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J Ethnopharmacol. 2011 Jul 14;136(3):488-95. doi: 10.1016/j.jep.2011.01.013. Epub 2011 Jan 18.

Suppressive effects of methoxyflavonoids isolated from Kaempferia parviflora on inducible nitric oxide synthase (iNOS) expression in RAW 264.7 cells.

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1
Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla, Thailand.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE:

The rhizomes of Kaempferia parviflora Wall. ex Baker have been traditionally used in Thailand to treat abscesses, gout, and peptic ulcers.

AIM:

Previously, we reported that the chloroform fraction of a Kaempferia parviflora extract had an inhibitory effect on rat paw-edema. In the present study, we isolated the constituents of this fraction and investigated the anti-inflammatory mechanism against nitric oxide (NO) production, tumor necrosis factor-α (TNF-α) and the expression of inducible nitric oxide synthase (iNOS) as well as phosphorylated extracellular signal-regulated kinase (p-ERK), and phosphorylated c-Jun N-terminal kinase (p-JNK). In addition, effects of trimethylapigenin (4) on the enzyme activities of protein kinases possibly leading to iNOS expression were examined to clarify the targets.

MATERIALS AND METHODS:

The chloroform fraction was isolated using silica gel column chromatography and HPLC. Isolated compounds were tested against NO and TNF-α using RAW264.7 cells. Cytotoxicity and iNOS, p-ERK and p-JNK expression were also examined.

RESULTS:

Three active components, 5,7-dimethoxyflavone (2), trimethylapigenin (4), and tetramethylluteolin (5), markedly inhibited the production of NO in lipopolysaccharide (LPS)-activated RAW264.7 cells. Compounds 2, 4, and 5 moderately inhibited production of TNF-α. Compounds 2, 4, and 5 strongly inhibited expression of iNOS mRNA and iNOS protein in a dose-dependent manner, but did not inhibit p-ERK or p-JNK protein expression. The most active compound, 4, did not inhibit the enzyme activity of inhibitor of κB kinases or mitogen-activated protein kinases, but inhibited that of spleen tyrosine kinase (SYK).

CONCLUSION:

The mechanism responsible for the anti-inflammatory activity of methoxyflavonoids from the chloroform fraction of the rhizomes of Kaempferia parviflora is mainly the inhibition of iNOS expression, and the inhibition of SYK by 4 may be involved in the suppression of LPS-induced signaling in macrophages.

PMID:
21251970
DOI:
10.1016/j.jep.2011.01.013
[Indexed for MEDLINE]

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