title: Dovyalicin-type spermidine alkaloids from Dovyalis species.
abstract: Phytochemical investigations of Dovyalis abyssinica, D. hebecarpa, and D. macrocalyx revealed two new spermidine-type alkaloids, dovyalicin E (3) and dovyalicin F (4), along with the previously described dovyalicin A (1), dovyalicin B (2), and dovyalicin C (5). In addition, a new phenol glucoside, 4-hydroxytremulacin (7), and the new 1,2-cyclohexanediol glucoside 9, as well as the known compounds methyl 1-hydroxy-6-oxocyclohex-2-enecarboxylate (6) and tremulacin (8), were isolated. The structures were established using homo- and heteronuclear two-dimensional NMR experiments and chiroptical methods. At ambient temperature, the N-disubstituted amide 4 exists as a mixture of cis and trans conformers. Variable-temperature (1)H NMR studies showed that time-averaged spectra are obtainable at 348 K, and the activation parameters determined for the rotation about the amide bond were DeltaH++ = 89 +/- 4.6 kJ/mol, DeltaS++ = 65 +/- 14 kJ/mol.K, and DeltaG++(298K) = 70 +/- 4.5 kJ/mol.
authors.affiliation: Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Rasmussen
authors.forename: Aimee-Justine
authors.initials: AJ
authors.lastname: Nkurunziza
authors.forename: Matthias
authors.initials: M
authors.lastname: Witt
authors.forename: Hellen A
authors.initials: HA
authors.lastname: Oketch-Rabah
authors.forename: Jerzy W
authors.initials: JW
authors.lastname: Jaroszewski
authors.forename: Dan
authors.initials: D
authors.lastname: Staerk
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification; D007630:Kenya; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D018547:Plant Stems / Q000737:chemistry; D031308:Salicaceae / Q000737:chemistry*; D013095:Spermidine / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000470:Alkaloids; C514319:dovyalicin E; C514320:dovyalicin F; D013095:Spermidine