NMR property calculations and experimental study of the 1,6-epoxycarvone and α-epoxypinene: a comparison of models.

This work aims at using theoretical calculations of shielding tensors (σ) through different methods [gauge-independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and individual gauges for atoms in molecules (IGAIM)] and spin-spin coupling constants J using GIAO method to compare these methods and to corroborate the data obtained with the assignment of all of (1)H and (13)C NMR signals and the relative stereochemistry of the 1,6-epoxycarvone and the α-epoxypinene. All the (1)H and (13)C NMR signals were assigned unequivocally. The stereochemistry for the epoxides is trans and the B3LYP theory level with CSGT and IGAIM methods is the best choice to evaluate theoretical chemical shifts for compounds studied.

1H and 13C NMR spectral data of bioactive cage-like polycyclic compounds.

Bioactive cage-like polycyclic compounds have attracted the attention of several research groups because of their unique appearance and their biological activities. Their structures were established on the basis of (1)H NMR and (13)C NMR spectroscopic data. The (1)H and (13)C signal assignments and most homonuclear hydrogen coupling constants were assigned by use of techniques such as 1D (1)H and (13)C NMR and 2D gCOSY, non-edited gHSQC and gHMBC. The gNOESY experiments proved the endo-stereochemistry.

Antimicrobial activity and potential use of monoterpenes as tropical fruits preservatives

Banana, papaya and pineapple are the most consumed tropical fruits in the world, being Brazil one of the main producers. Fungi Colletotrichum musae, Colletotrichum gloeosporioides and Fusarium subglutinans f.sp. ananas cause severe post harvest diseases and losses in fruits quality. The aim of this work was to evaluate the effectiveness of five monoterpenes to inhibit the mycelial growth and conidia germination of these three phytopathogens. The monoterpenes citral, citronellal, L-carvone, isopullegol and a-pinene were diluted in ethanol to final concentrations from 0.2 to 1 percent. All monoterpenes were found to inhibit the growth of the three studies fungi in a dose-dependent manner. Citral was the most effective of the oils tested and showed potent fungicidal activity at concentrations above 0.5 percent. Also, in vivo evaluation with these tropical fruits demonstrated the efficiency of citral to inhibit fungal growth. These results indicate the potential use of citral as a natural pesticide control of post-harvest fruit diseases.

Banana, mamão e abacaxi são as frutas tropicais mais consumidas no mundo, sendo o Brasil um dos principais produtores. Os fungos Colletotrichum musae, Colletotrichum gloeosporioides e Fusarium subglutinans f.sp ananas são os principais causadores de doenças e perdas em pós-colheita de frutas. A proposta deste estudo foi avaliar a eficácia de cinco monoterpenos em inibir o crescimento micelial e a germinação dos conídios destes três fitopatógenos. Os monoterpenos citral, citronelal, L-carvona, isopulegol e a-pineno foram diluídos em etanol à concentração final de 0,2 a 1 por cento. Todos os monoterpenos testados inibiram os três fungos estudados de maneira dose-dependente. Citral foi o mais efetivo dos óleos testados e apresentou uma potente atividade fungicida em concentrações acima de 0,5 por cento. Mais ainda, avaliação in vivo com estas frutas tropicais demonstrou a eficácia de citral como inibidor do crescimento fúngico. Estes resultados indicam o uso em potencial de citral como um pesticida natural no controle das doenças em pós-colheita de frutas tropicais.

Stereochemistry of cyclopentane derivatives from (2,3)J(CH) dependence on dihedral angle (theta H--C--C--X).

The (2,3)J(CH) dependence on dihedral angle (theta H--C--C--X) for cyclopentane derivatives was investigated. We observed that the combined use of experimentally obtained (2,3)J(CH) values and the theoretically determined dihedral angles between the corresponding nuclei can be used to infer the relative stereochemistry of the ring substituents in cyclopentane derivatives. There is a good correlation between the magnitude of (3)J(CH) and the dihedral angle between the hydrogen and the coupled carbon (R2 = 0.88).

Antimicrobial activity and potential use of monoterpenes as tropical fruits preservatives.

Banana, papaya and pineapple are the most consumed tropical fruits in the world, being Brazil one of the main producers. Fungi Colletotrichum musae, Colletotrichum gloeosporioides and Fusarium subglutinans f.sp. ananas cause severe post harvest diseases and losses in fruits quality. The aim of this work was to evaluate the effectiveness of five monoterpenes to inhibit the mycelial growth and conidia germination of these three phytopathogens. The monoterpenes citral, citronellal, L-carvone, isopullegol and α-pinene were diluted in ethanol to final concentrations from 0.2 to 1%. All monoterpenes were found to inhibit the growth of the three studies fungi in a dose-dependent manner. Citral was the most effective of the oils tested and showed potent fungicidal activity at concentrations above 0.5%. Also, in vivo evaluation with these tropical fruits demonstrated the efficiency of citral to inhibit fungal growth. These results indicate the potential use of citral as a natural pesticide control of post-harvest fruit diseases.

Inactivation of Colletotrichum gloeosporioides spores by high hydrostatic pressure combined with citral or lemongrass essential oil.

Anthracnose, caused by the fungus Colletotrichum gloeosporioides, is the main post-harvest disease of the papaya. Inactivation of the spores of C. gloeosporioides in saline solution by the use of high hydrostatic pressure, citral oil and lemongrass oil, alone and in combination, was studied. C. gloeosporioides spores were efficiently inhibited after a pressure treatment of 350 MPa for 30 min. When C. gloeosporioides was treated with 0.75 mg ml(-1) of citral or lemongrass oil, the pressure needed to achieve the same spore inhibition was 150 MPa. This work suggests the use of high hydrostatic pressure and plant essential oils as an alternative control for fruit diseases.