Amadori compounds as potent inhibitors of angiotensin-converting enzyme (ACE) and their effects on anti-ACE activity of bell peppers

- Fru-Glu and Fru-His were shown to be effective inhibitors of ACE.
- Processed bell pepper extract was an effective ACE inhibitor.
- ACs can contribute to increased anti-ACE activity of processed bell peppers.
- ACs and bell pepper extract may have potential use to develop ACE-inhibitory foods.

The angiotensin-converting enzyme (ACE) inhibitor activity of Amadori compounds (ACs) was evaluated in vitro. The results revealed that the N-(1-deoxy-d-fructose-1-yl) glutamic acid was the most active with the lowest IC50 value (0.2590 mM), followed by N-(1-deoxy-d-fructose-1-yl) histidine (0.5676 mM); others showed weak ACE inhibition. Besides, we further studied the change of AC content and corresponding anti-ACE activity during heating of the bell pepper. The AC content in fresh bell pepper was low and drying of the bell pepper led to a significant increase, especially at the beginning five days, in N-(1-deoxy-d-fructose-1-yl) glutamic acid, N-(1-deoxy-d-fructose-1-yl) histidine and the total of eight ACs respectively from nd (not detected) −5.53, 0.76-6.47 and 11.17-100.01 mg/g; simultaneously, the IC50 values for bell pepper extracts decreased from 0.2161 to 0.04627 mM during thermal processing, showing anti-ACE activity increase, which illustrated that the ACs formed during heating of the bell pepper can contribute to the increase of ACE inhibitory activities.