Cytotoxic and non-cytotoxic cardiac glycosides isolated from the combined flowers, leaves, and twigs of Streblus asper.
Bioorg Med Chem
; 28(4): 115301, 2020 02 15.
Article
in En
| MEDLINE
| ID: mdl-31953129
ABSTRACT
A new non-cytotoxic [(+)-17ß-hydroxystrebloside (1)] and two known cytotoxic [(+)-3'-de-O-methylkamaloside (2) and (+)-strebloside (3)] cardiac glycosides were isolated and identified from the combined flowers, leaves, and twigs of Streblus asper collected in Vietnam, with the absolute configuration of 1 established from analysis of its ECD and NMR spectroscopic data and confirmed by computational ECD calculations. A new 14,21-epoxycardanolide (3a) was synthesized from 3 that was treated with base. A preliminary structure-activity relationship study indicated that the C-14 hydroxy group and the C-17 lactone unit and the established conformation are important for the mediation of the cytotoxicity of 3. Molecular docking profiles showed that the cytotoxic 3 and its non-cytotoxic analogue 1 bind differentially to Na+/K+-ATPase. Compound 3 docks deeply in the Na+/K+-ATPase pocket with a sole pose, and its C-10 formyl and C-5, C-14, and C-4' hydroxy groups may form hydrogen bonds with the side-chains of Glu111, Glu117, Thr797, and Arg880 of Na+/K+-ATPase, respectively. However, 1 fits the cation binding sites with at least three different poses, which all depotentiate the binding between 1 and Na+/K+-ATPase. Thus, 3 was found to inhibit Na+/K+-ATPase, but 1 did not. In addition, the cytotoxic and Na+/K+-ATPase inhibitory 3 did not affect glucose uptake in human lung cancer cells, against which it showed potent activity, indicating that this cardiac glycoside mediates its cytotoxicity by targeting Na+/K+-ATPase but not by interacting with glucose transporters.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Cardiac Glycosides
/
Sodium-Potassium-Exchanging ATPase
/
Moraceae
/
Enzyme Inhibitors
/
Antineoplastic Agents, Phytogenic
Limits:
Humans
Language:
En
Journal:
Bioorg Med Chem
Journal subject:
BIOQUIMICA
/
QUIMICA
Year:
2020
Document type:
Article
Affiliation country:
United States