Zur Entstehung primärer Amidglykoside aus cyanogenen Glykosiden

Sendker J

Zusammenfassung

Prunasin and prunasinamide were isolated from air-dried leaves of Olinia ventosa. The amide was not detectable in fresh leaves or when the leaves were heat-treated before drying. It was shown that the generation of prunasinamid started when the leaves lost about 65% of their initial water content during drying. Prunasinamid could also be detected in the leaves of Holocalyx balansae, Pteridium aquilinium and Prununs laurocerasus for the first time. Experiments with different chlorotic leaves of Olinia ventosa and Prunus laurocerasus showed that prunasinamid was also detectable in the chlorotic parts without prior drying. Furthermore, prunasinamid was detected in leaves of Olinia ventosa after treatment with aminotriazole and paraquat which both provoke an increased production of reactive oxygen species in the leaves. Leaves of Olinia ventosa and Prunus laurocerasus that had become chlorotic due to senescence each contained an individual benzoic acid ester in 60fold to 100fold greater concentration than the respective green leaves: in case of Olinia ventosa the formerly unknown benzoic acid ester myo-Inositol-1-benzoate was found, Glukose-1-benzoate in case of Prunus laurocerasus. Quantitative examinations on leaves of Olinia ventosa and Prunus laurocerasus showed that prunasin was completely converted to prunasinamid or the respective benzoic acid esters in the course of drying or senescence. In contrast to prunasinamide, the benzoic acid esters were detectable also in fresh, green leaves and hence appear to be physiological metabolites. Because prunasinamide was only detectable after the leaves had produced increased amounts of reactive oxygen species, it was postulated that its generation was caused by the reaction of prunasin with hydrogen peroxide as described for the Radziszewski-reaction. It could be shown that prunasin can be converted in-vitro to prunasinamide quickly and completely at pH 6.8 and ambient temperature. Further degradation products were neither detectable as reaction products of the in-vitro conversion nor in dried leaves.