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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.

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RESUMO:A atividade antioxidante, avaliada pelo método DPPH (1,1-difenil-2-picrilidrazila), e o teor em compostos fenólicos totais do extrato bruto metanólico e frações das folhas da espécie Palicourea rigida Kunth, Rubiaceae, foram quantificadas neste trabalho. Apesar da baixa atividade apresentada pelo extrato bruto (500 ppm), a fração acetato de etila apresentou atividade moderada (192 ppm) e o maior teor de fenólicos totais dentre as frações ensaiadas. Assim, a fração acetato de etila foi submetida a procedimentos cromatográficos o que resultou no isolamento dos flavonoides quercetina 3-O-β-D-glicosídeo, quercetina 3-O-soforosídeo e isoraminetina 3-glicosídeo, cujas estruturas foram elucidadas por análise espectroscópica, incluindo RMN (1D e 2D) e comparação com os dados da literatura.Unitermos: Rubiaceae, Palicourea, flavonoides, atividade antioxidante.ABSTRACT: "Flavonoids and antioxidant activity in Palicourea rigida Kunth, Rubiaceae". The antioxidant activity, evaluated by DPPH (1,1-difenil-2-picrilidrazila) method, and the determination of the total phenolic compounds of the crude methanolic extract and fractions of the Palicourea rigida Kunth, Rubiaceae, leaves were quantified in this work. Despite weak activity exhibited by crude extract (500 ppm), the fraction ethyl acetate showed moderate activity (192 ppm), and the largest value for the phenolic compounds among all the assayed fractions. Then, the ethyl acetate fraction was submitted to the chromatography procedures which led to the isolation of the flavonoid quercetin 3-O-D-glicoside, quercetin 3-O-sophoroside and isorhamnetin 3-glicoside, which had the structures elucidated by spectroscopy analysis, including RMN (1D and 2D) and comparison with literature data.

This work describes a two-step, one-pot synthetic method for the formal aza-[3 þ 3] cycloaddition between N-alkyl substituted enaminones and benzoyl isothiocyanate, which afforded 4-thioxopyrimidines in reasonable yields. Reaction of acyclic enaminone with a sterically hindered group attached to the nitrogen atom afforded pyridine-2thione, yet in low yield. The antibacterial, antifungal, and trypanocidal activities of the thioxopyrimidines were evaluated and five compounds exhibited moderate activity against Candida albicans, Micrococcus luteus, and Trypanosoma cruzi. The solid state structures of a thioxopyrimidine, an organic disulfide, and a 1,2,4-triazole were determined by X-ray diffraction analysis.

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.