the connection between these antibiotics and the development of disease symptoms in the host plants. Definite conclusions must await further research. 

Waksman and Brian. It v/as recognized that v/hereas antibiotics could be considered as inhibitors of plant growth, they could sometimes stimulate growth either directly or by the removal of pathogens v/hich are inhibitory to growth. Antibiotics are often metabolic inhibitors of great specificity and potency and amongst those with inhibitory effects at 5 Pg/nil or less are actidione, azaserine, alternaric acid, and polymyxin. The activity of antibiotics on... 

Alternarively, the azeohopic condensation technique is used to remove the water. In the modified direct polymerization route, diaminodi-phenyl ether, m-phenylenediamine (MPD) and trimellitic acid anhydride in a ratio of total 1 mol of diamino compound and 2 mol of anhydride compound are condensed in NMP using xylene to remove the water formed. The resulting diimidedicarboxylic acid is treated with thionyl chloride to form the acid chloride on the fly and the PAl is created by adding a mixture of diaminodiphenyl ether and MPD. ... 

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