Structural Characterization and Immunomodulatory Activity of a New Oligosaccharide from Marine-Derived Penicillium Citrinum Scau-268

In this report, we detail the discovery and characterization of a new oligosaccharide, PCO-1, extracted from the culture broth of the marine fungus Penicillium citrinum SCAU-268. The molecular weight of PCO-1 was accurately measured to be 1476 Da, and its primary structure was identified as α-D-Glcp-(1,4)-α-D-Glcp-(1,4)-α-D-Glcp-(1,6)-α-D-Glcp-(1,6)-α-D-Glcp-(1,4)-α-D-Glcp-(1,4)-α-D-Glcp-(1,4)-α-D-Glcp-(1,4)-α-D-Glcp. Our results demonstrate that PCO-1 markedly elevated the secretion of cytokines IL-6, IL-1β, TNF-α, and nitric oxide (NO) in a concentration-dependent fashion. Metabolomic studies suggest that PCO-1 may act through the LACC1 pathway, promoting the conversion of citrulline to ornithine and modulating immune responses. In conclusion, our study has successfully elucidated the structure of the marine fungal-derived oligosaccharide PCO-1 and confirmed its potent immunomodulatory activity.