Many essential oils (EOs) of different plant species possess interesting antimicrobial effects on buccal bacteria and antioxidant properties. Eugenia klotzschiana Berg (pêra-do-cerrado, in Portuguese) is a species of Myrtaceae with restricted distribution in the Cerrado. The essential oils were extracted through the hydrodistillation technique using a modified Clevenger apparatus (2 hours) and chemically characterized by GC-MS. The major compounds were α-copaene (10.6 %) found in oil from leaves in natura, β-bisabolene (17.4 %) in the essential oil from dry leaves and α-(E)-bergamotene (29.9 %) in oil from flowers. The antioxidant activity of essential oils showed similarities in both methods under analysis (DPPH and ABTS˙+) and the results suggested moderate to high antioxidant activity. The antibacterial activity was evaluated by determining minimum inhibitory concentrations (MICs), using the microdilution method. MIC values below 400 µg/mL were obtained against Streptococcus salivarius (200 µg/mL), S. mutans (50 µg/mL), S. mitis (200 µg/mL) and Prevotella nigrescens (50 µg/mL). This is the first report of the chemical composition and antibacterial and antioxidant activities of the essential oils of E. klotzschiana. These results suggest that E. klotzschiana, a Brazilian plant, provide initial evidence of a new and alternative source of substances with medicinal interest.

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R E S U M OObjetivou-se, neste trabalho, avaliar o efeito de diferentes embalagens, ambientes e do tempo de armazenamento na qualidade de sementes de crambe. O crambe, com teor de água de 4,63% (b.u.), foi embalado em garrafas de polietileno de alta densidade (PEAD), em garrafas reutilizadas de polietileno tereftalato (PET) e em embalagens laminadas as quais foram armazenadas nos ambientes: refrigerado a 10 ± 1,19 °C e 34,84 ± 4,09% de umidade relativa (UR) e natural a 24,81 ± 1,82 °C e 54,93 ± 12,77% de umidade relativa (AN). Avaliaram-se, durante nove meses, o teor de óleo e de proteína bruta, os índices de acidez, peróxido e iodo, pH e acidez em álcool solúvel. As sementes acondicionadas em embalagem laminada no AN apresentaram maior teor de proteína bruta no 3° mês e as em AR, maiores índices de peróxido, nos 3° e 6° meses. Em AR, as sementes em embalagens de PEAD apresentaram menor acidez em álcool solúvel. Os teores de proteína bruta e de óleo diminuíram durante o armazenamento, o índice de peróxido e o pH aumentaram e o índice de iodo apresentou variação nos valores. No final do armazenamento os valores de acidez em álcool solúvel eram semelhantes aos do início. O índice de acidez não sofreu interferência das variáveis estudadas. Storage of crambe seeds in different containers and environments: Part II -Chemical quality A B S T R A C TThe aim of this study was to evaluate the effect of different packaging, environment and storage time on the chemical quality of crambe seeds. Crambe seeds, with a water content of 4.63% (dry basis), were packed into high density polyethylene (HDPE), reused polyethylene terephthalate (PET) bottles and laminated packages, which were stored in two different environments: refrigerated air (RA) at 10 ± 1.19 °C and 34.84 ± 4.09% relative humidity (RH) and natural air (AN) at 24.81 ± 1.82 °C and 54.93 ± 12.77 % RH. For nine months, the oil and crude protein content, acidity index, peroxide and iodine level, pH, and alcohol-soluble acidity were evaluated. Seeds in laminated packages stored in AN showed higher crude protein content after 3 rd month, and in AR, there were higher levels of peroxide after 3 rd and 6 th months. In AR, the seeds in HDPE packaging showed lower alcohol-soluble acidity. Crude protein and oil content decreased during storage, peroxide level and pH increased and iodine level varied. At the end of storage, the alcohol-soluble acidity returned to base line values. The acidity level was not affected by the changes in the variables studied. Palavras-chave:qualidade da semente teor de óleo proteína bruta Crambe abyssinica

ABSTRACT

A density functional theory (DFT) computational analysis, using the ωB97X-D functional, of a rapid amide cleavage in 2-carboxyphthalanilic acid (2CPA), where the amide group is flanked by two catalytic carboxyls, reveals key mechanistic information: (a) General base catalysis by a carboxylate coupled to general acid catalysis by a carboxyl is not operative. (b) Nucleophilic attack by a carboxylate on the amide carbonyl coupled to general acid catalysis at the amide oxygen can also be ruled out. (c) A mechanistic pathway that remains viable involves general acid proton delivery to the amide nitrogen by a carboxyl, while the other carboxylate engages in nucleophilic attack upon the amide carbonyl; a substantially unchanged amide carbonyl in the transition state; two concurrent bond-forming events; and a spatiotemporal-base rate acceleration. This mechanism is supported by molecular dynamic simulations which confirm a persistent key intramolecular hydrogen bonding. These theoretical conclusions, although not easily verified by experiment, are consistent with a bell-shaped pH/rate profile but are at odds with hydrolysis mechanisms in the classic literature.

The study of host−guest complexation between reactive 2-carboxyphthalanilic acid (CPA) and two cationic pillararenes has been carried out. Host−guest complexation with significant kinetic effects was observed only with the smaller cavity size pillararene (P5A). Kinetics in the pH range 1.50− 6.40, ESI−MS, 1 H NMR titration, and ROESY experiments were performed to characterize the complexes. High binding stoichiometry (H:G 2 ) was observed for all CPA protonation states. The system is pH-dependent, and inversion of cooperativity (negative to positive) occurs by increasing the dianionic CPA 2− concentration (allosteric behavior). Toward physiological pH, association constant K 1:1 does not change (10 4 M −1 ), and K 1:2 increased from 10 2 to 10 4 M −1 , as well as the inhibitory effect increased up to 222-fold. NMR results elucidated the structure of the complex and allowed us to create a map of H−H interactions that describes well the diversity and number of interactions in the complex.

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The molecular recognition of the carboxylatopillar[5]arene on methamphetamine showed interconversion between H2:G ⇋ H:G stoichiometries with dependence on drug concentration.