Resumo

GUERRERO-RODRIGUEZ, Eugenio et al. In vitro biological activity of extracts of Flourensia cernua D.C. on postharvest pathogens: Alternaria alternata (Fr.:Fr.) Keissl., Colletotrichum gloeosporioides (Penz.) Penz. y Sacc. y Penicillium digitatum (Pers.:Fr.) Sacc.. Rev. mex. fitopatol [online]. 2007, vol.25, n.1, pp.48-53. ISSN 2007-8080.

The effect of fresh leaf extracts from Flourensia cernua was evaluated for mycelial inhibition and sporulation of the pathogens Alternaria alternata, Colletotrichum gloeosporioides, and Penicillium digitatum. Extracts were obtained with methanol:chloroform (1:1), and by sequential extractions with hexane, diethyl ether, and ethanol. The concentrations evaluated were 500, 1000, 2000, and 4000 mg/ L in potato-dextrose-agar culture medium. Analysis of infrared spectrum was performed with an spectroscope using the Fourier transformation infrared technique (FTIR). The highest resin yield (19.1%) was obtained with methanol:chloroform. The highest mycelial inhibition of A. alternata ocurred with hexane fractions (91.9%) and methanol:chloroform (88.4%) at 4000 mg/L, whereas C. gloesporioides and Penicillium digitatum were inhibited 93.4% and 94%, respectively, from 500 mg/L of the ethanol fraction. All extracts showed fungistatic effect. A. alternata did not produce conidia when treated with the ethanol extract at 4000 mg/L and methanol:chloroform at 2000 and 4000 mg/L. The ethanol extract from 2000 mg/L caused the lowest conidia production by C. gloesporioides. The four extracts reduced conidia production by P. digitatum, although they were not statistical different. In general, the ethanolic extract was the most efficient to inhibit mycelial growth and conidia production of C. gloesporioides and P. digitatum. FTIR spectra of extracts showed that the fractions have the same functional groups but at different ratio.

Palavras-chave : Tarbush; plant extracts; antifungal; antisporulation.

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