Topical delivery and in vivo antileishmanial activity of paromomycin-loaded liposomes for treatment of cutaneous leishmaniasis.

The present study aimed to evaluate the potential of liposomes loaded with paromomycin (PA), an aminoglycoside antibiotic associated with poor skin penetration, for the topical treatment of cutaneous leishmaniasis (CL). Fluid liposomes were prepared and characterized for particle size, zeta potential, and drug entrapment. Permeation studies were performed with two in vitro models: intact and stripped skin. The antileishmanial activity of free and liposomal PA was evaluated in BALB/c mice infected by Leishmania (L.) major. Drug entrapment ranged from 10 to 14%, and the type of vesicle had little influence on this parameter. Particle size and polydispersity index of the vesicles composed by phosphatidylcholine (PC) and PC/cholesterol (Chol) ranged from of 516 to 362 nm and 0.7 to 0.4, respectively. PA permeation across intact skin was low, regardless of the formulation tested, while drug penetration into skin (percent of the applied dose) from PC (7.2 +/- 0.2%) and PC/Chol (4.8 +/- 0.2%) liposomes was higher than solution (1.9 +/- 0.1%). PA-loaded liposomes enhanced in vitro drug permeation across stripped skin and improved the in vivo antileishmanial activity in experimentally infected mice. Our findings suggest that the liposomes represent a promising alternative for the topical treatment of CL using PA.

Chromatographic evaluation and antimicrobial activity of Neem (Azadirachta indica A. Juss., Meliaceae) leaves hydroalcoholic extracts / Avaliação cromatográfica e atividade antimicrobiana de extratos hidroalcoólicos de folhas de Nim (Azadirachta indica A. Juss., Meliaceae)

Neem (Azadirachta indica) is an Indian tree well known for its several pharmacological activities, including antimicrobial activity. More than 300 composites have already been isolated and azadirachtin (AZA) is its main active component. In the present work, Neem leaves hydroalcoholic extracts were prepared by percolation in 96 percent ethanol different concentrations (50 percent, 60 percent, 70 percent, 80 percent and 90 percent (v/v)). The presence of AZA was tested by TLC by eluting the extracts and a standard solution of AZA through a chromatographic plate developed with anisaldehyde/sulfuric acid solution followed by heating. By HPLC, extracts elution took place on a C18 column, water:acetonitrile (60:40) as mobile phase, 1.0 mL/min flow rate and detection at λ217 nm. The extracts did not display AZA spots or peaks, however, they were tested against Gram-positive and Gram-negative bacteria, yeasts and a mold fungus. The extracts were tested in different increasing concentrations, in order to detect a dose-dependent relationship of the activity. Despite the absence of AZA, the 70 percent and 80 percent (v/v) ethanol extracts showed activity against Staphylococcus aureus. However, this activity was not dose-dependent according to Tukey's test (q0,05;3;7).

O Nim (Azadirachta indica A. Juss., Meliaceae) é uma árvore indiana conhecida por suas várias atividades farmacológicas, entre elas, a ação antimicrobiana. Dentre mais de 300 compostos já isolados, a azadiractina (AZA) é seu principal componente ativo. No presente trabalho, foram preparados extratos hidroalcoólicos de folhas de Nim em diferentes concentrações de etanol 96 por cento V/V (50 por cento, 60 por cento, 70 por cento, 80 por cento e 90 por cento (V/V)) por meio de percolação estática. A presença de AZA foi verificada por CCD, com eluição dos extratos e da solução padrão de trabalho AZA em cromatoplaca e revelação por solução de anisaldeído/ácido sulfúrico, seguida de aquecimento. Por CLAE, os extratos e da solução padrão de trabalho AZA foram eluídos em coluna C18, fase móvel água:acetonitrila (60:40), fluxo 1,0 mL/min e detecção em λ217 nm. Não foi verificada a presença de manchas ou picos correspondentes a AZA nos extratos. Entretanto, a sua atividade foi investigada contra bactérias Gram-positivas, Gram-negativas, leveduras e um fungo filamentoso. Os extratos foram testados em diferentes concentrações para avaliar a relação dose-resposta. Apesar da ausência de AZA, os extratos hidroalcoólicos a 70 por cento e 80 por cento (V/V) de etanol 96 por cento apresentaram atividade contra Staphylococcus aureus. Porém, não houve relação dose-efeito, de acordo com o teste de Tukey (q0,05;3;7).

Tissue distribution evaluation of stealth pH-sensitive liposomal cisplatin versus free cisplatin in Ehrlich tumor-bearing mice.

