Alessandra Regina Pepe Ambrozin

Evaluation of biodiesel-diesel blends quality using 1H NMR and chemometrics.

In this work, the use of (1)H NMR spectroscopy and statistical approach to the evaluation of biodiesel-diesel blends quality is described. Forty-six mixtures of oil-diesel, biodiesel-diesel, and oil-biodiesel-diesel were analyzed by (1)H NMR and such data were employed to design four predictive models. Thirty-six mixtures were used in the calibration set and the others in the validation. The PCR and PLS models were evaluated through statistical parameters. Briefly, PLS and PCR models were suitable for the prediction of biodiesel and oil concentration in mineral diesel. Specially, in higher concentration the predicted values were quite similar to the real ones. This fact was evidenced by the low relative errors of high concentrated samples; this means that the prediction of low concentrated samples will probably show high deviation. Therefore, (1)H NMR-PLS and (1)H NMR-PCR methods are fairly useful for the quality control of biodiesel-diesel blends, particularly they are suitable for prediction of concentrations greater than 2%.

Limonoids from andiroba oil and Cedrela fissilis and their insecticidal activity

Nine limonoids were isolated from Carapa guianensis and Cedrela fissilis. Among them, 1,2-dihydro-3b-hydroxy-7-deacetoxy-7-oxogedunin is a new compound. Moreover, the assignments of some chemical shifts of xyloccensin k have been corrected and 1H NMR data of 7-deacetylgedunin have been assigned for the first time. These isolated limonoids were assayed on Atta sexdens rubropilosa workers showing moderate insecticidal activities.

Trypanocidal activity of Meliaceae and Rutaceae plant extracts.

The in vitro trypanocidal activity of 22 extracts and 43 fractions of plants belonging to the families Meliaceae and Rutaceae was evaluated. The extracts from leaves of Conchocarphus heterophyllus and branches of Trichilia ramalhoi were the most active. The trypanocidal activity seems to be increased by fractionation of the extracts. Fractions from C. heterophyllus and Galipea carinata were the most active and a 100% lysis of the parasites was observed for five fractions. From one of them were isolated two flavonoids: flavone and 7-methoxyflavone, which showed weak trypanocidal activity. The results obtained from the extracts and fractions revealed that the order Rutales is a promising source for the search of new drugs for Chagas disease. Phytochemical studies with the other active fractions are underway in order to isolate compounds, which could be associated with observed activities.

Corrosão metálica associada ao uso de combustíveis minerais e biocombustíveis

Fuels and biofuels have a major importance in the transportation sector of any country, contributing to their economic development. The utilization of these fuels implies their closer contact to metallic materials, which comprise vehicle, storage, and transportation systems. Thus, metallic corrosion could be related to fuels and biofuels utilization. Specially, the corrosion associated to gasoline, ethanol, diesel, biodiesel, and their mixtures is discussed in this article. Briefly, the ethanol is the most corrosive and gasoline the least. Few investigations about the effect of biodiesel indicate that the corrosion is associated to their unsaturation degree and the corrosion of diesel is related to its acidity.

Trypanocidal activity of flavonoids and limonoids isolated from Myrsinaceae and Meliaceae active plant extracts

The activity of crude extracts of three Rapanea species (Myrsinaceae) and Cipadessa fruticosa (Meliaceae) was evaluated in vitro against the trypomastigote forms of Trypanosoma cruzi. Thirty-three extracts from different organs of these species were assayed and eleven of them showed significant activity (lysis % >50). The fractionation of an active extract from branches of R. lancifolia (99.5%) led to the isolation of two flavonoids: quercetin and taxifolin, which have weak trypanocidal activity. Additionally, one active extract from fruits of C. fruticosa (97.7%) afforded mexicanolide limonoids: cipadesin, mexicanolide, febrifugin and cipadesin A, that were slightly active on T. cruzi. Moreover, other two flavonoids (flavone and 7-methoxyflavone), previously assayed against T. cruzi, were isolated from the hexane extract from branches of C. fruticosa (100%). The results presented here suggest that the plants evaluated could be a source of new active compounds against T. cruzi.

