title: Derivatives of diterpen labdane-8α,15-diol as photosynthetic inhibitors in spinach chloroplasts and growth plant inhibitors.
abstract: In a search of new efficient herbicides of natural origin, four derivatives were prepared from labdane-8α,15-diol (1) and 15-O-acetyl-8α-hydroxy labdane (2) isolated from Croton ciliatoglanduliferus. Their inhibitory activity on photosynthetic electron transport on fresh, broken spinach chloroplasts and on the growth of plants were determined. Derivative 15-O-benzoyl-8α-hydroxy labdane (5) was seven times more active than 2 as reaction Hill inhibitor. Complex of 5 with the adjuvant 2-hydroxypropyl-β-cyclodextrin (5:HPB) (200 μM) was sprayed on Physalys ixocarpa (green tomato) plants; 48 h later the complex inhibited PS II by transforming the active reaction centers to silent reaction centers or "heat sinks". After 72 h this effect disappeared, probably 5:HPB was metabolized by the plant. Chlorophyll a fluorescence of Trifolium alexandrinum (clover) leaves was affected with 5:HPB at the level of PQ pool reduction. 5:HPB decreases the tomato and clover dry-biomass, without affecting Lolium perenne (grass) plants, suggesting that complex 5 acts as selective herbicide for dicotyledonous plants.
authors.affiliation: Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, Delegación Coyoacan, México DF, Mexico.
authors.forename: Félix
authors.initials: F
authors.lastname: Morales-Flores
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Aguilar
authors.forename: Beatriz
authors.initials: B
authors.lastname: King-Díaz
authors.forename: Blas
authors.initials: B
authors.lastname: Lotina-Hennsen
mesh_terms: D018533:Biomass; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism; D003505:Cyclodextrins / Q000737:chemistry / Q000494:pharmacology; D004224:Diterpenes / Q000737:chemistry / Q000494:pharmacology*; D006540:Herbicides / Q000737:chemistry / Q000494:pharmacology*; D008129:Lolium / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D010937:Plant Growth Regulators / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018724:Spinacia oleracea / Q000187:drug effects* / Q000378:metabolism; D029921:Trifolium / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D003505:Cyclodextrins; D004224:Diterpenes; D006540:Herbicides; D010937:Plant Growth Regulators; C521330:labdane-8alpha,15-diol; D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: Chlorophyll a fluorescence; Cyclodextrines; Herbicide activity; Labdane-8α,15-diol; Photosynthetic inhibitors; Silent reaction centers