Postmortale bildung von 5,7-dihydroxychromon-7-rutinosid in Mentha longifolia

5,7-Dihydroxychromone 7-rutinoside isolated from Mentha longifolia must be considered to be a product of postmortem processes. It is only formed after heating fresh plant material and its production is connected with the degradation of flavonoids, and particularly of eriodictyol 7-rutinoside. Investigations with four other Mentha species confirm these results. Eriodictyol 7-rutinoside and eriodictyol are degraded up to 50%, by horseradish peroxidase but 5,7-dihydroxychromone-7-rutinoside cannot be detected.