2.6. In vitro colorimetric COX (ovine) inhibitor assayThe purified lupeol was also evaluated for their ability toinhibit COX-1 and COX-2 enzymes by in vitro colorimetric COX(ovine) inhibitor assay, which utilizes the peroxidase compo-nent of cyclooxygenase. The peroxidase activity is assayed for monitoring the appearance of oxidized N,N,N´ı,N´ı-tetramethyl-p-phenylenediamine (TMPD), which is produced during thereduction of PGG2 to PGH2 at 590 nm. Aspirin was used as a positivecontrol. Purified lupeol and aspirin were dissolved in dimethylsul-foxide (DMSO) at several relations (range of 0.075–10 mg/mL) tocalculate their median inhibitory concentration (IC50). The assaywas performed in a 96 wells plate according to the procedure rec-ommended by the supplier.To calculate the inhibition activity, the average absorbance wascalculated for all samples (n = 3). The coefficient of the absorbanceof each inhibitor sample was divided between absorbance ofenzyme activity and multiplied by 100 to give the percent inhibitionwas subtracted from 100% of activity.