2-Guanidino-quinazolines as a novel class of translation inhibitors.

A variety of structurally unrelated organic compounds has been reported to have antibacterial activity. Among these, certain small-molecule translation inhibitors have attracted a great deal of attention, due to their relatively high selectivity against prokaryotes, and an appropriate therapeutic index with minor "off target" effects. However, ribosomes are being considered as poorly druggable biological targets, thereby making some routine computational-based approaches to rational drug design and its development rather ineffective. Taking this into account, diversity-oriented biological screening can reasonably be considered as the most advantageous strategy. Thus, using a high-throughput screening (HTS) platform, we applied a unique biological assay for in vitro evaluation of thousands of organic molecules, especially targeted against bacterial ribosomes and translation. As a result, we have identified a series of structurally diverse small-molecule compounds that induce a reporter strain sensitive to translation and DNA biosynthesis inhibitors. In a cell free system, several molecules were found to strongly inhibit protein biosynthesis. Among them, compounds bearing a 2-guanidino-quinazoline core demonstrated the most promising antibacterial activity. With regard to the preliminary structure-activity relationship (SAR) study, we revealed that relatively small substituents at positions 4, 6 and 8 of the quinazoline ring significantly enhance the target activity whereas modification of the guanidine group leads to decrease or loss of antibacterial potency. This novel class of translation inhibitors can properly be regarded as a promising starting point for the development of novel antibacterial therapeutic or screening tools.

[Application of reporter strains for new antibiotic screening].

Screening for new antibiotics remains an important area of biology and medical science. Indispensable for this type of research is early identification of antibiotic mechanism of action. Preferentially, it should be studied quickly and cost-effectively, on the stage of primary screening. In this review we describe an application of reporter strains for rapid classification of antibiotics by its target, without prior purification of an active compound and determination of chemical structure.

[Common features of antibacterial compounds: an analysis of 104 compounds library].

Antibacterial compounds are one of the essential classes of clinically important drugs. High throughput screening allowed revealing potential antibiotics active towards any molecular target in bacterial cell. We used a library of 9820 organic compounds with highly diversified structures to screen for antibacterial activity. As the result of automated screening, 103 compounds were found to possess antibacterial activity against Escherichia coli. The properties of these compounds were compared with those of initial library. Non-linear Kohonen mapping was used to analyze the differences between non-active molecules from initial library, identified antibacterial hits and compounds with reported antibacterial activity. It was found that identified antibacterial compounds are located in the separated area of chemical space. It can be therefore suggested that these molecules belong to novel classes of antibacterial compounds and could be studied further.