Akrobomycin, a new anthracycline 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.

Structure elucidation and in silico docking studies of a novel furopyrimidine antibiotics synthesized by endolithic bacterium Actinomadura sp. AL2

On screening of endolithic actinobacteria from a granite rock sample of Meghalaya for antibacterial compound, a novel antibacterial compound CCp1 was isolated from the fermentation broth of Actinomadura sp. AL2. On purification of the compound based on chromatographic techniques followed by characterization with FT-IR, UV-visible, ¹H NMR, ¹³C NMR and mass spectrometry, the molecular formula of the compound was generated as C₂₀H₁₇N₃O₂, a furopyrimidine derivative. In vitro antibacterial activity of the compound was evaluated against both Gram positive and negative bacteria by agar well diffusion assay. The compound had lowest MIC (2.00 µg/ml) for Bacillus subtilis and highest MIC (> 64 µg/ml) for Staphylococcus epidermidis and Pseudomonas aeruginosa. The study revealed that the compound has potential antibacterial activity. The mode of action of the antibacterial compound was evaluated through in silico studies for its ability to bind DNA gyrase, 30S RNA molecules, OmpF porins and N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU). The antibacterial compound demonstrated more favorable docking with DNA gyrase, 30S RNA molecules and OmpF porins than GlmU which support the antibacterial compound CCp1 can be as a promising broad spectrum antibiotic agent with "multitarget" characteristics.

In vivo and in vitro bioconversion of epsilon-rhodomycinone glycoside to doxorubicin: functions of DauP, DauK, and DoxA

We recently determined the function of the gene product of Streptomyces sp. strain C5 doxA, a cytochrome P-450-like protein, to be daunorubicin C-14 hydroxylase (M. L. Dickens and W. R. Strohl, J. Bacteriol. 178: 3389-3395, 1996). In the present study, we show that DoxA also catalyzes the hydroxylation of 13-deoxycarminomycin and 13-deoxydaunorubicin to 13-dihydrocarminomycin and 13-dihydrodaunorubicin, respectively, as well as oxidizing the 13-dihydro-anthracyclines to their respective 13-keto forms. The Streptomyces sp. strain C5 dauP gene product also was shown unequivocally to remove the carbomethoxy group of the epsilon-rhodomycinone-glycoside (rhodomycin D) to form 10-carboxy-13-deoxycarminomycin. Additionally, Streptomyces sp. strain C5 DauK was found to methylate the anthracyclines rhodomycin D, 10-carboxy-13-deoxycarminomycin, and 13-deoxy-carminomycin, at the 4-hydroxyl position, indicating a broader substrate specificity than was previously known. The products of Streptomyces sp. strain C5 doxA, dauK, and dauP were sufficient and necessary to confer on Streptomyces lividans TK24 the ability to convert rhodomycin D, the first glycoside in daunorubicin and doxorubicin biosynthesis, to doxorubicin.

Anthracycline and anthraquinone anticancer agents: current status and recent developments

The clinical treatment of neoplastic diseases relies on the complementary procedures of surgery, radiation treatment, immunotherapy and chemotherapy. The latter technique has matured from its earliest applications of mustard alkylating agents in the 1940s to an increasingly rationally based discipline, which is contributing significantly to the management of human malignancies. As the field of chemotherapy matured, several promising natural anticancer agents were identified. However, a more urgent need soon arose from the common experience of clinically limiting toxicities of most anticancer drugs, i.e. the necessity to develop less toxic clinical drug candidates. Thus, the medicinal chemist turned towards analog development involving certain anthraquinones. Hand-in-hand with this considerable synthetic effort, which uncovered several promising clinical leads, biochemical pharmacology, or study of the mechanisms of action of clinical anticancer agents, afforded deeper insight into drug metabolism and mode of action. More recently, therefore, the field of synthetic organic chemistry, which has been complemented by the methods of microbial chemistry, has been faced with new synthetic challenges, occasioned by the identification of hitherto unrecognized cellular targets for anticancer drugs, such as topoisomerases and helicases. The armementarium of the oncologist currently includes about 40-50 clinically useful chemical agents. The paradigm of cytotoxic anticancer agents is doxorubicin, an anthracycline, which is still amongst the most widely prescribed and effective of anticancer agents. The review attempts to summarize the discovery of anthracyclines and the elucidation of their several mechanisms of action and efforts towards improvement of their therapeutic efficacy.

Advances in bioconversion of anthracycline antibiotics

During the last decade new anthracycline-type structures with potential usefulness in cancer treatment have been supplied both by new microbial strains and by bioconversions of precursor molecules employing cells or enzymes. We highlight recent advances in bioconversion of anthracycline structures with the main focus on late transformations such as are carried out by oxidoreductases.

Anthracycline antitumour agents. A review of physicochemical, analytical and stability properties

A review of physicochemical and analytical properties of anthracycline antitumour agents is presented. The following subjects are discussed: protolytic equilibria, partition and partition coefficients, self-association, adsorptive properties, metal complexation, spectroscopy and chromatography. Furthermore, the stability of anthracyclines in solutions, in pharmaceutical preparations and in biological media is discussed.