A novel in vivo adjuvant activity of hydrocarbon isolated from Hippophae rhamnoides

The new generation vaccines containing purified antigens are safer to use but generally induce weaker immune responses. Therefore, purified subunit vaccines require the addition of an exogenous adjuvant to enhance the immune response to the antigens following immunization. In the present study, a molecule has been isolated and characterized from 70% ethanolic extract of the medicinal plant Hippophaerhamnoides L. (Elaeagnaceae), commonly known as seabuckthorn (SBT). In this study, we have fractionated SBT leaf extract using solvents to identify the bioactive compound(s) and evaluated its adjuvant efficacy with weak antigen ovalbumin in balb/c mice. The identified bioactive compound was found to have a hydrocarbon moiety and was identified as alkane (named SSFa1), which in combination with ovalbumin boost humoral response in terms of high antibody titers, cell-mediated immune response such as T cell activation marker (CD27), and increased nitric oxide and proinflammatory cytokines (TNF-a and IL-6) production by peritoneal macrophages.