Academic literature on the topic 'Photoactivatable probe'

Rational design, synthesis and nanotechnologies as tools in early drug discovery: cancer and neurodegeneration as targets The rubric “multifactorial” has been applied to several diseases spanning multiple therapeutic areas, e.g. schizophrenia, autism, depression, epilepsy, diabetes, rheumatoid arthritis, hypertension, cancer, Alzheimer's and Parkinson's disease, multiple sclerosis and probably hundreds of other conditions; such label entails that the disease is influenced by multiple genetic and environmental factors, and that its progression is also influenced by a plethora of elements.1 Diseases may earn this label either if they are clearly heritable/familial although influenced by environmental factors (as is the case for diabetes); alternatively also if genetic liabilities are insufficient to predict whether a person will actually develop the disease, while environmental/sporadic factors are (much) more relevant for disease development and progression (as is mostly the case for amyotrophic lateral sclerosis/ALS). The terms complex and multifactorial are also commonly used to describe the architecture of the genetic component of disease liability. In these cases, these terms are usually at least implicitly equated with the trait being polygenic; in fact, 'complex', 'multifactorial' and 'polygenic' are commonly used as synonyms. It is important here to make a distinction in how the term polygenic is used: the implication is that a given disorder arises in each individual due to the combined effects of a large number of genetic variants (multiple causative factors for a single pathology).2 This definition is distinct from a model of genetic heterogeneity, in which many different variants are involved across the population, but where each case is caused by a single variant, or a few (a single, or few causative factors for a multiplicity of closely related pathologies). Multifactorial disorders are difficult to study and treat because the most relevant causative factors that mostly influence the establishment and the progression of these disorders have not yet been identified. Although many technologies and strategies can be used to detect molecular factors influencing complex diseases, these technologies and strategies have inherent limitations.3 In fact, the very name “complex disease” suggests that the results from relevant studies will not be simple to decipher. The absence of a univocally recognized, disease-determining mechanism makes it difficult to develop any target-focused drug to treat these diseases, or to rationally improve the therapeutic potential of biologically active compounds that have an unknown mode of action. The first part of my Ph.D. thesis deals with this issue, that is the synthesis of photoactivatable probes (PAPs)4 to help with the identification of molecular targets for the treatment of neurodegenerative diseases. More in details: • Chapter 1 (pp. 19-85) deals with the synthesis of chemical probes built on edaravone, a known anti-oxidant with strong radical-scavenging activity5. Edaravone is commercialized in Japan and the US for the treatment of ALS, and was recently identified by an ISS research group in Rome (Dr. Agresti) as a remyelinating agent in oligodendrocytes progenitor cells (OPCs) with possible MS reverberations6. Several edaravone analogues, including PAL moieties, were synthetized in order to investigate together with ISS the existence of a putative molecular target specific for the MS-targeted activity. • Chapter 2 (pp. 87-152) regards Sephin1, a mono-chlorinated Guanabenz analogue that was introduced as a potent inhibitor of inducible PP1-GADD34/PPP1R15A phosphatase complex.7 However, recent literature8 seems to question such target identification; and recent studies performed in collaboration between my research group and Trento University (Prof. Piccoli) hypothesized its interaction with actin, a completely unrelated protein. Thus, several Sephin1-derived chemical probes were synthetized, including azides and diazirines as PAPs and biotin-functionalized derivatives for pull-down, affinity chromatography9 experiments. The treatment of complex, multifactorial diseases often requires a targeted delivery of active compounds to the site of action to avoid unwanted side effects. In particular, my efforts refer to neurodegenerative diseases, that require permeation of the blood brain barrier (BBB) in order to reach their site of action; and to multiple cancer types, where only mutated/hyperproliferating/immortalized cancer cells need to be targeted while limiting drug exposure for healthy cells. The second part of my Ph.D. thesis will thus deal with the targeted delivery of drug candidates, in particular suggesting their formulation as self-assembled nanoparticles as a possible solution. More in details: • Chapter 3 (pp. 179-216) concerns the use of betulinic