Chitooligosaccharide and its conjugates with different polyphenols: Antihypertensive activity and blood pressure lowering effects in spontaneously hypertensive rats

Abstract

Inhibitory effects of chitooligosaccharide (CHOS) and its conjugates with epigallocatechin gallate (CHOS-EGCG) and gallic acid (CHOS-GAL) on angiotensin-I-converting enzyme (ACE) and renin activities were determined. CHOS-EGCG showed the highest ACE and renin inhibitory activities. Enzyme inhibition kinetics showed that all samples inhibited ACE and renin activities through mixed-type inhibition. CHOS-EGCG exhibited stronger affinity towards ACE and renin molecules when compared to other samples as determined by intrinsic fluorescence intensity. Molecular docking results confirmed that the higher inhibitory effect of CHOS-EGCG might be due to greater degree of hydrogen bonding with the active or non-active sites of enzymes. Oral administration of CHOS-EGCG to spontaneously hypertensive rats resulted in blood pressure reductions up to −21 mmHg after 6 h and its efficacy was higher than other samples (P < 0.05). However, its capability decreased continuously up to 24 h. Therefore, CHOS-EGCG could serve as ingredients in developing nutraceuticals and functional foods for lowering hypertension.

Keywords

• Chitoologosaccharide-polyphenol conjugate
• Cardiovascular
• Angiotensin-I-converting enzyme
• Renin
• Hypertensive rat