Phycocyanobilin: A potential bioactive compound from Arthrospira platensis targeting LYN protein associated with systemic lupus erythematosus

Abstract

Phycocyanobilin, a bioactive compound derived from Arthrospira platensis C1, was investigated for its potential role in systemic lupus erythematosus (SLE) based on its structural similarity to bilirubin, with a Tanimoto score of 93%. Molecular docking revealed favorable binding affinities between phycocyanobilin and several protein targets, including EGFR, FYN, HLA-B, LCK, LYN, and TP53. 

Introduction

Systemic lupus erythematosus (SLE) is an autoimmune disease with a broad spectrum of clinical manifestations and an unclear etiology. The disease affects multiple organ systems and is associated with increased morbidity and mortality .Although immunosuppressive drugs can induce disease remission, relapses may still occur and are often unpredictable. Various factors, including sunlight exposure and stress, can trigger disease flares.

Materials and methods

Structural similarity between bioactive compounds of Spirulina and bilirubin
The structural similarity between bioactive compounds of Spirulina (A. platensis C1) and bilirubin was analyzed using the PubChem structural similarity tool based on compound identifiers (CIDs) (https://pubchem.ncbi.nlm.nih.gov/score_matrix/score_matrix.cgi)]. A total of 833 bioactive compounds from A

Molecular docking and molecular dynamics simulations of bioactive compounds and targets
To determine whether phycocyanobilin exhibits molecular signaling effects similar to bilirubin, the binding affinities of these two compounds toward several related receptors were evaluated using molecular docking. This approach aims to identify the most favorable binding modes between ligands and receptors

Results

Molecular docking of bioactive compounds and targets

We first assessed the structural similarity between bioactive compounds of Spirulina (A. platensis C1) and bilirubin. The results showed that bilirubin (https://pubchem.ncbi.nlm.nih.gov/compound/5280352#section=2D-Structure) shares a high Tanimoto score of 93% with phycocyanobilin (https://pubchem.ncbi.nlm.nih.gov/compound/137699530#section=2D-Structure), a notable bioactive compound in Spirulina

Discussion

In SLE patients, oxidative stress increases with disease activity. Previous studies have shown that serum bilirubin levels are negatively correlated with disease activity. Reduced bilirubin levels in SLE may be associated with inflammation and lupus-related renal involvement [3–5]. Bilirubin likely plays an important role in controlling oxidative stress, and its reduction may result from increased consumption under conditions of severe oxidative stress

Conclusions

Serum bilirubin levels in patients with SLE are negatively correlated with disease activity. Phycocyanobilin, a bioactive compound derived from Arthrospira platensis C1, showed high structural similarity to bilirubin (93%). Multiple complementary computational approaches, including molecular docking, target prediction, pathway enrichment, molecular dynamics simulations, and binding free energy analyse

Citation: Chaiprasert A, Han P, Laomettachit T, Ruengjitchatchawalya M (2026) 
Phycocyanobilin: A potential bioactive compound from Arthrospira platensis targeting LYN protein associated with systemic lupus erythematosus. PLoS One 21(8): e0357093. https://doi.org/10.1371/journal.pone.0357093

Editor: Eman Zahran, Mansoura University, EGYPT

Received: September 17, 2025; Accepted: August 8, 2026; Published: August 28, 2026

Copyright: © 2026 Chaiprasert et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Abbreviations: SLE, systemic lupus erythematosus; CID, compound identifier