Lantibiotics are a class of polycyclic peptide antibiotics that contain the characteristic thioether amino acids lanthionine or methyllanthionine, as well as the unsaturated amino acids dehydroalanine, and 2-aminoisobutyric acid. They belong to ribosomally synthesized and post-translationally modified peptides.
Novobiocin, also known as albamycin or cathomycin, is an aminocoumarin antibiotic that is produced by the actinomycete Streptomyces niveus, which has recently been identified as a subjective synonym for S. spheroides a member of the class Actinomycetia. Other aminocoumarin antibiotics include clorobiocin and coumermycin A1. Novobiocin was first reported in the mid-1950s.
Geldanamycin is a 1,4-benzoquinone ansamycin antitumor antibiotic that inhibits the function of Hsp90 by binding to the unusual ADP/ATP-binding pocket of the protein. HSP90 client proteins play important roles in the regulation of the cell cycle, cell growth, cell survival, apoptosis, angiogenesis and oncogenesis.
Cycloserine, sold under the brand name Seromycin, is a GABA transaminase inhibitor and an antibiotic, used to treat tuberculosis. Specifically it is used, along with other antituberculosis medications, for active drug resistant tuberculosis. It is given by mouth.
Platensimycin, a metabolite of Streptomyces platensis, is an antibiotic, which act by blocking enzymes.
The calicheamicins are a class of enediyne antitumor antibiotics derived from the bacterium Micromonospora echinospora, with calicheamicin γ1 being the most notable. It was isolated originally in the mid-1980s from the chalky soil, or "caliche pits", located in Kerrville, Texas. The sample was collected by a scientist working for Lederle Labs. It is extremely toxic to all cells and, in 2000, a CD33 antigen-targeted immunoconjugate N-acetyl dimethyl hydrazide calicheamicin was developed and marketed as targeted therapy against the non-solid tumor cancer acute myeloid leukemia (AML). A second calicheamicin-linked monoclonal antibody, inotuzumab ozogamicin an anti-CD22-directed antibody-drug conjugate, was approved by the U.S. Food and Drug Administration on August 17, 2017, for use in the treatment of adults with relapsed or refractory B-cell precursor acute lymphoblastic leukemia. Calicheamicin γ1 and the related enediyne esperamicin are the two of the most potent antitumor agents known.
Azaserine is a naturally occurring serine derivative diazo compound with antineoplastic and antibiotic properties deriving from its action as a purinergic antagonist and structural similarity to glutamine. Azaserine acts by competitively inhibiting glutamine amidotransferase, a key enzyme responsible for glutamine metabolism.
Thienamycin is one of the most potent naturally produced antibiotics known thus far, discovered in Streptomyces cattleya in 1976. Thienamycin has excellent activity against both Gram-positive and Gram-negative bacteria and is resistant to bacterial β-lactamase enzymes. Thienamycin is a zwitterion at pH 7.
Isopenicillin N synthase (IPNS) is a non-heme iron protein belonging to the 2-oxoglutarate (2OG)-dependent dioxygenases oxidoreductase family. This enzyme catalyzes the formation of isopenicillin N from δ-(L-α-aminoadipoyl)-L-cysteinyl-D-valine (LLD-ACV).
Indolocarbazoles (ICZs) are a class of compounds that are under current study due to their potential as anti-cancer drugs and the prospective number of derivatives and uses found from the basic backbone alone. First isolated in 1977, a wide range of structures and derivatives have been found or developed throughout the world. Due to the extensive number of structures available, this review will focus on the more important groups here while covering their occurrence, biological activity, biosynthesis, and laboratory synthesis.
Enediynes are organic compounds containing two triple bonds and one double bond.
Sparsomycin is a compound, initially discovered as a metabolite of the bacterium Streptomyces sparsogenes, which binds to the 50S ribosomal subunit and inhibits protein synthesis through peptidyl transferase inhibition. As it binds to the 50S ribosomal subunit, it induces translocation on the 30S subunit. It is a nucleotide analogue. It was also formerly thought to be a possible anti-tumor agent, but interest in this drug was later discarded after it was discovered that it resulted in retinopathy and as a tool to study protein synthesis; it is not specific for bacterial ribosomes and so not usable as an antibiotic.
