Structural characterization and anticancer properties of a novel mushroom-derived rhamnogalactan in a triple-negative...

Mushroom-derived polysaccharides are known for their diverse biological activities, including immunomodulatory and anticancer properties. Breast cancer, the leading cause of cancer-related death among women worldwide, lacks targeted molecular therapies, underscoring the need for novel therapeutic agents. In this study, we extracted, purified, and characterized a novel heteropolysaccharide (HTP) - a rhamnogalactan - composed of galactose (72.6 %) and rhamnose (27.4 %) from the edible mushroom Lactarius quieticolor. Structural analysis revealed that HTP consists of a (1 → 6)-linked α-d-galactopyranose backbone, heavily substituted at O-2 by non-reducing rhamnose units, with a weight-average molar mass of 2.41 × 10⁴ g.mol^-1. In vitro assays using a triple-negative breast cancer (TNBC) cell model - the most aggressive subtype - showed a significant reduction in cell viability (50 % at 1200 μg·mL^-1). Furthermore, an additive effect was observed when co-administered with the chemotherapy drug paclitaxel, reducing the cell viability to 42 %. These findings suggest potential therapeutic applications of the purified mushroom rhamnogalactan reported in this study against TNBC.