Esculetin reduces leukotriene B4 level in plasma of rats with adjuvant-induced arthritis.
OBJECTIVE
Esculetin (6,7-dihydroxycoumarin) is a natural coumarin with anti-oxidant, anti-inflammatory and anti-nociceptive activity. It acts as a potent inhibitor of lipoxygenases (5-LOX and 12-LOX) and decreases the production of matrix metalloproteinases (MMP-1, MMP-3 and MMP-9). Because both inhibition of lipoxygenases and inhibition of matrix metalloproteinases are effective strategies in the treatment of rheumatoid arthritis, we investigated whether esculetin may be effective in adjuvant-induced arthritis in rats.


METHODS
The study was performed on male Lewis rats, in the adjuvant-induced arthritis model. Rats were divided into two groups: control (treated with 1% methylcellulose) and experimental (treated with esculetin - 10 mg/kg ip.). The tested compound was administered for 5 consecutive days starting on the 21stday after induction of arthritis. Each group consisted of 7 animals. After 5 days of treatment, rats were anesthetized. The concentration of leukotriene B4 (LTB4) in plasma was determined by a competitive enzyme immunoassay.


RESULTS
The LTB4 level in plasma of rats with adjuvant-induced arthritis is increased in comparison to rats without inflammation (362 ±34 vs. 274 ±15 pg/ml,p< 0.01, respectively). Five-day treatment with esculetin in adjuvant-induced arthritis rats decreases the LTB4 level to a level comparable with rats without inflammation (284 ±23 pg/ml,p< 0.01).


CONCLUSIONS
LTB4 is the most potent chemotactic agent influencing neutrophil migration into the joint. It is known that its level in serum of patients with active rheumatoid arthritis is increased and correlates with disease severity. Some other lipoxygenase inhibitors have already been tested as potential drug candidates in clinical and preclinical trials for rheumatoid arthritis (Zileuton, PF-4191834). Because esculetin decreases the LTB4 level in plasma of rats in adjuvant-induced arthritis, it may also be considered as an attractive drug candidate for patients with rheumatoid arthritis.
Department of General and Experimental Pathology, CEPT Laboratory, Medical University of Warsaw, Poland; Department of Gerontology and Public Health, National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland.
Przemysław
P
Rzodkiewicz
Department of Pharmacodynamics, CEPT Laboratory, Medical University of Warsaw, Poland.
Emilia
E
Gąsińska
Department of Biochemistry and Molecular Biology, National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland.
Michał
M
Gajewski
Department of Pharmacodynamics, CEPT Laboratory, Medical University of Warsaw, Poland.
Magdalena
M
Bujalska-Zadrożny
Department of General and Experimental Pathology, CEPT Laboratory, Medical University of Warsaw, Poland.
Dariusz
D
Szukiewicz
Department of General and Experimental Pathology, CEPT Laboratory, Medical University of Warsaw, Poland.
Sławomir
S
Maśliński
adjuvant-induced inflammation; esculetin; leukotriene B4; treatment