|Tipo di tesi||Tesi di laurea magistrale|
|Titolo||Caratterizzazione di nuovi drug-lead inibenti la pteridina reduttasi (PTR1) come agenti antileihmaniosi, mediante la validazione dell'inibizione della pteridina reduttasi-diidrofolato reduttasi (PTR1-DHFR).|
|Titolo in inglese||Characterization of new drug leads inhibiting pteridine reductase (PTR1) as antileihsmania agents, towards the validation of the pteridine reductase-dihydrofolate reductase (PTR1-DHFR) inhibition proof of concept.|
|Struttura||Dipartimento di Scienze della Vita|
|Corso di studi||BIOTECNOLOGIE MEDICHE E FARMACEUTICHE (D.M. 270/04)|
|Data inizio appello||2013-04-15|
|Disponibilità||Accessibile via web (tutti i file della tesi sono accessibili)|
La Leishmaniosi è una malattia che colpisce milioni di persone in tutto il mondo, specialmente nelle aree tropicali e subtropicali, causando mortalità e morbidità. Secondo la World Health Organization (WHO) il patogeno è endemico in 88 paesi e la rilevanza della malattia è stimata di 12 milioni di persone infette e 350 milioni di persone a rischio. L'agente eziologico è la Leishmania, un parassita protozoo appartenente alla famiglia dei Tripanosomatidi nell'ordine dei Kinetoplastidi. Circa 20 specie e sottospecie diverse di Leishmania sono state descritte e la loro eterogeneità si riflette in un ampio spettro di manifestazioni cliniche. Le leishmaniosi può essere classificata come: cutanea, viscerale, muco-cutanea e post-kala azar. La trasmissione della leishmaniosi è attribuita ad insetti della specie Lutzomya e Phlebotomus. L'insetto acquisisce il parassita da un mammifero infetto e durante il successivo pasto di sangue il parassita è inoculato nell'ospite umano o animale.
Leishmaniasis is a major public disease that affects millions of people worldwide, especially in tropical and subtropical areas, causing morbidity and mortality. According to the World Health Organization (WHO) the pathogen is endemic in 88 countries and the magnitude of the disease is estimated of 12 million infected people and 350 million people at risk. The causative agent of the disease is Leishmania, a protozoan parasite belonging to the Trypanosomatidae family in the Kinetoplastidae order. Almost 20 different species and subspecies of Leishmania are described and this heterogeneity is reflected in a broad spectrum of clinical manifestations. Thus Leishmaniasis is classified as: cutaneous, visceral, muco-cutaneous. Cutaneous leishmaniasis and post-kala azar dermal leishmaniasis are the most diffuse form. The transmission of leishmaniasis is attributed to sandfly species, Lutzomya and Phlebotomus. The parasite enters the female sandflies by sucking the blood from an infected mammalian host. During a subsequent blood-meal the parasite is inoculated in the skin of human or mammalian hosts. Till date there are no effective vaccines available, so the current treatment is based solely on chemotherapy. Pentavalent antimonials, amphotericin B and its lipid formulation, miltefosine and paromomycin are available but their use is limited due to toxicity, high cost and difficult administration. The problem is compounded by a rise in drug resistance strains. Therefore, it is of great importance to look for effective drugs and new drug targets for the treatment of leishmaniasis. Folate pathway is a current drug target for the treatment of bacterial, cancer, and certain parasitic diseases (e.g. malaria), and it has been of interested for leishmaniasis diseases since few years; since their importance TS and DHFR, two main enzymes involved in the folates synthesis, are notable drug targets. Even though Trypanosomatids are auxotrophic for folates and pterins, antifolates are currently not employed in therapy of trypanosomatid infections, mainly because of PTR1. PTR1 is a short-chain dehydrogenase/reductase that can reduce both pterins and folates as DHFR-TS does but is much less susceptible to inhibition by antifolates than. This indicates that an inhibitor is required to target both the enzymes simultaneously or that two compounds specifically inhibiting both the enzymes can be used in combination. In according to these suggestions, the purpose of my thesis was to identify new hits and leads that could guide to the development of antileishmania drugs. To this aim I have studied thiadiazolic and benzothiadiazolic compounds through two different approaches: a) by medium throughput library screening (MTS) of their PTR1 enzymatic activity inhibition; b) antileishmania activity profile, alone or in combination with pyrimethamine, a known antifolate drugs. Strategy a) was applied to a 26 compounds library . The test was performed applying a chromogenic assay based on the reduction reaction of biopterin to dihydrobiopterin and tetrahydrobiopterin using NADPH as a cofactor. Strategy b) was performed in prof. Anabela Cordeiro laboratory at the IBMC-INEB Associate Laboratory in Oporto (Portugal). A cell based screening assay on Leishmania infantum promastigotes was performed for evaluating synergistic effect with pyrimethamine.