Isodon shikokianus

Kubota, T, and I. Kubo The Two Bitter Principles of Isodon shikokianus Kudo. Bull. Chem. Soc. Japan 42, 1778 (1969). 

IsoBE, T, T. Kamikawa, I. Kubo, and T. Kubota The Structure of Shikokianidin, a Minor Component of Isodon shikokianus Kara. Bull. Chem. Soc. Japan 46, 583 (1973). Kubo, I., M. J. Pettei, K. Hirotsu, H.Tsuji, andT. Kubota Structure of Shikodonin, a Unique Anti-Tumor Spiro-secokaurene Diterpenoid. J. Am. Chem. Soc. 100, 628 (1978). 

Fujita, T, Y. Takeda, and T. Shingu Bitter Diterpenoids from Isodon shikokianus var. intermedius. Phytochem. 18, 299 (1979). 

The diterpenoids of Isodon (Labiatae) species have been reviewed. The presence of an a-methylenecyclopentanone moiety in these diterpenoids is important for their anti-tumour and anti-bacterial activity. " Inflexin (79) is a cytotoxin and insect antifeedant which has been isolated from Isodon inflexus. Isodomedin (80) is another member of this series, isolated from /. shikokianus, which shows this type of biological activity. Its structure was assigned on the basis of its H and C n.m.r. spectra and on an interrelationship with kamebanin (81), isolated from /. kameba. 

Two new anti-tumour diterpenoids have been isolated from Isodon (Labiatae) species. Kamebanin, which was obtained from I. kameba, was assigned the structure (76) on the basis of a thorough n.m.r. study and a correlation with mebadonin, whose structure had been determined by X-ray analysis. Shikodonin (77) is a unique spiro-secokaurene which was obtained from I. shikokianus. Its structure was assigned by a combination of X-ray and spectroscopic methods. 

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