Chromatographic purification of C-phycocyanin from Spirulina platensis: assessing antioxidant activity and stability

The efficient separation and purification of proteins like C-phycocyanin (C-PC) from Spirulina platensis are essential for their commercialization, yet they remain challenging. This study investigated three chromatographic methods for C-PC purification: weak anion exchange chromatography (DEAE), strong anion exchange chromatography (Q Sepharose), and hydrophobic interaction chromatography (HIC).

Weak anion exchange chromatography achieved a recovery of 36.80 mg unit (57.08%) with a purity of 3.23, outperforming Q Sepharose (yield: 23.21 mg unit means that 46.33%, purity: 2.76) and HIC (yield: 22.95 mg unit means that 17.57%, purity: 3.02). The purified C-PC consisted of α and β subunits with molecular masses of 16 kDa and 17 kDa, respectively. Further assessment revealed its antioxidant capacity through a 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The stability of C-phycocyanin was tested at different pH levels and temperatures. Maximum stability was observed at pH 7, and pH 4 showed the lowest stability. Glutaraldehyde-treated C-PC (GC-PC) demonstrated gradual degradation up to 50 °C, retaining 73.25% after 30 min. Notably, GC-PC exhibited stability even at higher temperatures, with degradation rates of 57.32% at 70 °C and 50.96% at 80 °C.

Weak anion exchange chromatography proved superior for C-PC purification, offering higher yields and purity than Q Sepharose and HIC. The purified C-PC showed promising antioxidant capacity and stability, particularly GC-PC, which exhibited resistance to degradation, even at elevated temperatures. These findings underscore the potential of C-PC as a valuable compound for various applications, with DEAE chromatography being an efficient method for its production and commercialization. © 2024 Society of Chemical Industry.