Muscarinic receptor binding activity of polyoxygenated flavones from Melicope subunifoliolata.
The bark extract of Melicope subunifoliolata (Stapf) T.G. Hartley showed competitive muscarinic receptor binding activity. Six polymethoxyflavones [melibentin (1); melisimplexin (3); 3,3',4',5,7-pentamethoxyflavone (4); meliternatin (5); 3,5,8-trimethoxy-3',4',6,7-bismethylenedioxyflavone (6); and isokanugin (7)] and one furanocoumarin [5-methoxy-8-geranyloxypsoralen (2)] were isolated from the bark extract. Compounds 2 and 6 were isolated for the first time from M. subunifoliolata. The methoxyflavones (compounds 1, 3, 4, 5, 6, and 7) show moderate inhibition in a muscarinic receptor binding assay, while the furanocoumarin (compound 2) is inactive. The potency of the methoxyflavones to inhibit [(3)H]NMS-muscarinic receptor binding is influenced by the position and number of methoxy substitution. The results suggest these compounds are probably muscarinic modulators, agonists or partial agonists/antagonists.
Chung
L Y
LY
Department of Pharmacy, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. chungly@hotmail.com
Yap
K F
KF
Goh
S H
SH
Mustafa
M R
MR
Imiyabir
Z
Z
D001667:Binding, Competitive; D047309:Flavones / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism*; D027821:Rutaceae / Q000737:chemistry*; D013329:Structure-Activity Relationship
D047309:Flavones; D005419:Flavonoids; D010936:Plant Extracts; D011976:Receptors, Muscarinic; C474048:meliternatin