Recent trends in the design, synthesis and biological exploration of β-lactams

Since the discovery of penicillin, natural and synthetic β-lactams have aroused great interest not only as sources of effective antibacterial agents but also as specific inhibitors of proteases responsible for various non-bacterial pathological processes. This interest was reflected in our review published in Current Medicinal Chemistry in 2003. The present article summarises new data published during the last decade dedicated to the design, synthesis and biological exploration of new β-lactams with anti-inflammatory, antiviral, anticancer and other activities based on the inhibition of human leukocyte elastase, porcine pancreatic elastase, tryptase, chymase, human cytomegalovirus protease, fatty acid amide hydrolase, protein phosphatase methylesterase-1, serine protease responsible for tumor proliferation, cysteine proteases, matrix metalloproteinases, human 20s proteasome, human immunodeficiency virus, cholesterol absorption, human fatty acid synthase, bacterial RNase A and Leishmania D-mannosyl phosphate transferase. Antitumor effect was achieved also by new β-lactams activating apoptosis-specific poly(ADP-ribose) polymerase or participating in DNA intercalation.

The cognition-enhancing activity of E1R, a novel positive allosteric modulator of sigma-1 receptors

BACKGROUND AND PURPOSE

Here, we describe the in vitro and in vivo effects of (4R,5S)-2-(5-methyl-2-oxo-4-phenyl-pyrrolidin-1-yl)-acetamide (E1R), a novel positive allosteric modulator of sigma-1 receptors.

EXPERIMENTAL APPROACH

E1R was tested for sigma receptor binding activity in a [³H](+)-pentazocine assay, in bradykinin (BK)-induced intracellular Ca²⁺ concentration ([Ca²⁺](i)) assays and in an electrically stimulated rat vas deferens model. E1R's effects on cognitive function were tested using passive avoidance (PA) and Y-maze tests in mice. A selective sigma-1 receptor antagonist (NE-100), was used to study the involvement of the sigma-1 receptor in the effects of E1R. The open-field test was used to detect the effects of E1R on locomotion.

KEY RESULTS

Pretreatment with E1R enhanced the selective sigma-1 receptor agonist PRE-084's stimulating effect during a model study employing electrically stimulated rat vasa deferentia and an assay measuring the BK-induced [Ca²⁺](i) increase. Pretreatment with E1R facilitated PA retention in a dose-related manner. Furthermore, E1R alleviated the scopolamine-induced cognitive impairment during the PA and Y-maze tests in mice. The in vivo and in vitro effects of E1R were blocked by treatment with the selective sigma-1 receptor antagonist NE-100. E1R did not affect locomotor activity.

CONCLUSION AND IMPLICATIONS

E1R is a novel 4,5-disubstituted derivative of piracetam that enhances cognition and demonstrates efficacy against scopolamine-induced cholinergic dysfunction in mice. These effects are attributed to its positive modulatory action on the sigma-1 receptor and this activity may be relevant when developing new drugs for treating cognitive symptoms related to neurodegenerative diseases.

Synthesis and antitumor activity of selected 7-alkylidene substituted cephems

Selected 7-alkylidene substituted cephems were synthesized and subjected to antitumor assay. The effect of substituents was examined to establish structure-activity relationships. It was found that the intensive intracellular generation of nitric oxide induced by tert-butyl 7-alkylidene cephalosporanate sulfones could be also regarded as an additional cytotoxic factor taking place both in vitro and in vivo experiments.