Biochemistry and Molecular Biology - Belyasova N.A. 2002

Metabolism. Energy-Requiring Processes
Biological Role and Patterns of Antibiotic Biosynthesis
Water-Soluble Vitamins

Antibiotics are defined as specific metabolic products of living organisms, and their chemical modifications, characterized by high physiological activity—either biostatic or biocidal—against specific groups of microorganisms or malignant tumors.

The vast majority of known antibiotics are produced by filamentous Fungi and actinomycetes, although antibiotics of PLANT AND ANIMAL origin have also been discovered. A key distinguishing feature of antibiotics is their high potency against susceptible Cells (Viruses), allowing them to be effective even at very low concentrations, most commonly 1—100 µg/ml. Exposure to an antibiotic can either inhibit the growth of susceptible cells (biostatic activity) or cause their death (biocidal activity). While the most widespread antibiotics target Bacteria, exhibiting bacteriostatic or bactericidal effects, many others are active against fungi, Protozoa, viruses, and Cancer cells.

A characteristic feature that sets antibiotics apart from other antimicrobial agents is their selective toxicity. This means that each antibiotic affects strictly defined organisms without harming others. Furthermore, cells contain specific 'targets' that are disrupted According to the distinct MECHANISM OF ACTION inherent to each antibiotic.

Antibiotics are classified according to various criteria: chemical Structure; type of action (biostatic or biocidal); target Organism groups (antibacterial, antiviral, antitumor, etc.); cellular targets (Cell wall, Plasma Membrane, METABOLISM/36.html">DNA Replication, Transcription, and Translation machinery, Enzymes, etc.); and the type of producing organism (actinomycetes, filamentous fungi, plants, protozoa, etc.).

Based on their chemical structure, antibiotics can be divided into the following groups: Peptides and Amino Acid Derivatives, polyene compounds, carbohydrate-derived substances, aliphatic, polycyclic, and Aromatic Compounds, as well as oxygen- and nitrogen-containing heterocycles. This list alone demonstrates the remarkable diversity of antibiotics in both nature and biological function.

Currently, more than 6,000 different antibiotics are known, and the search for novel forms, along with the chemical modification of existing ones, continues unabated. This is driven, on the one hand, by their wide range of Applications—they are used in human and veterinary medicine, disease Prevention, plant protection, as growth promoters for livestock and poultry, and as preservatives. On the other hand, microorganisms targeted by antibiotics eventually develop resistance through various mechanisms, including the genetic exchange of drug-resistance factors (see below). Finally, antibiotics are widely used as research tools to elucidate the mechanisms of various cellular processes.

Since a comprehensive review of the Structure and properties of all known antibiotics is beyond The Scope of this publication, it is logical to focus on their Mechanisms of action against cellular targets, which will provide a deeper understanding of the interplay between metabolic processes.