Enhancement of neuroprotective effects of Spirulina platensis extract from a high-pressure homogenization process

Abstract

This study is the first to show that a simple high-pressure homogenization process (HP) could extract very heat-sensitive chlorophyll from a marine alga, Spirulina platensis. Up to 9.85 mg/g was produced at an optimal input pressure of 650 bar with a shear stress of approximately 20,000 (1/s) compared to 5.27 mg/g from conventional 70% ethanol extraction (EE) at 40 °C for 24 h. However, a higher input pressure did not increase the extraction yield and in fact decreased it, possibly due to the destruction of chlorophyll a at a high shear stress of approximately 50,000 (1/s) under 1370 bar of input pressure. Chlorophyll a and other components of the extract had additive effects, showing higher antioxidant activities of ca. 56% of DPPH radical scavenging activities than 10 μg/mL chlorophyll a alone, which corresponded to the same chlorophyll a content that existed in the extract. It was also confirmed that the high antioxidant activities of the HP extract reduced the production of reactive oxygen species (ROS) from glutamate-induced HT22 cells, which resulted in increased neuroprotective activity compared to EE and even chlorophyll a alone, in addition to effectively reducing the release of Ca2+ from nerve cells.