Evaluation of furocoumarins as photosynthetic inhibitor by chlorophyll a fluorescence assay

The evaluations of Chorophyll a fluorescence emitted by superior plants carry structural information and photosynthetic apparatus function. Quantitative analysis apparatus of fluorescence kinetic were measured by energy flows (ABS), (TR), (ET) and (DI), known as phenomenological phenomena of OJIP test. Four furocoumarins were isolated from Ruta graveolens (Rutaceae), and chorophyll a (Chl a) fluorescence assays were performed with these compounds to evaluate the photosynthesis inhibition potential. This test was realized in spinach`s leaf discs and in Lolium perenne leaves. The results indicated the herbicide potential mainly for bergapten and chalepin.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Universidade Federal de São Carlos Departamento de QuímicaUniversidade Federal de São Paulo (UNIFESP) Instituto de Ciências Ambientais, Químicas e FarmacêuticasUniversidad Nacional Autónoma de México Facultad de Química Departamento de BioquímicaUNIFESP, Instituto de Ciências Ambientais, Químicas e FarmacêuticasSciEL

Phytogrowth-Inhibitory lactones derivatives of Glaucolide B

The sesquiterpene lactone glaucolide B (1), isolated from Vernonia fruticulosa (Asteraceae), was transformed into six lactones (2-7). The structures of the products were elucidated by spectroscopic analysis. A series of solutions of compounds 1-7, at 200 μᴍ, were tested on the germination and on the root and shoot growth of the dicotyledons Physalis ixocarpa and Trifolium alexandrinum and of the monocotyledons Lolium multiflorum and Amaranthus hypochondriacus. Lactone 5 exhibited clear selectivity towards dicotyledonous species at 200 μᴍ, with an average inhibition of 90% on the germination of P. ixocarpa. Lactones 1, 3 and 4 had a greater effect on root length of monocotyledonous species, inhibiting around 70% at 200 μᴍ in L. multiflorum. It seems that the diol function is required in lactones 4-6 to increase the activity, the polarity in the molecule might be required to reach its target

Cobalt(II) Coordination Compounds of Ethyl 4-Methyl-5-Imidazolecarboxylate: Chemical and Biochemical Characterization on Photosynthesis and Seed Germination

In this work we present the synthesis, structural and spectroscopic characterization of Co(2+) coordination compounds with ethyl 4-methyl-5-imidazolecarboxylate (emizco). The effects of emizco, the metal salts CoCl(2).6H(2)O, CoBr(2), Co(NO(3))(2).6H(2)O and their metal coordination compounds [Co(emizco)(2)Cl(2)], [Co(emizco)(2) Br(2)].H(2)O, [Co(emizco)(2) (H(2)O)(2)(NO(2))(2).2H(2)O were evaluated on photosynthesis in spinach chloroplasts. Seed germination and seedling growth of the monocotyledonous species Lolium multiflorum and Triticum aestivum and the dicotyledonous species Trifolium alexandrinum and Physalis ixocarpa were also assayed under the effect of the compounds and salts. The results showed that cobalt(II) salts and their emizco coordination compounds inhibit photosynthetic electron flow and ATP-synthesis, behaving as Hill reaction inhibitors. Coordination compounds are more potent inhibitors than the salts. It was found that the salts target is at the b(6)f level while the complexes targets are at Q(B)(D1)-protein and b(6)f level. The Q(B) inhibition site was confirmed by variable chlorophyll a fluorescence yield. On the other hand, emizco inhibits seed germination, root and shoot development, in both weed and crop species. Cobalt(II) coordination compounds are the most effective photosynthesis inhibitors, but they are less potent than emizco in germination and seedling growth, while the metal salts are the least active of all

Tricolorin A as a Natural Herbicide

Tricolorin A acts as pre- and post-emergence plant growth inhibitor. In pre-emergence it displays broad-spectrum weed control, inhibiting germination of both monocotyledonous (Lolium mutliflorum and Triticum vulgare) and dicotyledonous (Physalis ixocarpa and Trifolium alexandrinum) seeds, being the dicotyledonous seeds the most inhibited. Tricolorin A also inhibited seedling growth, and seed respiration, and since the concentrations required for inhibiting both germination and respiration were similar, we suggest that respiration is one of its targets. Tricolorin A at 60 µM acts as a post- emergence plant growth inhibitor by reducing dry plant biomass by 62%, 37%, 33%, and 22% for L. multiflorum, T. alexandrinum, T. vulgare, and P. ixocarpa, respectively, 18 days after its application. In order to determine the potency of tricolorin A as a plant growth inhibitor, paraquat was used as control; the results indicate that tricolorin A acts as a non-selective post-emergence plant growth inhibitor similar to paraquat, since both reduced the biomass production in P. ixocarpa and T. alexandrinum. Therefore, we suggest that tricolorin A will be a good biodegradable herbicide for weeds