CP-54,883 a novel chlorine-containing polyether antibiotic produced by a new species of Actinomadura: taxonomy of the producing culture, fermentation, physico-chemical and biological properties of the antibiotic

Chemistry and biology of specialized metabolites produced by Actinomadura

Covering: up to the end of 2022In recent years rare Actinobacteria have become increasingly recognised as a rich source of novel bioactive metabolites. Actinomadura are Gram-positive bacteria that occupy a wide range of ecological niches. This review highlights about 230 secondary metabolites produced by Actinomadura spp., reported until the end of 2022, including their bioactivities and selected biosynthetic pathways. Notably, the bioactive compounds produced by Actinomadura spp. demonstrate a wide range of activities, including antimicrobial, antitumor and anticoccidial effects, highlighting their potential in various fields.

Natural Polyether Ionophores and Their Pharmacological Profile

This review is devoted to the study of the biological activity of polyether ionophores produced by bacteria, unicellular marine algae, red seaweeds, marine sponges, and coelenterates. Biological activities have been studied experimentally in various laboratories, as well as data obtained using QSAR (Quantitative Structure-Activity Relationships) algorithms. According to the data obtained, it was shown that polyether toxins exhibit strong antibacterial, antimicrobial, antifungal, antitumor, and other activities. Along with this, it was found that natural polyether ionophores exhibit such properties as antiparasitic, antiprotozoal, cytostatic, anti-mycoplasmal, and antieczema activities. In addition, polyethers have been found to be potential regulators of lipid metabolism or inhibitors of DNA synthesis. Further study of the mechanisms of action and the search for new polyether ionophores and their derivatives may provide more effective therapeutic natural polyether ionophores for the treatment of cancer and other diseases. For some polyether ionophores, 3D graphs are presented, which demonstrate the predicted and calculated activities. The data presented in this review will be of interest to pharmacologists, chemists, practical medicine, and the pharmaceutical industry.

Structures and properties of naturally occurring polyether antibiotics

Polyether ionophores represent a large group of natural, biologically active substances produced by Streptomyces spp. They are lipid soluble and able to transport metal cations across cell membranes. Several of polyether ionophores are widely used as growth promoters in veterinary. Polyether antibiotics show a broad spectrum of bioactivity ranging from antibacterial, antifungal, antiparasitic, antiviral, and tumour cell cytotoxicity. Recently, it has been shown that some of these compounds are able to selectively kill cancer stem cells and multidrug-resistant cancer cells. Thus, they are recognized as new potential anticancer drugs. The biological activity of polyether ionophores is strictly connected with their molecular structure; therefore, the purpose of this paper is to present an overview of their formula, molecular structure, and properties.

Polyether ionophores: broad-spectrum and promising biologically active molecules for the control of drug-resistant bacteria and parasites

BACKGROUND

As multidrug-resistant (MDR) pathogens continue to emerge, there is a substantial amount of pressure to identify new drug candidates. Carboxyl polyethers, also referred to as polyether antibiotics, are a unique class of compounds with outstanding potency against a variety of critical infectious disease targets including protozoa, bacteria and viruses. The characteristics of these molecules that are of key interest are their selectivity and high potency against several MDR etiological agents.

OBJECTIVE

Although many studies have been published about carboxyl polyether antibiotics, there are no recent reviews of this class of drugs. The purpose of this review is to provide the reader with an overview of the spectrum of activity of polyether antibiotics, their mechanism of action, toxicity and potential as drug candidates to combat drug-resistant infectious diseases.

CONCLUSION

Polyether ionophores show a high degree of promise for the potential control of drug-resistant bacterial and parasitic infections. Despite the long history of use of this class of drugs, very limited medicinal chemistry and drug optimization studies have been reported, thus leaving the door open to these opportunities in the future. Scifinder and PubMed were the main search engines used to locate articles relevant to the topic presented in the present review. Keywords used in our search were specific names of each of the 88 compounds presented in the review as well as more general terms such as polyethers, ionophores, carboxylic polyethers and polyether antibiotics.

Biosynthesis of halogenated metabolites by bacteria

Halogenated metabolites, originally thought to be infrequent in nature, are actually nothing unusual at all, and are produced by many different organisms, including bacteria. Whereas marine bacteria usually produce brominated compounds, terrestrial bacteria preferentially synthesize chlorometabolites, but fluoro- and iodometabolites can also be found. Haloperoxidases, enzymes capable of catalyzing the formation of carbon halogen bonds in the presence of hydrogen peroxide and halide ions (Cl-, Br- and I-) have been isolated and characterized from different bacteria. These enzymes turned out to be very unspecific and are obviously not the type of halogenating enzymes responsible for the formation of halometabolites in bacteria. A yet-unknown type of halogenating enzyme having both substrate and regio-specificity must be involved in the biosynthesis of halogenated compounds.

Detection of novel secondary metabolites

The study of antibiotics and other fermentation products has shown that a seemingly unlimited number of compounds with diverse structures are produced by microorganisms. The continued high rate of discovery of new chemical entities, in the light of the abundance of microbial products already described, is due to creative screening procedures that incorporate such features as the emphasis on unusual microorgnaisms, their special propagation and fermentation requirements, supersensitive and highly selective assays, genetic engineering both for the biosynthesis of new compounds and in the development of screening systems, early in vivo evaluation, improved isolation techniques, modern procedures for structure determination, computer-assisted identification, and an efficient multidisciplinary approach. This review focuses on the genesis and development of the gamut of methodologies that have led to the successful detection of the wide variety of novel secondary metabolites that include antibacterial, antigungal, antiviral and antitumour antibiotics, enzyme inhibitors, pharmacologically and immunologically active agents, products useful in agriculture and animal husbandry, microbial regulators, and other compounds for which no bioactive role has yet been found.