1492 ISSN 0326-2383 KEY WORDS: Antifungal activity, Candida, Criptococcus neoformans, Gewald reaction, Minimal Fungicidal Concentration, Thiophene derivatives. * Author to whom correspondence should be addressed. E-mail: franciscojbmendonca@yahoo.com.br Latin American Journal of Pharmacy (formerly Acta Farmacéutica Bonaerense) Lat. Am. J. Pharm. 30 (8): 1492-9 (2011) Regular Article Received: March 15, 2010 Revised version: June 9, 2011 Accepted: June 10, 2011 Synthesis and Evaluation of the Antifungal Activity of 2-(Substituted-Amino)-4,5-Dialkyl-Thiophene-3-Carbonitrile Derivatives Francisco J. B. MENDONÇA JUNIOR 1 *, Reginaldo G. LIMA-NETO 2 , Tiago B. de OLIVEIRA 3 , Maria do C.A. de LIMA 3 , Ivan R. PITTA 3 , Suely L. GALDINO 3 , Rayssa M.D. da CRUZ 1 , Rodrigo S.A. de ARAÚJO 1 & Rejane P. NEVES 2 1 Laboratório de Síntese e Vetorização de Moléculas, Universidade Estadual da Paraíba, CCBSA, R. Horácio Trajano, s/n, Cristo Redentor, João Pessoa/PB 58.070-450, Brazil. 2 Laboratório de Micologia Médica, Departamento de Micologia, Universidade Federal de Pernambuco, Recife 50670-910, Brazil. 3 Laboratório de Síntese e Planejamento de Fármacos, Departamento de Antibióticos, Universidade Federal de Pernambuco, Recife 50670-910, Recife-PE, Brazil. SUMMARY. Fifteen 2-[(substituted-benzylidene)-amino]-5-methyl-thiophene-3-carbonitrile (3a-g) and 2-[(sub- stituted-benzylidene)-amino]-4,5-cycloalkyl-thiophene-3-carbonitrile derivatives (4a-h) were synthesized and screened for their in vitro antifungal activity against 42 clinical isolates of Candida (representing 4 different species) and 2 isolates of Criptococcus. The antifungal activities of these compounds were compared to flucona- zole and amphotericin B as standard agents. All compounds presented fungicidal activity at different doses, but a few compounds showed moderate or poor antifungal activity when compared with the standard drugs. The Cryp- tococcus strains were more sensitive than those of the genus Candida, and compound 4d was the most active, with MFC values varying between 100-800 μg/mL. A preliminary SAR study demonstrated that the presence of a cycloalkyl ring linked to the thiophene moiety is essential for antifungal activity, and that the best antifungal candidates are cyclohexyl compounds (4d-f). The results suggest that thiophene derivatives may be interesting compounds for the further development of antifungal drugs. INTRODUCTION The incidence of invasive fungal infections caused by opportunistic pathogens has in- creased progressively over the last three decades, and such infections are often charac- terized by high mortality rates. Patients who be- come immunocompromised because of underly- ing diseases such as leukemia, tuberculosis or acquired immunodeficiency syndrome (AIDS) and patients who have undergone chemothera- py or organ transplantation are particularly sus- ceptible to opportunistic fungal infections 1-5 . Al- most all of the major classes of antifungal drugs with clinical application, the fungi have devel- oped resistance 6 . Fungal resistance to the avail- able antimycotics such as amphotericin B, flucy- tosine, polyenes, azoles (fluconazole, micona- zole and voriconazole) and echinocandins (caspofungin) has become a major worldwide health problem 7-9 . A matter of concern in the treatment of fun- gal infections is the limited number of effica- cious antimycotics drugs. Many of the currently available drugs are toxic, and have other draw- backs regarding their spectrum, tissue distribu- tion, central nervous system penetration, and high cost 10-13 . In addition, these drugs often produce recurrence because they are fungistatic and not fungicides. Resistance can be developed due to prolonged periods of administration, and the widespread use of antimicrobial agents for prophylaxis and treatment 14,15 . Therefore, there is a clear need for the dis- covery of new structures with antifungal proper-