Inês S. Resck

Cytotoxic profile of natural and some modified bufadienolides from toad Rhinella schneideri parotoid gland secretion

Cutaneous secretions of toad species are an important source of bufadienolides, compounds that exhibit interesting structural features and biopharmacological properties. Here we describe the isolation of bufadienolides from the Brazilian toad Rhinella schneideri parotoid glands secretion, including: marinobufagin (1), bufalin (2), telocinobufagin (3), hellebrigenin (4), and the atypical 20S,21R-epoxymarinobufagin (5) besides the widespread beta-sitosterol (6). Starting from natural bufadienolides four derivatives were prepared: 3beta-acetoxy-marinobufagin (7), 3beta-acetoxy-bufalin (8), 3beta-acetoxy-telocinobufagin (9), and 3beta-acetoxy-20S,21R-epoxymarinobufagin (10). The cytotoxic evaluation showed that all natural bufadienolides and their derivatives exhibited moderate to strong activity against human HL-60, SF-295, MDA-MB-435, and HCT-8 cancer cell strains without hemolysis of mouse erythrocytes. The acetylated bufadienolides (7-9) and the epoxide 10 showed lesser peripheral blood lymphocytes (PBLs) inhibitory activity than their precursors, suggesting that chemical modifications on such compounds can play an important role on the modulation of their cytotoxic profile.

Antigenotoxic activity and antioxidant properties of organic and aqueous extracts of pequi fruit (Caryocar brasiliense Camb.) pulp

The daily consumption of natural antioxidants protects against oxidative damage caused by reactive oxygen species (ROS), including DNA damage, and can reduce the risk of cancer, atherosclerosis and other degenerative diseases. The pulp of pequi (Caryocar brasiliense Camb.) fruit, a tree native to the Brazilian savannah, contains several compounds with antioxidant properties, including carotenoids, vitamin C, phenolic compounds such as flavonoids, saponins and tannins, and essential oils. In this work, we examined the ability of organic and aqueous extracts of pequi fruit pulp to protect against the genotoxicity induced by two antineoplastic drugs, cyclophosphamide (CP) and bleomycin (BLM). Micronucleus tests with mouse bone marrow cells and single-cell gel electrophoresis (comet assay) with peripheral blood leukocytes were used to examine the effects of CP and BLM, respectively. The antioxidant activity of the extracts was assessed by measuring lipid peroxidation with the TBARS method in mouse plasma. The fruit pulp extracts had no clastogenic or genotoxic effects in the cells studied, but both extracts protected against oxidative DNA damage caused by BLM or CP, indicating an ability to inhibit chemical mutagenesis in vivo. However, the protective effect against oxidative DNA damage depended on the dose of extract used. At the doses tested, the aqueous extract enhanced lipid peroxidation in mice of both sexes, especially in males. In contrast, the organic extract enhanced lipid peroxidation only in male mice, with no significant effect in females. These results suggest that, with adequate adjustment of the dose, an organic extract of pequi fruit pulp could be a useful dietary supplement with natural antioxidant activity, at least in females.

Asymmetric Synthesis of exo-Isobrevicomin and exo-Brevicomin via Conjugated Addition of Primary Alkyl Iodides to alpha,beta-Unsaturated Ketones

(-)-exo-Isobrevicomina (1) e (+)-exo-brevicomina (2) sao substâncias volateis produzidas pelos besouros machos Dendroctonus ponderosae, os quais habitam arvores do genero Pinus encontradas no hemisferio norte, frequentemente causando a morte dos hospedeiros. Objetivando a obtencao desses feromonios de agregacao, que apresentam a estrutura 6,8-dioxabiciclo[3.2.1]octano, as estrategias sinteticas utilizadas nesse trabalho tiveram como etapas-chaves a di-hidroxilacao assimetrica de Sharpless e a adicao conjugada, promovida pela liga Zn(Cu) em meio aquoso e acelerada por ultra-som. A adicao conjugada dos acetonideos 13 e 14 as respectivas cetonas insaturadas (metil-vinil-cetona e etil-vinil-cetona) gerou os adutos 15 e 16. A ciclizacao intramolecular catalisada dos compostos 15 e 16 com acido fosfotungstico (H3PW12O40) forneceu a exo-isobrevicomina (1) e a exo-brevicomina (2).

