Cadiolide analogues and their precursors as new inhibitors of bacterial quorum sensing and biofilm formation.

Bacterial quorum sensing (QS) and biofilm formation are promising targets for developing new therapies to treat chronic infections. Herein, we report the stereoselective synthesis of 18 new analogs of natural cadiolides. Among the new compounds, substances 8b, 8f, 8i, 9a, 9b and 9e completely inhibited the biofilm formation of Escherichia coli RP347 in vitro. In addition, compound 8b interfered acyl-homoserine lactone (AHL) mediated QS, while 9e interrupted the QS via autoinducer-2 (AI-2). Biological assays also revealed that synthetic intermediates alkynones are potent inhibitors of AI-2 and AHL-mediated QS. These results indicate that cadiolides and alkynones are good candidates for further structural modification for a new generation of more potent antimicrobial agents.

Tetroxanes as New Agents against Leishmania amazonensis.

Leishmaniasis is a neglected disease, caused by a parasite of Leishmania genus and widespread in the tropical and subtropical areas of the world. Currents drugs are limited due to their toxicity and parasite resistance. Therefore, the discovery of new treatment, more effective and less toxic, is urgent. In this study, we report the synthesis of six gem-dihydroperoxides (2a-2f), with yields ranging from 10 % to 90 %, utilizing a new methodology. The dihydroperoxides were converted into ten tetroxanes (3a-3j), among which six (3b, 3c, 3d, 3g, 3h and 3j) showed activity against intracellular amastigotes of Leishmania amazonensis. The cytotoxicity of all compounds was also evaluated against canine macrophages (DH82), human hepatoma (HepG2) and monkey renal cells (BGM). Most compounds were more active and less toxic than potassium antimonyl tartrate trihydrate, used as positive control. Amongst all tetroxanes, 3b (IC50 =0.64 µm) was the most active, being more selective than positive control in relation to DH82, HepG2 and BGM cells. In summary, the results revealed a hit compound for the development of new drugs to treat leishmaniasis.