Bioactive Properties of Alcalase-Derived Spirulina platensis Protein Hydrolysate: Amino Acid Composition, Antioxidant and Antiproliferative Activities (Early view)

Abstract

Spirulina platensis is a microalga rich in protein and bioactive compounds, offering potential as a natural antiproliferative agent. However, in its dried biomass form, the biological activity of its native proteins remains relatively low. This study aimed to investigate the potential use of S. platensis as a source of bioactive peptides by analyzing the amino acid profile, antioxidant through ABTS, FRAP, DPPH assays and antiproliferative activity of S. platensis protein hydrolysate. Protein extraction was performed using a combination of freeze-thawing and ultrasonication methods, followed by alcalase enzymatic hydrolysis at 55 °C and pH 8 for 2 hours. The resulting hydrolysate was characterized in terms of yield, degree of hydrolysis (DH), molecular weight distribution, amino acid profile, secondary structure, and antioxidant activity (ABTS, FRAP, and DPPH assays), as well as cytotoxicity assessed by the MTT assay. The hydrolysate protein of S. platensis showed a DH of 44.1 ± 0.20%, with a dominant molecular weight fraction below 20 kDa, and antioxidant activity with IC₅₀ 9.03 ± 0.25 ppm (ABTS), 22 ± 1.04 µg TE/mL (FRAP), and 44 ± 2.04 ppm (DPPH). Cytotoxicity analysis revealed a dose-dependent relationship between hydrolysate concentration and cytotoxic effects on MCF-7 cells. The highest cytotoxic activity of S. platensis protein hydrolysate was observed at 1000 ppm, reducing cell viability to 45.91±5.62%. These findings suggest that S. platensis protein hydrolysate has promising potential as a natural antiproliferative candidate.