Antifungal Activity of a New Phenolic Compound from Capitulum of a Head Rot-resistant Sunflower Genotype
In a previous study, we observed that bract and corolla extracts from a Sclerotinia sclerotiorum-resistant sunflower contained high amounts of the known coumarins scopoletin, scopolin, and ayapin. There was a correlation between coumarin concentration and disease resistance. Thin layer chromatography showed higher concentrations of three other compounds in the resistant genotype when compared to the susceptible. A bioassay-directed purification that used column chromatography and HPLC allowed the isolation of a new compound, 3-acetyl-4-acetoxyacetophenone, and known compounds, demethoxyencecalin and 3-acetyl-4-hydroxyacetophenone. Structures were assigned from spectral data, and bioactivities were characterized by in vitro bioassays against S. sclerotiorum. The new compound, 3-acetyl-4-acetoxyacetophenone, had an antifungal activity similar to the coumarin ayapin, previously described as a potent Sclerotinia inhibitor. The speed and simplicity by which these compounds can be detected make them suitable for use in screening procedures that may identify genotypes with valuable levels of resistance. A screening of seven sunflower genotypes in a field experiment showed a correlation between these compounds and resistance to Sclerotinia.
KeywordsAcetophenones Ayapin Demethoxyencecalin Scopoletin Phenolics Coumarins Sunflower Bracts Sclerotinia sclerotiorum Allelochemicals
This work was supported by the Spanish Ministry of Science and Technology, Project AGL 2001-2420.
- Acimovic, M. 1985. Sunflower disease mapping in Europe and some countries outside Europe in the period 1984–1986. Helia 11:41–49.Google Scholar
- Bate, N. J., Orr, J., Ni, W. T., Meromi, A., Nadlerhassar, T., Doerner, P. W., Dixon, R. A., Lamb, C. J., and Elkind, Y. 1994. Quantitative relationship between phenylalanine ammonia-lyase levels and phenylpropanoid accumulation in transgenic tobacco identifies a rate-determining step in natural product synthesis. Proc. Natl. Acad. Sci. U.S.A. 91:7608–7612.PubMedCrossRefGoogle Scholar
- Becerra, J., Silva, M., Delle Monache, G., and Delle Monache, F. 1983. Two new chromenes from Eupatorium glechonophyllum. Less. Rev. Latinoam. Quim. 14:92–94.Google Scholar
- Macías, F. A., Molinillo, J. M. G., Varela, R. M., Torres, A., and Galindo, J. C. G. 1999. Bioactive Compounds from the Genus Helianthus, pp. 121–148, in: F. A. Macías, Galindo, J. C. G., Molinillo, J. M. G., Cutler, H. G., (ed.). Recent Advances in Allelopathy, vol. I. A Science for the Future. Servicio de Publicaciones de la Universidad de Cádiz, Spain.Google Scholar
- Mullin, C. A., Alfatafta, A. A., Harman, J. L., Serino, A. A., and Everett, S. L. 1991. Corn rootworm feeding on sunflower and other compositae: Influence of floral terpenoid and phenolic factors, pp. 278–292, in: P. A. Hedin, (ed.). Naturally Occurring Pest Bioregulators, ACS Symposium Series No. 449. American Chemical Society, Washington, DC.Google Scholar
- Pereyra, V. R., Bazzalo, M. E., and Sala, C. 1991. Variabilidad y estabilidad entre hibridos comerciales de girasol para la resistencia a la podredumbre del capitulo provocada por el hongo Sclerotinia sclerotiorum (Lib.) de Bary. 1° R. Nac. Oleagin.Google Scholar
- Serghini, K. 2000. Papel defensivo de las 7-hidroxicumarinas simples de girasol (Helianthus annuus) frente a hongos (Plasmopara halstedii) y plantas parasitas (Orobanche cernua). Ph.D. Thesis. University of Cordoba, Spain.Google Scholar
- Srivastava, R. P., and Proksch, P. 1993. Insecticidal and antifeedant effects of compounds of plant origin against insect pests. Indian J. Plant Prot. 21:234–239.Google Scholar
- Tsuda, H., Ishitani, Y., Takemura, Y., Suzuki, Y., and Kato, T. 1997. 6-acetyl-8-hydroxy-2,2-dimethylchromene, an antioxidant in sunflower seeds; Its isolation and synthesis and antioxidant activity of its derivatives. Heterocycles 44:139–142.Google Scholar
- Varga, E., Szendrei, K., Dinya, Z., and Reisch, J. 1984. Aromatic compounds from the stalk of Helianthus annuus. Fitoterapia 55:307–309.Google Scholar
- Waiss, A. C., Chan, B. G., Elliger, C. A., Dreyer, D. L., Binder, R. G., and Gueldner, R. C. 1981. Insect growth inhibitors in crop plants. Ent. Soc. Am. Bull. 27:217–221.Google Scholar