(−)-6-epi-Artemisinin, a Natural Stereoisomer of (+)-Artemisinin in the Opposite Enantiomeric Series, from the Endemic Madagascar Plant <i>Saldinia proboscidea</i>, an Atypical Source
Saholinirina Randrianarivo,
Claudine Rasolohery,
Sitraka Rafanomezantsoa,
Heriniaina Randriamampionona,
Liti Haramaty,
Roger Marie Rafanomezantsoa,
Eric H. Andrianasolo
Affiliations
Saholinirina Randrianarivo
Ecole Doctorale de Géochimie et Chimie Médicinale (GEOCHIMED), Université de Fianarantsoa, Fianarantsoa 301, Madagascar
Claudine Rasolohery
Ecole Doctorale de Géochimie et Chimie Médicinale (GEOCHIMED), Université de Fianarantsoa, Fianarantsoa 301, Madagascar
Sitraka Rafanomezantsoa
Ecole Doctorale de Géochimie et Chimie Médicinale (GEOCHIMED), Université de Fianarantsoa, Fianarantsoa 301, Madagascar
Heriniaina Randriamampionona
Ecole Doctorale de Géochimie et Chimie Médicinale (GEOCHIMED), Université de Fianarantsoa, Fianarantsoa 301, Madagascar
Liti Haramaty
DMCS, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
Roger Marie Rafanomezantsoa
Ecole Doctorale de Géochimie et Chimie Médicinale (GEOCHIMED), Université de Fianarantsoa, Fianarantsoa 301, Madagascar
Eric H. Andrianasolo
Departement Chimie, Centre National de Recherches Industrielle et Technologique (CNRIT), Antananarivo 101, Madagascar
Chemical and biological investigation of the Madagascar endemic plant Saldinia proboscidea led to the isolation of an isomer of artemisinin, (−)-6-epi-artemisinin (2). Its structure was elucidated using a combination of NMR and mass spectrometry. The absolute configuration was established by chemical syntheses of compound 2 as well as a new stereoisomer (3). The comparable bioactivities of artemisinin (1) and its isomer (−)-6-epi-artemisinin (2) revealed that this change in configuration was not critical to their biological properties. Bioactivity was assessed using an apoptosis induction assay, a SARS-CoV-2 inhibitor assay, and a haematin polymerization inhibitory activity (HPIA) assay. This is the first report of an artemisinin-related compound from a genus not belonging to Artemisia and it is the first isolation of an artemisinin-related natural product that is the opposite enantiomeric series relative to artemisinin from Artemisia annua.
