New galloylated flavanonols from the Australian plant Glochidion sumatranum.
Bioassay-guided fractionation of the CH(2)Cl(2)/MeOH extract from the Australian plant Glochidion sumatranum resulted in the isolation of four new galloylated flavanonols, (2R,3R)-dihydromyricetin-4'-O-(3''-O-methyl)-gallate (1), (2R,3R)-dihydromyricetin-3'-O-(3''-O-methyl)-gallate (2), (2R,3R)-dihydromyricetin-4'-O-gallate (3), and (2R,3R)-dihydromyricetin-3'-O-gallate (4), along with the known compound, (2R,3R)-dihydromyricetin (5). The structures of 1-5 were determined by NMR and MS analysis and their absolute configuration was elucidated by comparison of the CD data with literature values. Compounds 1/2 and 3/4 are two pairs of structural isomers that were shown to interconvert by transesterification during NMR and LC-MS studies. This process involved the intramolecular migration of the galloyl moieties between C-3' and C-4' of the flavanonol skeleton. Compounds 1 and 3 were identified as the more stable isomers. Compounds 1, 3, and 5 showed weak activity against the gram-negative bacterium Pseudomonas aeruginosa and the gram-positive bacterium Staphylococcus aureus.
Yin
Sheng
S
Eskitis Institute, Griffith University, Brisbane, Australia.
Sykes
Melissa L
ML
Davis
Rohan A
RA
Shelper
Todd
T
Avery
Vicky M
VM
Camp
David
D
Quinn
Ronald J
RJ
D000900:Anti-Bacterial Agents / Q000302:isolation & purification* / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D007536:Isomerism; D019684:Magnoliopsida / Q000737:chemistry*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry*; D018515:Plant Leaves; D018547:Plant Stems; D011549:Pseudomonas / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D005419:Flavonoids; D010936:Plant Extracts; C040015:myricetin