Xyloglucan nano-aggregates: Physico-chemical characterisation in buffer solution and potential application as a carrier for camptothecin, an anti-cancer drug

In this work, native xyloglucan was extracted from Tamarindus indica seeds (XGT), and its properties in phosphate buffer solution (PBS) were evaluated in comparison with a commercial tamarind kernel powder (TKP). The physico-chemical characteristics of the polysaccharides such as molar mass, critical concentration and intrinsic viscosity were determined. Furthermore, using spectroscopic and microscopy techniques, it was observed that the XGs tested can be considered macromolecules able to aggregate as nano-entities of 60-140 nm. The XGT tended to an ordered and compact spherical conformation determined by the Huggins constant, circular dichroism, atomic force microscopy and transmission electron microscopy. After the determination of the properties in PBS the XGs, at concentrations of 25% above their critical aggregation concentration, were used to encapsulate camptothecin, an anti-cancer drug. The XGT sample showed an encapsulation efficiency of 42% and first-order drug delivery kinetics. These results demonstrated the importance of knowledge of the physico-chemical properties of polysaccharides, for example, to better conduct their biotechnological applications as drug carriers. (C) 2010 Elsevier Ltd. All rights reserved.

Poly(epsilon-caprolactone)nanocapsules as carrier systems for herbicides: Physico-chemical characterization and genotoxicity evaluation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Poly(Lactide-co-Glycolide) Nanocapsules Containing Benzocaine: Influence of the Composition of the Oily Nucleus on Physico-Chemical Properties and Anesthetic Activity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Computational analysis and physico-chemical characterization of an inclusion compound between praziquantel and methyl-beta-cyclodextrin for use as an alternative in the treatment of schistosomiasis

Schistosomiasis is still an endemic disease in many regions, with 250 million people infected with Schistosoma and about 500,000 deaths per year. Praziquantel (PZQ) is the drug of choice for schistosomiasis treatment, however it is classified as Class II in the Biopharmaceutics Classification System, as its low solubility hinders its performance in biological systems. The use of cyclodextrins is a useful tool to increase the solubility and bioavailability of drugs. The aim of this work was to prepare an inclusion compound of PZQ and methyl-beta-cyclodextrin (MeCD), perform its physico-chemical characterization, and explore its in vitro cytotoxicity. SEM showed a change of the morphological characteristics of PZQ:MeCD crystals, and IR data supported this finding, with changes after interaction with MeCD including effects on the C-H of the aromatic ring, observed at 758 cm(-1). Differential scanning calorimetry measurements revealed that complexation occurred in a 1:1 molar ratio, as evidenced by the lack of a PZQ transition temperature after inclusion into the MeCD cavity. In solution, the PZQ UV spectrum profile in the presence of MeCD was comparable to the PZQ spectrum in a hydrophobic solvent. Phase solubility diagrams showed that there was a 5.5-fold increase in PZQ solubility, and were indicative of a type A(L) isotherm, that was used to determine an association constant (K(a)) of 140.8 M(-1). No cytotoxicity of the PZQ:MeCD inclusion compound was observed in tests using 3T3 cells. The results suggest that the association of PZQ with MeCD could be a good alternative for the treatment of schistosomiasis.

Thermal study and physico-chemical characterization of some functional properties of guava seeds protein isolate (Psidium guajava)

The guava seed protein isolate ( PI) was obtained from the protein precipitation belonging to the class of the gluteline (Ip 4.5). The conditions for the preparation of the PI were determined by both the solubility curve and simultaneous thermogravimetry-differential thermal analysis (TG-DTA): pH 11.5, absence of NaCl and whiteners and T=( 25 +/- 3) degrees C. Under these conditions a yield of 77.0 +/- 0.4%, protein content of 94.2 +/- 0.3, ashes 0.50 +/- 0.05% and thermal stability, T= 200 degrees C, were obtained. The TG-DTA curves and the PI emulsification capacity study showed the presence of hydrophobic microdomains at pH 11.5 and 3.0 suggesting a random coil protein conformation and, to pH 10.0, an open protein conformation. The capacity of emulsification (CE), in the absence of NaCl, was verified for: 1 - pH 3.0 and 8.5, using the IP extracted at pH 10.0 and 11.5, CE >= 343 +/- 5 g of emulsified oil/g of protein; 2 - pH 6.60 just for the PI obtained at pH 11.5, CE >= 140 +/- 8 g of emulsified oil/g of protein.

