Structure-function insights into the digestive fate of angiotensin-converting enzyme-inhibitory peptides from microwave-treated corn gluten meal.
Microwave pretreatment boosts peptide yield from corn gluten meal, but digestion can reduce their ACE-inhibitory effectiveness, impacting potential functional food applications.
Where it sits
this study against the rest of the thymulin (facteur thymique serique) corpusSummary and findings
The study examined the impact of microwave pretreatment on corn gluten meal to enhance peptide release and its subsequent effects on ACE-inhibitory activity. The peptide DVPSADAPAAAV (DV-12) showed potent in vitro ACE inhibition, but digestion reduced its potency. Both DV-12 and its digested form DA-11 crossed epithelial barriers at low rates.
Abstract
Corn gluten meal (CGM) is an underutilized byproduct with rigid structure, which limits efficient peptide release during enzymatic hydrolysis. While microwave pretreatment can disrupt the rigid CGM matrix and enhance peptide release, this study investigated how downstream gastrointestinal modification and transport behavior ultimately influence the functional fate of the enzymatically liberated peptide sequences. Enzymatic hydrolysis of microwave-pretreated CGM led to a 3.3-fold increase in peptide yield while maintaining angiotensin-converting enzyme (ACE)-inhibitory activity at a level comparable to that of the untreated CGM hydrolysate. From this digest, the purified peptide DVPSADAPAAAV (DV-12) exhibited potent <i>in vitro</i> ACE inhibition (IC₅₀ = 57 μM). Simulated gastrointestinal digestion partially hydrolyzed DV-12 to DVPSADAPAAA (DA-11), a minor structural modification that was overestimated by <i>in silico</i> digestion models yet resulted in a substantial reduction in ACE-inhibitory potency. Kinetic analysis and molecular dynamics simulations revealed that this truncation fundamentally altered peptide-ACE interactions: DV-12 (<i>K</i>ᵢ = 8 μM) maintained more stable coordination near the ACE Zn<sup>2+</sup> catalytic center, whereas DA-11 displayed substantially weaker binding (<i>K</i>ᵢ = 1.06 mM). In Caco-2 monolayers, both peptides crossed the epithelial barrier at low rates, with apparent permeability coefficients of 9.96 × 10<sup>-8</sup> and 8.23 × 10<sup>-8</sup> cm·s<sup>-1</sup> for DV-12 and DA-11, respectively, while unabsorbed peptide fractions, particularly DV-12, concurrently reduced intracellular reactive oxygen species. These findings demonstrated that increasing peptide yield alone does not guarantee preserved downstream functionality, as subtle structural modifications occurring during digestion and transport toward absorption could markedly alter peptide bioactivity and should therefore be considered in the development of functional food ingredients.
Background
The study addresses the challenge of enhancing peptide release from corn gluten meal (CGM), a byproduct with limited use due to its rigid structure. Previous research has shown that enzymatic hydrolysis can release bioactive peptides, but the efficiency is often low. This study explores how microwave pretreatment can improve peptide yield and examines the functional implications of these peptides in terms of ACE-inhibitory activity.
Methods
The study utilized enzymatic hydrolysis of microwave-pretreated CGM to increase peptide yield. The primary peptide of interest, DVPSADAPAAAV (DV-12), was evaluated for ACE-inhibitory activity. Simulated gastrointestinal digestion and transport behaviors were assessed using in vitro models, including Caco-2 monolayers. Kinetic analysis and molecular dynamics simulations were employed to understand peptide-ACE interactions.
Results
Microwave pretreatment led to a 3.3-fold increase in peptide yield while maintaining ACE-inhibitory activity similar to untreated CGM hydrolysate. The peptide DV-12 exhibited an IC₅₀ of 57 μM for ACE inhibition. Simulated digestion partially hydrolyzed DV-12 to DA-11, reducing its ACE-inhibitory potency. Kinetic analysis showed that DV-12 had a Kᵢ of 8 μM, whereas DA-11 had a Kᵢ of 1.06 mM. Both peptides crossed epithelial barriers at low rates, with permeability coefficients of 9.96 × 10⁻⁸ and 8.23 × 10⁻⁸ cm·s⁻¹ for DV-12 and DA-11, respectively.
Interpretation
The study suggests that while microwave pretreatment can enhance peptide yield, the downstream functionality of these peptides can be significantly altered by digestion and transport processes. The reduction in ACE-inhibitory potency of DV-12 after digestion highlights the importance of considering structural modifications in peptide development. The low permeability rates suggest limited bioavailability, which may affect the clinical relevance of these findings.
Key findings
- 3.3-fold increase in peptide yield with microwave pretreatment.
- IC₅₀ of DV-12 for ACE inhibition was 57 μM.
- Simulated digestion reduced ACE-inhibitory potency of DV-12.
- Kᵢ for DV-12 was 8 μM, while DA-11 was 1.06 mM.
- Permeability coefficients were 9.96 × 10⁻⁸ and 8.23 × 10⁻⁸ cm·s⁻¹ for DV-12 and DA-11, respectively.
Limitations
- in vitro study
- reliance on simulated digestion models
- limited bioavailability data
- potential discrepancies between in vitro and in vivo outcomes