(P06-012-23) A Study on the Optimal Extraction and Drying Method To Enhance the Antioxidant and Anti-Inflammatory Activity of Melosira nummuloides, a Microalgae

Objectives: Melosira nummuloides is a microalga belonging to the Melosiracease diatom. The ability of the diatoms to mass-produce essential fatty acids and carotenoid pigments was reported. We hypothesized that when applying various extraction and drying methods to increase the nutritional value of Melosira, it could affect the composition of Melosira's physiologically active substances and its antioxidant and anti-inflammatory effects.

Methods: The total polyphenol content (TPC) and total flavonoid content (TFC), the 2,2-diphenyl-1-picrylhydrazyl(DPPH) radical-scavenging activity and 2,2ʹ-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging activity assay were determined for antioxidant activity. Inhibition of nitric oxide (NO) production and the cytoprotective effect against inflammatory damage induced by LPS was examined studied in H₂O₂-Induced RAW 264.7 Cells. Gas chromatography-mass spectrometry (GC/MS) analysis and Gas chromatography with flame ionization detection (GC-FID) analysis, and High-performance liquid chromatography (HPLC) analysis were performed to compare the composition of all these extracts.

Results: The C:M(2:1) extract showed the greatest  TPC, DPPH• and ABTS• radical scavenging activity, and anti-inflammation activity among other solvent extracts. Through GC-MS and GC-FID analysis, it was confirmed that lipophilic compounds were significantly higher in freeze-dried samples than in hot air-dried samples. The Pearson Product-Moment Correlation analysis showed a significant positive relationship between TPC, palmitoleic acid, myristic acid, α-linolenic acid, stearic acid, heptadecanoic acid, palmitic acid and DPPH•, ABTS• radical scavenging activity and inhibitory activity NO production, suggesting their role for Melosira nummuloides extract in supporting the antioxidant, and anti-inflammatory potential.

Conclusions: Melosira nummuloides can be used to develop food products with enhanced antioxidant and anti-inflammatory activities, and provide insight into the appropriate application of extraction and drying methods of raw Melosira.

Funding Sources: This study was funded by the Ministry of Oceans and Fisheries, Korea with the JDK BIO organization.