Rubem Mário Figueiró Vargas

Supercritical fluid extraction of volatile and non-volatile compounds from Schinus molle L.

Schinus molle L., also known as pepper tree, has been reported to have antimicrobial, antifungal, anti-inflammatory, antispasmodic, antipyretic, antitumoural and cicatrizing properties. This work studies supercritical fluid extraction (SFE) to obtain volatile and non-volatile compounds from the aerial parts of Schinus molle L. and the influence of the process on the composition of the extracts. Experiments were performed in a pilot-scale extractor with a capacity of 1 L at pressures of 9, 10, 12, 15 and 20 MPa at 323.15 K. The volatile compounds were obtained by CO2 supercritical extraction with moderate pressure (9 MPa), whereas the non-volatile compounds were extracted at higher pressure (12 to 20 MPa). The analysis of the essential oil was carried out by GC-MS and the main compounds identified were sabinene, limonene, D-germacrene, bicyclogermacrene, and spathulenol. For the non-volatile extracts, the total phenolic content was determined by the Folin-Ciocalteau method. Moreover, one of the goals of this study was to compare the experimental data with the simulated yields predicted by a mathematical model based on mass transfer. The model used requires three adjustable parameters to predict the experimental extraction yield curves.

Antidepressant-like effect of Valeriana glechomifolia Meyer (Valerianaceae) in mice

The antidepressant-like effect of a supercritical CO2 (SCCO2) Valeriana glechomifolia extract enriched in valepotriates was investigated in a mice tail suspension test (TST) and forced swimming test (FST). The SCCO2 extract decreased mice immobility in the FST (0.5-20 mg/kg p.o.) and elicited a biphasic dose-response relationship in the TST (1-20 mg/kg p.o.) with no alterations in locomotor activity and motor coordination (assessed in the open-field and rota-rod tests, respectively). The anti-immobility effect of the SCCO2 extract (5 mg/kg, p.o.) was prevented by mice pre-treatment with yohimbine (1 mg/kg, i.p., an α2 adrenoceptor antagonist), SCH 23390 (15 μg/kg, s.c., D1 dopamine receptor antagonist) and sulpiride (50 mg/kg, i.p., D2 dopamine receptor antagonist). However, mice pre-treatments with prazosin (1 mg/kg, i.p., α1 adrenoceptor antagonist) and p-chlorophenilalanine methyl ester (4×100 mg/kg/day, i.p., a serotonin synthesis inhibitor) were not able to block the anti-immobility effect of the SCCO2 extract. Administration (p.o.) of the SCCO2 extract (0.25 mg/kg) and imipramine (10 mg/kg), desipramine (5 mg/kg) and bupropion (3 mg/kg) at sub-effective doses significantly reduced mice immobility time in the FST. These data provide the first evidence of the antidepressant-like activity of V. glechomifolia valepotriates, which is due to an interaction with dopaminergic and noradrenergic neurotransmission.

Supercritical fluid extraction and high performance liquid chromatographic determination of benzopyrans and phloroglucinol derivative in Hypericum polyanthemum

The aerial parts of Hypericum polyanthemum Klotzsch ex Reichardt (Guttiferae) were successively extracted with supercritical carbon dioxide (SC CO(2)) under pressures of 90, 120, 150 and 200 bar at different temperatures (40, 50 and 60 degrees C), and compared with the n-hexane extract obtained by ultrasound-assisted extraction. The samples obtained were examined regarding extraction yield and HPLC quantification of the main secondary metabolites, the benzopyrans HP1 (6-isobutyryl-5,7-dimethoxy-2,2-dimethylbenzopyran), HP2 (7-hydroxy-6-isobutyryl-5-methoxy-2,2-dimethyl-benzopyran) and HP3 (5-hydroxy-6-isobutyryl-7-methoxy-2,2-dimethyl) and the phloroglucinol derivative, uliginosin B. SFE presented higher selectivity than the n-hexane maceration, and the best condition to extract the target metabolites has been determined to be at 50 degrees C and for the high molecular-weight compound, uliginosin B, higher pressures were required.

