Recebido em 29/6/05; aceito em 23/9/05; publicado na web em 31/3/06 RECENT ACHIEVEMENTS TO COMBAT BACTERIAL RESISTANCE. This article provides an overview on the recent achievements to combat Gram-positive bacteria and the mechanisms related to antimicrobial activity and bacterial resistance. Selected synthetic methodologies to access structurally diverse bioactive compounds are presented in order to emphasize the most important substances currently developed to overcome multiresistant strains. The main properties of vancomycin and related glycopeptide antibiotics are also discussed as a background to understanding the design of new chemotherapeutic agents.

Este trabalho descreve a preparação de ésteres e amidas derivados do ácido caurenóico e a avaliação da atividade antifúngica frente a cepas padronizadas de fungos patogênicos. Ésteres alquílicos e benzílicos foram obtidos com bons rendimentos, sob condições brandas, a partir da esterificação do ácido caurenóico com haletos de alquila em KOH-acetona. Todos os compostos sintetizados foram submetidos aos testes de inibição contra leveduras, hifomicetos e dermatófitos, mas somente o ácido caurenóico e os derivados contendo um grupo carboxilato livre apresentaram atividade moderada frente a dermatófitos.Representative esters derived from kaurenoic acid were prepared in order to evaluate their antifungal properties. Alkyl and substituted benzyl esters were obtained in good yield under mild conditions by esterification of kaurenoic acid with the corresponding alkyl halide in KOH-acetone. All synthesized compounds were tested for antifungal properties against pathogenic yeasts, hialohyphomycetes and dermatophytes. Kaurenoic acid and derivatives containing a free carboxyl group were moderately active against dermatophytes.

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A highly regio- and stereoselective synthesis of novel β,γ-disubstituted γ-lactams with either an anti or syn relative configuration was developed from readily available epoxide and aziridine acetates. The key steps include the regio- and diastereocontrolled nucleophilic ring-opening of these three-membered heterocycles followed by mild reductive cyclization of the γ-azido ester intermediate. The method was also extended to an asymmetric synthesis of (4R,5S)-4-hydroxy-5-phenylpyrrolidin-2-one from a chiral epoxide acetate. The main features of this versatile synthesis of functionalized γ-lactams include the involvement of inexpensive reagents and mild conditions together with high chemical efficiency.

Fusarium is an emerging opportunistic fungal pathogen that causes local or systemic infections. The successful use of a therapeutic drug or combination antifungal therapies against Fusarium spp. are compromised because reports of multidrug resistance are currently frequent. Thus, the development of new antifungal capable of combating multidrug‐resistant Fusarium strains becomes necessary. This study presents the synthesis of seven new allylic selenocyanates and their screening against Fusarium spp. Minimum inhibitory concentrations (MICs) of these compounds ranged from 4 to 64 μg mL−1, with the mechanism of action being related to fungal cell membrane disruption. Specific structural changes, such as widespread thinning along the hyphae, were observed by scanning electron microscopy. The effect of selenocyanates on cell viability and genotoxicity are concentration dependent, however they did not cause mutagenicity in human cells. Five selenocyanates were identified as nonirritant by the ex‐vivo HET‐CAM (Hen′s Egg Test‐Chorioallantoic Membrane) method. Allylic selenocyanates represents a promising alternative in the treatment and prevention of fusariosis.