Characterization of the major nutritional components of Caryocar brasiliense fruit pulp by nmr spectroscopy

Camb.), a typical fruit of Brazilian Cerrado, is well known in regional cookery and used in folk medicine to treat various illnesses. Mass spectrometry and chromatographic methods have identified the organic composition of pequi fruit pulp; however, NMR spectroscopy is used for the first time to characterize the nutritional components of organic and aqueous-ethanolic extracts. This spectroscopic technique determined the triacylglycerols in the pequi organic fraction, which is constituted mainly by oleate and palmitate esters, and detected the carbohydrate mixtures as the major components of aqueous and ethanolic fractions, respectively. In this study, presence of phenolic compounds was only evidenced in the ethanolic fraction.Keywords:

Synthesis of polyols and polyurethanes from vegetable oils–kinetic and characterization

The demand of vegetable oils by several sectors of the chemical industry is growing at a fast pace fueled by the fossil oil scarcity, its unpredictable price fluctuations and the ever increasing environmental concerns. The present work reports for the first time the synthesis of polyols and polyurethanes (PUs) from linseed seed (Linum usitatissimun L.) and passion fruit (Passiflora edulis Sims f. flavicarpa Degener) oils. The in situ epoxidation and hydroxylation of vegetable oils in a single step was successfully accomplished using a mixture of hydrogen peroxide (H2O2) and formic acid. Kinetic studies were performed on this system. The oils and the corresponding polyols were characterized by Fourier transform infrared (FT-IR), gel permeation chromatography (GPC) and thermogravimetry (TG)/derivative termogravimetry (DTG). The PUs were characterized by FT-IR, TG/DTG, dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The study revealed a marked deviation on the properties between the starting materials and the end products. The PUs produced showed similar dynamic mechanical properties.

New application of triphosgene in a convenient synthesis of 3-aryl-1,3-benzoxazine-2,4-diones from anacardic acids

In conjunction with a search program focused on utilization of cashew (Anacardium occidentale) nut shell liquid (CNSL) as starting material for the preparation of useful compounds, a convenient synthesis of novel series of 3-aryl-1,3-benzoxazine-2,4-diones was prepared from anacardic acids by using of the triphosgene.

Purification and full characterisation of citreoviridin produced by Penicillium citreonigrum in yeast extract sucrose (YES) medium

The mycotoxin citreoviridin has been associated with the ‘yellow rice’ disease, which caused cardiac beriberi in Japan. In Brazil, the consumption of contaminated rice was suspected to be involved in a recent beriberi outbreak. In this work, citreoviridin was produced by Penicillium citreonigrum, cultivated in 500 ml yeast extract sucrose (YES) liquid medium for 8 days at 25ºC, and the toxin extracted with chloroform from the liquid medium and the mycelium. A total of 15.3 g of crude extract was obtained from 48 culture flasks, with an estimated citreoviridin contend of 5.54 g, 74.3% being present in the mycelia. Semi-preparative HPLC of the crude extract yielded 27.1% citreoviridin. The HPLC-purified citreoviridin fraction was fully characterised by UV/VIS, FT-IR, 1H- and 13C-NMR, LC-MS/MS and LC-MSD TOF, and purity confirmed by gravimetric analysis. Isocitreoviridin was also produced by P. citreonigrum, accounting for about 10% of the citreoviridin present in the crude extract, most transformed into citreoviridin after 10 months under freezing conditions protected from light. Citreoviridin was shown to be stable under the same conditions, although it can suffer isomerisation after a longer storage period. Isomerisation is a potential source of variability in toxicological studies and purity of the material should be checked before study initiation.

