New acylated triterpenoid saponins from Maesa lanceolata.
Ten new acylated triterpenoid saponins were isolated from the leaves of Maesa lanceolata. For their structure elucidation extensive use was made of homo- and heteronuclear 2D NMR techniques such as COSY, NOESY, HSQC and HMBC. All saponins identified contained the same tetraglycosidic side chain, but the triterpenoid moiety showed a variable esterification pattern. Monoester, diester and triester derivatives were present. Maesasaponin I was a 21-monoester derivative, i.e. ¿3 beta-O-[alpha-L-rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl- (1-->3)]-[beta-D-galactopyranosyl-(1-->2)]-beta-D-glucuronopyranosyl+ ++¿-21 beta-angeloyloxy-13 beta, 28-oxidoolean-16 alpha, 22 alpha, 28 alpha-triol. Maesasaponins III, IV3, V3 and VI2 had an additional acetyl, propanoyl, n-butanoyl and angeloyl substituent, respectively, in position 22. Maesasaponins II, IV2, V2, VI3 and VII1 were characterised as the 16-acetyl derivatives of maesasaponins I, III, IV3, V3 and VI2, respectively. Structures of saponins previously reported in M. lanceolata had to be revised.
Apers
S
S
Department of Pharmaceutical Sciences, University of Antwerp, Belgium. sapers@uia.ua.ac.be
De Bruyne
T E
TE
Claeys
M
M
Vlietinck
A J
AJ
Pieters
L A
LA
D000107:Acetylation; D002240:Carbohydrate Sequence; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D012503:Saponins / Q000737:chemistry* / Q000302:isolation & purification*; D014197:Trees / Q000737:chemistry; D014315:Triterpenes / Q000737:chemistry* / Q000302:isolation & purification*
D012503:Saponins; D014315:Triterpenes