Comparative Analysis of Antioxidant, Macrophage Proliferation, and Nitric Oxide Scavenging Properties of Molecular Weight–Fractionated Polysaccharides Derived From Protaetia brevitarsis seulensis Larvae

Polysaccharides extracted from Protaetia brevitarsis seulensis larvae were separated into three fractions based on their molecular weights, and the biological activities of each fraction were evaluated: L-PBSL (Mw: < 3.5 kDa), I-PBSL (Mw: 3.5–13 kDa), and H-PBSL (Mw: > 13 kDa). All PBSL fractions exerted antioxidant activities at 0.5–2 mg/mL, with L-PBSL producing the greatest effect: 19.34%–42.93% ABTS radical scavenging activity. Additionally, dramatic increases in macrophage proliferation were induced by 25–100 μg/mL L-PBSL and I-PBSL treatments, which were confirmed to be driven by a prolongation of the S-phase of the cell cycle. Finally, 100 μg/mL L-PBSL and I-PBSL treatments significantly decreased the nitric oxide produced by LPS-treated macrophages, with 62% and 43% reductions, respectively. Also, an LPS-conditioned medium model confirmed that L-PBSL and I-PBSL directly scavenge secreted nitric oxide. In summary, this study characterized the antioxidant, macrophage stimulatory, and nitric oxide scavenging activities of PBSL in relation to their molecular weight, with L-PBSL, the polysaccharides with a molecular weight below 3.5 kDa, showing significantly greater effects.