Are fat acids of human milk impacted by pasteurization and freezing

The Human Milk Bank undergo human milk to pasteurization, followed by storage in a freezer at -18° C for up to six months to thus keep available the stocks of this product in maternal and infant hospitals. The objective of this study was to evaluate the effects of processing on the lipid fraction of human milk. A sample of human milk was obtained from a donor and was subdivided into ten sub-samples that was subjected to the following treatments: LC = raw milk; T0 = milk after pasteurization; T30 = milk after pasteurization and freezing for 30 days; T60 = milk after pasteurization and freeze for 60 days, and so on every 30 days until T240 = milk after pasteurization and freezing for 240 days, with 3 repetitions for each treatment. Lipids were extracted, methylated and fatty acid profiles determined by gas chromatography. The fatty acids were characterized by nuclear magnetic resonance and functional groups were identified by infrared spectroscopy. There were variations in the concentration of fatty acids. For unsaturated fatty acids there was increasing trend in their concentrations. The IR and NMR analyze characterized and identified functional groups presents in fatty acids.

Rendimento e análises espectroscópicas (RMN ¹H, 13C; IV) da composição química dos óleos essenciais de quatro plantas do cerrado

A obtencao de oleos essenciais de especies nativas no Brasil ainda e pequena, apesar das suas florestas apresentarem grande potencial para a exploracao desses produtos. No caso do Cerrado, ate agora apenas algumas especies foram estudadas quanto a presenca de oleos essenciais, sendo necessarias mais pesquisas para verificar o potencial desse importante Bioma. Objetivou-se, nesta pesquisa, avaliar o potencial de plantas arboreas e arbustivas do Cerrado para a producao de oleos essenciais, determinando o rendimento e a composicao quimica preliminar de oleos de algumas especies do Bioma. Foram selecionadas em campo as especies Baccharis sp. (assa-peixe), Blepharocalyx salicifolius (maria preta), Psidium myrsinites (araca do cerrado) e Protium ovatum (almecega). Essa selecao foi feita com base em estudos previos sobre familias botânicas produtoras de oleos essenciais, junto com a constatacao da presenca de odores nas folhas maceradas das plantas. A extracao dos oleos foi feita com um minidestilador por arraste de vapor utilizando as folhas das plantas no processo. Para analisar quimicamente cada oleo, primeiramente, foi realizada a separacao das fases orgânica e aquosa dos hidrolatos com o solvente acetato de etila. Posteriormente, foram feitas analises cromatograficas (cromatografia em camada delgada, CCD) e espectroscopicas de Ressonância Magnetica Nuclear (RMN) de ¹H e ¹³C e Infravermelho (IV). Foram obtidos rendimentos de 0,06% para Baccharis sp., 0,12% para Blepharocalyx salicifolius, 0,10% para Protium ovatum e 0,13% para Psidium myrsinites. Nas analises espectroscopicas foi observado que esses oleos sao misturas complexas de hidrocarbonetos saturados (grupos alifaticos) e insaturados (olefinas ou alquenos) e oxigenados (aldeidos, cetonas, esteres, dentre outros). As especies Psidium myrsinites e Blepharocalyx salicifolius apresentaram sinais caracteristicos de carbonilas de cetonas. A primeira apresentou o componente linalol, enquanto a segunda apresentou forte odor caracteristico. Pelos resultados mostrou-se o potencial das plantas do Cerrado como produtoras de oleos essenciais. Com a analise quimica, observou-se que esses oleos essenciais sao constituidos por complexas misturas que devem ser melhor estudadas para avaliar, detalhadamente, a composicao de cada oleo.

Synthesis of (±)-Recifeiolide and Its Homologs via Acetylenic Lactones

Abstract The title compounds (7c,d) have been prepared by the Z to E isomerization (NaNC2, HNO3) of the corresponding Z-lactones (6c,d), which are stereoselectively available (H2, Lindlar cat.) from the acetylenic lactones 4a-d, prepared earlier from cycloalkanones.