Isoflavones from Camphorosma lessingii Inhibit the Organic Anion Transporters OAT1 and OAT3.

ABSTRACT

Phytochemical investigation of Camphorosma lessingii has resulted in the isolation of four previously unreported isoflavones (1 -4 ) and eight known compounds (5 -12 ). Nine of these compounds (1 -6, 8 -10 ) are reported for the first time from members of the family Amaranthaceae. The structures of all isolated compounds were determined by spectroscopic methods, primarily one-dimensional and two-dimensional nuclear magnetic resonance and mass spectrometry. The absolute configuration of 6 was confirmed by circular dichroism. Inhibition of the organic anion transporters, OAT1 and OAT3, by the isolated compounds was evaluated. Among them, 7, 2'-dihydroxy- 6,8-dimethoxyisoflavone (1 ), 2'-hydroxy-6,7,8-trimethoxyisoflavone (2 ), 6,2'-dihydroxy-7,8-dimethoxyisoflavone (3 ), and 7-methoxyflavone (5 ) showed a significant inhibitory effect on 6-carboxyfluorescein uptake mediated by OAT1 and OAT3.