Yunnanensine type indole and seco stemmadenine-yunnanensine type bisindole alkaloids from the bark of Alstonia scholaris
Document Type
Article
Publication Date
6-1-2024
Abstract
Two previously undescribed monoterpenoid indole alkaloids, N -formylyunnanensine ( 1 ) and scholaphylline ( 2 ), along with eight known alkaloids, namely, 19,20- E -vallesamine ( 3 ), 19,20- Z -vallesamine ( 4 ), 19,20- E -valles- amine N -oxide ( 5 ), 6,7- seco -19,20 alpha-epoxyangustilobine B ( 6 ), 16 R -19,20- E -isositsirikine ( 7 ), N -demethylal- stogustine N -oxide ( 8 ), E -vallesiachotamine ( 9 ), and Z -vallesiachotamine ( 10 ), were isolated from the bark of Alstonia scholaris. Alkaloid 1 was determined to be the N -formyl derivative of the known alkaloid, yunnanensine, comprising a pair of inseparable E / Z -formamide rotamers, while scholaphylline ( 2 ) was identified as the first member of the seco stemmadenine-yunnanensine type bisindole alkaloid. The structures of these alkaloids and their absolute configurations were established based on detailed analysis of the spectroscopic data in conjunction with the TDDFT-ECD method. A possible biogenetic pathway to 1 and 2 , involving stemmadenine as the primary precursor, was proposed. Scholaphylline ( 2 ) showed modest cytotoxicity against Panc1 (IC 50 27.7 +/- 5.1 mu M), MDA-MB-231 (IC 50 32.0 +/- 2.2 mu M), and MDA-MB-468 (IC 50 34.1 +/- 3.3 mu M) cancer cell lines, while N -for- mylyunnanensine ( 1 ) did not show appreciable cytotoxicity against any of the tested cell lines.
Keywords
Alstonia scholaris, Apocynaceae, Alkaloids, Bisindole, Rotamers
Divisions
CHEMISTRY
Publication Title
Phytochemistry Letters
Volume
61
Publisher
Elsevier
Publisher Location
RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS