Carlos Alberto da Silva Riehl

Chemical composition and antibacterial activity of Cordia verbenacea extracts obtained by different methods

The present study describes the chemical composition and the antibacterial activity of extracts from Cordia verbenacea DC (Borraginaceae), a traditional medicinal plant that grows widely along the southeastern coast of Brazil. The extracts were obtained using different extraction techniques: high-pressure operations and low-pressure methods. The high-pressure technique was applied to obtain C. verbenacea extracts using pure CO(2) and CO(2) with co-solvent at pressures up to 30MPa and temperatures of 30, 40 and 50 degrees C. Organic solvents such as n-hexane, ethyl acetate, ethanol, acetone and dichloromethane were used to obtain extracts by low-pressure processes. The antibacterial activity of the extracts was also subjected to screening against four strains of bacteria using the agar dilution method. The extraction yields were up to 5.0% w/w and up to 8.6% w/w for supercritical fluid extraction with pure CO(2) and with ethyl acetate as co-solvent, respectively, while the low-pressure extraction indicates yields up to 24.0% w/w in the soxhlet extraction using water and aqueous mixture with 50% ethanol as solvents. The inhibitory activity of the extracts in gram-positive bacteria was significantly higher than in gram-negative. The quantification and the identification of the extracts recovered were accomplished using GC/MS analysis. The most important components identified in the extract were artemetin, beta-sitosterol, alpha-humulene and beta-caryophyllene, among others.

Correlation of anti-inflammatory activity with phenolic content in the leaves of syzygium cumini (l.) skeels (myrtaceae)

Phenolic contents of extracts of Syzygium cumini leaves, collected monthly over a one-year period, were quantitatively determined by the modified Folin-Ciocalteau method. Extracts and tannin-free fractions were assayed by their potential to inhibit mouse paw edema induced by C48/80. HPLC showed high molecular weight phenolic species and flavonoids in the active extracts and fractions. The highest total phenolic content corresponded to the most potent degree of inhibition and the flavonoids were supposed to be the main species responsible for the activity, given that the flavonoid-enriched ethyl-acetate fraction maintained its effect down to a dose of 0.01 mg/kg in a dose-response manner.

The effect of neutral oximes on the reactivation of human acetylcholinesterase inhibited with paraoxon

Important defense agents against chemical warfare weapons, which are reactivators of human acetylcholinesterase (huAChE) inhibited by neurotoxic organophosphorus compounds (OP), need a reasonable permeation of the hematoencephalic barrier (HB). In this work, neutral oximes, which permeate HB better than the cationic oximes currently used as defense agents, were tested as reactivators of huAChE inhibited with paraoxon using the modified Ellman test with pralidoxime (2-PAM) as positive standard. The most active neutral oxime was (thiophen-2-yl)aldoxime, which reactivated 93% of the inhibited huAChE and was 12% more effective than 2-PAM. The results showed that simple neutral oximes have potential to function as antidotes for intoxication with neurotoxic OPs, suggesting further research on the development of neutral defense agents.

Simultaneous Distillation-Extraction, Hydrodistillation and Static Headspace Methods for the Analysis of Volatile Secondary Metabolites of Alpinia zerumbet (Pers.) Burtt et Smith. from Southeast Brazil

Abstract Alpinia zerumbet (Zingiberaceae) is cultivated in several tropical areas. It has a high value all over the world as a spice in culinary preparations and for its medicinal properties. The composition of the essential oil obtained by simultaneous distillation-extraction (SDE) and hydrodistillation (HD) from fresh leaves of A. zerumbet was analyzed by GC-MS. In both samples the main constituents were terpinen-4-ol, 1,8-cinole, sabinene and λ-terpinene together with caryophyllene and caryophyllene oxide sesquiterpenes. However, individual percentage values of compounds varied between the methods. The components camphene (0.3 %), p-2-mentha-4(8)-diene (1.4 %) and trans-sabinene hydrate (1.0 %) were obtained only by SDE. Static-headspace (S-HS) was for the first time used to analyze the aroma from fresh leaves of A. zerumbet. Sabinene, 1,8 cineole and λ- terpinene were the main terpenes detected through S-HS. Flower oil was extracted by HD method, and the major components identified were 1,8 cineole (15.5 %), λ-terpinene (13.1 %) and terpinen-4- ol (42.3 %). There was a predominance of monoterpenes.

