Fig. 4 in Alkaloid and iridoid glucosides from Palicourea luxurians (Rubiaceae: Palicoureeae) indicate tryptamine- and tryptophan-iridoid alkaloid formation apart the strictosidine pathway

Fig. 4. Tautomeric structures of dehydrorudgeifoline (2), including the electron pair movement indicated as red arrows. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)