Inhibition of Cytotoxicity of Shiga toxin of Escherichia coli O157:H7 on Vero cells by Prosopis alba Griseb (Fabaceae) and Ziziphus mistol Griseb (Rhamnaceae) extracts

MARIA GABRIELA PELLARIN, CLAUDIA ALBRECHT, MARÍA JOSÉ ROJAS, JOSÉ JAVIER AGUILAR, BRENDA KONIGHEIM, MARÍA GABRIELA PARAJE, INÉS ALBESA, AND ALBERTO JORGE ERASO.

JOURNAL OF FOOD PROTECTION

INT ASSOC FOOD PROTECTION

Año: 2013 vol. 76 p. 1733 - 1739

0362-028X

The capacity of Prosopis alba Griseb and Ziziphus mistol Griseb fruit extracts to inhibit the toxic action of Shiga toxin (Stx) was investigated. Purification of Stx from Escherichia coli O157:H7 was performed by saline precipitation and affinity chromatography using a column with Gb3, whereas the fruits were subjected to ethanolic or aqueous extractions. The results indicated that the cytotoxic damage exerted by Stx on Vero cells was comparable with the cytotoxicity of cycloheximide. The extraction of the polyphenols and flavonoids was effective, and more polyphenols/mg of dissolved solids in P. alba were obtained than in Z. mistol. However there were more flavonoids in Z. mistol than in P. alba. Components of both fruits increased the viability of cells treated with Stx when the extracts were pre-incubated with Stx for 1 h before being applied to the cell cultures. Extracts were less effective in protecting cells when Stx, extracts and cells were co-incubated together, without a previous incubation of Stx with the extracts. Investigation into this difference in the protection of cells indicated that the protein molecule of Stx suffered degradation to advanced oxidative protein products (AOPP) during pre-incubation with extracts, principally with P. alba, which exhibited a higher amount of non-flavonoids polyphenols than Z. mistol. The pro-oxidant action on Stx favored the cells and enhanced the protective action of both fruits.