9,10-dihydro-2,5-dimethoxyphenanthrene-1,7-diol, from Eulophia ochreata, inhibits inflammatory signalling mediated by Toll-like receptors.
OBJECTIVE
9,10-Dihydro-2,5-dimethoxyphenanthrene-1,7-diol (RSCL-0520) is a phenanthrene isolated from Eulophia ochreata, one of the Orchidaceae family, known by local tradition to exhibit medicinal properties. However, no anti-inflammatory activity or any molecular mechanisms involved have been reported or elucidated. Here, for the first time, we evaluate the anti-inflammatory properties of RSCL-0520 on responses induced by lipopolysaccharide (LPS) and mediated via Toll-like receptors (TLRs).


METHODS
The in vitro anti-inflammatory activities of RSCL-0520 were investigated in LPS-stimulated monocytic cells, measuring activation of cytokine and inflammatory genes regulated by nuclear factor-kappaB (NF-kappaB). Tumour necrosis factor (TNF)-alpha levels in serum following LPS stimulation in mice and carrageenan-induced paw oedema in rats were used as in vivo models.


RESULTS
Pretreatment with RSCL-0520 effectively inhibited LPS-induced, TLR4-mediated, NF-kappaB-activated inflammatory genes in vitro, and reduced both LPS-induced TNF-alpha release and carrageenan-induced paw oedema in rats. Treatment with RSCL-0520 reduced LPS-stimulated mRNA expression of TNF-alpha, COX-2, intercellular adhesion molecule-1, interleukin (IL)-8 and IL-1beta, all regulated through NF-kappaB activation. RSCL-0520, however, did not interfere with any cellular processes in the absence of LPS.


CONCLUSIONS
RSCL-0520 blocked signals generated by TLR4 activation, as shown by down-regulation of NF-kappaB-regulated inflammatory cytokines. The inhibitory effect involved both MyD88-dependent and -independent signalling cascades. Our data elucidated the molecular mechanisms involved, and support the search for plant-derived TLR antagonists, as potential anti inflammatory agents.
Datla
Praneel
P
Drug Discovery and Development Group, Reliance Life Sciences Ltd., Dhirubhai Ambani Life Sciences Center, Rabale, Navi Mumbai, India.
Kalluri
Mani Deepthi
MD
Basha
Khalander
K
Bellary
Akshaya
A
Kshirsagar
Rajendra
R
Kanekar
Yogesh
Y
Upadhyay
Shakti
S
Singh
Shiva
S
Rajagopal
Vikram
V
D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy; D005260:Female; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism*; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D029595:Orchidaceae; D010616:Phenanthrenes / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects*; D051193:Toll-Like Receptors / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
C550091:9,10-dihydro-2,5-dimethoxyphenanthrene-1,7-diol; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D010616:Phenanthrenes; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha