The current study was planned to explore the therapeutic potency of M2000 (
beta-D-mannuronic acid), a novel designed non-steroidal anti-inflammatory
drug (
NSAID) in adjuvant-induced
arthritis model.
Arthritis was induced in Lewis rats by a single
intradermal injection (0.1 ml) of heat-killed Mycobacterium tuberculosis (0.3 mg) in Freund's incomplete adjuvant into the right footpad. Fourteen days after injection of adjuvant, the contralateral left footpad volume was measured. The animals with paw volumes 0.37 ml greater than normal paws were then randomized into treatment groups. Orally and intraperitoneally administrations of test drugs (M2000, 40/mg/kg/day and
indomethacin, 2/mg/kg/day) were started on day 15 post-adjuvant injection and continued until final assessment on day 25. The left hind limb was removed for histological evaluation. The WEHI-164 cell line was used for assaying tolerability and
matrix metalloproteinase type 2 (MMP-2) activity. MMP-2 activity was assessed using zymography. Pharmacotoxicology study was carried out on animal models based on the evaluation of serum and urine determinants, histology of kidney, gastrointestinal tolerability and body temperature. Results showed that the orally administration as well as intraperitoneally injection of M2000 to arthritic rats induced a significant reduction in paw oedema. Histopathological assessment showed a reduced inflammatory cells infiltrate in joints of treated rats, as well as the number of osteoclasts present in the subchondral bone, tissue oedema and bone erosion in the paws were markedly reduced following M2000
therapy. Cytotoxicity analysis of M2000 showed a much higher tolerability compared with other tested drugs (
diclofenac,
piroxicam and
dexamethasone). The inhibitory effect of M2000 in MMP-2 activity was significantly greater than that of
dexamethasone and of
piroxicam at a concentration of 200 microg/ml. Moreover, the toxicological study revealed that M2000 had no influence on serum (blood
urea nitrogen,
creatinine,
triglyceride and
cholesterol) and urine (
urea and urinary
protein excretion) determinants, glomerular histology and body temperature in normothermic rats and had no ulcerogenic effects on rats' stomach. Our data show that M2000, as a novel
NSAID, could be strongly suggested as the safest anti-inflammatory
drug for long-term administration.