New pyrone and quinoline alkaloid from Almeidea rubra and their trypanocidal activity

O estudo da fracao acetato de etila do extrato metanolico das folhas de Almeidea rubra A. St.- Hil. (Rutaceae) permitiu o isolamento de duas substâncias ineditas: 4-metoxi-6-(2-(metilamino)fenil)- 2H-piran-2-ona e acetato de rel-(7R,8R)-8-((E)-3-hidroxi-3-metil-1-butenil)-4,8-dimetoxi-5,6,7,8- tetraidrofuro(2,3-b)quinolin-7-ila; e dos alcaloides arborinina, N-metil-1-hidroxi-3-metoxiacridona, esquimianina, cocusagina, isodutaduprina, isoesquimianina e isococusagina. Atraves da analise dos dados espectroscopicos foram estabelecidas as estruturas quimicas das substâncias isoladas sendo que para os alcaloides ineditos tais dados sao descritos pela primeira vez. Alem disso, os ensaios bilogicos sobre as formas tripomastigotas do Trypanosoma cruzi das substâncias isoladas mostraram que elas possuem atividade tripanocida moderada. The investigation of the ethyl acetate fraction of methanol extract from leaves of Almeidea rubra A. St.-Hil. (Rutaceae) afforded two new compounds 4-methoxy-6-(2-(methylamino)phenyl)-2H- pyran-2-one and rel-(7R,8R)-8-((E)-3-hydroxy-3-methyl-1-butenyl)-4,8-dimethoxy-5,6,7,8- tetrahydrofuro(2,3-b)quinoline-7-yl acetate, along with the known compounds arborinine, N-methyl- 1-hydroxy-3-methoxyacridone, skimmianine, kokusagine, isodutaduprine, isoskimmianine, and isokokusagine. Their structures were established based on their spectral data, and for the new compounds these data are described herein. Additionally, these compounds were assayed on the tripomastigote forms of Trypanosoma cruzi showing moderate trypanocidal activity.

Evaluation of Metallic Corrosion Caused by Alcohol Fuel and Some Contaminants

In the present work, it is evaluated the effect of water and other contaminants of alcohol fuel on the corrosion behavior of different materials, which can constitute vehicles, storage and transportation fuels systems. For such, 5 metallic materials (zamak, low-carbon steel, stainless steel, and two Al alloys) were chosen and 5 alcoholic solutions were prepared: anhydrous ethanol (AEAC; solution 1); hydrated ethanol (AEHC; solution 2); AEAC and water with some impurities (AEAC + 6 % “corrosive” water; solution 3); AEHC and water with some impurities (AEHC + 6 % “corrosive” water; solution 4); and, AEAC and tap water (AEAC + 6 % tap water; solution 5). The crevice corrosion was investigated in static immersion tests, which were carried out at 50 °C for 2 months. The evaluation of the corrosive process was carried out by visual inspection, weight loss, optic microscopy, and scanning electron microscopy (SEM). Also, some quality parameters of the alcoholic solutions (specific mass, alcoholic content, pH, and conductivity) was analyzed in order to determine the influence of corrosion of the materials on them. The results have shown that crevice corrosion of all materials mostly occurred in solutions 3-5, which had a high amount of water and impurities. Some corrosion rates in such solutions were 90-400 times higher than those obtained in AEAC and AEHC. Among the materials, zamak and carbon steel suffered severe corrosive attack. The physicochemical properties of alcoholic solutions employed in the tests also changed, mainly the increase of pH and conductivity was observed. Therefore, the results demonstrate that the quality control of alcohol fuel is essential in order to avoid the damage of engine parts and storage and transportation systems. Specially, water, sulphate, chloride and acetate content must be monitored.

Piranoflavonas inéditas e atividades tripanocidas das substâncias isoladas de conchocarpus heterophyllus

The phytochemical investigation of trypanocidal extracts from leaves and stems of Conchocarpus heterophyllus (A. St.-Hil.) Kallunki & Pirani (Rutaceae) afforded new pyranoflavones along with the known compounds flavone, 7-methoxyflavone, 5-hydroxyflavone, haplotusine, 1-methyl-2-phenyl-4-quinolone alkaloid, b-sitosterol, stigmasterol, and b-sitosteryl benzoate. Their structures were established based on their spectral data. NMR data for the alkaloid haplotusine and the new pyranoflavones are described for the first time herein. These compounds were assayed on the tripomastigote forms of Trypanosoma cruzi. Among them, haplotusine and 1-methyl-2-phenyl-4-quinolone showed moderate values of IC50 136.9 and 144.9 mM, respectively.