LAUSR

Previously 3 sesquiterpenoids from Conocephalum conicum (L.) Dum. (Conocephalaceae) were found to modulate lymphocyte response to different stimuli, suggesting their immunomodulatory potential. Herein we evaluated the impact of low concentrations of these sesquiterpenoids on rat splenocyte viability and membrane permeability, as well as lactate dehydrogenase (LDH) activity, in order to, possibly, shed light on their mechanism of action. After a 24 h incubation of splenocytes with the sesquiterpenoids (from 10−8 to 10−6 M), MTT and trypan blue (TB) assays, as well as histochemical staining for LDH, were performed. The tested compounds were shown not to reduce the ability of cells to metabolize MTT; however, cell membrane permeability to TB was altered, suggesting that a certain percentage of cells were dead. Histochemical staining for LDH presence releveled that only 2, out of the 3 sesquiterpenoids, decreased the staining intensity, indicating either LDH leakage or its inhibition. In conclusion, having in mind the already proven modulatory potential of the tested sesquiterpenoids, the present results suggest that through the changes in the cell membrane function and leakage/inhibition of LDH in unaltered immune cells, some of the tested compounds could be considered promising candidates for further research as anticancer agents.