Chair of Forest Zoology and Entomology, Albert-Ludwigs-Universität Freiburg i.Br. Chair of Forest Zoology and Entomology
Albert-Ludwigs-Universität Freiburg i.Br.

Chair of Forest Zoology and Entomology
Freiburg i.Br.

PAs in Apocynoideae

Colegate SM, Gardner DR, Betz JM, Fischer OW, Liede-Schumann S, Boppré M (2016) Pro-toxic 1,2-dehydropyrrolizidine alkaloid esters, including unprecedented 10-membered macrocyclic diesters, in the medicinally-used Alafia cf. caudata and Amphineurion marginatum (Apocynaceae: Apocynoideae: Nerieae and Apocyneae). Phytochem Anal 17: 257-276 link

Introduction – Within the Apocynoideae (Apocynaceae) pro-toxic dehydropyrrolizidine alkaloids have been reported only in Echiteae. However, attraction of pyrrolizidine alkaloid-pharmacophagous insects suggested their presence in Alafia cf. caudata Stapf (Nerieae: Alafinae) and Amphineurion marginatum (Roxb.) D.J. Middleton (Apocyneae: Amphineuriinae), both used as medicinal plants.
Objective – To confirm the presence of dehydropyrrolizidine alkaloids in Alafia cf. caudata and Amphineurion marginatum and identify their structures.
Methods – Methanol extracts of air-dried roots, stems and leaves of non-flowering plantswere analysed using HPLC-ESI(+)MS and MS/MS or collision-induced dissociation MS in low and/or high resolution modes. Pyrrolizidine alkaloids were tentatively identified based on the mass spectrometry data. Solid phase extraction combinedwith semi-preparative HPLC were used to isolate major alkaloids. Structures were elucidated using NMR spectroscopy.
Results – Monoesters of retronecine with senecioic, hydroxysenecioic or syringic acids were identified in roots of Alafia cf. caudata. Two, unprecedented 10-membered macrocyclic dehydropyrrolizidine alkaloid diesters were isolated from roots of Amphineurion marginatum. Pyrrolizidine alkaloids were detected in root and leaf material of Alafia cf. caudata at 0.34 and 0.01% dry weight (DW), and 0.13, 0.02 and 0.09% DW in root, leaf and stem material of Amphineurion marginatum.
Conclusions – The presence of pro-toxic dehydropyrrolizidine alkaloids suggests that medical preparations of these plants pose potential health risks to consumers. Dehydropyrrolizidine alkaloids are evidently more widespread in Apocynoideae than previously assumed, and it would seem rewarding to study other members of this family for the presence of pyrrolizidines, dehydropyrrolizidines and dihydropyrrolizines.

Auf dem International Congress of Botany 2005 in Wien wurde folgendes Poster präsentiert.

Boppré M, Kaufmann E, Edgar JA (2006) Lepidopteran associations with and pyrrolizidine alkaloids in Apo­cynoideae (Apocynaceae). Manuscript

Pyrrolizidine alkaloids (1,2-dehydro-pyrrolizidine ester alkaloids; PAs) are reported here to occur in Aganosma marginata, Alafia c.f. caudata, Allotoonia agglutinata, Echites umbellatus, Fernaldia pandurata, Parsonsia buruensis, P. ferruginea, P. straminea, P. velutina and in Prestonia quinquangularis by using pharmacophagous Lepidoptera as bioindicators and by the application of TLC and in some cases verified by LC-MS. PAs thus occur in 7 apocynad genera, currently belonging to 3 tribes, at the very least. Further studies appear to have great potential to provide data of value to current discussions on the taxonomy of Apocynoideae. Using 'PA-insects' as finely tuned bioindicators of PAs and their N-oxides, in combination with targeted phytochemical studies, it is possible to identify relationships within the Apocynoideae and to add new data to morphological and molecular approaches. This will illuminate the phylogenetic relationships of certain apocynads and particular Lepidoptera as well as facilitate our understanding of insect-plant relationships. Protocols for practical application are provided.