Progress in extraction, purification, chemical structure, bioactivities, and food preservation applications of polysaccharides from Portulaca oleracea L.

ETHNOPHARMACOLOGICAL RELEVANCE: Portulaca oleracea L. is a classic medicinal-edible herb with longstanding traditional use in treating inflammatory disorders, dysentery, skin infections, and metabolic conditions such as diabetes and hyperlipidemia. Polysaccharides (POPs) are among its major bioactive macromolecules and are considered key contributors to these therapeutic effects, supporting high translational value in foods and medicines. AIM OF THE STUDY: To systematically review advances in extraction-purification, structure, bioactivities, mechanisms and food preservation applications of POPs (2015-2025), and provide a theoretical basis for structure-activity research and industrial development. MATERIALS AND METHODS: Literature and patents were searched from CNKI, PubMed, Web of Science and patent databases using core keywords related to Portulaca oleracea, polysaccharides, extraction, purification, structure and bioactivities. RESULTS: Among the extraction methods reviewed, ultrasonic-enzymatic extraction was associated with the highest reported yield (21.2%), while hot water extraction was noted for its low cost. Purification methods include ethanol precipitation, column chromatography and macroporous resins. POPs are classified into neutral, acidic and heteropolysaccharides; their bioactivities have been linked to medium molecular weight (104-105 Da), high galacturonic acid content, and specific glycosidic linkages. Reported signaling pathways include NF-κB and PI3K/Akt, through which POPs exert antioxidant, cardiovascular-protective, anti-inflammatory, hypoglycemic, antitumor and immunomodulatory effects in preclinical studies. They also show potential applications in edible films and natural preservatives. CONCLUSIONS: POPs have diverse structures, potent preclinical bioactivities and favorable safety profiles, making them promising functional ingredients and preservatives, though clinical evidence remains limited. Key challenges are unclear structure - activity relationships, high costs and unstable quality. Future work should clarify structure - activity links, optimize green production and expand applications.