Optimization of alkaline transesterification of soybean oil and castor oil for biodiesel production

This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.     

Probing the basicity of regular and defect sites of alkaline earth metal oxide surfaces by BF3 adsorption: a theoretical analysis.

The basicity of regular and low-coordinate (LC) sites (steps, edges and corners) at the surface of alkaline earths with NaCl structure (MgO, CaO, SrO, and BaO) has been investigated by using BF3 as a probe molecule. B-O and B-F distances; O-B-F bond angles; B-F asymmetric stretching frequencies; O, B and F 1s core-level binding energies; and the interaction energy of adsorbed BF3 were determined by means of DFT calculations on cluster models. These adsorption properties were compared with those of complexes of BF3 with molecules with various basicities (water, ammonia, phosphine, etc.). We show that many properties of adsorbed BF3, and in particular the experimentally accessible shifts in vibrational frequency, in B and F 1s core levels, and in BF3 desorption temperature, exhibit a linear correlation with the surface basicity as measured by the vertical ionization potential of the oxide anions. On the other hand, shifts of the O 1s core level binding energy do not provide a simple way to detect surface basicity. On a given oxide surface, the differing basicities of various sites result in measurable differences in adsorption properties. This suggests the potential use of BF3 as a probe molecule for titrating LC sites on the surface of ionic oxides.     

Chemical composition of the essential oil from the leaves of Anaxagorea brevipes (Annonaceae) and evaluation of its bioactivity

The essential oil obtained by hydrodistillation from leaves of Anaxagorea brevipes was analysed by gas chromatography fitted with a flame ionisation detector (GC–FID) and coupled to mass spectrometry (GC–MS). Thirty one components were identified, representing around 75.7% of total oil. The major components were β-eudesmol (13.16%), α-eudesmol (13.05%), γ-eudesmol (7.54%), guaiol (5.12%), caryophyllene oxide (4.18%) and β-bisabolene (4.10%). The essential oil showed antimicrobial activity against Gram-positive bacteria and yeast with the MIC values between 25.0 and 100 μg/mL. The highest antiproliferative activity was observed for the oil against MCF-7 (breast, TGI = 12.8 μg/mL), NCI-H460 (lung, TGI = 13.0 μg/mL) and PC-3 (prostate, TGI = 9.6 μg/mL) cell lines, while against no cancer cell line HaCat (keratinocyte) the TGI was 38.8 μg/mL. The oil exhibited a small antioxidant activity assessed through ORAC-FL assay (517 μmol TE/g). This is the first report regarding the chemical composition and bioactivity of A. brevipes essential oil.     

Complete NMR data assignments for novel pterocarpans from Harpalyce brasiliana

A NMR study of two new pterocarpans isolated from the roots of Harpalyce brasiliana is described. In addition to 1D NMR, 2D shift-correlated NMR pulse sequences ((1)H-(1)H-COSY, HSQC and HMBC) were used to establish the structures, and unambiguously perform the (1)H and (13)C chemical shift assignments.     

Identification of N,N-dimethyltryptamine and beta-carbolines in psychotropic ayahuasca beverage

Recently many people have shown great interest in traditional indigenous practices and popular medicine, involving the ingestion of natural psychotropic drugs. We received a request to analyze and determine the nature of a dark green liquid with a dark brown plant sediment, which the police had seized at an airport and inside the home of a person belonging to the 'Santo Daime' religious movement. Gas chromatography/mass spectrometry analysis of the extract identified N,N-dimethyltryptamine, a potent hallucinogen, and the beta-carboline alkaloids harmine and harmaline, revealing monoamine oxidase A-inhibiting properties. These substances are typical components of Ayahuasca, a South American psychotropic beverage obtained by boiling the bark of the liana Banisteriopsis caapi together with the leaves of various admixture plants, principally Psychotria viridis.     

Comparison Between Fluorescence and Pulsed Integrated Electrochemical Detectors for the Determination of Taurine in Human Skin, Urine and Plasma by CE

Simple methods for the quantification of taurine by capillary electrophoresis are described. Qualitative and quantitative comparisons between fluorescence detection after precolumn derivatization and direct detection by integrated pulse amperometry were performed. A calibration curve was constructed with standard taurine solutions and confirmed by standard addition to representative sample solutions. Fluorescence detection gave superior sensitivity (LOD, 7.5 × 10^?6 μmol L^?1). There was no significant difference in taurine values (p > 0.001) observed by either method of detection.     

