SYNTHESIS OF NEW POLYCYCLIC COMPOUNDS WITH POTENTIAL ANTIMALARIAL AND/OR ANTILEISHMANIAL ACTIVITY

ABSTRACT Malaria and leishmaniasis are potentially lethal protozoan diseases affecting a huge number of people worldwide, especially in underdeveloped countries. The alarming spread of drug resistance concerning both Plasmodium and Leishmania parasites makes the search of novel antimalarial and antileishmanial agents an urgent need. Unfortunately, at the moment even the combination therapies are failing in many regions afflicted by the diseases and alternatives are scarcely found. In addition, the available antileishmanial drugs are quite toxic, expensive and very often need monitoring and hospitalization. In the light of this dramatic situation, the discovery of novel effective, safe and affordable molecules is vital. Thus far, several strategies have been developed to overcome resistance mechanisms; among them, of particular interest are the structural optimization of already known antiprotozoal molecules, the development of hybrid compounds and the search of new chemical scaffolds. Based on these considerations, the aim of the present thesis was the synthesis of different novel sets of molecules, potentially candidates for the treatment of malaria and/or leishmaniasis. On one hand I prepared derivatives of the antiprotozoal agents chloroquine and clofazimine, in order to improve the biological activity and to reduce resistance mechanisms. On the other hand, I explored the potenzialities of new chemical scaffolds, such as indeno[2,1-c]quinolines, to design new antimalarials. Moreover, I evaluated the possibility of creating hybrid molecules, combining moieties with different mechanism of action which could carry out a synergistic effect. In particular, the quinoline nucleus has been combined with different HDACs inhibiting structures to generate antiplasmodial hybrids, whereas aphidicolin (a fungal metabolite with antileishmanial activity) has been condensed with other molecules endowed with antileishmanial activity, such as ethyl 3-chloroacetamidobenzoate and eflornithine. Biological assays were in general quite encouraging and suggested that these new classes of compounds could be considered as potential leads for the synthesis of new effective antiprotozoal drugs that, in some cases, could hopefully overcome resistance mechanisms

Functional and structural abnormalities in deferoxamine retinopathy : a review of the literature

Deferoxamine mesylate (DFO) is the most commonly used iron-chelating agent to treat transfusion-related hemosiderosis. Despite the clear advantages for the use of DFO, numerous DFO-related systemic toxicities have been reported in the literature, as well as sight-threatening ocular toxicity involving the retinal pigment epithelium (RPE). The damage to the RPE can lead to visual field defects, color-vision defects, abnormal electrophysiological tests, and permanent visual deterioration. The purpose of this review is to provide an updated summary of the ocular findings, including both functional and structural abnormalities, in DFO-treated patients. In particular, we pay particular attention to analyzing results of multimodal technologies for retinal imaging, which help ophthalmologists in the early diagnosis and correct management of DFO retinopathy. Fundus autofluorescence, for example, is not only useful for screening patients at high-risk of DFO retinopathy, but is also a prerequisite for identify specific high-risk patterns of RPE changes that are relevant for the prognosis of the disease. In addition, optical coherence tomography may have a clinical usefulness in detecting extent and location of different retinal changes in DFO retinopathy. Finally, this review wants to underline the need for universally approved guidelines for screening and followup of this particular disease

