| Title:  Showdomycin CAS Registry Number:  16755-07-0 CAS Name:  3-b-D-Ribofuranosyl-1H-pyrrole-2,5-dione Additional Names:  2-b-D-ribofuranosylmaleimide Molecular Formula:  C9H11NO6 Molecular Weight:  229.19 Percent Composition:  C 47.16%, H 4.84%, N 6.11%, O 41.89% Literature References:  Nucleoside antibiotic isolated from Streptomyces showdoensis:  Nishimura et al., J. Antibiot. 17A, 148 (1964); Nishimura, FR M2751 corresp to US 3316149 (1964, 1967, both to Shionogi).  Structure:  Nakagawa et al., Tetrahedron Lett. 1967, 4105; Darnall et al., Proc. Natl. Acad. Sci. USA 57, 548 (1967).  Synthesis:  Kalvoda et al., Tetrahedron Lett. 1970, 2297; Trummlitz, Moffatt, J. Org. Chem. 38, 1841 (1973); T. Sato et al., Tetrahedron Lett. 1978, 1829; J. G. Buchanan et al., J. Chem. Soc. Perkin Trans. 1 1979, 225; T. Inoue, I. Kuwajima, Chem. Commun. 1980, 251; A. P. Kozikowski, A. Ames, J. Am. Chem. Soc. 103, 3923 (1981); Y. Araki et al., Tetrahedron Lett. 29, 351 (1988).  Exhibits antitumor activity:  Shinzo et al., J. Antibiot. 17A, 234 (1964).  Review:  D. W. Visser, S. Roy-Burman in Antibiotics vol. 5(pt. 2), F. E. Hahn, Ed. (Springer-Verlag, New York, 1979) pp 363-371. Properties:  Leaflets from acetone + benzene, mp 153-154°.  [a]D22.5 +49.9° (H2O).  uv max:  220-221 nm (E1%1cm 422).  Sol in water, alcohol, acetone, dioxane; insol in ethyl ether, benzene, petr ether.  More stable in acid media than in neutral or alkaline.  LD50 in mice (mg/kg):  25 i.p.; 18 s.c.; 110 i.v. (Nishimura). Melting point:  mp 153-154° Optical Rotation:  [a]D22.5 +49.9° (H2O) Absorption maximum:  uv max:  220-221 nm (E1%1cm 422) Toxicity data:  LD50 in mice (mg/kg):  25 i.p.; 18 s.c.; 110 i.v. (Nishimura)  |