Bioactive Seco-Lanostane-Type Triterpenoids from the Roots of Leplaea mayombensis.

J Nat Prod. 2017 Oct 27;80(10):2644-2651. doi: 10.1021/acs.jnatprod.7b00210. Epub 2017 Sep 25. Sidjui LS1,2, Eyong KO2,3, Hull KG3, Folefoc GN2, Leddet VM4, Herbette G5, Ollivier E4, Taube J6, Klausmeyer K3, Romo D3. Author information 1 Institute of Medical Research and Medicinal Plant Studies , P.O. Box 6163, Yaoundé, Cameroon. 2 Department of Organic Chemistry, Faculty of Science, University of Yaounde I , P.O. Box 812, Yaoundé, Cameroon. 3 Department of Chemistry and Biochemistry & The CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University , Waco, Texas 76798, United States. 4 Laboratory of Pharmacognosy and Ethnopharmacology, UMR-MD3, Faculty of Pharmacy, Aix Marseille University , 27 Boulevard Jean Moulin, CS 30064, 13385 Marseille, Cedex 5, France. 5 Spectropole, FR1739, Aix-Marseille University , Campus de St Jérôme-service 511, 13397 Marseille, Cedex 20, France. 6 Department of Biology, Institute for Biomedical Sciences, Baylor University , Waco, Texas 76798, United States. Abstract Fractionation of the ethyl acetate-soluble extract of the roots of Leplaea mayombensis afforded two new 3,4-seco-lanostane-type triterpenoids, leplaeric acids A and B (1, 2), the new lanostane-type triterpenoid leplaeric acid C (3), and six known natural products (5-10). Derivatization of the main constituent, 1, afforded the dimethyl ester 4, the monoamide 11, and diamide 12 for SAR studies. The structures of these compounds were established through spectroscopic methods, and a single-crystal X-ray diffraction analysis was used to confirm the relative configuration of compound 1. These lanostane derivatives are unique since they are the first C-21-oxygenated lanostanes isolated from plant sources. Preliminary biological assays against the MDA MB 231 breast cancer cell line showed that compounds 1, 2, 4, and 11 have modest cytotoxic activity. Compound 2 was the most active, with an IC50 of 55 ± 7 μM. From these results, the amides (11, 12) derived from triterpenoid 1 were found to be less active than the derived esters (2, 4). PMID: 28945373 DOI: 10.1021/acs.jnatprod.7b00210