Three New Ring-A Modified Ursane Triterpenes from Davidia involucrata

Abstract

Three new ursane triterpenes, 3α,19α-dihydroxy-2-nor-urs-12-en-23,28-dioic acid-23-methyl ester (1), 19α3-dihydroxy-3-oxo-2-nor-urs-12-en-28-oic acid (2), and 2,3-seco-3-methoxy-3,19α3-trihydroxy-urs-12-en-2-al-28-oic acid (3), were isolated from the MeOH extract of the branch barks of Davidia involucrata, together with six known compounds. Their structures were elucidated by means of various spectroscopic analyses. The isolated triterpenes provide important evolutionary and chemotaxonomic knowledge about the monotypic genus Davidia. Five of the identified compounds showed moderate cytotoxicities against the cell proliferation of SGC-7901, MCF-7, and BEL-7404 with IC 50 range from 7.26 to 47.41 μM.

Five New Taraxerene-Type Triterpenes from the Branch Barks of Davidia involucrata

“…One of the six degrees of unsaturation came from a trisubstituted double bond at δC 116.0 and 158.5, and the remaining five degrees of unsaturation were therefore indicative of a pentacyclic skeleton. The characteristics of NMR data of compound 1 were comparable to those of myricadiol (6) [13].…”

“…The novel compounds, namely davinvolunols A-B (1-2) and davinvolunones A-C (3-5), are all taraxerene-type triterpenoids with a D-friedoolean-14-en skeleton. To the best of our knowledge, compounds 1-3, as well as previously reported two ursane triterpenes, davinvolunic acid A and B from the same plant [13], are the first reported 2-nor pentacyclic triterpenoids with 29 carbons and a five-membered A-ring. The results provided important, evolutionary and chemotaxonomic knowledge of monotypic genus Davidia.…”

“…The in vitro cytotoxic activity was determined by the MTT colorimetric method as described previously in our paper [13]. Three tumor cell lines, SGC-7901 cells (human gastric adenocarcinoma), MCF-7 cells (human breast cancer) and BEL-7404 (human hepatocellular carcinoma), provided by Department of Hepatobiliary Surgery, Affiliated Union Hospital, Fujian Medical University, were cultured in RPMI-1640 medium supplemented with 10% fetal bovine serum and 100 IU·mL −1 of penicillin-streptomycin at 37 °C in humidified atmosphere with 5% CO2.…”

“…The branch barks of D. involucrata have been intensively studied in our previous work and were found containing diverse constituents including flavonoids, alkaloids, lignans, and phenols, among which were three alkaloids including vicosamide, strictosidinic acid and puimiloside, which were proposed to be the intermediate precursors between strictosamide and camptothecin [5][6][7][8][9][10][11][12]. Moreover, we have recently reported the identification of two novel 2-nor-ursane triterpenes having a unique five-membered A-ring from the water insoluble fraction of the branch barks of D. involucrata [13].…”

Cytotoxic 24-nor-ursane-type triterpenoids from the twigs of Mostuea hirsuta

“…The above information suggests compound 1 to be an urs-12-ene derivative possessing an α-hydroxyl group at C-19 [11].…”