An assay was performed to test the anti-inflammatory activity of glabridin when used for topical application. UVB-induced pigmented skins of guinea pigs were treated with 0.5% glabridin solution. It was observed that glabridin decreased the inflammation induced by UVB irradiation on the skin. The erythema manifested as redness in skin color is indicated by a* values. The extent by which the inflammation decreased was calculated by recording the a* values (of a L*a*b* colorimeter) before irradition, after irradiation and after the topical application of glabridin. The a* value increases with the appearance of erythema. As shown in Figure 3, the a* values of of the skin treated with glabridin were lower than those of the control, indicating a decrease in the inflammation.

An assay was performed to determine the inhibitory effect of glabridin on cyclooxygenase activity. Cyclooxygenase is an enzyme that metabolizes arachidonic acid into prostaglandins, which are mediators that initiate the inflammatory cascade reaction. It was observed that addition of 6.25 µg/ml glabridin inhibited the cyclooxygenase activity with respect to the control. The positive control in this experiment was indomethacin, a known cyclooxygenase inhibitor It is believed that glabridin has the anti-inflammatory effect through the arachidonic acid cascade by inhibition to cyclooxygenase.