From medicinal plant extracts to defined chemical compounds targeting the histamine H receptor: Curcuma longa in the treatment of inflammation.

OBJECTIVES

The aim was to evaluate the activity of seven medicinal, anti-inflammatory plants at the hHR with focus on defined chemical compounds from Curcuma longa.

MATERIALS

Activities were analyzed with membrane preparations from Sf9 cells, transiently expressing the hHR, G and G subunits.

METHODS

From the methanolic extract of C. longa curcumin (1), demethoxycurcumin (2) and bis(4-hydroxy-cinnamoyl)methane (3) were isolated, purified with HPLC (elution-time 10.20, 9.66, 9.20 min, respectively) and together with six additional extracts, were characterized via radioligand binding studies at the hHR.

RESULTS

Compounds from C. longa were the most potent ligands at the hHR. They exhibited estimated K values of 4.26-6.26 µM (1.57-2.31 µg/mL) (1); 6.66--8.97 µM (2.26-3.04 µg/mL) (2) and 10.24-14.57 µM (3.16-4.49 µg/mL) (3) (95% CI). The estimated K value of the crude extract of curcuma was 0.50-0.81 µg/mL. Fractionated curcumin and the crude extract surpassed the effect of pure curcumin with a K value of 5.54 µM or 2.04 µg/mL [95% CI (4.47-6.86 µM), (1.65-2.53 µg/mL)].

CONCLUSION

Within this study, defined compounds of C. longa were recognized as potential ligands and reasonable lead structures at the hHR. The mode of anti-inflammatory action of curcumin was further elucidated and the role of extracts in traditional phytomedicine was strengthened.