A reliable quantitative method for the analysis of phenolic compounds in Brazilian propolis by reverse phase high performance liquid chromatography

A sensitive and reliable RP-HPLC method was developed using a C18 CLC-ODS (M) - 4.6x250 mm(2)column and gradient elution for the analysis of phenolic compounds in propolis raw material and its products. A procedure for the extraction of phenolic compounds using aqueous ethanol (90%) with the addition of veratraldehyde as the internal standard (IS) was developed allowing to quantify ten compounds: caffeic acid, coumaric acid, ferulic acid, cinnamic acid, aromadendrin-4'-methyl ether (AME), isosakuranetin, drupanin, artepellin C, baccharin, and 2,2-dimethyl-6-carboxyethenyl-2H-1-benzopyran acid (DCBEN). The developed method gave good detection response and linearity in the range of 20.83-533.33 microg/mL.     

Photobiomodulation Therapy on the Guided Bone Regeneration Process in Defects Filled by Biphasic Calcium Phosphate Associated with Fibrin Biopolymer

The aim is to evaluate the effects of photobiomodulation therapy (PBMT) on the guided bone regeneration process (GBR) in defects in the calvaria of rats filled with biphasic calcium phosphate associated with fibrin biopolymer. Thirty male Wistar rats were randomly separated: BMG (n = 10), defects filled with biomaterial and covered by membrane; BFMG (n = 10), biomaterial and fibrin biopolymer covered by membrane; and BFMLG (n = 10), biomaterial and fibrin biopolymer covered by membrane and biostimulated with PBMT. The animals were euthanized at 14 and 42 days postoperatively. Microtomographically, in 42 days, there was more evident bone growth in the BFMLG, limited to the margins of the defect with permanence of the particles. Histomorphologically, an inflammatory infiltrate was observed, which regressed with the formation of mineralized bone tissue. In the quantification of bone tissue, all groups had a progressive increase in new bone tissue with a significant difference in which the BFMLG showed greater bone formation in both periods (10.12 ± 0.67 and 13.85 ± 0.54), followed by BFMG (7.35 ± 0.66 and 9.41 ± 0.84) and BMG (4.51 ± 0.44 and 7.11 ± 0.44). Picrosirius-red staining showed greater birefringence of collagen fibers in yellow-green color in the BFMLG, showing more advanced bone maturation. PBMT showed positive effects capable of improving and accelerating the guided bone regeneration process when associated with biphasic calcium phosphate and fibrin biopolymer.     

Oxovanadium(IV) and (V) complexes of acetylpyridine-derived semicarbazones exhibit insulin-like activity

Reaction of 2-acetylpyridine semicarbazone (H2APS), 3-acetylpyridine semicarbazone (H3APS) and 4-acetylpyridine semicarbazone (H4APS) with [VO(acac)₂] (acac = acetylacetonate) gave [VO(H2APS)(acac)₂] (1), [VO(H3APS)(acac)₂] (2) and [VO(4APS)(acac)(H₂O)] · 1/2H₂O (3). Oxidation of complex 1 in acetonitrile gave [VO₂(2APS)] (4). The crystal structures of complexes 1 and 4 have been determined. Complexes 1–3 were able to enhance glucose uptake and to inhibit glycerol release from adipocytes, which indicate their potential to act as insulin-mimics.     

Phenolic antioxidants identified by ESI-MS from Yerba maté (Ilex paraguariensis) and green tea (Camelia sinensis) extracts

Aqueous extracts of green yerba maté (Ilex paraguariensis) and green tea (Camellia sinensis) are good sources of phenolic antioxidants, as already described in the literature. The subject of this study were organic extracts from yerba maté, both green and roasted, and from green tea. Their phenolic profiles were characterized by direct infusion electrospray insertion mass spectrometry (ESI-MS) and their free radical scavenging activity was determined by the DPPH assay. Organic extracts containing phenolic antioxidants might be used as natural antioxidants by the food industry, replacing the synthetic phenolic additives used nowadays. Ethanolic and aqueous extracts from green yerba maté, roasted yerba maté and green tea showed excellent DPPH scavenging activity (>89%). The ether extracts from green and roasted yerba maté displayed a weak scavenging activity, different from the behavior observed for the green tea ether extract. The main phenolic compounds identified in green yerba maté water and ethanolic extracts were: caffeic acid, quinic acid, caffeoyl glucose, caffeoylquinic acid, feruloylquinic acid, dicaffeoylquinic acid and rutin. After the roasting process two new compounds were formed: caffeoylshikimic acid and dicaffeoylshikimic acid. The ethanolic extracts from yerba maté, both roasted and green, with lower content of phenolic compounds (3.80 and 2.83 mg/mL) presented high antioxidant activity and even at very low phenolic concentrations, ether extract from GT (0.07 mg/mL) inhibited DPPH over 90%.     

On exact boundary controllability for linearly coupled wave equations

In this paper we study exact boundary controllability for a system of two linear wave equations coupled by lower order terms. We obtain square integrable control of Neuman type for initial state with finite energy, in nonsmooth domains of the plane.     

A new Branch and Bound method for a discrete truss topology design problem

Our paper considers a classic problem in the field of Truss Topology Design, the goal of which is to determine the stiffest truss, under a given load, with a bound on the total volume and discrete requirements in the cross-sectional areas of the bars. To solve this problem we propose a new two-stage Branch and Bound algorithm. In the first stage we perform a Branch and Bound algorithm on the nodes of the structure. This is based on the following dichotomy study: either a node is in the final structure or not. In the second stage, a Branch and Bound on the bar areas is conducted. The existence or otherwise of a node in this structure is ensured by adding constraints on the cross-sectional areas of its incident bars. In practice, for reasons of stability, free bars linked at free nodes should be avoided. Therefore, if a node exists in the structure, then there must be at least two incident bars on it, unless it is a supported node. Thus, a new constraint is added, which lower bounds the sum of the cross-sectional areas of bars incident to the node. Otherwise, if a free node does not belong to the final structure, then all the bar area variables corresponding to bars incident to this node may be set to zero. These constraints are added during the first stage and lead to a tight model. We report the computational experiments conducted to test the effectiveness of this two-stage approach, enhanced by the rule to prevent free bars, as compared to a classical Branch and Bound algorithm, where branching is only performed on the bar areas.     

Molecularly imprinted solid-phase extraction and high-performance liquid chromatography with ultraviolet detection for the determination of urinary trans,trans-muconic acid: a comparison with ionic exchange extraction

A new molecularly imprinted polymer (MIP) has been synthesized for the selective extraction of trans,trans-muconic acid (ttMA) from urine samples, followed by high-performance liquid chromatography analysis with ultraviolet detection. The synthesis was based on non-covalent interactions, and 4-vinylpyridine was used as a functional monomer. The analytical calibration curve was prepared using a pool of five urine samples of non-smokers spiked with ttMA standards with concentrations that ranged from 0.3 to 10 mg L(-1) (r(2) = 0.999). The limit of quantification was 0.3 mg L(-1) (lower than the biological exposure limits suggested by the ACGIH). The within-day and between-day precision and accuracy presented relative standard deviations and relative errors of less than 15%. The analytical frequency was 4 h(-1) (considering extraction and separation/quantification steps), and the same MIP cartridge was efficiently used for approximately 100 cycles. All figures of merit were similar or better than those obtained by the procedure based on ionic exchange extraction. The proposed method could be an interesting alternative for the routine analysis of ttMA in urine for biological monitoring procedures of human exposure to benzene.