Helianthus Trachylobanes

Varieties of sunflower (Helianthus annums, Asteraceae) that are resistant to attack by larvae of the sunflower moth (Homeosoma electellum) contain high concentrations of trachyloban-19-oic acid and (-)-16-kauren-19-oic acid in their florets (84,132). 

Ferguson, G., McCrindle, R., Murphy, S. T., and Parvez, M. 1982. Further diterpenoid constituents of Helianthus annuus I. Crystal and molecular-structure of methyl-er7M5-beta-hydroxy-trachyloban-19-oate. J. Chem. Res.-S.t 8, 200-201... 

Four structural types of diterpenes are known from Helianthus labdanes, kauranes, atisiranes and trachylobanes (Figure 2), with the tetracyclic kaurane type being the most widespread in the genus. The majority of Helianthus diterpenes have an Ol-oriented carboxylic acid function attached to carbon 4. 

Trachylobanes.—Trachyloban-19-oic acid (92), together with ( —)-kaur-16-en-19-oic acid, has been isolated from Helianthus annuus. The structure was confirmed by the use of n.m.r. shift reagents. 

The Trachylobane Series.-—Ciliaric acid has been isolated from Helianthus ciliaris and shown to be 7a-hydroxytrachyloban-19-oic acid. 

Herz, W., and P. Kulanthaivel Ent-kmvencs and trachylobanes from Helianthus radula. Phytochem. 22, 2543 (1983). 

Mitscher, L.A., G.S.R. Rao, T. Veysoglu, S. Drake, and T. Haas Isolation and identification of trachyloban-19-oic and (-)-kaur-16-en-19-oic acids as antimicrobial agents from the prairie sunflower, Helianthus annuus, J. Nat. Prod. 46, 745 (1983). 

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