title: Synthetic analogues of the natural compound cryphonectric acid interfere with photosynthetic machinery through two different mechanisms.
abstract: 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.
authors.affiliation: Department of Chemistry, Universidade Federal de Viçosa, Av. P. H. Rolfs S/N, 36.570.000 Viçosa, Minas Gerais, Brazil. robsonr.teixeira@ufv.br
authors.forename: Róbson Ricardo
authors.initials: RR
authors.lastname: Teixeira
authors.forename: Wagner Luiz
authors.initials: WL
authors.lastname: Pereira
authors.forename: Deborah Campos
authors.initials: DC
authors.lastname: Tomaz
authors.forename: Fabrício Marques
authors.initials: FM
authors.lastname: de Oliveira
authors.forename: Samuele
authors.initials: S
authors.lastname: Giberti
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Forlani
mesh_terms: D001572:Benzofurans / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects; D010788:Photosynthesis / Q000187:drug effects*; D018724:Spinacia oleracea / Q000187:drug effects / Q000378:metabolism*; D046940:Synechococcus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001572:Benzofurans; C449755:cryphonectric acid