11 伊豆半島産群体ホヤRitterella tokiokaの強力な細胞毒性を有する新規ステロイドアルカロイドRitterazine類の構造と活性(口頭発表の部)

概要

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Three new cytotoxic dimeric steroidal alkaloids, ritterazines A (1), B (2), and C (3) have been isolated fom the tunicate, Ritterella tokioka (family, Polyclinidae) collected off the Izu Peninsula. Ritterazines A, B, and C exhibited cytotoxicity against P388 murine leukemia cells with IC_<50>, values of 3.8, 0.018, 9.6ng/mL, respectively. Their structures have been elucidated by detailed spectroscopic analyses. Ritterazine A had a molecular fomula of C_<54>H_<76>N_2O_<10> as established by HR-FABMS. Partial structures derived from the COSY spectrum were connected by interpretation of HMBC data, which led to two polyoxygenerated steroid skeletons, one with a rearranged skeleton. The presence of a pyrazine ring which linked the two units was deduced from UV, NMR, and HR-FABMS data. Ritterazine B had a molecular formula of C_<54>H_<78>N_2O_9 as determined by HR-FABMS. A gross structure similar to ritterazine A was deduced by interpretation of NMR data. Relative stereochemistry of each steroid nucleus was determined by NOESY data and coupling constants. Ritterazine C was an isomer of ritterazine B. In fact, ritterazine C was readily derived from ritterazine B by acid-catalized isomerization. The structure of ritterazine C including absolute stereochemistry was determined by spectral and chemical methods.
天然有機化合物討論会の論文
1994-09-20