Showdomycin

Showdomycin is a nucleoside antibiotic derived from Streptomyces showdoensis. It is known for its antitumor and antimicrobial properties.^[1] Showdomycin was first isolated in the 1960s and has since been studied for its potential applications in cancer research and microbiology.^[2][3]

Showdomycin

Names
IUPAC name (1S)-1,4-Anhydro-1-(2,5-dioxo-2,5-dihydro-1H-pyrrol-3-yl)-D-ribitol
Other names 2-β-D-Ribofuranosylmaleimide 3-β-D-Ribofuranosyl-1H-pyrrole-2,5-dione
Identifiers
CAS Number	16755-07-0
3D model (JSmol)	Interactive image
ChEBI	CHEBI:226519
ChEMBL	ChEMBL5207810
ChemSpider	26074
MeSH	Showdomycin
PubChem CID	28032
UNII	E1V8315QHY
CompTox Dashboard (EPA)	DTXSID001043162
InChI InChI=1S/C9H11NO6/c11-2-4-6(13)7(14)8(16-4)3-1-5(12)10-9(3)15/h1,4,6-8,11,13-14H,2H2,(H,10,12,15)/t4-,6-,7-,8+/m1/s1 Key: FFLUMYXAPXARJP-JBBNEOJLSA-N
SMILES C1=C(C(=O)NC1=O)[C@H]2[C@@H]([C@@H]([C@H](O2)CO)O)O
Properties
Chemical formula	C9H11NO6
Molar mass	229.188 g·mol−1
Melting point	153–154 °C (307–309 °F; 426–427 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Discovery and History

Showdomycin was first discovered in 1964 by Japanese researchers during a screening of Streptomyces species for novel antibiotics. It was isolated from Streptomyces showdoensis, a soil bacterium, and its structure was elucidated shortly thereafter. The compound gained attention for its unusual structure, which includes a maleimide ring fused to a ribose sugar, distinguishing it from other nucleoside antibiotics.^[4]

Chemical Structure

Showdomycin is a C-nucleoside, meaning the sugar is directly bonded to a carbon atom of the maleimide ring rather than a nitrogen atom, as seen in typical nucleosides. Its chemical formula is C₉H₁₁NO₆, and its systematic name is 1-β-D-ribofuranosyl-1H-pyrrole-2,5-dione. The maleimide moiety is responsible for its reactivity, particularly its ability to act as a Michael acceptor in biochemical reactions.^[1][5] It displays a high similarity with uridine and pseudouridine.^[6][7]

Mechanism of Action

Showdomycin exhibits its biological activity through several mechanisms:

• Antitumor Activity: Showdomycin and its derivatives act as uridine mimics, thereby delaying RNA extension and hence RNA synthysis. This makes it effective against rapidly dividing cancer cells.^[1][8]
• Antimicrobial Activity: It inhibits the growth of various fungi and bacteria, especially Streptococcus hemolyticus^[3] and Streptococcus pyogenes^[9] by disrupting essential metabolic pathways.^[10]
• Inhibition of Enzymes: It is a sulfhydryl reactive agent and acts as an inhibitor of certain enzymes, particularly those with thiol groups, by forming covalent bonds with cysteine residues.^[6]

Applications

Showdomycin is a compound commonly used in biochemical research to investigate enzyme mechanisms and protein interactions.^[6] It works by selectively modifying thiol groups, making it a valuable tool for studying protein structure and function.^[1] Although it has not been developed into a commercial drug, researchers have explored its potential therapeutic uses. Preclinical studies have shown that showdomycin possesses both antitumor and antimicrobial properties.^[2] It has demonstrated effectiveness against certain antibiotic-resistant pathogens,^[3][7] making it a potential candidate for future drug development. However its use in therapeutic applications is limited by its lack of selectivity, which can lead to adverse effects on healthy cells.