Enrico Davini

The quantitative isolation and antimicrobial activity of the aglycone of aucubin

Abstract Despite the reported instability of iridoid aglycones, a new procedure was developed for the quantitative extraction of aucubigenin from an enzymatic hydrolysate of aucubin. The aglycone was obtained in crystalline form and was for the first time spectroscopically characterized ( 1 H and 13 C NMR spectra). Its antimicrobial activity against yeasts, bacteria and moulds was also accurately tested.

Cynanchoside, a highly oxygenated iridoid glucoside from Macfadyena cynanchoides

Abstract The elucidation of the structure and stereochemistry of cynanchoside, a new highly oxygenated iridoid glucoside isolated from Macfadyena cynanchoides (Bignoniaceae), has been accomplished using mainly 1 H and 13 C NMR spectral data and further confirmed by simple chemical transformations.

Structure and configuration of unedide, an iridoid glucoside from Arbutus unedo

Abstract Unedide, a novel iridoid glucoside isolated from Arbutus unedo (Ericaceae), has been established to be 6,7-dihydro-6β-hydroxymonotropein by detailed analysis of 1 H and 13 C NMR spectral data.

Iridoid glucosides as sources of cyclopentanoid 1,5-dialdehydes: Conversion of aucubigenin to aucommial and eucommiol

Abstract Aucubigenin, which exists only in the closed hemiacetal form, has been transformed into a stable conjugated 1,5-dialdehyde form, ‘eucommialrs, by a base-catalysed Δ7 → Δ8 double-bond shift. Further reduction of eucommial leads to eucommiol, which co-occurs with aucubin in the autumn in Eucommia ulmoides and Aucuba japonica. The successful transformation of aucubin to eucommiol seems to support an in vivo relationship between these compounds.

Organomercury chemistry of iridoid glucosides. Part 2. Chemoselective methoxymercuriation-demercuriation of aucubin: a new approach to optically active cyclopentenols

Methoxymercuriation of aucubin (1) occurred chemoselectively at the enol ether Δ3 double bond with formation, after the demercuriation of the organomercurial intermediate (6), of the chiral cyclopentenoid O-methyl ethers (5), (12), and (13). The mechanism proposed for the demercuriation of (6) was supported by selective formation of the three products on adjusting the pH of the reduction medium. The structural features of (5), (12), and (13) make them useful precursors for syntheses of bioactive cyclopentanoid compounds.