# A Phycoerythrin-SOD Fluorescent Probe Enables Detection of Oxidative Stress for Assessing Astaxanthin in NAFLD

## TL;DR

A new fluorescent probe detects oxidative stress in liver disease and shows that astaxanthin can reduce liver damage.

## Contribution

A novel Phycoerythrin-SOD fluorescent probe was developed for real-time SOD activity monitoring in NAFLD.

## Key findings

- The Phycoerythrin-SOD probe effectively detected SOD activity in NAFLD models.
- Astaxanthin reduced triglyceride and cholesterol levels in NAFLD-affected cells.
- Astaxanthin restored 60% of SOD activity to control levels in NAFLD cells.

## Abstract

Objective: To develop a superoxide dismutase (SOD) fluorescent detection probe based on Phycoerythrin (PE) from Porphyridium cruentum for real-time monitoring of SOD activity, a core biomarker of oxidative stress, in a nonalcoholic fatty liver disease (NAFLD) model, and to explore the regulatory effect of astaxanthin. Methods: Phycoerythrin and SOD were covalently coupled using the heterobifunctional cross-linker N-Succinimidyl 3-(2-pyridyldithio) propionate (SPDP), and the probe concentration and incubation time were optimized. A NAFLD model was established in HepG2 cells induced by free fatty acids (FFAs). The fluorescence intensity of the probe was detected by flow cytometry, and the intervention effect of astaxanthin was evaluated by measuring triglyceride (TG)/total cholesterol (TC) contents and SOD activity. Results: The optimal conditions for the Phycoerythrin-SOD probe were determined. Astaxanthin at 20 μM significantly reduced FFA-induced TG (56.8%) and TC (63.6%) contents and restored SOD activity to 60% of that in the control group. Conclusion: The Phycoerythrin-SOD probe serves as an efficient tool for dynamic monitoring of SOD activity in NAFLD. Astaxanthin alleviates liver injury by multi-target regulation of lipid metabolism and antioxidant pathways.