Constituents in watercress: inhibitors of histamine release from RBL-2H3 cells induced by antigen stimulation.
Histamine release inhibitors in watercress (Nasturtium officinale) were isolated using a monitoring system with antigen-stimulated RBL-2H3 cells. Of the 15 compounds isolated, flavonols and megastigmanes significantly inhibited histamine release. Two flavonols, 3-O-sophorosides of rhamnetin and rhamnazin, were new compounds. To investigate the inhibitory mechanism, the effects of rhamnetin, rhamnetin 3-O-sophoroside and an isolated megastigmane glucoside on the increase in the intracellular free calcium concentration were examined at a concentration providing 60% inhibition of histamine release. The results suggest that these compounds did not affect the calcium influx at that concentration. The structure-activity relationships of the megastigmanes on histamine release were also investigated.
Goda
Y
Y
National Institute of Health Sciences, Tokyo, Japan.
Hoshino
K
K
Akiyama
H
H
Ishikawa
T
T
Abe
Y
Y
Nakamura
T
T
Otsuka
H
H
Takeda
Y
Y
Tanimura
A
A
Toyoda
M
M
D000818:Animals; D002118:Calcium / Q000378:metabolism; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology; D044948:Flavonols; D006633:Histamine Antagonists / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology; D051381:Rats; D019685:Rosales / Q000737:chemistry*; D014407:Tumor Cells, Cultured
D005419:Flavonoids; D044948:Flavonols; D006633:Histamine Antagonists; D010936:Plant Extracts; D002118:Calcium