Cyanogenic allosides and glucosides from Passiflora edulis and Carica papaya

Leaf and stem material of Passiflora edulis (Passifloraceae) contains the new cyanogenic glycosides (2R)-beta-D-allopyranosyloxy-2-phenylacetonitrile (1a) and (2S)-beta-D-allopyranosyloxy-2-phenylacetonitrile (1b), along with smaller amounts of (2R)-prunasin (2a), sambunigrin (2b), and the alloside of benzyl alcohol (4); the major cyanogens of the fruits are (2R)-prunasin (2a) and (2S)-sambunigrin (2b). The major cyanogenic glycoside of Carica papaya (Caricaceae) is 2a; only small amounts of 2b also are present. We were not able to confirm the presence of a cyclopentenoid cyanogenic glycoside, tetraphyllin B, in Carica papaya leaf and stem materials. In detailed 1H NMR studies of 1a/b and 2a/b, differences in higher order effects in glucosides and allosides proved to be valuable for assignment of structures in this series. The diagnostic chemical shifts of cyanogenic methine and anomeric protons in 1a/b are sensitive to anisotropic environmental effects. The assignment of C-2 stereochemistry of 1a/b was made in analogy to previous assignments in the glucoside series and was supported by GLC analysis of the TMS ethers.     

A galloylated cyanogenic glycoside from the Australian endemic rainforest tree Elaeocarpus sericopetalus (Elaeocarpaceae)

A cyanogenic glycoside - 6'-O-galloylsambunigrin - has been isolated from the foliage of the Australian tropical rainforest tree species Elaeocarpus sericopetalus F. Muell. (Elaeocarpaceae). This is the first formal characterisation of a cyanogenic constituent in the Elaeocarpaceae family, and only the second in the order Malvales. 6'-O-galloylsambunigrin was identified as the principal glycoside, accounting for 91% of total cyanogen in a leaf methanol extract. Preliminary analyses indicated that the remaining cyanogen content may comprise small quantities of sambunigrin, as well as di- and tri-gallates of sambunigrin. E. sericopetalus was found to have foliar concentrations of cyanogenic glycosides among the highest reported for tree leaves, up to 5.2 mg CN g(-1) dry wt.     

Metabolic differentiations of dwarf elder by NMR-based metabolomics

Sambucus plants have prominent place in folk medicine of the people from Europe and the Middle East. Sambucus ebulus (both above and under ground parts) preparations showed anti-neoplastic, antimicrobial (incl. antiviral) and anti-inflammatory properties. Elderberries accumulate sugars and fibers, vitamins and minerals, besides abundant secondary metabolites, as flavonoids, anthocyanins, phytosterols, triterpenes and iridoid glycosides, among others. Sambucus plants, however, also accumulate cyanogenic glycosides, whose presence is undesirable. Despite many applications so far the knowledge of the metabolites, accumulated in Sambucus species, is still limited and based mainly on determination of the major compounds. Here we report the application of ¹H NMR metabolic fingerprinting in combination with principal component and hierarchical clustering analyses to reveal the metabolic differences of Sambucus mature and immature fruits, and plant leaves. Moreover, we show that immature fruits and leaves of S. ebulus have similar metabolome, which apparently undergoes significant changes during the fruit ripening stage. Sambunigrin was not detectable in any sample. To the best of our knowledge this is the first report on the systematic analysis of S. ebulus metabolome.