A case of mistaken identity: Lupeol-3-(3′R)-hydroxy-stearate can be mistakenly identified as lupeol acetate when only analyzed by GC–MS

Isotopologue Profiling of Triterpene Formation under Physiological Conditions. Biosynthesis of Lupeol-3-(3′-R-hydroxy)-stearate in Pentalinon andrieuxii

“…The 1 H and 13 C NMR signals of procrim b ( 1 ) were unequivocally assigned by COSY, HSQC, and HMBC spectroscopy (Table ) . The 13 C-coupled satellites in the 1 H NMR spectrum of 1 displayed a 13 C-abundance of approximately 1.5%, in full agreement with the GC–MS analysis described above.…”

“…Procrim b (1) was then isolated from the stems of labeled P. andrieuxii in a yield of approximately 0.5 mg per g of dry weight (total amount of purified 1, 20 mg). The GC−MS analysis of lupeol acetate, which was formed from pyrolysis of 1 as a consequence of the high injector temperature, 32 revealed a low but significant 13 C-excess of about 0.4%. This 13 C-enrichment is well in line with the expectation for downstream metabolites obtained from pulse-chase experiments with short pulse periods of 13 CO 2 (i.e., 5 h), since the newly formed labeled material is harvested together with that having a natural abundance that had already been present at the start of the pulse-chase experiment.…”

“…More recently, procrim b [lupeol-3-(3′ R -hydroxy)-stearate, 1 ] was isolated from the stems of Pentalinon andrieuxii Muell-Arg (syn. : Urechites andrieuxii ; Apocynaceae), a plant used in Yucatecan traditional medicine for the treatment of leishmaniasis (“chiclero’s ulcer”), − which is known to produce cardenolides, pyrrolizidine alkaloids, trinorsesquiterpenoids, triterpenoids, pregnane sterols, glycosides, and coumarins. − …”

“…31 More recently, procrim b [lupeol-3-(3′R-hydroxy)-stearate, 1] was isolated from the stems of Pentalinon andrieuxii Muell-Arg (syn. : Urechites andrieuxii; Apocynaceae), 32 a plant used in Yucatecan traditional medicine for the treatment of leishmaniasis ("chiclero's ulcer"), 33−35 which is known to produce cardenolides, pyrrolizidine alkaloids, trinorsesquiterpenoids, triterpenoids, pregnane sterols, glycosides, and coumarins. 36−39 Whereas the biosynthetic steps in the formation of triterpenes are well-known on the basis of pioneering studies by Ruzicka, Eschenmoser, Arigoni, and their co-workers, the origin of the basic building units IPP and DMAPP in triterpenes is still unknown.…”

Natural Products from the Yucatecan Flora: Structural Diversity and Biological Activity

“…However, both the 1 H and 13 C NMR spectra of the pure metabolite showed a number of signals that could not be accounted for in the proposed structure. A careful analysis of the fragmentation pattern of the isolated metabolite allowed the identification of the correct structure as lupeol-3-(3′ R -hydroxy)­stearate ( 85 ), also known as procrim b . The initial identification of 85 as lupeol acetate ( 84 ) can be explained by the fact that thermolysis of β-hydroxy-esters occurs readily under GC-MS analysis conditions.…”