Synthesis and in vitro antifungal activity of 4-substituted phenylguanidinium salts

Guanidine-Containing Antifungal Agents against Human-Relevant Fungal Pathogens (2004-2022)-A Review

The guanidine moiety is typically a highly basic group, and can be found in a wide variety of drugs, such as zanamivir (Relenza) and metformin (Fortamet), as well as in biologically active compounds for numerous disease areas, including central nervous system (CNS) diseases and chemotherapeutics. This review will focus on antifungal agents which contain at least one guanidine group, for the treatment of human-related fungal pathogens, described in the literature between 2004 and 2022. These compounds include small molecules, steroids, polymers, metal complexes, sesquiterpenes, natural products, and polypeptides. It shall be made clear that a diverse range of guanidine-containing derivatives have been published in the literature and have antifungal activity, including efficacy in in vivo experiments.

Biological activities of guanidine compounds

BACKGROUND

The guanidine group defines chemical and physicochemical properties of many compounds of medical interest and guanidine-containing derivatives constitute a very important class of therapeutic agents suitable for the treatment of a wide spectrum of diseases.

OBJECTIVE

To review the most important pharmacological properties, mechanisms of action and therapeutic uses of simple guanidine derivatives, cyclic analogues of guanidines as well as peptides, peptidomimetics and peptoids incorporating arginine.

METHODS

The review presents both the recent patent literature and original papers dealing with guanidine derivatives that show interesting biological activity and emphasizes the newest developing drugs.

CONCLUSION

Recent achievements in the synthesis of guanidine-containing molecules with diverse chemical, biochemical and pharmacological properties make them of great importance to the design and development of novel drugs acting at CNS, anti-inflammatory agents, inhibitors of Na(+)/H(+) exchanger, inhibitors of NO synthase, antithrombotic, antidiabetic and chemotherapeutic agents as well as guanidinium-based transporters and vectors.

Guanidine and 2-Aminoimidazoline Aromatic Derivatives as α2-Adrenoceptor Antagonists, 1: Toward New Antidepressants with Heteroatomic Linkers

The efficient preparation and pharmacological characterization of different families of (bis)guanidine and (bis)2-aminoimidazoline derivatives ("twin" and "half" molecules) as potential alpha(2)-adrenoceptor antagonists for the treatment of depression is presented. The affinity toward the alpha(2)-adrenoceptor of all the compounds prepared was measured in vitro in human brain tissue. Additionally, the activity as agonist or antagonist of those compounds with a pK(i) larger than 7 was determined in functional [(35)S]GTPgammaS binding assays in human brain tissue. Finally, the activity of the most promising compounds was confirmed by means of in vivo microdialysis experiments in rats. Compounds 1, 2b, 3b, 12b, 13b, 17b, 18b, 22b, 25b, 26b, 28b, and 30 showed a good affinity toward the alpha(2)-ARs. In general, the 2-aminoimidazoline derivatives displayed higher affinities than their guanidine analogues. Finally and most importantly, compounds 18b and 26b showed antagonistic properties over alpha(2)-ARs not only in vitro [(35)S]GTPgammaS binding but also in vivo microdialysis experiments. Moreover, both compounds have shown to be able to cross the blood-brain barrier and, therefore, they can be considered as potential antidepressants.

Effect of subinhibitory concentration of some established and experimental antifungal compounds on the germ tube formation in Candida albicans

The influence of subinhibitory concentrations of six established and 19 newly synthesized antifungal compounds on the dimorphic transition of three C. albicans strains was evaluated in the filamentation-inducing medium. Amphotericin B was found to produce almost complete inhibition in the germination at a concentration of 1/10 of the corresponding MIC and partial inhibition at a concentration as low as MIC/50. Flucytosine and four azole derivatives were proven ineffective. From the newly synthesized drugs, the incrustoporin derivative LNO6-22, two phenylguanidine derivatives (PG15, PG45), and four thiosalicylanilide derivatives, in particular, showed results comparable to those of amphotericin B, with a high inhibition of germ tube formation at concentrations of MIC/10. In general, concentrations of MIC/50 had no visible effect.

Synthesis and antifungal activity of alkyland arylsulfanylpyridinylguanidines

A series of alkyl- and arylsulfanylpyridylguanidines was synthesized and their antimicrobial activity was evaluated in vitro against eight potentially pathogenic strains of fungi. Compounds with an alkylsulfanyl substitution have antifungal activity, which improves with increasing length of the aliphatic chain.