Immunoinhibitory Effect of Teuclatriol a Guaiane Sesquiterpene from Salvia mirzayanii

Background: Salvia mirzayanii, a native plant to Iran, is shown to have immunomodulatory effects on lymphocyte proliferation. Objective: To identify the bioactive immunomodulatory compound(s) present in S. mirzayanii. Methods: The crude extract was fractionated to five fractions in two steps using different solvents. The fractions were subjected to bioassay-guided fractionation. All the fractions were tested for bioactivity on human activated-peripheral blood lymphocytes (PBLs) using cell proliferation assay. Results: The methanol fraction (Fr. M) showed the highest inhibitory effect on PBLs compared to other fractions. Fr. M was applied on a gravity column chromatography for further fractionation. Resultant fractions, demonstrated inhibitory effects at higher concentrations. Fr. 4 with an 18.9 ± 0.2% inhibitory activity at 200 μg/ml and with the highest quantity was applied on preparative TLC plates for further purification. The final purified compound was identified as teuclatriol, a guaiane sesquiterpene, by NMR analysis. This compound showed a significant anti-proliferative effect on human activated- peripheral blood lymphocytes (IC50, 72.8 ± 5.4 μg/ml). Conclusion: Teuclatriol was found to be one of the compounds responsible for the immunoinhibitory effect of Salvia mirzayanii. We suggest further studies on teuclatriol, exploring its mechanism of action as an immunomodulatory compound.