Novel LacdiNAc-specific lectin from Dioclea reflexa seeds exhibits inflammatory and hypernociceptive properties

Diocleinae lectins are well known for their prevalent affinity for glycomannosides. However, a rare subset displays specificity towards galactosides. This study describes the characterization of DrfL II, a novel lectin from Dioclea relexa seeds with specificity for N,N'-diacetyl-lactosamine (LacdiNAc). Isolated by lactose-affinity chromatography, DrfL II exists as a homotetramer formed by associations of a 29 kDa chainis a tetrameric lectin composed of identical 29 kDa subunits and strongly agglutinates rabbit erythrocytes, an activity inhibited by α-lactose. DrfL II binds preferentially to LacdiNAc (GalNAcβ1-4GlcNAc) over N-acetyl-lactosamine (LacNAc, Galβ1-4GlcNAc), functioning optimally between pH 6-8 and retaining stability up to 60 °C. Partial protein sequencing revealed homology with other legume lectins. Beyond its distinct carbohydrate specificity, DrfL II induced significant inflammatory and hypernociceptive responses in mice, as shown by paw edema and von Frey assays, while remaining non-toxic to Artemia nauplii. This finding expand our understanding of the galactoside-specific lectins within the Diocleinae subtribe, suggesting potential roles in physiological processes yet to be fully elucidated and potential biological application within the inflammation field.