Multidrug resistance and drug toxicity represent major obstacles to cancer chemotherapy. Drug delivery systems, such as liposomes, offer improved chemical stability of encapsulated drugs, enhanced accumulation in tumors and decreased toxicity. The aim of this study was to evaluate the tissue distribution of stealth pH-sensitive liposomes containing cisplatin (SpHL-CDDP), compared with free cisplatin (CDDP), in solid Ehrlich tumor-bearing mice. After administering a 6 mg/kg single intravenous bolus injection of either free radiolabeled cisplatin or SpHL containing radiolabeled cisplatin, blood and tissues were analyzed for cisplatin content by determining radioactivity using an automatic scintillation apparatus. The area under the CDDP concentration-time curve (AUC) obtained for blood after SpHL-CDDP administration was 2.1 fold larger when compared with free CDDP treatment. The longer circulation of SpHL-CDDP led to a higher tumor AUC, and the determination of the ratio between AUC in each tissue and that in blood (Kp) showed a higher accumulation of CDDP in SpHL-CDDP administrated tumors. The SpHL-CDDP was also significantly uptaken by the liver and spleen. The distribution of SpHL-CDDP in these organs was extensive, revealing a high extravasation of CDDP to the tissues. The SpHL-CDDP kidney uptake was also greater than that of free CDDP; however, the Kp value found was lower. This indicates that the SpHL-CDDP led to a reduction of CDDP retention by renal tissue. Thus, these results indicate that the SpHL-CDDP may indeed be useful in alleviating renal damage induced by CDDP and thus represents a promising delivery system for cancer treatment through CDDP.

Antibacterial activity of coffee extracts and selected coffee chemical compounds against enterobacteria.

The in vitro antimicrobial activity of commercial coffee extracts and chemical compounds was investigated on nine strains of enterobacteria. The antimicrobial activity investigated by the disc diffusion method was observed in both the extracts and tested chemical compounds. Even though pH, color, and the contents of trigonelline, caffeine, and chlorogenic acids differed significantly among the coffee extracts, no significant differences were observed in their antimicrobial activity. Caffeic acid and trigonelline showed similar inhibitory effect against the growth of the microorganisms. Caffeine, chlorogenic acid, and protocatechuic acid showed particularly strong effect against Serratia marcescens and Enterobacter cloacae. The IC(50) and IC(90) for the compounds determined by the microtiter plate method indicated that trigonelline, caffeine, and protocatechuic acids are potential natural antimicrobial agents against Salmonella enterica. The concentrations of caffeine found in coffee extracts are enough to warrant 50% of the antimicrobial effect against S. enterica, which is relevant to human safety.

In vitro skin permeation and retention of paromomycin from liposomes for topical treatment of the cutaneous leishmaniasis.

Paromomycin (PA), a very hydrophilic antibiotic, has been tested as an alternative topical treatment against cutaneous leishmaniasis (CL). Although this treatment has shown promising results, it has not been successful in accelerating the recovery in most cases. This could be attributed to the low skin penetration of PA. Liposomal formulations usually provide sustained and enhanced drug levels in skin. The aim of this study was to prepare liposomal formulations containing PA and to investigate their potential as topical delivery systems of this antileishmanial. Large multilamellar vesicles (MLVs) were prepared by conventional solvent evaporation method. Large unilamellar vesicles (LUVs) were prepared by reverse-phase evaporation method. The lipids used were soybean phosphatidylcholine (PC) and PC:cholesterol (CH) (molar ratio 1:1). The skin permeation experiments across stripped and normal hairless mice skin were performed in modified Franz diffusion cells. The PA entrapment in LUV liposomes (20.4 +/- 2.2%) was higher than that observed for MLV liposomes (7.5 +/- 0.9%). Drug entrapment was 41.9 +/- 6.2% and 27.2 +/- 2.4% for PC and PC:CH LUV, respectively. The skin permeation was 1.55 +/- 0.31%, 1.29 +/- 0.40%, 0.20 +/- 0.08%, and 0.50 +/- 0.19% for PC LUV, PC:CH LUV, empty LUV +/- PA and aqueous solution, respectively. Controlled topical delivery, across stripped skin, was observed for PA entrapped in LUV liposomes.

Effect of age on body distribution of Tityustoxin from Tityus serrulatus scorpion venom in rats.

Previous research from our Laboratory has shown a greater susceptibility of young animals, when compared to adults, to envenomation by tityustoxin (TsTX), one of the main toxins from Tityus serrulatus scorpion venom. Our hypothesis is that a differential body distribution of TsTX among adult and young animals could account for the worse prognosis of scorpion envenomation in infants. Thus, TsTX labeled with technetium-99m was injected (6 microg, subcutaneous) in adult (150-160 day-old) and young (21-22 day-old) male rats. Groups of animals were sacrificed at different times after TsTX injection (0.08, 1.0, 3.0, 6.0, 12.0 and 24.0 hours) under Urethane anesthesia (140 mg/100 g, i.p.). The brain, heart, lungs, liver, kidneys, spleen and thyroid were excised and blood collected. Young rats presented a shorter latency toxin concentration peak in all studied organs except for the liver and the kidney, when compared to adults. The ratio between the area under the curve of the toxin concentration in each organ and that in blood (Kp) indicates higher accumulation in the organs of young animals mainly for brain, liver and heart. These observations suggest a faster toxin distribution in the organs of young rats. The higher uptake of TsTX in the brain is suggestive of a greater permeability for the toxin along the blood-brain barrier of young rats. In conclusion, the higher uptake in heart, together with data from the brain, may help to elucidate the clinical manifestations frequently observed in children under scorpion envenomation.