Comparison of the Photodynamic Action of Porphyrin, Chlorin, and Isobacteriochlorin Derivatives toward a Melanotic Cell Line.

Melanoma is the most dangerous form of skin cancer, with an abrupt growth of its incidence over the last years. It is extremely resistant to traditional treatments such as chemotherapy and radiotherapy, but therapies for this cancer are gaining attention. Photodynamic therapy (PDT) is considered an effective modality to treat several types of skin cancers and can offer the possibility to treat one of the most aggressive ones: melanoma. In this work, the effect of PDT on a melanotic cell line (B16F10 cells) was assessed by exposing cultured cells to 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin (PS1) and to its chlorin (PS2) and isobacteriochlorin (PS3) corresponding derivatives and red LED light (λ = 660 ± 20 nm). The PDT effect in the cells' viability was measured using the MTT assay. The cell apoptosis was quantified by flow cytometry, and the subcellular localization of the photosensitizer was determined by fluorescence microscopy. In addition, the ability of PS2 to generate superoxide radicals was qualitatively assessed by tyrosine nitration. The results show that the efficiency of the PDT process is dependent on the structure of the PS and on their ability to produce singlet oxygen. Besides that, the photoactivation efficiency is highly dependent on the cellular sublocalization of the PS and on its cellular uptake and singlet oxygen production. We also found that the resistant cell line B16F10 has distinctive chlorin, isobacteriochlorin, or porphyrin-specific resistance profiles. Furthermore, it is shown that the highly fluorescent chlorin derivative PS2 can also be considered in imaging diagnostics.

Determination of serum aflatoxin B1-lysine to evaluate the efficacy of an aflatoxin-adsorbing feed additive in pigs fed an aflatoxin B1-contaminated diet.

In this study, serum aflatoxin B1 (AFB1)-lysine was determined in order to evaluate the in vivo efficacy of a hydrated sodium calcium aluminosilicate (HSCAS) in pigs fed AFB1. Twenty-four 49-day-old crossbred barrows were maintained in individual cages and allowed ad libitum access to feed and water. A completely randomized design was used with six animals assigned to each of four dietary treatments for 21 days as follows: (A) basal diet (BD), (B) BD supplemented with 0.5 % HSCAS, (C) BD supplemented with 1.1 mg/kg AFB1, and (D) BD supplemented with 0.5 % HSCAS and 1.1 mg/kg AFB1. HSCAS was able to alleviate the toxic effects of AFB1 on pigs and reduce (P < 0.05) the levels of serum AFB1-lysine. Cumulative reductions of adduct yield values, calculated through the equation [(pg AFB1-lysine/mg albumin) / (µg AFB1/kg body weight)], were 53.0, 62.8, and 72.1 after 7, 14, and 21 days of oral exposure, respectively. AFB1-lysine has potential as an AFB1-specific biomarker for diagnostic purposes and for evaluating the efficacy of chemoprotective interventions in pigs.

Development of a fast capillary electrophoresis method to determine inorganic cations in biodiesel samples.

The aim of this study was to develop a fast capillary electrophoresis method for the determination of inorganic cations (Na(+), K(+), Ca(2+), Mg(2+)) in biodiesel samples, using barium (Ba(2+)) as the internal standard. The running electrolyte was optimized through effective mobility curves in order to select the co-ion and Peakmaster software was used to determine electromigration dispersion and buffer capacity. The optimum background electrolyte was composed of 10 mmol L(-1) imidazole and 40 mmol L(-1) of acetic acid. Separation was conducted in a fused-silica capillary (32 cm total length and 23.5 cm effective length, 50 microm I.D.), with indirect UV detection at 214 nm. The migration time was only 36 s. In order to obtain the optimized conditions for extraction, a fractional factorial experimental design was used. The variables investigated were biodiesel mass, pH, extractant volume, agitation and sonication time. The optimum conditions were: biodiesel mass of 200 mg, extractant volume of 200 microL and agitation of 20 min. The method is characterized by good linearity in the concentration range of 0.5-20 mg kg(-1) (r>0.999), limit of detection was equal to 0.3 mg kg(-1), inter-day precision was equal to 1.88% and recovery in the range of 88.0-120%. The developed method was successfully applied to the determination of cations in biodiesel samples.

Optimizing the separation of food dyes by capillary electrophoresis.

In this work, the separation of eleven food dyes was evaluated by MEKC in electrolytes composed of tetraborate (TBS), Brij 35, and acetonitrile (ACN) using a factorial design at the following levels: TBS concentration (5 and 10 mmol L(-1)), pH (9.5 and 10.1), Brij concentration (5 and 20 mmol L(-1)), and ACN (5 and 15%). Several response functions were evaluated and indicated 10 mmol L(-1) TBS (pH 10.1), 15% ACN, and 20 mmol L(-1) Brij 35 as best values. However, baseline resolution was not achieved (R(cp) = 0.76) and the method lacked robustness. New conditions were sought by studying the dye mobility versus Brij concentration (5-20 mmol L(-1)). A set of well resolved and more uniformly spaced peaks was obtained with an electrolyte consisting of 7.5 mmol L(-1) TBS (pH 10.1), 10 mmol L(-1) Brij, and 15% ACN. Under these new conditions, complete resolution of the 11 dyes was achieved in less than 9 min. Migration time and peak area repeatabilities were better than 1.6% and 5% CV and the LODs were 0.47 to 2.3 microg mL(-1). The methodology was applied to fruit juice powders, lollipops, and other hard and soft chewable treats.