Evaluation of in vitro and in vivo Efficacy of a Novel Amphotericin B-Loaded Nanostructured Lipid Carrier in the Treatment of Leishmania braziliensis Infection.

BACKGROUND: Leishmaniasis is a neglected disease, and the current therapeutic arsenal for its treatment is seriously limited by high cost and toxicity. Nanostructured lipid carriers (NLCs) represent a promising approach due to high drug loading capacity, controlled drug release profiles and superior stability. Here, we explore the efficacy of a unique pH-sensitive amphotericin B-loaded NLC (AmB-NLC) in Leishmania braziliensis infection in vitro and in vivo. METHODS AND RESULTS: AmB-NLC was assessed by dynamic light scattering and atomic force microscopy assays. The carrier showed a spherical shape with a nanometric size of 242.0 ± 18.3 nm. Zeta potential was suggestive of high carrier stability (-42.5 ± 1.5 mV), and the NLC showed ~99% drug encapsulation efficiency (EE%). In biological assays, AmB-NLC presented a similar IC50 as free AmB and conventional AmB deoxycholate (AmB-D) (11.7 ± 1.73; 5.3 ± 0.55 and 13 ± 0.57 ng/mL, respectively), while also presenting higher selectivity index and lower toxicity to host cells, with no observed production of nitric oxide or TNF-α by in vitro assay. Confocal microscopy revealed the rapid uptake of AmB-NLC by infected macrophages after 1h, which, in association with more rapid disruption of AmB-NLC at acidic pH levels, may directly affect intracellular parasites. Leishmanicidal effects were evaluated in vivo in BALB/c mice infected in the ear dermis with L. braziliensis and treated with a pentavalent antimonial (Sb5+), liposomal AmB (AmB-L) or AmB-NLC. After 6 weeks of infection, AmB-NLC treatment resulted in smaller ear lesion size in all treated mice, indicating the efficacy of the novel formulation. CONCLUSION: Here, we preliminarily demonstrate the effectiveness of an innovative and cost-effective AmB-NLC formulation in promoting the killing of intracellular L. braziliensis. This novel carrier system could be a promising alternative for the future treatment of cutaneous leishmaniasis.

Yangambin and Epi-yangambin Isomers: New Purification Method from Ocotea fasciculata and First Cytotoxic Aspects Focusing on In Vivo Safety.

Ocotea fasciculata presents yangambin (YAN) and its isomer epi-yangambin (EPI-YAN) as major lignans, which are employed as the plant markers for quality control purposes and as potential pharmacological compounds. However, a gap between the pure isomers and safety and efficacy protocols is faced by the scientific community. In this context, this work aimed to report (i) a new and advantageous purifying process in a semi-preparative scale for YAN and EPI-YAN isolation from Ocotea fasciculata, and (ii) an in vitro cytotoxicity study to estimate, for the first time, the LD50 values of the isolated epimers, as well as the influence of albumin concentration in cell culture medium. The best condition for epimers isolation was achieved in normal-phase liquid chromatography. The lignan fraction (LF), previously obtained from the plant ethanolic extract, was purified yielding 17% and 29% of YAN and EPI-YAN, respectively. The in vitro study demonstrated that YAN and EPI-YAN were safe, and only at the highest concentration studied, a decrease on cell viability was observed. The estimated LD50 value was higher than 1612 mg/kg for both epimers. The LF, on the other hand, demonstrated an estimated LD50 of 422 mg/kg. Lignan cytotoxicity studies also evidenced that the higher cell viability was related to the higher concentration of fetal bovine serum as a source of albumin in medium. This is the first time the LD50 and safety of the isolated epimers were estimated, opening up great perspectives of success in in vivo studies.

Electrochemical Sensors Containing Schiff Bases and their Transition Metal Complexes to Detect Analytes of Forensic, Pharmaceutical and Environmental Interest. A Review.

Schiff bases and their transition metal complexes are inexpensive and easy to synthesize. These compounds display several structural and electronic features that allow their application in numerous research fields. Over the last three decades, electroanalytical scientists of various areas have developed electrochemical sensors from many compounds. The present review discusses the applicability of Schiff bases, their transition metal complexes and new materials containing these compounds as electrode modifiers in sensors to detect analytes of forensic, pharmaceutical and environmental interest. In forensic sciences, Schiff bases are mainly used to analyze illicit drugs: chemical reactions involving Schiff bases can help to elucidate illicit drug production and to determine analytes in seized samples. In the environmental area, given that most methodologies provide Limit of Detection (LOD) values below the values recommended by regulatory agencies, Schiff bases constitute a promising strategy. As for pharmaceutical applications, Schiff bases represent an approach for analysis of complex biological samples containing low levels of the target analytes in the presence of a large quantity of interfering compounds. This review will show that new highly specific materials can be synthesized based on Schiff bases and applied in the pharmaceutical industry, toxicological studies, electrocatalysis and biosensors. Most literature papers have reported on Schiff bases combined with carbon paste to give a chemically modified electrode that is easy and inexpensive to produce and which displays specific and selective sensing capacity for different applications.