Comparison of Anti-inflammatory Activities of Six Curcuma Rhizomes: A Possible Curcuminoid-independent Pathway Mediated by Curcuma phaeocaulis Extract

Abstract

We aimed to compare the anti-inflammatory activities of six species of Curcuma drugs using adjuvant arthritis model mice. When orally administered 1 day before the injection of adjuvant, the methanol extract of Curcuma phaeocaulis significantly inhibited paw swelling and the serum haptoglobin concentration in adjuvant arthritis mice. Also when orally administered 1 day after the injection of adjuvant, the methanol extract of Curcuma phaeocaulis significantly inhibited paw swelling. Other Curcuma species (Curcuma longa, Curcuma wenyujin, Curcuma kwangsiensis, Curcuma zedoaria and Curcuma aromatica) had no significant inhibitory effects on adjuvant-induced paw swelling. Cyclooxygenase (COX)-2 activity was significantly inhibited by the methanol extract of C. phaeocaulis. Curcuminoids' (curcumin, bis-demethoxycurcumin and demethoxycurcumin) were rich in C. longa, but less in C. phaeocaulis and C. aromatica, not in C. wenyujin, C. kwangsiensis and C. zedoaria, suggesting that curcuminoids' contents do not relate to inhibition of arthritis swelling. Therefore, C. phaeocaulis may be a useful drug among Curcuma species for acute inflammation, and the active constituents of C. phaeocaulis are not curcuminoids.

Figure 1

Morphologies of used Curcuma drugs.

Figure 2

Effects of pretreatment with methanol extracts of Curcuma drugs on paw swelling and increase in serum haptoglobin induced by adjuvant injection. Extracts of Curcuma drugs (500 mg kg⁻¹, hatched columns), dexamethasone (5 mg kg⁻¹) or were administered once 1 day before the adjuvant injection. Arthritis was induced by the injection of Complete Freund's adjuvant (CFA) into the right-hind footpad. Paraffin oil was injected in control mice. (A) Immediately before, and 1 day after injection of the adjuvant, swelling of the right footpad was measured with slide calipers. Change rate of the swelling of Day 2 compared with Day 1 was calculated. (B) After footpad measurement, serum was collected. The concentration of haptoglobin in serum was measured. The time schedule of treatments is shown in the bottom. The values represent the means and SEM of 5 mice. *P < 0.05 when compared with Veh.

Figure 3

Post-treatment with methanol extracts of Curcuma drugs and its effect on paw swelling and increase in serum haptoglobin induced by adjuvant injection. Extracts of Curcuma drugs (500 mg kg⁻¹), dexamethasone (5 mg kg⁻¹) or 20% DMSO in olive oil (Veh) were administered once 1 day after the adjuvant injection. Arthritis was induced by the injection of Complete Freund's adjuvant (CFA) into the right-hind footpad. Paraffin oil was injected in control mice. (A) Immediately before, 1 day after and 2 days after injection of the adjuvant, swelling of the right footpad was measured with slide calipers. Change rates of the swelling of Day 1 (open columns) and Day 2 (hatched columns) compared with Day 0 were calculated. (B) After footpad measurement, serum was collected at Day 2. The concentration of haptoglobin in serum was measured. The time schedule of treatments is shown in the bottom. The values represent the means and SEM of five mice. *P < 0.05 when compared between before and after extract treatment in (A); *P < 0.05 when compared with Veh in (B).

Figure 4

Inhibitory activities of methanol extracts of Curcuma drugs on COX-2 and COX-1 activities. The methanol extracts of Curcuma drugs (500 µg ml⁻¹, hatched columns), indomethacin (10 and 100 µM, closed columns), or the vehicle (0.1% DMSO, open columns) were added to the enzyme reaction mixture. COX-2 (A) and COX-1 (B) activities were measured using the Colorimetric COX inhibitor assay kit. The values represented the means and SEM. n = 3. *P < 0.05 when compared with Veh.