Transesterification and epoxide ring-opening reactions are two mechanism routes that explain chemical modifications of macromolecules by glycidyl methacrylate (GMA). Although the coupling reaction of the GMA with macromolecules has widely been investigated, there are still mechanisms that remain to be explained when GMA is processed in an aqueous solution at different pH conditions. To this end, reaction mechanisms of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAAc) by GMA in water in acidic and basic conditions were investigated thoroughly. The presence of hydroxyl groups in PVA and carboxyl groups in PAAc allowed for a better evaluation of the reaction mechanisms. The analysis of the (1)H and (13)C NMR spectra clearly demonstrated that the chemical reactions of GMA with carboxyl groups and alcohols of the macromolecules in an aqueous solution are dependent on pH conditions. At pH 3.5, the GMA reacts with both the carboxylic and the hydroxyl groups through an epoxide ring-opening mechanism. At pH 10.5, the GMA undergoes a hydrolysis process and reacts with hydroxyl groups by way of both the transesterification and the epoxide ring-opening mechanisms, whereas the ring-opening reaction is the preferential pathway.

Chemical recycling of poly(ethylene terephthalate) (PET) in supercritical ethanol has been investigated. In the presence of water, under supercritical conditions (temperature and pressure above 516 K and 6,384 kPa, respectively) excess ethanol reacts with PET to form diethyl terephthalate (DET) as the main product. A laboratory-made 0.1 l-batch reactor was used at 528 K under pressures from 7,600 and 11,600 kPa. After the required reaction times, the reaction products were analyzed by reverse phase high pressure liquid chromatography and nuclear magnetic resonance. It was found that PET is completely depolymerized into monomers in about 5 h. The influences of water, pressure, ethanol/PET weight ratio, PET sources, as well as depolymerization time were investigated. Maximum DET recovery yield was 98.5%.

Este trabalho descreve um procedimento rápido e eficiente para a separação e identificação de alcalóides indólicos do extrato etanólico de Tabernaemontana fuchsiaefolia (Apocynaceae). As frações alcaloídicas obtidas dos extratos etanólicos (das folhas, das cascas do caule e das cascas das raízes) foram fracionadas e analisadas por cromatografia em camada delgada (CCD) e por cromatografia gasosa acoplada a espectrometria de massa (CG-EM). Foram identificados os alcalóides indólicos ibogamina, coronaridina, pseudoindoxil ibogaina, hidroxiindolenina voacangina, pseudoindoxil voacangina, tabernantina, catarantina, voacangina, 19-oxovoacangina, 10-hidroxicoronaridina, afinisina, 16-epi-afinina, voachalotina, ibogalina e conofaringina. This paper describes a fast and efficient procedure to separate and identify indole alkaloids from the ethanolic extract of Tabernaemontana fuchsiaefolia (Apocynaceae). The alkaloidal fractions obtained from ethanolic extracts of leaves and stem barks and root barks were fractioned and analyzed by Thin-Layer Chromatography (TLC) and by Gas Chromatography coupled to Mass Spectrometry (GC-MS). The following indole alkaloids were identified: ibogamine, coronaridine, ibogaine pseudoindoxyl, voacangine hydroxyindolenine, voacangine pseudoindoxyl, tabernanthine, catharanthine, voacangine, 19-oxovoacangine, 10-hydroxycoronaridine, affinisine, 16-epi-affinine, voachalotine, ibogaline, and conopharyngine.

Um extrato metanólico das folhas de Luehea divaricata (Tiliaceae), vulgarmente conhecida no Brasil como "açoita-cavalo", forneceu um novo triterpeno caracterizado como ácido 3β-phidroxibenzoiloxitormentico [ácido 3β-(p-hidroxibenzoiloxi)-2α-hidroxiurs-12-en-28-óico], juntamente com uma mistura contendo o ácido maslínico, um triterpeno conhecido. As estruturas dos compostos foram estabelecidas por métodos espectroscópicos.A methanolic extract from leaves of Luehea divaricata (Tiliaceae), known in Brazil as "açoita-cavalo", yielded two triterpene: a novel characterized as 3β-p-hydroxybenzoyloxytormentic acid [3β-(p-hydroxybenzoyloxy)-2α-hydroxyurs-12-en-28-oic acid] and a mixture containing the maslinic acid. The new compound's structure was established by spectroscopic methods.

A series of new thiosemicarbazones derived from natural diterpene kaurenoic acid were synthesized and tested against the epimastigote forms of Trypanosoma cruzi to evaluate their antitrypanosomal potential. Seven of the synthesized thiosemicarbazones were more active than kaurenoic acid with IC 50 values between 2-24.0 µM. The o-nitrobenzaldehyde-thiosemicarbazone derivative was the most active compound with IC 50 of 2.0 µM. The results show that the structural modifications accomplished enhanced the antitrypanosomal activity of these compounds. Besides, the thiocyanate, thiosemicarbazide and the p-methyl, p-methoxy, p-dimethylamine, m-nitro and o-chlorobenzaldehydethiosemicarbazone derivatives displayed lower toxicity for LLMCK 2 cells than kaurenoic acid, exhibing an IC 50 of 59.5 µM. OPEN ACCESSMolecules 2011, 16 1167

Um novo triterpeno caracterizado como ácido 6α-hidroxibetulínico foi isolado das folhas e caule da planta, vulgarmente conhecida no Brasil como Cambuí, Eugenia moraviana (Myrtaceae), juntamente com três outras substâncias conhecidas, identificadas como ácido platânico, ácido betulínico e β-sitosterol. Através da análise de espectros incluindo NOE e experimentos de RMN em duas dimensões foi realizada a atribuição inequívoca dos deslocamentos químicos de 1 H e de 13 C do ácido 6α-hidroxibetulínico(ácido-3β,6α-diidróxi-20(29)-lupen-28-óico) e do ácido platânico.A novel triterpene, characterized as 6α-hydroxybetulinic acid, was isolated from the leaves and stems of Eugenia moraviana (Myrtaceae), known in Brazil as Cambuí, together with three known compounds, platanic acid, betulinic acid and β-sitosterol. Unequivocal 1 H and 13 C assignments of 6α-hydroxybetulinic acid (3β,6α-dihydroxy-20(29)-lupen-28-oic acid) and platanic acid were undertaken by spectral analysis including NOE and 2 D NMR experiments.

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a b s t r a c tThe chemical investigation of Heliotropium transalpinum var. transalpinum Vell. (Boraginaceae) led to the isolation of transalpinecine (1), a novel pyrrolizidine alkaloid, in addition to known alkaloids subulacine (1b-2b-epoxy-1a-hydroxymethyl-8a-pyrrolizidine) (2), and 1a-2a-epoxy-1b-hydroxymethyl-8a-pyrrolizidine (3). The structures of the isolated compounds were elucidated based on spectroscopic data and theoretical calculations.