A Prodrug Approach to Improve the Physico-Chemical Properties and Decrease the Genotoxicity of Nitro Compounds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Temporal stability for unpredictable annual climatic variability for Hevea genotype selection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

First Description of a Cluster of Acute/Subacute Paracoccidioidomycosis Cases and Its Association with a Climatic Anomaly

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Physico-chemical and harvest time alterations in pineapple fruits Smooth Cayenne caused by paclobutrazol

O objetivo deste trabalho foi avaliar o efeito de um inibidor da diferenciação floral nas características físico-químicas dos frutos do abacaxizeiro, bem como, no período de colheita. Utilizou-se paclobutrazol a 100, 150 e 200 mg L-1 aplicados 2, 3 ou 4 vezes, em plantas de abacaxi cv. Smooth Cayenne. Os tratamentos não influenciaram nas características químicas dos frutos, e mesmo alterando algumas características físicas, os frutos permaneceram dentro dos padrões de qualidade para comercialização. O período de colheita foi ampliado em todos os tratamentos comparando-se com o controle, porém, 150 mg L-1 aplicados 2 vezes promoveu melhor resultado analisando-se em conjunto a época de colheita com a massa fresca do fruto.

Socio-climatic hotspots in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Poly(hydroxybutyrate-co-hydroxyvalerate) microspheres loaded with atrazine herbicide: screening of conditions for preparation, physico-chemical characterization, and in vitro release studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alternatives for the Treatment of Schistosomiasis: Physico-Chemical Characterization of an Inclusion Complex Between Praziquantel and Hydroxypropyl-beta-Cyclodextrin

"Alternatives for the Treatment of Schistosomiasis: Physico-Chemical Characterization of an Inclusion Complex Between Praziquantel and Hydroxypropyl-beta-Cyclodextrin". Praziquantel (PZQ) is the drug of choice commonly used for the treatment of shistosomiasis. However, it has low aqueous solubility, which could limit its bioavailability in the body. To circumvent these features, an inclusion complex with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was prepared. Thus, the objective of this work was to prepare and characterize the PZQ/HP-beta-CD inclusion complex. Morphological, spectroscopic, and calorimetric analysis showed the first signs of the guest/host interaction. The complexation kinetic analysis was used to determine the kinetic constant and, besides that, it was possible to establish the time consumed to reach equilibrium. Using the solubility isotherm, it was observed that the interaction with HP-beta-CD increased 2.4 fold the aqueous solubility of plain PZQ. In vitro cytotoxicity tests, using fibroblast cells, evidenced no toxicity for these cells at the concentrations tested. These results demonstrated that there is a potential use of PZQ in formulations with HP-beta-CD.

Thermoregulation and Respiratory Metabolism in two Brazilian Stingless Bee Subspecies of Different Climatic Distribution, Tetragonisca angustula fiebrigi and T a angustula (Hymenoptera: Apidae: Meliponinae)

The thermoregulatory capacity of colonies of the stingless bee subspecies Tetragonisca angustula fiebrigi Schwarz 1938, and Tetragonisca angustula angustula Latreille 1807, was investigated during winter and summer. The temperatures [T] inside and outside the nests were measured for 48 hh every 2 hh. In the brood area, the mean T observed for T a fiebrigi are 28.1° and 29.5° C, respectively, during winter and summer, whereas for T a angustula they are 28.6° and 31.6° C The ambient T in the same period range from 10.5° - 24.4° C (winter) and 20.1 - 36.3° C (summer). In workers, the respiratory rates [RR] increase with a rise in T, however, the differences between workers of the subspecies are not significant in contrast to the RR measured within subspecies in winter and summer. The Q10 values indicate an optimal T range from 15 - 25° C in winter, and from 20 - 30° C in summer for T a fiebrigi. For T a angustula the corresponding values were 25 - 35° C and 30 - 40° C, respectively.

Physico-chemical parameter correlations in the [RuCl2(CO)(L)(PPh3)2] complexes (L = N-heterocycles)

Fourteen complexes in the series [RuCl2(CO)(L)(PPh3)2] (where L = N-heterocycles) have been prepared and characterized by IR and NMR spectroscopies, and cyclic voltammetry. A good correlation is found between observed and calculated electrochemical potentials; E1/2 vs pKa or (Gp, σm for a series of similar ligands. It is now reported that the carbonyl stretching frequency, νCO, and the 13C and 31P NMR signals do not correlate well with any of the physico-chemical parameters used (E1/2, Taft's and Hammett's parameters). This behaviour is probably due to the characteristics of the Ru(II) species, which does not transmit the steric and electron donor/acceptor properties of the ligands to the carbonyl group, or because the measurements are not able to detect the effect induced by the changes in the ligand L. Indeed, good correlations are obtained when the measurements directly involve the metal centre, as is the case in the E1/2 measurements. Crystals of o[RuCl2(CO)(4-pic)(PPh3)2] are monoclinic, space group P21/n, a = 12.019(2), b = 13.825(3) and c = 22.253(3) . The structure was solved by the Patterson method and was refined by full-matrix least-squares procedure to R = 0.054 and Rw = 0.055, for 2114 reflections with I > 3σ(I). For L = 2-acetylpyridine and 2-methylimidazole, complexes with formulae [RuCl2(CO)(L)(PPh3)] · L and [RuCl2(CO)(L)2 (PPh3)], respectively, were obtained. © 1998 Elsevier Science Ltd. All rights reserved.