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Biofactors. 2007;31(2):107-16.

Suppressive effects of demethylated metabolites of nobiletin on phorbol ester-induced expression of scavenger receptor genes in THP-1 human monocytic cells.

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1
Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan.

Abstract

Unregulated uptake of oxidized low-density lipoproteins (ox-LDL) via macrophage scavenger receptors (SRs) is a key event in atherosclerosis. We previously reported that nobiletin (NOB), a citrus polymethoxylated flavone, markedly reduced 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced SRs and adhesion molecules mRNA expression and blockade of DiI-acLDL uptake in THP-1 human monocyte-like cells. In this study, we examined the effects of NOB metabolites, 3'-hydroxy-5,6,7,8,4'-pentamethoxyflavone (3'-demethyl-NOB), 4'-hydroxy-5,6,7,8,3'-pentamethoxyflavone (4'-demethyl-NOB) and 3', 4'-dihydroxy-5,6,7,8,-tetramethoxyflavone (3', 4'-didemethyl-NOB) and NOB analog, tangeretin, on SRs and adhesion molecules mRNA expression. 3'-Demethyl-NOB significantly suppressed CD36 expression, moreover, 4'-demethyl- and 3', 4'-didemethyl-NOB significantly suppressed TPA-induced expression of SR-A and LOX-1. Further, the suppressive effects of 4'-demethyl- and 3', 4'-didemethyl-NOB on the expression of CD36 mRNA were greater extent than parent NOB. The inhibitory effects of the metabolites toward TPA-induced SR mRNA expression are partly associated with the suppression of AP-1 and NF-kappaB transcriptional activities. Together, our results suggest that metabolites of NOB, such as 4'-demethyl- and 3', 4'-didemethyl-NOB, have comparable or higher potentials to attenuate SR expression than NOB.

PMID:
18806314
[Indexed for MEDLINE]

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