Supercritical extraction of phloroglucinol and benzophenone derivatives from Hypericum carinatum: Quantification and mathematical modeling

The aerial parts of Hypericum carinatum (Guttiferae) were extracted with supercritical carbon dioxide under constant temperature (40, 50 or 60°C) and gradual pressure increase (90, 120, 150 and 200 bar) aiming at the recovery of enriched fractions containing uliginosin B, cariphenone A and cariphenone B, compounds of pharmaceutical interest. The yields of these substances were determined by high-performance liquid chromatography and compared with those obtained with n-hexane maceration. The supercritical-fluid extraction showed higher selectivity than the conventional solvent extraction method. After defining 40°C and 90 bar as the best conditions to obtain the target compounds, a mathematical model was used for the extraction process and a good correlation was achieved with the experimental data.

Determination of antibacterial activity of vacuum distillation fractions of lemongrass essential oil

Essential oils are natural substances composed of terpenoids and phenylpropanoid molecules that have many biological activities. Because of their activity, essential oils are widely used in foods, cosmetics, and pharmaceutical products, but new applications of such mixtures are still dependent on separation processes that are able to produce compounds with specific standardized and reproducible compositions. This work studies the fractionation of lemongrass essential oil by vacuum distillation with the goal of obtaining an antimicrobial fraction that acts against Salmonella choleraesuis, Pseudomonas aeruginosa and Staphylococcus aureus. The samples were analyzed by gas chromatography–mass spectrometry and evaluated for antimicrobial activity using the indirect bioautography method and minimum inhibitory concentrations. Vacuum distillation was found to be an efficient method for obtaining distinct fractions with increased antimicrobial activity. The fractions that showed the best response against the three microorganisms tested were F3b, F3a1, F2, F3a2 and F1, with the most effective being F3a2, which also presented the highest yield.

Supercritical CO2 extraction of Schinus molle L with co-solvents: mathematical modeling and antimicrobial applications

This work investigates the antimicrobial activity of the Schinus molle L. leaves extracts obtained under supercritical conditions using carbon dioxide and co-solvents. Antimicrobial qualitative evaluation was carried out through the bioautography technique and the microorganisms studied were Staphylococcus aureus, Pseudomonas aeruginosas, Escherichia coli, Micrococcus luteus, and Salmonella choleraesuis. The supercritical fluid extraction was carried out in a pilot scale equipment using carbon dioxide modified by the addition of co-solvents, such as ethanol and water at 150 bar and 333 K. A mathematical modeling of the process was also performed.

Effect of Storage Time and Conditions on the Diene Valepotriates Content of the Extract of Valeriana glechomifolia Obtained by Supercritical Carbon Dioxide

INTRODUCTION Valepotriates (epoxy iridoid esters) represent an important group of constituents that contribute to pharmacological effects for the genus Valeriana. Storage and extraction of valepotriates is a demanding task, as these compounds are thermolabile and unstable: even when decomposition products are not formed, isovaleric acid liberation from the iridoid nucleus originate compounds with less complex substituents. OBJECTIVE To study the influence of time and storage conditions on the diene valepotriates (valtrate, isovaltrate, acevaltrate, 1-β-acevaltrate, 1-β-aceacevaltrate) content of the Valeriana glechomifolia (native to southern Brazil), extract was obtained by supercritical fluid extraction using CO₂ as the fluid (SF-CO₂). METHODOLOGY Above-ground and below-ground material of V. glechomifolia was extracted by SF-CO₂ (40 °C, 90 bar). The extract was stored under nitrogen atmosphere or solubilised in methanol. Valepotriates stability was accessed during storage at -20 °C over 8 months through reverse-phase HPLC (mobile phase acetonitrile:water 50:50 (v/v); 254 nm). RESULTS A gradual increase in valtrate levels and decrease in acevaltrate, 1-β-acevaltrate and 1-β-aceacevaltrate, concentration were observed from the first month of storage for the dry extract. However, for the methanol solubilised extract these changes occurred only after the third month and were accompanied by reduction in isovaltrate levels and formation of decomposition products. CONCLUSION SF-CO₂ showed high selectivity for valepotriates extraction. This is the first report on valepotriates molecular conversion, which was less accelerated when the extract was stored in methanol, but under this condition degradation products are also present, probably baldrinals, that are not observed in the dry extract.

