Evaluation of the in vitro anti-inflammatory activity of different fractions of the aqueous extract of Curcuma zedoaria Roscoe rhizome and formulation of a cream with anti-inflammatory potential

Introduction: Curcuma zedoaria Roscoe (C. zedoaria) is used in traditional medicine for various diseases, including inflammation. This study aimed to evaluate the in vitro anti-inflammatory activity of the aqueous extract of C. zedoaria rhizome and its fractions and develop an anti-inflammatory cream incorporating its aqueous extract.

Methods: The crude aqueous extract of C. zedoaria rhizome was prepared by the decoction method. A portion of it was freeze-dried and the other part was subjected to sequential fractionation using hexane, dichloromethane and ethyl acetate. All the fractions were dried using a rotary vacuum evaporator. The dry powders of the above extracts were assessed for their in vitro anti-inflammatory activity using heat-induced egg albumin denaturation assay and compared with the reference drug, diclofenac sodium. A cream was formulated by incorporating the most effective fraction; the aqueous extract and its anti-inflammatory activity was compared against a commercially available diclofenac sodium cream.

Results: The aqueous extract of C. zedoaria rhizome and its hexane, dichloromethane, ethyl acetate fractions and the remaining aqueous extract showed anti-inflammatory activity against heat-induced protein denaturation with the IC₅₀ values; 94.45 µg/mL, 3822 µg/mL, 373.2 µg/mL, 337.7 µg/mL and 565.4 µg/mL respectively. The IC₅₀ value obtained for diclofenac sodium powder was 915.7µg/mL. The IC₅₀ value obtained for the formulated cream (containing 3% w/w aqueous extract of C. zedoaria rhizome) was 1894 µg/mL. The observed IC₅₀ value of the commercially available diclofenac sodium 1% w/w cream was 1227 µg/mL.

Conclusion: The cream formulated with the aqueous extract of C. zedoaria rhizome possesses in vitro anti-inflammatory efficacy. Further studies are required to improve its drug-releasing capacity.