Acanthothamine, a sesquiterpenoid alkaloid from Acanthothamnus aphyllus

Nitrogen-Containing Dihydro-β-agarofuran Derivatives from Tripterygium wilfordii

“…Tripterygiumines A–L ( 1 – 12 ) contain the same 2-(3-carboxybutan-2-yl)nicotinic acid moiety; the relative configuration of this moiety was determined from the NOESY data, J -based configuration analysis, and analysis of the biosynthetic pathway. Owing to the limited amounts of these new alkaloids, we performed only chemical degradation of alkaloid 4 (Supporting Information), using a reported procedure . The 2-(3-carboxybutan-2-yl)nicotinic acid moiety of 4 was defined as (1′ S ,2′ S )-evoninic acid.…”

Antitumor Agents, 112. Emarginatine B, a Novel Potent Cytotoxic Sesquiterpene Pyridine Alkaloid from Maytenus emarginata

“…Also worth noting is that two acetate carbonyl carbons at the C-6 and C-9 positions were ascertained by their correlations with the H-6 and H-9 protons, respectively, and the methyl proton signals of these two substituents were, therefore, indirectly located. The chemical shift values established for methyl protons, H-12 and H-14, are different from literature values (6)(7)(8) for similar analogues, which need to be revised.…”

“…This would not only suggest their nearness in space, but and that the macrocyclic diester bridge assumes a conformation in solution similar to that in solid state established by X-ray study (3). It is worth noting in this regard that the chemical shift of the 4-OH proton always appears near 4.5 among analogues of euonymine-type alkaloids (4)(5)(6)(7). Finally, the enhancement of the H-6'" signal by irradiation of protons -1, H-2, and H-14 serves to confirm the C-2a substitution of the pyridone ring.…”

“…All carbon and proton signals on the ß-agarofuran skeleton, evoninate diester bridge, and pyridone substituents showed close correspondence with those of emarginatine A [1], except that an acetate signal was missing and replaced by a set of signals corresponding to a benzoate group. These include the aromatic carbon signals of C-1"" ( 129.37), C-2"", -6"" ( 128.44), C-3"", -5 "" ( 129.28), C-4"" ( 133.34), and benzoyl carbonyl ( 164.55), and the proton signals at 7.70 (d), 7.52 (t), and 7.38 (t), constituting an A2M2X spin system. This is also supported by the eims fragment ion at mlz 105, representing a benzoate group, and, in addition, a base peak ion at mlz 136 from the N-methylpyridone group, and the ion at mlz 206, reflecting the evoninate diester bridge.…”

The dihydro-β-agarofuran sesquiterpenoids

“…63 Acanthothamine, the first example of an iso-evoninic acid residue and also a 8iso-euonyminol macrolide sesquiterpene alkaloid, was isolated from Acanthothamnus aphyllus. 64 This work constitutes the first report on the chemistry of the genus Acanthothamnus. In 1987, efficient isolation of crude extracts of khat using recycling high-performance gel permeation chromatography afforded three cathedulins that possess significant insect antifeedant properties.…”