Effect of the Presence of Surfactants and Immobilization Conditions on Catalysts’ Properties of <Emphasis Type="Italic">Rhizomucor miehei</Emphasis> Lipase onto Chitosan

Lipase from Rhizomucor miehei (RML) was immobilized onto chitosan support in the presence of some surfactants added at low levels using two different strategies. In the first approach, the enzyme was immobilized in the presence of surfactants on chitosan supports previously functionalized with glutaraldehyde. In the second one, after prior enzyme adsorption on chitosan beads in the presence of surfactants, the complex chitosan beads-enzyme was then cross-linked with glutaraldehyde. The effects of surfactant concentrations on the activities of free and immobilized RML were evaluated. Hexadecyltrimethylammonium bromide (CTAB) promoted an inhibition of enzyme activity while the nonionic surfactant Triton X-100 caused a slight increase in the catalytic activity of the free enzyme and the derivatives produced in both methods of immobilization. The best derivatives were achieved when the lipase was firstly adsorbed on chitosan beads at 4 °C for 1 h, 220 rpm followed by cross-link the complex chitosan beads-enzyme with glutaraldehyde 0.6% v.v^?1 at pH 7. The derivatives obtained under these conditions showed high catalytic activity and excellent thermal stability at 60° and 37 °C. The best derivative was also evaluated in the synthesis of two flavor esters namely methyl and ethyl butyrate. At non-optimized conditions, the maximum conversion yield for methyl butyrate was 89%, and for ethyl butyrate, the esterification yield was 92%. The results for both esterifications were similar to those obtained when the commercial enzyme Lipozyme® and free enzyme were used in the same reaction conditions and higher than the one achieved in the absence of the selected surfactant.     

Synthesis of copper(II) and zinc(II) complexes with chalcone–thiosemicarbazone hybrid ligands: X-ray crystallography,spectroscopy and yeast activity

Four chalcone–thiosemicarbazones (C-TSCs) of the type 2-((E)-3-(4-R-phenyl)-1-phenylallylidene)-N-phenylhydrazinecarbothioamide, where R?=?Cl (HL1), NO₂ (HL2), CH₃ (HL3) or CN (HL4), were prepared in good yields from the reaction of the respective chalcone with 4-phenyl-3-thiosemicarbazide and HCl in EtOH. Reaction of HL with CuCl₂·2H₂O or ZnCl₂ in the presence of Et₃N afforded the complexes [M(L)₂], M?=?Cu(II) or Zn(II). X-ray diffraction analysis revealed that the ligands coordinate in their deprotonated form, in a bidentate fashion through the iminic nitrogen and sulfur atoms. Yeast activities of the compounds were tested, where the ligand HL4 was the most damaging derivative, exhibiting cell viability at about 50%. On the other hand, lipid peroxidation assays revealed that the ligand HL1 was able to better induce membrane damage compared to the other compounds. It has been found that coordination with Cu(II) and Zn(II) did not increase the biological activities of the C-TSCs.     

Phenolic profile of hazelnut (Corylus avellana L.) leaves cultivars grown in Portugal

In this study, phenolic compounds of hazelnut leaves of 10 different cultivars with the same cultural, geographical, geological and climatic conditions were analyzed by HPLC/DAD and HPLC/DAD/MS/MS - ESI. Eight phenolic compounds (3-caffeoylquinic acid, 5-caffeoylquinic acid, caffeoyltartaric acid, p-coumaroyltartaric acid, myricetin 3-rhamnoside, quercetin 3-glycoside, quercetin 3-rhamnoside and kaempferol 3-rhamnoside) were identified and quantified. All of the analyzed samples showed a similar phenolic profile, in which myricetin 3-rhamnoside and quercetin 3-rhamnoside were the major compounds and caffeoyltartaric and p-coumaroyltartaric acids were present in vestigial amounts.