Investigation of Chlorella pyrenoidosa Protein as a Source of Novel Angiotensin I-Converting Enzyme (ACE) and Dipeptidyl Peptidase-IV (DPP-IV) Inhibitory Peptides

Abstract

Chlorella pyrenoidosa (C. pyrenoidosa) is a microalgae species with a remarkably high protein content that may potentially become a source of hypotensive and hypoglycemic peptides. In this study, C. pyrenoidosa proteins were extracted and hydrolyzed overnight with pepsin and trypsin with final degrees of hydrolysis of 18.7% and 35.5%, respectively. By LC-MS/MS, 47 valid peptides were identified in the peptic hydrolysate (CP) and 66 in the tryptic one (CT). At the concentration of 1.0 mg/mL, CP and CT hydrolysates inhibit in vitro the angiotensin-converting enzyme (ACE) activity by 84.2 ± 0.37% and 78.6 ± 1.7%, respectively, whereas, tested at cellular level at the concentration of 5.0 mg/mL, they reduce the ACE activity by 61.5 ± 7.7% and 69.9 ± 0.8%, respectively. At the concentration of 5.0 mg/mL, they decrease in vitro the DPP-IV activity by 63.7% and 69.6% and in Caco-2 cells by 38.4% and 42.5%, respectively. Short peptides (≤10 amino acids) were selected for investigating the potential interaction with ACE and DPP-IV by using molecular modeling approaches and four peptides were predicted to block both enzymes. Finally, the stability of these peptides was investigated against gastrointestinal digestion.

Integrated Evaluation of the Multifunctional DPP-IV and ACE Inhibitory Effect of Soybean and Pea Protein Hydrolysates

“…In this study, it was clearly demonstrated that both SH and PH maintain their ability to reduce the activity of both DPP-IV and ACE on Caco-2 cells, even though both hydrolysates are active at a concentration ranging between 0.1 and 5 mg/mL, indicating that SH and PH are less active in cell-based than in cell-free conditions, respectively. Similar results have been previously obtained on peptic and tryptic hydrolysates of spirulina and chlorella proteins, respectively [32,34,35]. Also, in those cases, it was observed that all the tested hydrolysates were more active in cell-free than in cell-based assays, respectively.…”

“…DPP-IV and ACE are important membrane peptidases which are physiological expressed by many tissues; i.e., intestine [30,31]. Indeed, human intestinal Caco-2 cells represent a reliable model which has been already developed and validated for the study of peptides with DPP-IV or ACE inhibitory properties [23,32,33]. In this study, it was clearly demonstrated that both SH and PH maintain their ability to reduce the activity of both DPP-IV and ACE on Caco-2 cells, even though both hydrolysates are active at a concentration ranging between 0.1 and 5 mg/mL, indicating that SH and PH are less active in cell-based than in cell-free conditions, respectively.…”

“…Also, in those cases, it was observed that all the tested hydrolysates were more active in cell-free than in cell-based assays, respectively. The reduced activity in the cellular assays may be explained considering the metabolic ability of Caco-2 cells [32]. Indeed, the intestinal brush border expresses many active proteases and peptidases that might actively hydrolyze food peptides modulating their bioactivity through the production of new breakdown fragments.…”

Rainbow Trout (Oncorhynchus mykiss) as Source of Multifunctional Peptides with Antioxidant, ACE and DPP-IV Inhibitory Activities

“…In this study, findings clearly demonstrated that FPH maintain their ability to reduce the DPP-IV activity on Caco-2 cells, even with less activity. Comparable findings have been already obtained on plant-derived hydrolysates [ 58 , 59 , 61 ]. Protein hydrolysates showed better activity in cell-free than cell-based assays, even in these cases.…”

“…In this context, DPP-IV is a relevant peptidase physiological expressed by many tissues, i.e., intestine [ 56 , 57 ]. Human intestinal Caco-2 cells are widely used for the study of peptides with DPP-IV inhibitory activity, as they represent a reliable and validated model [ 58 , 59 , 60 ]. In this study, findings clearly demonstrated that FPH maintain their ability to reduce the DPP-IV activity on Caco-2 cells, even with less activity.…”