**4. Conclusions**

Sulfavants are bioactive molecules able to induce DC maturation and trigger an adaptive immune response in vivo [13–15]. The activity of these products is largely dependent on the formation of colloidal particles under aqueous conditions [12]. Mixing diastereoisomers **2** and **3**, both active at nanomolar concentrations in pure form, determined a consistent decrease of the biological response in agreemen<sup>t</sup> with formation of supramolecular aggregates of di fferent size and stability. Multiple equilibria between free active monomers and di fferent aggregates control the concentration of the products able to bind the cellular targets, thus a ffecting the results of biological tests and accuracy of the evaluation of the therapeutic potential. In our opinion, this behavior is common to many other lipophilic or amphiphilic compounds, such as natural products, lipopeptides and glycolipids, whose activity can be significantly altered by supramolecular self-assembly in aqueous media. This e ffect could be more relevant in in vitro assays than in vivo trials since the presence of proteins and other molecules in the body fluids can reduce the tendency of these compounds to aggregate. Sulfavant S (**3**) was synthesized by a modified protocol involving the preparation of (*S*)-1,2- *O*-distearoylglycerol as an alternative acceptor of the glucosyl-trichloroacetimidate donor. This approach allows to overcome the technical issues arising by the low stereocontrol of the coupling reaction and represents a starting point for the preparation of other members of this new family of immunomodulatory agents.

**Author Contributions:** E.M. and A.F. conceived and coordinated the study. L.F., M.Z., G.N. and G.D. carried out the experimental works and data analysis. L.F., A.B. and A.F. (Antonio Fabozzi) DLS analysis. R.D.P. and C.G. performed biological tests. E.M. and A.F. (Angelo Fontana) wrote the manuscript with contributions of all coauthors. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded in the frame of the project ADViSE Antitumor Drugs and Vaccines from the SEa approved by Campania with D.D 403 of 12/11/2018 and integration D.D: n.422 of 16/11/2018.

**Acknowledgments:** E.M. and A.F. thank BioSEArch SRL for the generous support; moreover, the authors wish to thank European Union (FSE, PON Ricerca e Innovazione 2014–2020, Azione I.1 "Dottorati Innovativi con caratterizzazione Industriale") for funding a Ph.D. gran<sup>t</sup> to one of the authors (Laura Fioretto).

**Conflicts of Interest:** The authors declare no conflict of interest.
