Dopamine-iridoid alkaloids in Carapichea affinis (= Psychotria borucana) confirm close relationship to the vomiting root Ipecac

Broad-based HPLC-UV comparison of 57 methanolic crude extracts of the Psychotria complex (Rubiaceae), representing about 20 different species collected in Costa Rica, exhibited a clear chemical segregation of Psychotria borucana. In contrast to the more widespread tryptamine-iridoid alkaloids it deviated by an accumulation of dopamine-iridoid alkaloids. Similar to the South American vomiting root Ipecac, Psychotria ipecacuanha (= Cephaelis ipecacuanha), cephaeline and emetine were found together with four related glycosides characterized by various N-acylations. Two glycosides were identified as the known N-acetates ipecoside and 6- O-methylipecoside, whereas the two others represent corresponding N- O-methylcaffeate derivatives from which borucoside was described as a new compound. Structure elucidation of all compounds was carried out by NMR- and MS-analyses supported by CSEARCH-NMR-database system. In addition to morphological characters and analyses of nucleotide sequence variation the chemical profile of P. borucana supported a recent taxonomic rearrangement where it has been grouped together with P. ipecacuanha in a separate genus Carapichea. [Display omitted] ► HPLC-UV comparison of 57 methanolic crude extracts of 20 different Psychotria species from Costa Rica showed a clear chemical segregation of P. borucana. ► Instead of the more widespread tryptamine-iridoid alkaloids P.borucana deviates by an accumulation of dopamine-iridoid alkaloids. ► Together with morphological characters and DNA sequence data phytochemical results confirm the taxonomic rearrangement of P. borucana in a separate genus Carapichea together with C. ipecacuanha. ► Apart from the known aglyca cephaeline and emetine four related glycosides were isolated and identified from which borucoside was described as a new compound.