Inhibition of inducible nitric oxide production and iNOS protein expression in lipopolysaccharide-stimulated rat aorta and Raw 264.7 macrophages by ethanol extract of a Chinese herbal medicine formula (RCM-101) for allergic rhinitis.
OBJECTIVE
A Chinese herbal formula (RCM-101) has shown to be effective in reducing symptoms of seasonal allergic rhinitis (SAR) in a randomised, placebo-controlled clinical trial. The aim of this study is to investigate the effects of RCM-101 on the actions and synthesis of nitric oxide (NO). l-Arginine-induced endothelium-independent relaxations were studied in rat isolated aorta which was pre-treated with lipopolysaccharide (LPS).


METHODS
NO production and inducible nitric oxide synthase (iNOS) protein expression were studied in LPS and interferon gamma-stimulated murine macrophages (Raw 264.7), measured by NO sensors and Western blotting.


RESULTS
In rat aortic preparations, RCM-101 significantly inhibited endothelium-independent relaxations to l-arginine, but not affected those to sodium nitroprusside (SNP). In Raw 264.7 cells, RCM-101 and some of its individual ingredients (e.g., Radix glycyrrhizae, Radix bupleuri, Radix saposhnikoviae and Atractylodis rhizome macrocephalae) significantly inhibited the NO production and iNOS protein expression.


CONCLUSIONS
The findings indicate that RCM-101 may inhibit inducible NO production by suppressing iNOS. In addition, its inhibitory action of iNOS is likely to be mediated by several key herbal ingredients.
Lenon
George Binh
GB
The Chinese Medicine Research Group, RMIT University, Bundoora West Campus, Bundoora, Victoria 3083, Australia. george.lenon@rmit.edu.au
Li
Chung Guang
CG
Xue
Charlie Changli
CC
Thien
Francis Chung Kong
FC
Story
David Frederick
DF
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D002460:Cell Line; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D000431:Ethanol / Q000737:chemistry; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects*; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis* / Q000235:genetics; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D006255:Rhinitis, Allergic, Seasonal / Q000188:drug therapy; D014665:Vasodilator Agents / Q000494:pharmacology
D004365:Drugs, Chinese Herbal; D008070:Lipopolysaccharides; D014665:Vasodilator Agents; D009599:Nitroprusside; D009569:Nitric Oxide; D000431:Ethanol; D052247:Nitric Oxide Synthase Type II