Isodon

As with sweetness, an enantiomeric difference in response is observed in the bitter-taste quality. Isodonal (113) and dihydroisodonal (114) are bitter. 

Kratzing J.E. (1978). The olfactory apparatus of the Bandicoot (Isodon macrourus). J Anat 125, 601-613. 

Isodon diterpenes. Highly oxygenated.- -seco-ent-kaurane diterpenoids, the isodons (Figure 7), isolated from species of Isodon (now Rhabdosia)... 

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. 

Dihydroxy-6,7,4 -trimethoxyflavone (8-hydroxysalvigenin) 8-Glucoside Isodon erianderianus leaves Labiatae 144... 

Na, Z. et al., Flavonoids from Isodon enanderianus, Yunnan Zhiwu Yangiu, 24, 121, 2002. 

TriOH-5-OMe C16H14O6 302 Oresbiusin Isodon oresbius Lamiaceae Whole 21... 

Hydroxyflavanone represents the simplest compound of this class and is found in many legumes.9 2-Hydroxyflavanones, which are expected to be quite labile and converted to their corresponding flavones, have also been identified. These include the 2,5,7-trihydroxyflavanone 7-0-glucoside (8) in Malus spp.,80 2,5-dihydroxy-7-methoxyflavanone in Populus nigra, 1 6,7,8-trihydroxy-5-methoxyflavanone (9) in Isodon oresbius,82 and 2,5-dihydroxy-7-methoxyflavanone and its 6-C- and 8-C-methyl isomers (10) in Friesodielsia enghiana.83 All of these exhibit a lack of B-ring hydroxylation. 

HAO, H, HANDONG, S., SHOUXUN, Z., Flavonoids from Isodon oresbius. Phytochemistry, 1996,42,1247-1248. 

The 13C resonances of a series of urs-12-enes have been assigned"7 to facilitate biosynthetic studies on the metabolites of tissue cultures of Isodon japonicus. 

Tissue cultures of Isodon japonicus could biosynthesize oleanane- and ursane-type triterpenoids from [4-13C]MVA with sufficient incorporation of tracer to allow the elucidation of the labelling pattern by 13C n.m.r. spectroscopy.356 The results verify the hypothesis of Ruzicka involving cyclization of 2,3-oxidosqualene in a chair-chair-boat form, followed by specific 1,2-hydride shifts, and the rearrangement of... 

Various studies have also been reported on sesquiterpenoid lactones in Xanthium strumarium and Vemonia species,452,453 diterpenoids of Isodon species,454 and triterpenoids in Lycopodium species.455 Analyses of the carotenoids of Medicago species and of berries from a range of sources reinforce previously held views that the distribution of carotenoids in these sources has no taxonomic significance.456,457 Although most higher plants that have been investigated do not retain the capacity to biosynthesize the normal pattern of terpenoids when in tissue culture, it has been reported that Ruta graveolens did retain this ability.458... 

Inflexin Isodon excisus, I. lungshengensis (Lamiaceae) Antifeedant (AROM)... 

Ursolic acid Isodon excisus, Salvia triloba AROM (31)... 

Ursolic acid 3-O-acetate Isodon excisus (Lamiaceae) AROM (86)... 

Huang, H. Sun, H. Zhao, S. 1996. Flavonoids from Isodon oresbius. Phytochem. 42 1247-1248. 

The partial synthesis from epicandicandiol of some C- and H-labelled kaurene derivatives has been described.These have possible application in the study of the biosynthesis of the Isodon diterpenoids. The syntheses of [17- C]kaur-16-en-20-ol from enmein and of 3-oxygenated derivatives of [17- C]kaur-16-ene from ent-3jS,19-dihydroxy-kaur-16-ene have also been described. The synthesis of radioactive aphidicolin has also been reported. It has been shown ° that ent-kaur-15-ene is formed by the dwarf mutant (ds) of maize in place of ent-kaur-16-ene. 

Some resonances in the ursene series have been reassigned.The labelling pattern in ursolic acid and 2a-hydroxyursolic acid isolated from tissue cultures of Isodon japonicus fed with sodium [l,2- C]acetate conforms with the original Ruzicka hypothesis for the biogenesis of pentacyclic triterpenoids. 

Investigations with tissue cultures of Isodon japonicus using [l,2- C]acetate have been extended to the study of the formation of ring E of ursolic acid. Ruzicka s hypothesis for the cyclization of 2,3-oxidosqualene appears to hold for the ursanes (103) and (104) as indicated in Scheme 17, and routes involving the carbonium ion (105) can be excluded. 

Although a number of Isodon species have been reclassified as Rabdosia (Labiatae) species, their similarity is revealed by the highly hydroxylated kaurenoids which they contain. Effusin, which was isolated from R. effusus and shown to inhibit insect growth, possesses90 the unusual spiro-secokaurene structure (50). A... 

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