Figure 1

Chemical structure and DC activation of natural sulfoquinovosides (α-SQDG) from marine diatoms. (A) Structures of DC agonists: monophosphoryl lipid A (MPLA, 1) (reference compound), natural α-SQDG (2) and synthetic (3-5) α-SQDG. Colors underline the chemical differences in type and position of the anionic function, configuration of the anomeric carbon, second sugar residue and fatty acid acyl chain between MPLA (1) and α-SQDG (2-5); (B) LC-MS profile of active α-SQDG (2) in the extract of the marine diatom Thalassiosira weissflogii. The insert reports the type and distribution of fatty acids bound to the sulfoquinovosyl glycerol residue; (C) expression of IL-12 (mean/standard deviation) and (D) expression of HLA-DR by MoDCs stimulated with natural and synthetic analogs of α-SQDG at 10 ng/mL and 10 µg/mL. Results (mean +/− standard deviation) are reported as percentage of positive cells (marker expression value over 10⁴) out of the total DC population. LPS was used as positive control. Asterisks indicate significant differences from the cells treated only with vehicle (control, Ctr) at a 95% (P < 0.05) confidence level, as determined using two-way ANOVA analysis.