The general mechanisms of attack of nitrogen nucleophiles on carbonyl compounds: facts that determine the change of the rate-pH profiles

It have been described a general mechanism for the attack step of the reactions between nitrogen nucleophiles and carbonyl compounds to form a neutral tetrahedral addition intermediate. This general mechanism is based on the relative importance of the "concerted" hydronium-ion catalyzed attack of the nitrogen base on the carbonyl compound with respect to the "step wise" mechanism that involves the previous formation of a zwitterionic tetrahedral intermediate (T±) and the posterior proton transfer to it from the hydronium-ion. The relative importance of this pathway gives origin to three kinds of profile rates vs pH for these reactions. On the other hand, the importance of the "stepwise" mechanism was attributed to a dependence on the stability of the T± intermediate that is related to the pKa of the nitrogen base and the Kad (the equilibrium constant for the formation of the neutral tetrahedral addition intermediate (T0)). The comparison of the reactions of p-chlorobenzaldehyde and norcamphor with different nitrogen nucleophiles led to the observation that the general mechanism depends on each type of carbonyl compound. This is due to the great influence of the steric and electronic effects of the compounds structure, and the fact that the pKa value of the nitrogen base, which is more related to the stability of the T± than the T0 intermediate, is more important as a factor of prediction of the profiles than the value of Kad, this value being more related to the stability of the T0 intermediate

Antioxidant, allelopathic and toxic activity of Ochna serrulata

Ochna serrulata (Ochnaceae) is an ornamental plant introduced into Brazil from Asia and Africa. Species of the Ochna genus are rich in phenolic compounds, mainly flavonoids. The biological screening of extracts and fractions showed that this plant exhibited a significant antioxidant activity, when evaluated by the DPPH and reducing potential assays. Ochna serrulata also demonstrated slight toxic activity against Artemia salina and a potential inhibitory allelopathic activity, when evaluated using the Lactuca sativa seed germination test. The ethyl acetate fraction, the most active one, was partitioned on a silica gel column to obtain epicatechin, which showed potential antioxidant activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Antioxidant, allelopathic and toxic activity of Ochna serrulata

Ochna serrulata (Ochnaceae) is an ornamental plant introduced into Brazil from Asia and Africa. Species of the Ochna genus are rich in phenolic compounds, mainly flavonoids. The biological screening of extracts and fractions showed that this plant exhibited a significant antioxidant activity, when evaluated by the DPPH and reducing potential assays. Ochna serrulata also demonstrated slight toxic activity against Artemia salina and a potential inhibitory allelopathic activity, when evaluated using the Lactuca sativa seed germination test. The ethyl acetate fraction, the most active one, was partitioned on a silica gel column to obtain epicatechin, which showed potential antioxidant activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Antioxidant, allelopathic and toxic activity of Ochna serrulata

Ochna serrulata (Ochnaceae) is an ornamental plant introduced into Brazil from Asia and Africa. Species of the Ochna genus are rich in phenolic compounds, mainly flavonoids. The biological screening of extracts and fractions showed that this plant exhibited a significant antioxidant activity, when evaluated by the DPPH and reducing potential assays. Ochna serrulata also demonstrated slight toxic activity against Artemia salina and a potential inhibitory allelopathic activity, when evaluated using the Lactuca sativa seed germination test. The ethyl acetate fraction, the most active one, was partitioned on a silica gel column to obtain epicatechin, which showed potential antioxidant activity.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Antioxidant activity of three species of Eugenia (Myrtaceae)

A atividade antioxidante dos extratos vegetais de Eugenia brasiliensis, E. beaurepaireana e E. umbelliflora foi avaliada usando diferentes métodos: Determinação da ação sequestrante de radicais livres usando DPPH, determinação do potencial redutor e determinação do potencial inibidor da peroxidação lipídica. Foi correlacionado também a o conteúdo de fenólicos totais e de flavonóides contidos nestes extratos e frações com a atividade antioxidante. As espécies E. brasiliensis e E. beaurepaireana mostraram maior capacidade antioxidante em relação a todos os métodos utilizados. Estas espécies exibiram também maior teor de compostos fenólicos. Uma significante relação entre a atividade antioxidante e o conteúdo de fenólicos foi observado, indicando que estes compostos são os principais contribuintes para as propriedades antioxidantes nestas plantas.Extracts of Eugenia brasiliensis, E. beaurepaireana and E. umbelliflora were investigated for their antioxidant activity using DPPH, reducing potential and B-carotene-linoleate system. Total phenolics and flavonoids contents were also determined. E. brasiliensis and E. beaurepaireana showed the highest antioxidant capacities in all methods used. These species exhibited too the highest phenolic contents. A significant relationship between antioxidant capacity and total phenolic content was found, indicating that phenolic compounds are the major contributors to the antioxidant properties of these plants.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Topical antiinflammatory activity and chemical composition of the epicuticular wax from the leaves of Eugenia beaurepaireana (Myrtaceae)

In order to verify the topical antiinflammatory effect of epicuticular wax from leaves of Eugenia beaurepaireana, it was tested in mice croton oil-induced inflammation. Our findings show that topical application of Eugenia beaurepaireana epicuticular wax was significantly active in inhibiting both oedema (Inhibitory dose 50 % (ID50) = 0.31 (0.26 - 0.39) mg.ear -1, inhibition = 79 ± 6 %) and tissue myeloperoxidase activity (indicative of polymorphonuclear leukocytes influx) (ID50 =0.34 (0.20 - 0.41) mg.ear -1, inhibition = 77 ± 4 %) in mice ear treated with croton oil. Two main compounds were detected on epicuticular wax of E. beaurepaireana. These compounds were identified as α- and β-amyrin by flame ionization detection (GC-FID) and spectroscopic methods (IR, NMR ¹H and 13C). In conclusion, the results indicate a topical antiinflammatory activity for the Eugenia specie studied and, that, at least in part, α- and β-amyrin are responsible for this activity.A atividade antiinflamatória tópica da cera epicuticular das folhas de Eugenia beaurepaireana foi avaliada pelo modelo do edema de orelha induzido pelo óleo de cróton em camundongos. Os resultados do estudo mostram que a aplicação tópica da cera epicuticular de Eugenia beaurepaireana inibiu significativamente a formação do edema (Dose inibitória 50 % (DI50) = 0,31 (0,26 - 0,39) mg.orelha-1, inibição = 79 ± 6 %) e a atividade da mieloperoxidase tissular (indicativo do influxo de leucócitos polimorfonucleares) (DI50 =0,34 (0,20 - 0,41) mg.orelha-1, inibição = 77 ± 4 %) em camundongos tratados com o óleo de cróton. Dois compostos majoritários foram detectados e isolados da cera epicuticular de E. beaurepaireana. Estes compostos foram identificados como os triterpenos α-amirina e β-amirina, através de técnicas cromatográficas (CG-FID) e espectroscópicas (IV, RMN ¹H e 13C). Em conclusão, os resultados indicam que a espécie E. beaurepaireana apresenta um efeito antiinflamatório tópico relevante, sendo os compostos α-amirina e β-amirina responsáveis, pelo menos em parte, por esta atividade

Evaluation of chitosan microparticles containing curcumin and crosslinked with sodium tripolyphosphate produced by spray drying

The aim of this study was to encapsulate curcumin into chitosan, using sodium tripolyphosphate (TPP) as an ionic crosslinker by the spray drying method. The influence of TPP on the properties of the final product, such as solubility, morphology, loading efficiency, thermal behavior, swelling degree and release profiles, was evaluated. The microparticles had a spherical morphology (0.5-20 µm) with no apparent porosity or cracks. Results indicated the formation of a polymeric network, which ensures effective protection for curcumin. Controlled-release studies were carried out at pH 1.2 and 6.8, to observe the influence of pH on curcumin release while the mechanism was analyzed using the Korsmeyer-Peppas equation

Analysis of the Potential Topical Anti-Inflammatory Activity of Averrhoa carambola L. in Mice

Inflammatory skin disorders, such as psoriasis and atopic dermatitis, are very common in the population; however, the treatments currently available are not well tolerated and are often ineffective. Averrhoa carambola L. (Oxalidaceae) is an Asian tree that has been used in traditional folk medicine in the treatment of several skin disorders. The present study evaluates the topical anti-inflammatory effects of the crude ethanolic extract of A. carambola leaves, its hexane, ethyl acetate, and butanol fractions and two isolated flavonoids on skin inflammation. Anti-inflammatory activity was measured using a croton oil-induced ear edema model of inflammation in mice. Topically applied ethanolic extract reduced edema in a dose-dependent manner, resulting in a maximum inhibition of 73 ± 3% and an ID50 value of 0.05 (range: 0.02–0.13) mg/ear. Myeloperoxidase (MPO) activity was also inhibited by the extract, resulting in a maximum inhibition of 60 ± 6% (0.6 mg/ear). All of the fractions tested caused inhibition of edema formation and of MPO activity. Treatment with the ethyl acetate fraction was the most effective, resulting in inhibition levels of 75 ± 5 and 54 ± 8% for edema formation and MPO activity, respectively. However, treatment of mice with isolated compounds [apigenin-6-C-β-l-fucopyranoside and apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside] did not yield successful results. Apigenin-6-C-(2″-O-α-l-rhamnopyranosyl)-β-l-fucopyranoside caused only a mild reduction in edema formation (28 ± 11%). Taken together, these preliminary results support the popular use of A. carambola as an anti-inflammatory agent and open up new possibilities for its use in skin disorders

Gênero Baccharis (Asteraceae): aspectos químicos, econômicos e biológicos The Baccharis genus (Asteraceae): chemical, economic and biological aspects

<abstract language="eng">The Baccharis genus is represented by more than 500 species distributed mainly in the tropical areas of South America. Many of them are extensively used in folk medicine in the treatment or prevention of anemias, inflammations, diabetes and stomach, liver and prostate diseases. Phytochemical and biological investigations in about 120 species resulted mainly in the isolation of clerodane and labdane diterpenes and flavonoid aglicones with the flavone unit being the most frequent