# Identification and In Vitro Evaluation of Milkfish (Chanos chanos) Frame Proteins and Hydrolysates with DPP-IV Inhibitory and Antioxidant Activities

## TL;DR

This study explores milkfish by-products as a source of peptides that may help manage type 2 diabetes and act as antioxidants.

## Contribution

The study identifies and evaluates milkfish frame proteins and hydrolysates for DPP-IV inhibition and antioxidant activity.

## Key findings

- Pepsin hydrolysis produced the highest DPP-IV inhibitory activity and peptide content.
- MFH showed improved bioactivity after ultrafiltration and simulated digestion.
- MFH was non-toxic and improved cell viability in TNF-α-induced hepatocytes.

## Abstract

The study presents the potential of milkfish frame, a by-product of milkfish processing, as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides with potential applications in type 2 diabetes management. Proteomic analysis identified key proteins, including 65 kDa warm temperature acclimation protein 1 and myosin heavy chain. In silico prediction (BIOPEP-UWM) guided the selection of proteases for generating DPP-IV inhibitory peptides. Enzymatic hydrolysates were produced and evaluated for bioactivity. Among the treatments, pepsin hydrolysis (2% v/v, 8 h) yielded the highest peptide content (283.64 mg/g), soluble protein (86.46%), and DPP-IV inhibitory activity (68.47%). The resulting milkfish frame pepsin hydrolysate (MFH) was further enhanced through ultrafiltration and simulated gastrointestinal digestion, which improved the DPP-IV inhibitory and antioxidant capacities. Cytotoxicity assays confirmed that MFH (0–100 μg/mL) was non-toxic to FL83B hepatocytes after 24 h. Moreover, treating TNF-α-induced FL83B cells with 10 μg/mL MFHs improved cell viability, reducing the toxicity induced by TNF-α in cells. These findings show that MFHs exhibit promising antidiabetic potential and could serve as natural alternatives to synthetic drugs for type 2 diabetes management. This also demonstrates the valorization of fish processing by-products into functional food ingredients, advancing sustainable approaches in food innovation.