Mayura M. M. Rubinger

Syntheses, crystal structure, spectroscopic characterization and antifungal activity of new N-R-sulfonyldithiocarbimate metal complexes.

Five new compounds with the general formula of (Bu(4)N)(2)[M(RSO(2)NCS(2))(2)], where Bu(4)N=tetrabutylammonium cation, (M=Ni, R=4-FC(6)H(4)) (1), (M=Zn, R=4-FC(6)H(4), 4-ClC(6)H(4), 4-BrC(6)H(4), 4-IC(6)H(4)), (2), (3), (4) and (5), respectively, were obtained by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO(2)N=CS(2)K(2)) with nickel(II) chloride hexahydrate or zinc(II) acetate dihydrate in metanol:water 1:1. The elemental analyses and the IR data are consistent with the formation of the expected bis(dithiocarbimato)metal(II) complexes. The (1)H and (13)C NMR spectra showed the signals for the tetrabutylammonium cation and the dithiocarbimate moieties. The compounds 1, 2 and 5 were also characterized by X-ray diffraction techniques. The nickel(II) is coordinated by two N-4-fluorophenylsulphonyldithiocarbimato(2-) ligands forming a planar coordination. The zinc(II) exhibits distorted tetrahedral configuration in compounds 2 and 5 due to the chelation effect of two sulfur atoms of the N-R-sulfonyldithiocarbimate ligands. The antifungal activities of the compounds were tested in vitro against Colletotrichum gloeosporioides, an important fungus that causes the plant disease known as anthracnose in fruit trees. All the complexes were active.

Preparation, X-ray structural studies and plant growth regulatory activity of methyl 6alpha,7beta-thiocarbonyldioxyvouacapan-17 beta-oate

The 6a,7b-dihydroxyvouacapan-17b-oic acid (1) and methyl 6a,7b-dihydroxyvouacapan-17b-oate (2) are natural products isolated from the hexane extract of Pterodon polygalaeflorus Benth fruits. Here we describe the preparation and characterization by infrared and nuclear magnetic resonance spectroscopy, and by elemental analysis of the novel derivative methyl 6a,7b-thiocarbonyldioxyvouacapan-17b-oate (5), from the ester 2. The structure of compound 5 was determined by X-ray diffraction. At the concentration of 100 ppm, this compound inhibited the radicle growth of Sorgum bicolor L. (-28%) and showed no significant effect on Cucumis sativus L..

Synthesis and antifungal activity of new bis-gamma-lactones analogous to avenaciolide

In a study of the antifungal activity of selected compounds as potentials agrochemicals, we have prepared and characterized by elemental analyses, infrared and NMR spectroscopies three new bis-g-lactones analogous to avenaciolide, where the octyl group of this natural product was replaced by heptyl, hexyl and pentyl groups. The effects on the mycelia development and conidia germination of Colletotrichum gloesporioides of these compounds and their synthetic precursors were evaluated in vitro. The title compounds were active in the tested conditions, while all the synthetic precursors were inactive. The preparation and characterization of 15 new synthetic intermediates are also described.

Preparation of novel palladium(II) complexes with dithiocarbimates from sulfonamides

Potassium N-R-sulfonyldithiocarbimates, K2(RSO2N=CS2) (R = Me, Ph, 2-MeC6H4), react with Pd(OAc)2 to yield complex anions bis(N-R-sulfonyldithiocarbimato)palladate(II), [Pd(RSO2N=CS2)2]2−, which were isolated as their n-Bu4N+ salts. When the reaction was performed in the presence of Ph3P in a 2:1 ratio with respect to Pd(OAc)2, the N-R-sulfonyldithiocarbimatobis(triphenylphosphine)palladium(II) complexes were obtained. Elemental analyses, i.r. spectra and electronic spectra data were consistent with the formation of palladium–sulfur diamagnetic square planar complexes in the first case and mixed square planar complexes of palladium with Ph3P and dithiocarbimates in the second case. The 1H-n.m.r., 13C-n.m.r. and 31P-n.m.r. spectra showed the expected signals for the Bu4N+ cation, Ph3P and the dithiocarbimate moieties.

BIS(4-FLUOROPHENYLSULFONYLDITHIOCARBIMATO)ZINCATE(II) SALTS: NEW ANTIFUNGALS FOR THE CONTROL OF Botrytis BLIGHT

Botrytis blight or gray mold is a highly destructive disease caused by Botrytis spp., that infects flowers, trees vegetables, fruit, especially grapevines and strawberry. Three new compounds with general formula (A)2[Zn(4-FC6H4SO2N=CS2)2], where A = PPh3CH3 (2a), PPh3C2H5 (2b), PPh3C4H9 (2c), and the previously published compounds where A = PPh4 (2d) and NBu4 (2e), were synthesized by the reaction of 4-fluorophenylsulfonyldithiocarbimate potassium dihydrate and zinc(II) acetate dihydrate with the appropriate counter cations (A) halides. The new compounds were characterized by infrared, 1H and 13C NMR spectroscopies. All these salts inhibited the growth of Botrytis cinerea, with compounds 2c and 2d showing greater antifungal activity than zinc dimethyldithiocarbamate, the active principle of the fungicide Ziram. The bis(dithiocarbimate)zincate(II) salts are also active against the bacteria Escherichia coli and Staphylococcus aureus.