On the Analytical Solution of the SN Radiative Transport Equation in a Slab for a Space-dependent Albedo Coefficient

In this work, we report a genuine general analytical solution for the linearized SN radiative-conductive transfer problem in a heterogeneous plane parallel atmosphere with the albedo coefficient depending continuously on the spatial variable. By general solution, we mean that the solution is valid for an arbitrary albedo coefficient continuous functions of the spatial variable having the property of fulfill the requirements of existence and uniqueness. The key feature of this novel approach embodies the steps: following the idea of the Decomposition method, we transform the original problem into a set of recursive problems with constant albedo coefficients, having the main feature that the sources terms takes the information of the spatial dependency of the albedo coefficient into account. This procedure allows us to solve, analytically, the resulting recursive system by the LTSN method developed for a constant albedo coefficient. Finally, we present the error control analysis of the solution and numerical comparisons against the literature results.

Mathematical Modeling of Essential Oil Extraction by Steam Distillation for Native Plants from Southern Brazil

Abstract In this study, a desorption model to predict the essential oil extraction curves and global yield versus time was performed for extraction by steam distillation of three native plants of southern Brazil (Schinus molle L., Drimys angustifolia Miers., and Calyptranthes grandifolia O. Berg). The model assumed that the extractable materials were initially available uniformly in the vegetal matrix and adsorbed on the internal microstructures. The volatile extracts were obtained by steam distillation and the chemical composition was determined. The essential oil yields (w/w) were 0.4 %, 0.3 %, and 0.2 %, respectively, for S. molle, D. angustifolia, and C. grandifolia, and the major compounds identified by CG-MS were α-pinene, sabinene, bicyclogermacrene and spathulenol for all the plants here investigated. The desorption model fitted very well the overall extraction curves.

Effects of diene valepotriates from Valeriana glechomifolia on Na+/K+-ATPase activity in the cortex and hippocampus of mice.

Diene valepotriates obtained from Valeriana glechomifolia present antidepressant-like activity, mediated by dopaminergic and noradrenergic neurotransmissions. Also, previous studies have shown inhibitory activity of diene valepotriates towards Na(+)/K(+)-ATPase from the rat brain in vitro. Nevertheless, in vivo studies regarding the action of diene valepotriates on this enzyme are still lacking. Considering that Na(+)/K(+)-ATPase cerebral activity is involved in depressive disorders, the aim of this study was to investigate the effects of acute (5 mg/kg, p. o.) and repeated (5 mg/kg, p. o., once a day for three days) diene valepotriate administration on Na(+)/K(+)-ATPase activity in the cortex and hippocampus of mice submitted or not submitted to the forced swimming test. In addition, the protein expression of Na(+)/K(+)-ATPase α1, α2, and α3 isoforms in the cortex of mice repeatedly treated with diene valepotriates (and submitted or not submitted to the forced swimming test) was investigated. Diene valepotriates significantly decreased mice immobility time in the forced swimming test when compared to the control group. Only the animals repeatedly treated with diene valepotriates presented increased Na(+)/K(+)-ATPase activity in the cerebral cortex, and the exposure to the forced swimming test counteracted the effects of the diene valepotriates. No alterations in the hippocampal Na(+)/K(+)-ATPase activity were observed. Repeated diene valepotriate administration increased the cortical content of the α2 isoform, but the α3 isoform protein expression was augmented only in mice repeatedly treated with diene valepotriates and forced to swim. Mice treated with the vehicle and submitted to the forced swimming test also presented an increase in the content of the α2 isoform, but no alterations in Na(+)/K(+)-ATPase activity. These results suggest that cortical Na(+)/K(+)-ATPase may represent a molecular target of the diene valepotriates in vivo and long-term regulatory mechanisms are involved in this effect. Also, the forced swimming test per se influences the protein expression of Na(+)/K(+)-ATPase isoforms and counteracts the effects of the diene valepotriates on cortical Na(+)/K(+)-ATPase.