Pristinamycin IIA is a macrolide antibiotic. It is a member of the streptogramin A group of antibiotics and one component of pristinamycin. Pristinamycin IIA was first isolated from the Streptomyces virginiae, but has been isolated from other microorganisms and thus has been given a variety of other names such as Virginiamycin M1, Mikamycin A, and Streptogramin A. Pristinamycin IIA structure was determined by chemical and instrumental techniques, including X-ray crystallography. Pristinamycin IIA is of interest from a biosynthetic viewpoint because it contains the unusual dehydroproline and oxazole ring systems. The only experimental evidence bearing on the formation of the oxazole ring is found in work on the biosynthesis of the alkaloid annuloline.
6-Diazo-5-oxo-L-norleucine (DON) is a glutamine antagonist, which was isolated originally from Streptomyces in a sample of Peruvian soil. This diazo compound is biosynthesized from lysine by three enzymes in bacteria. It is one of the most famous non-proteinogenic amino acid and was characterized in 1956 by Henry W Dion et al., who suggested a possible use in cancer therapy. This antitumoral efficacy was confirmed in different animal models. DON was tested as chemotherapeutic agent in different clinical studies, but was never approved. In 2019, DON was shown to kill tumor cells while reversing disease symptoms and improve overall survival in late-stage experimental glioblastoma in mice, when combined with calorie-restricted ketogenic diet.
Dynemicin A is an anti-cancer enediyne drug. It displays properties which illustrate promise for cancer treatments, but still requires further research.
Callystatin A is a polyketide natural product from the leptomycin family of secondary metabolites. It was first isolated in 1997 from the marine sponge Callyspongia truncata which was collected from the Goto Islands in the Nagasaki Prefecture of Japan by the Kobayashi group. Since then its absolute configuration has been elucidated and callystatin A was discovered to have anti-fungal and anti-tumor activities with extreme potency against the human epidermoid carcinoma KB cells (IG50 = 10 pg/ml) and the mouse lymphocytic leukemia Ll210 cells (IG50 = 20 pg/ml).
(6S)-6-Fluoroshikimic acid is an antibacterial agent acting on the aromatic biosynthetic pathway. It may be used against Plasmodium falciparum, the causative agent of malaria. The molecule is targeting the enzymes of the shikimate pathway. This metabolic pathway is not present in mammals. The mechanism of action of the molecule is not through the inhibition of chorismate synthase but by the inhibition of 4-aminobenzoic acid synthesis.
Stephacidin A and B are antitumor alkaloids isolated from the fungus Aspergillus ochraceus that belong to a class of naturally occurring 2,5-diketopiperazines. This unusual family of fungal metabolites are complex bridged 2,5-diketopiperazine alkaloids that possess a unique bicyclo[2.2.2]diazaoctane core ring system and are constituted mainly from tryptophan, proline, and substituted proline derivatives where the olefinic unit of the isoprene moiety has been formally oxidatively cyclized across the α-carbon atoms of a 2,5-diketopiperazine ring. The molecular architecture of stephacidin B, formally a dimer of avrainvillamide, reveals a complex dimeric prenylated N-hydroxyindole alkaloid that contains 15 rings and 9 stereogenic centers and is one of the most complex indole alkaloids isolated from fungi. Stephacidin B rapidly converts into the electrophilic monomer avrainvillamide in cell culture, and there is evidence that the monomer avrainvillamide interacts with intracellular thiol-containing proteins, most likely by covalent modification.
The arylomycins are a class of antibiotics initially isolated from a soil sample obtained in Cape Coast, Ghana. In this initial isolation, two families of closely related arylomycins, A and B, were identified. The family of glycosylated arylomycin C lipopeptides were subsequently isolated from a Streptomyces culture in a screen for inhibitors of bacterial signal peptidase. The initially isolated arylomycins have a limited spectrum of activity against Gram-positive bacteria, including Staphylococcus aureus and Streptococcus pneumoniae. The only activity against Gram-negative bacteria was seen in strains with a compromised outer membrane.
Aureothin is a natural product of a cytotoxic shikimate-polyketide antibiotic with the molecular formula C22H23NO6. Aureothin is produced by the bacterium Streptomyces thioluteus that illustrates antitumor, antifungal, and insecticidal activities and the new aureothin derivatives can be antifungal and antiproliferative. In addition, aureothin, a nitro compound from Streptomyces thioluteus, was indicated to have pesticidal activity against the bean weevil by interfering with mitochondrial respiratory complex II.
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