Oleuropein and Other Polyphenols from Olive (Olea europea) for Protecting the Plant Against Pseudomonas syringae subsp. savastanoi

Abstract

Among the main polyphenols isolated from waste waters of olive (Olea europea) mill, catechol, 4-methylcatechol and hydroxytyrosol were toxic for Pseudomonas syringae subsp. savastanoi, the causal agent of olive knot disease. In particular the most toxic was 4-methylcatechol. Among some synthetic derivs. of catechol, as o-quinone, guaiachol, veratrole and diacetylcatechol, which were tested on P. savastanoi and on Corynebacterium michiganense (Gram+), o-quinone was strongly toxic for both bacteria, whereas veratrole and diacetylcatechol were toxic only for P. savastanoi. From fruits and leaves of olive a well known phenolic glucoside oleuropein was isolated, from which was prepd. its aglycon, by using a com. $β$-glucosidase and hydroxytyrosol by chem. hydrolysis. The oleuropein was significantly toxic on P. savastanoi at a concn. of 10-3 M, while its aglycon was toxic in the range between 10-2 and 10-4 M and hydroxytyrosol at 10-2 and 10-3 M. It is interesting to note that free glucose was growth stimulant of P. savastanoi at 10-2 M, while it was growth inhibiting at 10-3 and 10-4 M. Among all the compds. cited above, the most interesting bioproducts for a possible application in agriculture are oleuropein, its aglycon and hydroxytyrosol, because of the other polyphenols are toxic on olive and human cells. [on SciFinder(R)]