Inhibition and uncoupling of photosynthetic electron transport by diterpene lactone amide derivatives.

Nine diterpene lactone amide derivatives 1-9 were synthesized from 6-oxovouacapan- 7β,17β-lactone, which was obtained from 6α,7β-dihydroxyvouacapan-17β-oic acid isolated from Pterodon polygalaeflorus Benth., and tested for their activity on photosynthetic electron transport. Amide derivatives 3-5 behaved as electron transport chain inhibitors; they inhibited the photophosphorylation and uncoupled non-cyclic electron transport from water to methylviologen (MV). Furthermore, 4 and 5 enhanced the basal electron rate acting as uncouplers. Compound 6 behaved as an uncoupler; it enhanced the light-activated Mg2+-ATPase and basal electron flow, without affecting the uncoupled non-cyclic electron transport. Compounds 1-2 and 7-9 were less active or inactive. Compounds 3-5 did not affect photosystem I (PSI); they inhibited photosystem II (PSII) from water to 2,6-dichlorophenol indophenol (DCPIP). Compound 4 inhibited PSII from water to silicomolybdate (SiMo), but it had no effect on the reaction from diphenylcarbazide (DPC) to DCPIP indicating that its inhibition site was at the water splitting enzyme complex (OEC). Compounds 3 and 5 inhibited PSII from water to DCPIP without any effect from water to SiMo, therefore they inhibited the acceptor site of PSII. Chlorophyll a fluorescence kinetics confirmed the behaviour of 3-5

Synthesis and phytotoxicity evaluation of novel 6α,7β-dihydroxyvouacapan-17p-oic acid derivatives

The 6α,7β-dihydroxyvouacapan-17β-oic acid (1) isolated from Pterodon polygalaeflorus Benth has shown allelopathic and plant growth regulatory properties. Six novel esters of (1) were prepared and their effects on the radical growth of Sorghum bicolor L. and Cucumis sativus L. were evaluated.

Syntheses, characterization and antifungal activity of tris(1,10-phenanthroline)iron(ii) bis(n-r-sulfonyldithiocarbimate)zincate(ii)

Four new compounds with the general formula [Fe(phen)3][Zn(RSO2N=CS2)2], where phen = 1,10-phenanthroline, R = 4-FC6H4 (1), 4-ClC6H4 (2), 4-BrC6H4 (3) and 4-IC6H4 (4), respectively, were obtained by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO2N=CS2K2) and tris(1,10-phenanthroline)iron(II) sulfate, with zinc(II) acetate dihydrate in dimethylformamide. The elemental analyses and the IR data were consistent with the formation of the expected complexes salts. The 1H and 13C NMR spectra showed the signals for the cationic iron(II) complex and dithiocarbimate moieties. The molar conductance data were consistent with the 1:1 cation:anion complexes in 1-4. The antifungal activities of the compounds were tested in vitro against Candida albicans, Candida tropicalis and Colletotrichum gloeosporioides.

Avaliação de Bis(4-Metilfenilditiocarbimato)Zincato(II) de Tetrabutilamônio como Acelerador em Composições de Borracha Natural

The acceleration potential of ZNIBU [tetrabutyl ammonium bis(4-methylphenyldithiocarbimatozincate(II))] in the vulcanization process of natural rubber compounds was investigated. The vulcanized compounds were tested for hardness, resilience and density and compared with those vulcanized with commercial accelerators such as CBS (N-cyclohexyl-2-benzothiazolesulphenamide), TMTD (tetramethyl thiuram disulphide) and MBTS (dibenzothiazole disulphide). The new accelerator tested was found to be too slow for a commercial application, but its properties were similar to those of other accelerators.

A Diterpene γ-Lactone Derivative from Pterodon polygalaeflorus Benth. as a Photosystem II Inhibitor and Uncoupler of Photosynthesis

6α,7β-Dihydroxyvouacapan-17β-oic acid (1) was isolated from Pterodon polygalaeflorus Benth. Modification of 1 yielded 6α-hydroxyvouacapan-7β,17β-lactone (2) and then 6-oxovouacapan- 7β,17β-lactone (3). Photosynthesis inhibition by 3 was evaluated in spinach chloroplasts. The uncoupled non-cyclic electron transport rate and ATP synthesis were inhibited by 3, which behaved as a Hill reaction inhibitor. Furthermore, 3 acted as an uncoupler because it enhanced the basal and phosphorylating electron transport rate on thylakoids. This last property of 3 was corroborated when it was observed that it enhances the Mg2+-ATPase activity. In contrast, 3 did not affect photosystem I (PSI) activity. Analysis of the partial photosystem II (PSII) reactions from water to DCPIPox and water to silicomolybdate allowed to locate the inhibition sites at the redox components of PSII. The OJIP test of the chlorophyll a fluorescence transient confirmed that the inhibition sites were 1.) the oxygen-evolving complex (OEC) and 2.) by the formation of silent centers in the non-QA reducing centers.