Extraction yield and biological activity of phycobiliproteins from Porphyridium purpureum using atmospheric cold plasma discharge and jet systems

Phycobiliproteins (PBPs) extracted from Porphyridium purpureum (P.p) have bioactive properties and are widely used as ingredients in nutraceutical and food applications. This study investigated the use of two cold plasma systems, namely cold plasma discharge system (CPDS) and cold plasma jet system (CPJS), for the aqueous extraction of PBPs from P. p. Three types of PBPs, namely phycoerythrin (PE), phycocyanin (PC) and allophycocyanin (APC) were identified in the crude extracts obtained. The highest PBPs extraction yield (11.31 ± 1.02 mg/g DW P. p) was obtained from CPDS treated samples at 25 kV using N2 for 9 min. CPDS treatments were also shown to be more effective than CPJS treatments in increasing antioxidant activities of the PBPs crude extracts obtained. PBPs crude extracts obtained using CPDS (25 kV; 6 min; N2) had the highest DPPH (69.44 ± 0.10%) and FRAP (207.34 ± 12.96 μmol/L) antioxidant activities observed. PBPs obtained from samples treated with CPDS (25 kV; 9 min; N2) exhibited the highest cytotoxicity potential in Caco-2 human colorectal adenocarcinoma cell lines. This study demonstrates that cold plasma treatments increase the extraction yield of PBPs obtained from P. p and also enhance antioxidant and cytotoxic properties of the PBP crude extracts. However, an increase in treatment time beyond 6 min for both plasma systems was shown to reduce the level of antioxidant activity in PBPs.