In this study, a high-temperature extracting procedure; was developed to isolate phlorotannin extracts from U. pinnatifida sporophyll (PEUPS). The heating temperature, heating time, and extraction solvent (i.e., ethanol) concentration study by the response surface method (RSM); to determine the optimal conditions to achieve the maximum extraction rate. In addition, PEUPS evaluate for their antioxidant and anti-inflammatory activities.
Phlorotannins are generally found as complexes within algae cell wall components; which greatly limits its extraction with common protocols used typically for fruits, vegetables, and grains which have less rigid cell wall structures. Hence, utilization of advance extraction procedures such as centrifugal partition extraction (CPE), supercritical fluid extraction (SFE); pressurized liquid extraction (PLE), and enzyme-assisted extraction (EAE) has become necessary.
Antioxidant activity of the PEUPS
Undaria pinnatifida (U. Pinnatifida) is a brown algae that normally grows in the seas of China; Korea, and Japan. During 2015, around 193,000 tons harvested in China; while the worldwide production reached 2,359,000 tons. In order to assess the effect of ethanol concentration; on the total phlorotannin content (TPC) and antioxidant activity of the PEUPS, four ethanol concentrations (25%, 50%, 75%, and 100%) test with heating temperature of 115 °C and heating time of 4 h.
To investigate the antioxidant and anti-inflammatory properties of the PEUPS; we used RAW 264.7 macrophage cells as a model system and epigallocatechin gallate (EGCG) as a positive control. Results were consistent with previous studies; which report that phlorotannins can develop into a potential bio-molecular candidate to inhibit ROS formation.
The chronic presence of nitric oxide (NO) is associated with various carcinomas; and inflammatory conditions. The anti-inflammatory characteristics of phlorofucofuroeckol A isolated from Ecklonia cava has studied in LPS-stimulated RAW 264.7 cells. the immunomodulatory activity assessment; the PEUPS did not show any cytotoxic effect on the RAW 264.7 cells. The NO production of PEUPS at the concentration of 80 μg/mL (procedure 1) was 0.57 ± 0.02 μmol/mL.
It seemed not to inhibit COX-2 protein expression much, different from EGCG; which down-regulates both iNOS and COX-2. Nonetheless, PEUPS is clearly a good anti-inflammatory agent that could reduce stimulated NO production in RAW 264.7 macrophages. In the current study, a group of single-factor experiments coupled with RSM modeling utilized to optimize the extraction conditions for phlorotannins from U. pinnatifida sporophyll.
In the current study, a group of single-factor experiments coupled with RSM modeling utilized to optimize the extraction conditions for phlorotannins from U. pinnatifida sporophyll. The optimal conditions obtained are: heating temperature of 170 °C, heating time of 5.2 h, and an ethanol concentration of 52% with a yield of 10.7 ± 0.2 mg GAE/g DW. The PEUPS exhibited strong antioxidant and anti-inflammatory activities in vitro. These findings suggest that there is a good potential for the utilization of PEUPS in the design and development of novel functional foods and food supplements.