Synthetic Analogues of the Natural Compound Cryphonectric Acid Interfere with Photosynthetic Machinery through Two Different Mechanisms

• Published in: Journal of agricultural and food chemistry Vol. 61; no. 23; pp. 5540 - 5549
• Main Authors: Teixeira, Róbson Ricardo, Pereira, Wagner Luiz, Tomaz, Deborah Campos, de Oliveira, Fabrício Marques, Giberti, Samuele, Forlani, Giuseppe
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 12-06-2013
• Subjects: active ingredients; Benzofurans - chemical synthesis; Benzofurans - chemistry; Benzofurans - pharmacology; Biological and medical sciences; chloroplasts; Chloroplasts - drug effects; Chloroplasts - metabolism; culture media; Electron Transport - drug effects; electron transport chain; energy transfer; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; growth retardation; Handling, storage, packaging, transport; nuclear magnetic resonance spectroscopy; Photosynthesis - drug effects; spinach; Spinacia oleracea - drug effects; Spinacia oleracea - metabolism; Synechococcus - drug effects; Synechococcus - growth & development; Synechococcus - metabolism; Synechococcus elongatus; weed control; phtalides; isobenzofuran-1(3H)-ones; photosynthetic electron transport; uncouplers; herbicides; Acids; Pesticides; Natural compound; Transport; Herbicide; Mechanism
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf400698j

A series of isobenzofuran-1(3H)-ones (phthalides), analogues of the naturally occurring phytotoxin cryphonectric acid, were designed, synthesized, and fully characterized by NMR, IR, and MS analyses. Their synthesis was achieved via condensation, aromatization, and acetylation reactions. The measurement of the electron transport chain in spinach chloroplasts showed that several derivatives are capable of interfering with the photosynthetic apparatus. Few of them were found to inhibit the basal rate, but a significant inhibition was brought about only at concentrations exceeding 50 μM. Some other analogues acted as uncouplers or energy transfer inhibitors, with a remarkably higher effectiveness. Isobenzofuranone addition to the culture medium inhibited the growth of the cyanobacterium Synechococcus elongatus, with patterns consistent with the effects measured in vitro upon isolated chloroplasts. The most active derivatives, being able to completely suppress algal growth at 20 μM, may represent structures to be exploited for the design of new active ingredients for weed control.