Anti-AIDS agents 81. Design, synthesis, and structure-activity relationship study of betulinic acid and moronic acid derivatives as potent HIV maturation inhibitors.

In our continuing study of triterpene derivatives as potent anti-HIV agents, different C-3 conformationally restricted betulinic acid (BA, 1) derivatives were designed and synthesized in order to explore the conformational space of the C-3 pharmacophore. 3-O-Monomethylsuccinyl-betulinic acid (MSB) analogues were also designed to better understand the contribution of the C-3' dimethyl group of bevirimat (2), the first-in-class HIV maturation inhibitor, which is currently in phase IIb clinical trials. In addition, another triterpene skeleton, moronic acid (MA, 3), was also employed to study the influence of the backbone and the C-3 modification toward the anti-HIV activity of this compound class. This study enabled us to better understand the structure-activity relationships (SAR) of triterpene-derived anti-HIV agents and led to the design and synthesis of compound 12 (EC(50): 0.0006 microM), which displayed slightly better activity than 2 as a HIV-1 maturation inhibitor.

High-throughput identification of chemical inhibitors of E. coli Group 2 capsule biogenesis as anti-virulence agents.

Rising antibiotic resistance among Escherichia coli, the leading cause of urinary tract infections (UTIs), has placed a new focus on molecular pathogenesis studies, aiming to identify new therapeutic targets. Anti-virulence agents are attractive as chemotherapeutics to attenuate an organism during disease but not necessarily during benign commensalism, thus decreasing the stress on beneficial microbial communities and lessening the emergence of resistance. We and others have demonstrated that the K antigen capsule of E. coli is a preeminent virulence determinant during UTI and more invasive diseases. Components of assembly and export are highly conserved among the major K antigen capsular types associated with UTI-causing E. coli and are distinct from the capsule biogenesis machinery of many commensal E. coli, making these attractive therapeutic targets. We conducted a screen for anti-capsular small molecules and identified an agent designated "C7" that blocks the production of K1 and K5 capsules, unrelated polysaccharide types among the Group 2-3 capsules. Herein lies proof-of-concept that this screen may be implemented with larger chemical libraries to identify second-generation small-molecule inhibitors of capsule biogenesis. These inhibitors will lead to a better understanding of capsule biogenesis and may represent a new class of therapeutics.

Bacteriophages as anti-infective agents: recent developments and regulatory challenges.

The biennial meeting on 'Exploiting Bacteriophages for Bioscience, Biotechnology and Medicine', held in London, UK, on 20 January 2012, and chaired by George Salmond (University of Cambridge, UK) hosted over 50 participants representing 13 countries. The highly multidisciplinary meeting covered a diverse range of topics, reflecting the current expansion of interest in this field, including the use of bacteriophages as the source of biochemical reagents for molecular biology, bacteriophages for the treatment of human and animal diseases, bacteriophage-based diagnostics and therapeutic delivery technologies and necessity for, and regulatory challenges associated with, robust clinical trials of phage-based therapeutics. This report focuses on a number of presentations from the meeting relating to cutting-edge research on bacteriophages as anti-infective agents.

IQ-motif peptides as novel anti-microbial agents

The IQ-motif is an amphipathic, often positively charged, a-helical, calmodulin binding sequence found in a number of eukaryote signalling, transport and cytoskeletal proteins. They share common biophysical characteristics with established, cationic a-helical antimicrobial peptides, such as the human cathelicidin LL-37. Therefore, we tested eight peptides encoding the sequences of IQ-motifs derived from the human cytoskeletal scaffolding proteins IQGAP2 and IQGAP3. Some of these peptides were able to inhibit the growth of Escherichia coli and Staphylococcus aureus with minimal inhibitory concentrations (MIC) comparable to LL-37. In addition some IQ-motifs had activity against the fungus Candida albicans. This antimicrobial activity is combined with low haemolytic activity (comparable to, or lower than, that of LL-37). Those IQ-motifs with anti-microbial activity tended to be able to bind to lipopolysaccharide. Some of these were also able to permeabilise the cell membranes of both Gram positive and Gram negative bacteria. These results demonstrate that IQ-motifs are viable lead sequences for the identification and optimisation of novel anti-microbial peptides. Thus, further investigation of the anti-microbial properties of this diverse group of sequences is merited.

