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Diterpenoids of Isodon and Teucrium Plants

1976; Elsevier BV; Volume: 5; Issue: 1 Linguagem: Inglês

10.3987/s-1976-01-0793

1881-0942

Eiichi Fujita, Yoshimitsu Nagao, Manabu Node,

Plant-derived Lignans Synthesis and Bioactivity

The Chemistry on diterpenoids of the plants belonging to the genera Isodon and Teucriwn (Labiatae) has recently been developed.This review deals mainly with our research works concerning isolation and characterization of new diterpenoids, their reaction and interconversion, synthesis, biosynthesis, and biological activity. IntroductionThe genera Isodon and Teucriwn belong to Labiatae.Since 1963, Fujita and co-workers have investigated the diterpenoids of Isodon trichocarpus Kudo and I. japonicus Hara.First, a chemical conversion o f the major bitter diterpenoid enmein (1) into ent-kaurane (2) was carried out to provide a chemical evidence for the structure and absolute configuration of enmein ( I ) .' Then, many kinds of diterpenoids have been isolated and their structures elucidated.From I .japonicus were isolated the pure enmein, which was not contaminated by dihydroenmein, and enmein 3-acetate (3).2 From I. trichocarpus was isolated trichokaurin ( 4 ) . 3 t This paper is dedicated to Dr. Ken'ichi Takeda on the occasion of the 70th anniversary of his birth.Isodocarpin (5),' nodosin (6),lay5 isodotricin (7),4a,6* oridonin ( 8 ) , " y 7 and trichodonin ( 9 ) ' ' 'were isolated from both species, and their structures were elucidated.In relation to these investigations, a formal chemical conversion3d of trichokaurin (4) into ant-16-kaurene (lo), atisine (ll), garryine (I?), and veatchine (1 3), the chemical conversion1' of enmein (1) into ent-abietane ( 14), and the total synthesis1' of abietane (15) were accomplished.An interesting epimerisation of enmein derivatives (16) and ( 17) to ( 18) and ( 19), respectively, was studied under mild a1 kaline conditions.") The determination of the stereochemistry of C-16 is described in section 2-1-2 Research works in other qroups Kubota e t aZ.determined the structures of isodonal (20) ,' a ' 9 epinodosin (21): b.9C and trichodonin (9)9b'9C isolated from I .japonimrs.After this work, they investigated seven species of the Isodon genus.From I. shikokianus Kudo, they isolated oridonin (8) and two novel diterpenoids, shikokianin (33)" and shikodianidin (3412' and determined their structures on the basis of chemical and spectroscopic evidence.From I. Zongitubus Kudo were isolated the known nodosin (61, isodocarpin ( 5 ) , lasiokaurin (28), and oridonin (8).From I. m e b a Okuyama were isolated two new diterpenoids, kamebanin and m e b a d ~n i n .~~ The structure of mebadonin was