Methanethiosulfonate derivatives as ligands of STAT3-SH2 domain

It is well known that inflammatory conditions in selected organs increase the risk of cancer. Compounds of the inflammatory tumor microenvironment include leukocytes, cytokines, complement components, are orchestrated by transcription factors, such as STAT-3 (Signal Transducer and Activator of Transcription 3) and NF-kB. Therefore drugs able to inhibit one or both transcription factors could be useful tools to treat cancer disease. Two main approaches have been explored to inhibit STAT-3 signalling: \u2022 indirect, inhibiting the upstream tyrosine kinases that are responsible for STAT-3 activation or blocking factors such as JAK, Src, Bcr-Abl, FLT3 and EGFR that are involved in the activation of STAT-3 signalling. This kind of inhibition induces tumour-cell apoptosis but is poor selective. \u2022 direct, by interaction of small molecules with the protein. In this selective approach the starting point is the crystallographic structure of STAT-3 SH2 domain. S-methyl methanethiosulfonate, isolated from cauliflower has been shown to inhibit colon tumor incidence when administered to rats during the post-initiation phase of carcinogenesis [1]. Recently, a new methanethiosulfonate derivative of valproic acid (ACS33) was reported by some of us to show good in vitro antiproliferative activity and to inhibit in vivo the growth of PC3 in subcutaneous xenograft mice models [2]. Fig.1: Structures of the studied thiosulfonate hybrids. Since the influence of methanethiosulfonates on STAT-3 activity has not been yet studied, we decided to synthesize a set of thiosulfonate-drug hybrids (Fig.1) and to submit them and their parent compounds to the AlphaScreen-based assay, to investigate their ability to bind STAT-3 SH2 domain. Moreover, in order to check the selectivity of our molecules on STAT-3, other SH2-containing proteins, such as STAT-1, exhibiting a high degree of sequence homology to STAT-3, have also been tested. Results showed that most of the synthesized thiosulfonate-hybrids are able to strongly and selectively bind STAT-3 SH2 domain, whereas the parent drugs were completely devoid of this ability. Studies are ongoing to better define the profile of our new methanethiosulfonate derivatives as potential dual STAT-3/NFkB inhibitors. References 1. Reddy, B. S.; Kawamori, T.; Lubet, R.; Steele, V.; Kelloff, G.; Rao, C. V. Chemopreventive effect of S-methylmethane thiosulfonate and sulindac administered together during the promotion/progression stages of colon carcinogenesis Carcinogenesis 1999, 20, 1645-8. 2. Wedel S. A.; Sparatore A.; Del Soldato P.; Al-Batran S. E.; Atmaca A.; Juengel E.; Hudak L.; Jonas D.; Blaheta R. A. New histone deacetylase inhibitors as potential therapeutics tools for advanced prostate carcinoma. J. Cell. Mol Med 2008, 12, 2457-66

Choroidal volume variations during childhood

Purpose. We analyzed choroidal volume (CV) variations during childhood using enhanced depth imaging optical coherence tomography, and evaluated its association with age, axial length (AXL), sex, weight, and height. Methods. Imaging studies of the right eyes of 52 healthy children were reviewed and included in this study. Subjects underwent a complete ocular examination and AXL measurement, as well as a raster macular scan using the Heidelberg Spectralis device. The choroid was segmented manually. Results. Subjects included 21 males and 31 females, with mean age of 9 years (range, 2-17 years) and mean AXL of 22.8 \ub1 0.98 mm. Mean CV was 0.263 \ub1 0.068 mm3 for the foveal circle and 8.545 \ub1 1.822 mm3 for the total Early Treatment of Diabetic Retinopathy Study (ETDRS) grid. The CV of the nasal quadrant was significantly lower than all others (P < 0.001). Total and foveal CV showed significant negative correlation with AXL after adjustment for age (P < 0.001), and significant positive correlation with age after adjustment for AXL (P < 0.001). Total CV was correlated significantly with sex after adjusting for AXL (P = 0.01), while no correlations were found between total CV and height or weight. The CV increased by 0.214 mm3 (2.5%) for every year, and decreased by 1.0 mm3 (11.7%) for every millimeter of axial length. Regression analysis confirmed a trend of higher CV in females than in males (P = 0.056). Conclusions. The CV increases with age during childhood, but decreases with AXL. This finding supports the hypothesis that the choroid grows progressively during childhood. Intersexual differences of CV also may be present

Visual Function Assessment in Simulated Real-Life Situations in HIV-Infected Subjects

Visual function abnormalities are common in people living with HIV disease (PLWH) without retinitis, even after improvement in immune status. Abnormalities such as reduced contrast sensitivity, altered color vision, peripheral visual field loss, and electrophysiological changes are related to a combination of retinal dysfunctions, involving inner and outer retinal structures. The standard protocol for testing vision performance in clinical practice is the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. However, this method poorly correlates with activities of daily living that require patients to assess visual stimuli in multiple light/contrast conditions, and with limited time. We utilized a novel interactive computer program (Central Vision Analyzer) to analyze vision performance in PLWH under a variety of light/contrast conditions that simulate stressful and real-world environments. The program tests vision in a time-dependent way that we believe better correlates with daily living activities than the non-timed ETDRS chart. We also aimed to correlate visual scores with retinal neuro-fiber layer thickness on optical coherence tomography. Here we show that visual acuity is more affected in PLWH in comparison to HIV-seronegative controls in varying contrast and luminance, especially if the nadir CD4+ T-cell count was lower than 100 cells/mm3. Visual impairment reflects the loss of retinal nerve fiber layer thickness especially of the temporal-inferior sector. In PLWH the ETDRS chart test led to better visual acuity compared to the Central Vision Analyzer equivalent test, likely because patients had indefinite time to guess the letters. This study confirms and strengthens the finding that visual function is affected in PLWH even in absence of retinitis, since we found that the HIV serostatus is the best predictor of visual loss. The Central Vision Analyzer may be useful in the diagnosis of subclinical HIV-associated visual loss in multiple light/contrast conditions, and may offer better understanding of this entity called "neuroretinal disorder"