Essential oils as anti-nematode agents and their influence on in vitro nematode

Tese de doutoramento, Biologia (Biotecnologia), Universidade de Lisboa, Faculdade de Ciências, 2015

Synthesis and cytotoxicity studies of new dimethylamino-functionalised and aryl-substituted titanocene anti-cancer agents

From the carbolithiation of 6-N,N-dimethylamino fulvene (3a) and different lithiated aryl species [p-N,N-dimethylanilinyl lithium, p-anisyl lithium and 4-lithio-benzo[1.3]dioxole (2a-c)], the corresponding lithium cyclopentadienide intermediates 4a-c were formed. These three lithiated intermediates underwent a transmetallation reaction with TiCl4 resulting in dimethylamino-functionalised and aryl-substituted titanocenes 5a-c. When these titanocenes were tested against LLC-PK cells, the IC50 values obtained were of 54, 45 and 26 mu M for titanocenes 5a, b and c, respectively. The most cytotoxic titanocene in this paper, 5c is approximately 10 times less cytotoxic than cis-platin, which showed an IC50 value of 3.3 mu M, when tested on the LLC-PK cell line, but approximately 100 times better than titanocene dichloride. (C) 2007 Elsevier Masson SAS. All rights reserved.

Natural chromens and chromene derivatives as potential anti-trypanosomal agents

The aim of the study was to investigate the anti-trypanocidal activities of natural chromene and chromene derivatives. Five chromenes were isolated from Piper gaudichaudianum and P. aduncum, and a further seven derivatives were prepared using standard reduction, methylation and acetylation procedures. These compounds were assayed in vitro against epimastigote forms of Trypanosoma cruzi, the causative agent of Chagas disease. The results showed that the most of the compounds, especially those possessing electron-donating groups as substituents on the aromatic ring, showed potent trypanocidal activity. The most active compound, [(2S)-methyl-2-methyl-8-(3 ``-methylbut-2 ``-enyl)-2-(4`-methylpent-3`-enyl)-2H-chromene-6-carboxylate], was almost four times more potent than benznidazole (the positive control) and showed an IC50 of 2.82 mu M. The results reveal that chromenes exhibit significant anti-trypanocidal activities and indicate that this class of natural product should be considered further in the development of new and more potent drugs for use in the treatment of Chagas disease.

Piperamides and their derivatives as potential anti-trypanosomal agents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Natural chromenes and chromene derivatives as potential anti-trypanosomal agents

The aim of the study was to investigate the anti-trypanocidal activities of natural chromene and chromene derivatives. Five chromenes were isolated from Piper gaudichaudianum and P. aduncum, and a further seven derivatives were prepared using standard reduction, methylation and acetylation procedures. These compounds were assayed in vitro against epimastigote forms of Trypanosoma cruzi, the causative agent of Chagas disease. The results showed that the most of the compounds, especially those possessing electron-donating groups as substituents on the aromatic ring, showed potent trypanocidal activity. The most active compound, [(2S)-methyl-2-methyl-8-(3″-methylbut-2″-enyl)-2- (4′-methylpent-3′-enyl)-2H-chromene-6-carboxylate], was almost four times more potent than benznidazole (the positive control) and showed an IC 50 of 2.82 μM. The results reveal that chromenes exhibit significant anti-trypanocidal activities and indicate that this class of natural product should be considered further in the development of new and more potent drugs for use in the treatment of Chagas disease. © 2008 Pharmaceutical Society of Japan.

Hydroxyquinoline derived vanadium(IV and V) and copper(II) complexes as potential anti-tuberculosis and anti-tumor agents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)