Anti-Inflammatory Activity of a Phycocyanin–Protein Complex in THP-1 Cells: Implications for Dermocosmetic Applications

Phycocyanin, a phycobiliprotein derived from the cyanobacterium Limnospira (Arthrospira) platensis (commonly known as Spirulina), is recognized for its antioxidant, immunomodulatory, and bioactive properties. This research aims to develop a new cosmetic ingredient based on phycocyanin incorporated into a high-lipid matrix, such as shea butter. A comprehensive characterization of the cytotoxicity and anti-inflammatory activity of this new bioactive phycocyanin–protein complex in human THP-1 monocytic cells was performed. For this purpose, cytocompatibility was evaluated using MTT assays at concentrations ranging from 10 to 0.0006% v/v. Anti-inflammatory activity was measured under LPS-induced inflammatory stress by measuring IL-6 and IL-8 secretion using ELISA in PMA-differentiated THP-1 cells treated with non-cytotoxic concentrations (0.04, 0.02, and 0.01% v/v). A crucial finding was the absence of anti-inflammatory activity at 0.01% v/v, indicating a minimum effective concentration threshold and, consequently, effective doses. The results of this research indicate that the phycocyanin and shea butter ingredients demonstrate strong cytocompatibility at relevant cosmetic doses and significant anti-inflammatory activity, supporting their suitability for formulations targeting skin sensitivity, erythema reduction, and post-inflammatory recovery.