Fig. 6.

Comparison of the inhibitory effects of various DPP4 inhibitors on rDPP4 and mDPP4 activities at different time points. The DPP4 inhibitory activities of evogliptin, sitagliptin, diprotin A, and berberine were measured using recombinant DPP4 (rDPP4) protein or cell pellets of H9 Th1 cells. DPBS or DMSO were used as a control. The recombinant DPP4 proteins were incubated with evogliptin and sitagliptin (2 ng/mL and 2 µg/mL) or diprotin A and berberine (20 and 50 µg/mL); harvested after 0, 0.5, 1, 3, 6, 12, and 24 h; and subjected to assays for measuring the DPP4 activity (A, C). The results of DPP4 enzymatic activity after 30 min of incubation are shown (B, D). The H9 Th1 cell pellets were incubated with evogliptin and sitagliptin (2 ng/mL and 2 µg/mL, respectively) or diprotin A and berberine (20 and 50 µg/mL); harvested after 0, 0.5, 1, and 3 h; and subjected to DPP4 assays (E, G). The results of DPP4 activity after 30 min incubation are shown (F, H). All analyses were performed in three independent experiments, and the data are represented as the means and standard deviation. *p<0.05; **p<0.005; and ***p<0.001 (paired t-test).