Anti-inflammatory and irritant activities of curcumin analogues in rats.

The anti-inflammatory activity of curcumin (C), sodium curcuminate (NaC), diacetyl curcumin (DAC), triethyl curcumin (TEC), tetrahydro curcumin (THC) and ferulic acid (FA) was compared with that of phenylbutazone (PB) using the carrageenin-induced rat paw edema and cotton pellet granuloma tests. The rank order of potencies of curcumin analogues and PB in carrageenin-induced inflammation were NaC greater than THC greater than C greater than PB greater than TEC. The curcumin analogues de decreased carrageenin-induced paw edema at low doses, however, at higher doses this effect was partially reversed. FA and DAC were devoid of anti-inflammatory activity. Curcumin analogues were less effective in inhibiting the granulomatous tissue formation. Maximum activity was observed with TEC whereas C, NaC and PB were almost half as effective as TEC. C and NaC possess both anti-inflammatory and irritant properties as was evident from experiments in which drugs were incorporated into carrageenin and the cotton pellets for inducing inflammation. The anti-inflammatory action of NaC is not mediated through release of steroids from the adrenal cortex or inhibition of the biosynthesis of prostaglandins from arachidonic acid. The results of the present study support the rationale for the use of powdered rhizome of tumeric (contains 0.6% of curcumin) for conditions of sprain and inflammation.