Design, Synthesis and Pro-Inflammatory Activity of Palmitoylated Derivatives of Thioglycolic Acid as New Immunomodulators

The immune system is essential for the defense against infections and is critically implicated in various disorders, including immunodeficiency, autoimmunity, inflammation and cancer. The current study includes a new design of palmitoylated derivatives of thioglycolic acids (PTGAs) capable of triggering innate immune responses. The new series were accessible through a three-step synthetic route, including N-palmitoylation, Claisen-Schmidt condensation and thia-Michael addition. Their structures were elucidated using different 1D and 2D NMR spectroscopic techniques and their purity was confirmed by elemental analysis. The most active PTGAs induced a 12-26-fold increase in the expression of TNF-α and IL-1β mRNA and triggered a marked release of NO in isolated macrophages. These levels were comparable to the responses elicited by heat-killed E. coli and S. aureus. The position of the palmitamide chain and aryl substitution had a significant effect on the TNF-α and IL-1β mRNA expression and NO release. Simulations of molecular dockings showed that the new PTGA derivatives occupy the same TLR2/TLR6 heterodimer active binding site of the microbial diacylated lipoproteins. The new immunomodulators may have a profound impact on various clinical disorders associated with dysfunctional innate immunity.