Bioactive food-derived peptides have been increasingly studied and the multiple health benefits they provide have been acknowledged. Since the most investigated sources of bioactive peptides are eggs, meat, fish, soybean, wheat, milk, and their derivatives or byproducts. More recently, some attention is being paid to microalgae, a promising unconventional protein source. On this basis, the PhD thesis was focused on the evaluation of the potential of microalgae to generate peptides with cardiovascular-promoting effects, especially hypotensive and antidiabetic activities, by targeting two therapeutic agents – angiotensin I converting enzyme (ACE) and peptidyl-peptidase IV (DPP-IV), respectively. To achieve this objective, multidisciplinary approaches were employed, involving peptidomic techniques to profile the peptide sequences, biochemical tools to analyze the bioactivity, and emerging molecular modelling methods to predict potentially bioactive peptides as well as to explore their possible mechanism of action. Briefly, the results showed that the protein hydrolysates from spirulina, PBP and chlorella generally presented significant ACE and/or DPP-IV inhibitory activities. By comparison, peptic hydrolysate of spirulina protein showed the best in vitro inhibiting effect on ACE with IC50 value of 0.1 ± 0.04 mg/mL while the tryptic hydrolysate of PBP stands out with the lowest IC50 value of DPP-IV inhibition (0.5 – 1.0 mg/mL). Noticeably, when working on the intestinal Caco-2 cells, all the hydrolysates turned to be less bioactive than in vitro, indicating their susceptibility to metabolic degradation by intestinal cells. This is further in line with the kinetics of DPP-IV inhibition of PBP tryptic hydrolysate working on the intestinal cells, which showed the decreasing trend of its bioactivity after incubation with Caco-2 cells for 3 h. This reflects the issue of peptide bioavailability, which could be stressed in further studies. Moreover, peptides Pep2 (FLKPLGSGK), Pep7 (QIYTMGK), Pep8 (FLFVAEAIYK), and Pep10 (QHAGTKAK) were screened from hydrolysates of chlorella protein by peptidomics combined with docking and MD. The modelling results indicated that they may block the important domain of both ACE and DPP-IV and generate dynamically stable peptide-ACE/DPP-IV complexes. Based on this theoretical evidence, further study will focus on the verification of their actual bioactivity by biochemical approaches. In conclusion, the bioactivity investigation of microalgae protein hydrolysates provides new evidence that microalgae protein are great sources to produce peptides with health-promoting properties. The exclusive data of peptide characterization makes a foundation to isolate single bioactive peptides as well as offers useful structural and functional implications for food ingredient formulation or pharmacological use.

MICROALGAE PEPTIDES IN CARDIOVASCULAR DISEASE PREVENTION: STRUCTURE ELUCIDATION,BIOACTIVITY INVESTIGATION,AND IN SILICO MOLECULAR MODELING ANALYSIS / Y. Li ; Faculty advisor: A. Arnoldi ; PhD coordinator: G. Aldini. - : . Dipartimento di Scienze Farmaceutiche, 2021 Jun 14. ((33. ciclo, Anno Accademico 2020. [10.13130/li-yuchen_phd2021-06-14].

MICROALGAE PEPTIDES IN CARDIOVASCULAR DISEASE PREVENTION: STRUCTURE ELUCIDATION,BIOACTIVITY INVESTIGATION,AND IN SILICO MOLECULAR MODELING ANALYSIS

Y. Li
2021

Abstract

Bioactive food-derived peptides have been increasingly studied and the multiple health benefits they provide have been acknowledged. Since the most investigated sources of bioactive peptides are eggs, meat, fish, soybean, wheat, milk, and their derivatives or byproducts. More recently, some attention is being paid to microalgae, a promising unconventional protein source. On this basis, the PhD thesis was focused on the evaluation of the potential of microalgae to generate peptides with cardiovascular-promoting effects, especially hypotensive and antidiabetic activities, by targeting two therapeutic agents – angiotensin I converting enzyme (ACE) and peptidyl-peptidase IV (DPP-IV), respectively. To achieve this objective, multidisciplinary approaches were employed, involving peptidomic techniques to profile the peptide sequences, biochemical tools to analyze the bioactivity, and emerging molecular modelling methods to predict potentially bioactive peptides as well as to explore their possible mechanism of action. Briefly, the results showed that the protein hydrolysates from spirulina, PBP and chlorella generally presented significant ACE and/or DPP-IV inhibitory activities. By comparison, peptic hydrolysate of spirulina protein showed the best in vitro inhibiting effect on ACE with IC50 value of 0.1 ± 0.04 mg/mL while the tryptic hydrolysate of PBP stands out with the lowest IC50 value of DPP-IV inhibition (0.5 – 1.0 mg/mL). Noticeably, when working on the intestinal Caco-2 cells, all the hydrolysates turned to be less bioactive than in vitro, indicating their susceptibility to metabolic degradation by intestinal cells. This is further in line with the kinetics of DPP-IV inhibition of PBP tryptic hydrolysate working on the intestinal cells, which showed the decreasing trend of its bioactivity after incubation with Caco-2 cells for 3 h. This reflects the issue of peptide bioavailability, which could be stressed in further studies. Moreover, peptides Pep2 (FLKPLGSGK), Pep7 (QIYTMGK), Pep8 (FLFVAEAIYK), and Pep10 (QHAGTKAK) were screened from hydrolysates of chlorella protein by peptidomics combined with docking and MD. The modelling results indicated that they may block the important domain of both ACE and DPP-IV and generate dynamically stable peptide-ACE/DPP-IV complexes. Based on this theoretical evidence, further study will focus on the verification of their actual bioactivity by biochemical approaches. In conclusion, the bioactivity investigation of microalgae protein hydrolysates provides new evidence that microalgae protein are great sources to produce peptides with health-promoting properties. The exclusive data of peptide characterization makes a foundation to isolate single bioactive peptides as well as offers useful structural and functional implications for food ingredient formulation or pharmacological use.
ARNOLDI, ANNA
ALDINI, GIANCARLO
Settore CHIM/10 - Chimica degli Alimenti
MICROALGAE PEPTIDES IN CARDIOVASCULAR DISEASE PREVENTION: STRUCTURE ELUCIDATION,BIOACTIVITY INVESTIGATION,AND IN SILICO MOLECULAR MODELING ANALYSIS / Y. Li ; Faculty advisor: A. Arnoldi ; PhD coordinator: G. Aldini. - : . Dipartimento di Scienze Farmaceutiche, 2021 Jun 14. ((33. ciclo, Anno Accademico 2020. [10.13130/li-yuchen_phd2021-06-14].
Doctoral Thesis
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/850789
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