title: The different inhibitory effects of Huang-Lian-Jie-Du-Tang on cyclooxygenase 2 and 5-lipoxygenase.
abstract: BACKGROUND
  Huang-Lian-Jie-Du-Tang (HLJDT), a famous traditional Chinese prescription with wide anti-inflammatory applications, is an aqueous extract of four herbal materials: Rhizoma coptidis, Radix scutellariae, Cortex phellodendri, and Fructus gardeniae. Its effects on the cyclooxygenase (COX)-2 and 5-lipoxygenase (5-LOX) pathways are thought to be responsible for its anti-inflammatory activity. However, our previous work found that the inhibitory effects of HLJDT act on the 5-LOX pathway but not on the COX pathway. The possibility that HLJDT inhibits COX-2- or 5-LOX-catalyzed eicosanoid generation by downregulating enzyme expression requires further investigation.
  
  
  OBJECTIVE
  To observe the effects of HLJDT and its four major components (baicalin, baicalein, berberine and geniposide) on COX-2- or 5-LOX-catalyzed eicosanoid generation and to distinguish the effects of HLJDT on enzyme activity from those on enzyme expression.
  
  
  METHODS
  The topical anti-inflammatory activities and inhibition of eicosanoid formation of HLJDT and its components were observed in an arachidonic acid (AA)-induced mouse ear edema model. Macrophage-based systems were established to observe the effects of the drugs on enzyme activity and enzyme expression of COX-2 and 5-LOX. Further experiments were carried out to confirm these effects at the mRNA and protein levels.
  
  
  RESULTS
  Topical treatment of HLJDT significantly inhibited AA-induced mouse ear edema and reduced PGE(2) and LTB(4) release in the edematous ears. Baicalein, geniposide, and berberine also ameliorated the symptoms and suppressed eicosanoid generation with varying efficacies. Cell-based assays showed that HLJDT and baicalein inhibited the PGE(2) levels by decreasing COX-2 enzyme expression without affecting COX-2 enzyme activity in RAW 246.7 murine macrophages. The other experiments on rat peritoneal macrophages indicated that HLJDT and baicalein exerted significant inhibition on LTB(4) production by decreasing 5-LOX enzyme activity. The real-time PCR and western blotting data demonstrated that HLJDT and baicalein reduced COX-2 expression at the mRNA and protein levels, whereas no inhibition on 5-LOX expression was observed.
  
  
  CONCLUSIONS
  HLJDT can suppress eicosanoid generation via both the COX and LOX pathways, which definitely contributes to its topical anti-inflammatory activity. We have confirmed that its dual inhibition on the COX and LOX pathways mainly result from the downregulation of COX-2 expression and direct inhibition of 5-LOX activity, respectively. Baicalein worked as a potent active component in most of the tests. These findings about the different inhibitory effects of HLJDT on COX-2 and 5-LOX help to better understand the mechanism of HLJDT and promote safer applications of drug.
authors.affiliation: Department of Natural Product Chemistry, School of Pharmacy, Second Military Medical University, Shanghai 200433, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Huawu
authors.initials: H
authors.lastname: Zeng
authors.forename: Lei
authors.initials: L
authors.lastname: Shan
authors.forename: Xin
authors.initials: X
authors.lastname: Yuan
authors.forename: Yushan
authors.initials: Y
authors.lastname: Li
authors.forename: Runhui
authors.initials: R
authors.lastname: Liu
authors.forename: Weidong
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology* / Q000627:therapeutic use; D001094:Arachidonate 5-Lipoxygenase / Q000235:genetics / Q000378:metabolism; D016718:Arachidonic Acid; D001599:Berberine / Q000494:pharmacology / Q000627:therapeutic use; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D015232:Dinoprostone / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology* / Q000627:therapeutic use; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism*; D044950:Flavanones / Q000494:pharmacology / Q000627:therapeutic use; D005419:Flavonoids / Q000494:pharmacology / Q000627:therapeutic use; D039823:Iridoids / Q000494:pharmacology / Q000627:therapeutic use; D007975:Leukotriene B4 / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D004365:Drugs, Chinese Herbal; D044950:Flavanones; D005419:Flavonoids; D039823:Iridoids; D016859:Lipoxygenase Inhibitors; D012333:RNA, Messenger; C061676:oren gedoku to; D001599:Berberine; C007835:geniposide; D007975:Leukotriene B4; D016718:Arachidonic Acid; C038044:baicalin; C006680:baicalein; D001094:Arachidonate 5-Lipoxygenase; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D015232:Dinoprostone