Leaf volatiles and secretory cells of Alpinia zerumbet (Pers.) Burtt et Smith (Zingiberaceae)

Plant leaves are commonly used in folk medicine and food industry. Their volatile composition is an important determinant in such applications. However, to properly assess the quality of volatiles, proper analytic tools must be utilised. Accordingly, the static headspace technique was used to evaluate the main volatiles emitted from in vitro-grown Alpinia zerumbet plants cultured with indole-3-acetic acid, thidiazuron, benzyladenine or kinetin, under standard physical conditions, as compared to those of field-grown donor plants. Although the leaf aroma of the donor plants was found to be a complex mixture, mainly consisting of sabinene, α and γ-terpinene, 1,8-cineole and caryophyllene, volatile analyses from most of the in vitro samples only revealed the presence of sabinene and caryophyllene. Many alkanes were found in the aromas after treating plantlets with cytokinins. Histochemical analysis of leaf sections was also carried out. Secretory cells found in the epidermis and mesophyll showed a strong positive reaction to lipophilic compounds using Oil red and Nile blue reagents. These findings demonstrated how in vitro conditions may alter the quality of volatiles in micropropagation systems, while leaf anatomy analysis revealed a large quantity of oil cells in the mesophyll as a constant feature responsible for the production of volatile compounds in both donor and in vitro-grown plants.

A cleistanthane diterpene lactone from Vellozia compacta

8,11,13-cleistanthatrien-7-one-19,20 beta-olide and six other previously described diterpenes were isolated by silica gel chromatography of the ethyl alcohol extract of Vellozia compacta. The structure of the cleistanthane lactone was deduced on the basis of spectral data analysis.

Eugenia neonitida Sobral and Eugenia rotundifolia Casar. (Myrtaceae) essential oils: composition, seasonality influence, antioxidant activity and leaf histochemistry

Investigou-se a influencia da sazonalidade na composicao do oleo essencial de folhas frescas de Eugenia neonitida Sobral e Eugenia rotundifolia Casar. (Myrtaceae) coletadas trimestralmente, assim como a atividade antioxidante do oleo essencial de folhas secas e a histoquimica foliar. Os componentes majoritarios do oleo essencial de E. neonitida foram biciclogermacreno, germacreno D e β-cariofileno e os de E. rotundifolia foram n, β-pineno e β-cariofileno. Os oleos essenciais de ambas as especies apresentaram principalmente hidrocarbonetos e alcoois ciclicos, sendo o oleo essencial de E. neonitida composto principalmente por sesquiterpenos e o de E. rotundifolia por monoterpenos. A precipitacao parece influenciar na composicao dos oleos essenciais de ambas as especies. O oleo essencial de folhas secas apresentou baixa atividade antioxidante. Os testes histoquimicos evidenciaram que as cavidades secretoras armazenam solucoes complexas e contem, alem dos oleos essenciais, outras classes de lipideos.

Application of Full Factorial Design to Evaluate the Effect of Different Variables on the Stability of Biodiesel:Diesel Blends under Storage Conditions

Biodiesel is obtained from a renewable source and has been used as an alternative to fossil fuels. It has unsaturated fatty acid methyl esters that can degrade due to oxidation of the double bonds. The instability of biodiesel during storage may cause problems regarding the maintenance and operation of motors. This work evaluated the effect of several variables on the storage conditions of biodiesel:diesel blends. The study was performed using an experimental design, and the variables were water content in biodiesel (0.01, 0.05 and 0.09%), biodiesel content in diesel (5.0, 7.5 and 10.0%), time (15, 30 and 45 days) and temperature (30, 40 and 50 °C). The levels simulated actual Brazilian storage conditions. The degradation was evaluated based on direct measurement of methyl linoleate and methyl oleate in the blends by gas chromatography-mass spectrometry. These unsaturated fatty acid methyl esters are target compounds in the oxidation process. All experiments were carried out in sealed flasks. The results suggest that the restriction of oxygen limited the degradation of biodiesel in blends with higher percentage of the biofuel. The variables temperature, time and water content in biodiesel individually did not affect the degradation process within the range investigated at 95% confidence interval.

Isolation and Structural Determination of Xerophytolic Acid, a Novel 3-Geranyl-4-Hydroxybenzoate Derivative from Xerophyta Plicata

Abstract A novel 3-geranyl-4-hydroxybenzoic acid derivative, methyl xerophytolate (1), was isolated from the crude extract of Xerophyta plicata (Velloziaceae) collected in Rio de Janeiro, Brazil. the structure of 1 was elucidated using spectroscopic methods. This is the first time that this type of skeleton is reported in this family.

Isolation and structural determination of xerophytolic acid A, a 3-geranyl-4-hydroxybenzoate derivative from Xerophyta plicata

A novel compound of a rare class of secondary metabolites, 3-geranyl-4-hydroxybenzoic acid derivative, methyl xerophytolate A (2), was isolated from the crude extract of Xerophyta plicata (Velloziaceae) collected in Rio de Janeiro, Brazil. The structure of 2 was elucidated using spectroscopic methods.