acid as self-assembly inducer for the formation of nanoparticles.10 Among its biological activities, betulinic acid is known as a cytotoxic agent. Thus, we wanted to investigate its use not only as a self-assembly inducer but also as an anticancer drug, hoping to take advantage of both these abilities. In particular, several betulinic conjugates were synthetized with cytotoxic drugs acting on microtubules dynamics. • Chapter 4 (pp. 217-258) regards the synthesis of trehalose-based, self-assembled nanoparticles.11 Trehalose is a disaccharide known to induce autophagy and to reduce protein misfolding and aggregation.12 Unfortunately, high mM trehalose concentrations are needed in vivo for efficacy, due to its high hydrophilicity and due to trehalase enzymes in the gut of humans that inactivate it by hydrolysing it to glucose.13 To improve its bioavailability by both preventing its hydrolysis and masking its hydrophilicity, we thought that squalene-trehalose conjugates and their self-assembled nanoparticles could be a promising approach towards the use of trehalose as an autophagy-inducing, neuroprotective drug. • Chapter 5 (pp. 259-339) addresses a different aspect of nanoparticles in nanomedicine, that is drug targeting. The need to discriminate between healthy and tumoral cells to reduce side effects of cytotoxic drugs is among the main issues in the treatment of cancer. We exploited folate targeting14 by preparing hetero-nanoparticles bearing both folic acid and an anticancer drug in order to have folate recognition/receptor targeting, followed by selective internalization of folate-drug conjugates inside tumoral cells. While the first two parts of my thesis mostly deal with medicinal chemistry approaches, during my Ph.D. I dealt also with total synthesis and chemical methodologies. Total synthesis is important both to confirm the structure of largely complex natural products and to obtain them and their analogues in significant amounts, expanding the pool of pharma-focused chemical diversity. That’s why the third part of my Ph.D. thesis concerns some of these aspects, in particular: • Chapter 6 (pp. 357-435) covers the total synthesis of triazole analogue of epothilones. Epothilones are a class of macrolides presenting different biological activities, among which the stabilization of microtubules that makes them good candidates for cancer treatment.15 However, since they present issues related to stability, we modified their structure using a triazole as bioisostere of their amidic function to improve their physiological stability. • Chapter 7 (pp. 437-495) reports the results I obtained during my period abroad, spent at the University of Barcelona from April to July 2019. There I obtained some preliminary results in the total synthesis of Schoberine B, a polycyclic alkaloid extracted from Myrioneuron faberi,16 and I performed a methodological study on the main reaction involved in its total synthesis - in particular, the stereoselective cyclocondensation of trisubstituted 2,4,6-cyclohexanone derivatives. Each Chapter in this Ph.D. thesis is divided in five Sections: 1) A short introduction on the targeted molecular pathway, and in particular the molecular targets involved; 2) A description of the chemical routes used for the preparation of all target compounds, and their key intermediates; 3) Their virtual and tangible characterization (in-silico docking, in vitro and sometimes in vivo profiling); 4) A critical evaluation of project results, and planned future activities; 5) An experimental part reporting in details the synthesis, the purification and the analytical characterization of each intermediate and of each final, targeted molecule.   Bibliography 1 K. J. Mitchell, Genome Biol., 2012, 13, 237–247. 2 R. Plomin, C. M. A. Haworth and O. S. P. Davis, Nat. Rev. Genet., 2009, 10, 872–878. 3 N. J. Schork, Am. J. Respir. Crit. Care Med., 1997, 156, S103–S109. 4 E. Smith and I. Collins, Futur. Med Chem, 2015, 7, 159–183. 5 M. P. Cruz, Pharm. Ter., 2018, 43, 25–28. 6 C. Eleuteri et al., Sci. Rep., 2017, 7, 45780–45794. 7 I. Das et al., Science, 2015, 348, 239–242. 8 A. Crespillo-Casado, J. E. Chambers, P. M. Fischer, S. J. Marciniak and D. Ron, Elife, 2017, 6, 1–29. 9 C. Mulder, N. Leijten and S. Lemeer, Curr. Opin. Syst. Biol., 2018, 10, 9–18. 10 E. Colombo et al., ACS Med. Chem. Lett., 2020, 11, 895–898. 11 E. Colombo et al., Pharmaceutics, 2019, 11, 422. 12 A. B. Richards et al., Food Chem. Toxicol., 2002, 40, 871–898. 13 S. Maicas, J. P. Guirao-Abad and J.-C. Argüelles, Biochim. Biophys. Acta - Gen. Subj., 2016, 1860, 2249–2254. 14 M. Fernández, F. Javaid and V. Chudasama, Advances in targeting the folate receptor in the treatment/imaging of cancers, Royal Society of Chemistry, 2018, vol. 9. 15 K. Gerth, N. Bedorf, G. Höfle, H. Irschik and H. Reichenbach, J. Antibiot. (Tokyo)., 1996, 49, 560–563. 16 M. M. Cao et al., RSC Adv., 2016, 6, 10180–10184.