Choroidal abnormalities detected by near-infrared reflectance imaging as a new diagnostic criterion for neurofibromatosis 1

Objective: To investigate in a large sample of consecutive patients with neurofibromatosis type 1 (NF1) the possibility of including the presence of choroidal abnormalities detected by near-infrared reflectance (NIR) as a new diagnostic criterion for NF1. Design: Cross-sectional evaluation of a diagnostic test. Participants and Controls: Ninety-five consecutive adult and pediatric patients (190 eyes) with NF1, diagnosed based on the National Institutes of Health (NIH) criteria. Controls included 100 healthy age- and gender-matched control subjects. Methods: Confocal scanning laser ophthalmoscopy was performed for each subject, investigating the presence and the number of choroidal abnormalities. Main Outcome Measures: Sensitivity, specificity, and diagnostic accuracy for the different cutoff values of the criterion choroidal nodules detected by NIR compared with the NIH criteria. Results: Choroidal nodules detected by NIR imaging were present in 79 (82%) of 95 of the NF1 patients, including 15 (71%) of the 21 NF1 pediatric patients. Similar abnormalities were present in 7 (7%) of 100 healthy subjects, including 2 (8%) of the 25 healthy pediatric subjects. The highest accuracy was obtained at the cutoff value of 1.5 choroidal nodules detected by NIR imagery. Sensitivity and specificity of the examination at the optimal cutoff point were 83% and 96%, respectively. Diagnostic accuracy was 90% in the overall population and 83% in the pediatric population. Both of these values were in line with the most common NIH diagnostic criteria. Conclusions: Choroidal abnormalities appearing as bright patchy nodules detected by NIR imaging frequently occurred in NF1 patients. The present study shows that NIR examination to detect choroidal involvement should be considered as a new diagnostic criterion for NF1

Characterization of microaneurysm closure after focal laser photocoagulation in diabetic macular edema

Purpose: To characterize microaneurysm closure following focal laser photocoagulation in diabetic macular edema (DME) using simultaneous fluorescein angiography (FA) and spectral-domain optical coherence tomography (SD-OCT). Design: Retrospective observational case series. Methods: Leaking microaneurysms (n\ua0= 123) were analyzed in eyes (n\ua0= 29) with nonproliferative diabetic retinopathy (NPDR) that underwent navigated focal laser photocoagulation in DME and were followed at 3, 6, and 12\ua0months. Closure of diabetic microaneurysms was characterized in detail following focal laser using SD-OCT. Results: Closure rate of microaneurysms by both FA and SD-OCT was 69.9% (84/123), 79.7% (98/123), and 82.9% (102/123) at 3, 6, and 12\ua0months, respectively. Microaneurysm closure rate increased at 6 and 12\ua0months compared to 3\ua0months (P < .003, P < .001). Over half of closed microaneurysms (45/86, 52.3%) left hyperreflective spots while the remaining half (41/86, 47.7%) disappeared without any hyperreflectivity by SD-OCT at 3\ua0months. Hyperreflective spots decreased at 6 (36/99, 36.4%) and 12\ua0months (17/102, 16.7%) with a concomitant increase in complete loss of reflectivity at 6 (63/99, 63.6%) and 12\ua0months (85/102, 83.3%). Smaller outer and inner diameters and heterogeneous lumen reflectivity were positively associated with microaneurysm closure at 12\ua0months (P < .0001, P < .001, P < .03). Conclusions: Characterization of microaneurysms following focal laser photocoagulation resulted in hyperreflective spots and complete resolution of all reflectivity using SD-OCT. Smaller microaneurysms and those with heterogeneous lumen were positively associated with microaneurysm closure. These findings provide greater understanding of localized retinal changes following focal laser photocoagulation in DME treatment