Development of novel lipidated analogs of picroside as vaccine adjuvants: acylated analogs of picroside-II elicit strong Th1 and Th2 response to ovalbumin in mice.

The acylated analogs of picroside-II were synthesized and tested for immune-adjuvant activity in the presence of weak antigen ovalbumin found to stimulate anti-OVA IgG titer, neutralizing antibody (IgG1 and IgG2a) titer as well as the production of soluble mediators of a Th1 response (IL-2 and IFN-γ) and Th2 response (IL-4) and proliferation of T lymphocytes sub-sets (CD4/CD8). Furthermore, these modified analogs of picroside-II were able to elicit a substantial increase in anti-OVA IgG when compared with OVA alone. These results support the use of acylated analogs particularly PK-II-3 and PK-II-4 as potent enhancer of antigen-specific Th1 and Th2 immune responses and thus are promising immune-adjuvant candidate for vaccines.