Differences in extraction methods influence the physicochemical properties, antiradical, and anti-inflammatory effects of porphyran from Pyropia dentata.

The anti-inflammatory and anti-radical activities of Pyropia dentata porphyran (PDP) prepared by different extraction techniques were investigated. Water shaking extraction (WE), ultrasound extraction (UE), acid extraction (Aci.E), and alkaline extraction (Alk.E) yielded four pure constituents of PDP. Various PDPs were characterized for their chemical composition and structure. Alk.E-PDP exhibited the most potent anti-radical activity among the four PDP extracts. Alk.E-PDP demonstrated 81 % DPPH radical scavenging activity at 15 mg/mL, approximately two-fold higher than the other extracts. All four PDP extracts were also investigated for their anti-inflammatory and immunoregulatory functions using lipopolysaccharide (LPS)-stimulated THP-1 macrophages. WE-PDP stimulated the secretion of IL-6 (1250 pg/mL) and IL-10 (400 pg/mL) at 1 mg/mL in THP-1 macrophages. Under LPS-stimulated conditions, Alk.E-PDP reduced IL-6 levels from 200 to 100 pg/mL and TNF-α levels from 550 to 230 pg/mL. These results indicated that the obtained extracts can significantly inhibit LPS-induced inflammation and promote cytokine production in THP-1 cells. WE-PDP and Alk.E-PDP exhibited the most potent activities among the four extracts. Collectively, PDP's potential as a natural, non-toxic anti-inflammatory agent was demonstrated. PDP may be utilized in various biomedical applications, including vaccine adjuvants.