Enantiopure Indolizinoindolones with in vitro Activity against Blood- and Liver-Stage Malaria Parasites.

Malaria continues to be a major cause of morbidity and mortality to this day, and resistance to drugs like chloroquine has led to an urgent need to discover novel chemical entities aimed at new targets. Here, we report the discovery of a novel class of potential antimalarial compounds containing an indolizinoindolone scaffold. These novel enantiopure indolizinoindolones were synthesized, in good-to-excellent yields and excellent diastereoselectivities, by cyclocondensation reaction of (S)- or (R)-tryptophanol and 2-acyl benzoic acids, followed by intramolecular α-amidoalkylation. Interestingly, we were able to synthesize for the first time 7,13b-cis indolizinoindolones in a two-step route. The novel compounds showed promising activity against erythrocytic stages of the human malaria parasite, Plasmodium falciparum, and liver stages of the rodent parasite Plasmodium berghei. In particular, an (S)-tryptophanol-derived isoindolinone was identified as a promising starting scaffold to search for novel antimalarials, combining excellent activity against both stages of the parasite's life cycle with low cytotoxicity and excellent metabolic and chemical stability in vitro.

Synthesis and evaluation of N-acylamino acids derivatives of triazenes. Activation by tyrosinase in human melanoma cell lines.

In this research work we report the synthesis of a new series of triazene prodrugs designed for Melanocyte-Directed Enzyme Prodrug Therapy (MDEPT). These compounds are derived from the N-acyltyrosine amino acid - a good enzyme substrate for the tyrosinase enzyme, which is significantly overexpressed in melanoma cells. We analysed their chemical stability and plasma enzymatic hydrolysis, and we also evaluated the release of the antitumoral drug in the presence of the tyrosinase. Subsequently, we performed the evaluation of the prodrug cytotoxicity in melanoma cell lines with different levels of tyrosinase activity. Prodrug 5c showed the highest cytotoxicity against melanoma cell lines, and this effect correlated well with the tyrosinase activity suggesting that prodrug cytotoxicity is tyrosinase-dependent.

The multifactorial nature of Alzheimer's disease for developing potential therapeutics.

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder with several target proteins contributing to its aetiology. Pathological, genetic, biochemical, and modeling studies all point to a critical role of Aß aggregation in AD. Though there are still many enigmatic aspects of the Aß cascade, none of the gaps invalidate the hypothesis. The amyloid hypothesis determines that the production, aggregation and accumulation of Aß in the brain gives rise to a cascade of neurotoxic events that proceed to neuronal degeneration. Different targets of the disease include APP pathogenic cleavage, cytoskeletal destabilization, neurotransmitter and ion dyshomeostasis, metal ion accumulation, protein misfolding, oxidative stress, neuronal death and gene mutations. Thus, disease-modifying treatments for AD must interfere with the pathogenic steps responsible for the clinical symptoms: the deposition of extracellular Aß plaques, the intracellular neurofibrillary tangles, inflammation, oxidative stress, iron deregulation, among others. The observations supporting the development of multifunctional compounds in association with the perception that several dual binding site AChEIs were able to reach different targets guided the development of a new drug design strategy, the multi-target-directed-ligand (MTDL) approach. This may be regarded as the buildup of hybrid molecules composed of distinct pharmacophores of different drugs. Thus, each pharmacophore of the new hybrid drug would preserve the capacity of interacting with their specific sites on the targets and, therefore, generate multiple specific pharmacological responses which would enable the treatment of multi-factorial diseases. This review summarizes a few current therapeutic trends on MTDL strategy intended to halt or revert the progression of the disease.

Development of triazene prodrugs for ADEPT strategy: new insights into drug delivery system based on carboxypeptidase G2 activation.

Six novel urea triazene prodrugs have been synthesized to apply in antibody-directed enzyme prodrug therapy (ADEPT). The chemical and plasmatic stability of l-glutamate triazene prodrugs were evaluated and the chemical reactivity was mainly attributed to an intramolecular catalysis promoted by the neighbouring carboxylate group of the glutamic moiety. These prodrugs showed an elevated binding to plasma proteins. The L-glutamate triazenes were evaluated as prodrugs of the alkylating agent's monomethyltriazenes, by activation of the bacterial enzyme carboxypeptidase G2 (CPG2). The synthesized prodrugs have been shown to be good substrates for CPG2, and therefore new candidates for ADEPT strategy.

Dopamine- and tyramine-based derivatives of triazenes: activation by tyrosinase and implications for prodrug design.

A range of triazene derivatives were synthesized and investigated as prodrug candidates for melanocyte-directed enzyme prodrug therapy (MDEPT). The prodrugs contained a tyramine or dopamine promoiety required for tyrosinase activation and this was joined via a urea functional group to the cytotoxic triazene. The stability of each of the prodrugs in phosphate buffer, human plasma and in mushroom tyrosinase is discussed. The identification of the main peak formed after the tyrosinase reaction was attempted by LC-MS and the conversion of prodrug to the quinone was confirmed.