Evidence of biological activity of Mentha species extracts on apoptotic and autophagic targets on murine RAW264.7 and human U937 monocytic cells

International audienceContext: Mints (Lamiaceae) are used as traditional remedies for the treatment of several diseases. Their extracts are recognized as anti-inflammatory compounds. Objective: This study characterized the cytotoxic effects of Mentha spicata L. (MS), Mentha pulegium L. (MP) and Mentha rotundifolia (L). Huds (MR) on macrophage cells (RAW264.7; U937) and determined their impact on apoptosis and autophagy, which can play a role in controlling inflammation. Materials and methods: The extracts were prepared in culture medium and tested from 25 to 400 mu g/mL after 24-48 h of treatment. To show the effect of the aqueous ethanol (50%) extracts on apoptosis and authophagy, the presence of cleaved caspase-3, and the conversion of LC3-I to LC3-II was evaluated by Western blotting. Results: Compared with the MTT assay, crystal violet showed a pronounced decrease in the number of cells with all extracts at 48 h. Calculated IC50 values were 257.31, 207.82 and 368.02 mu g/mL for MS, MP and MR, respectively. A significant increase in PI positive cells was observed with all extracts at 200-400 mu g/mL. Mitochondrial dysfunctions and nuclear morphological changes were detected with MS and MR extracts at 400 mu g/mL. At this concentration, no cleaved caspase-3 was found whereas stabilized caspase-3 in its dimeric form was identified. MS and MR extracts also favour LC3-I to LC3-II conversion which is a criterion of autophagy. Conclusions: The cytotoxic profiles depend on the extracts considered; MS extract showed the strong activity. However, all the mint extracts studied interact with the apoptotic and autophagic pathways at elevated concentrations

The effect of oxysterols on nerve impulses.

International audienceThe propagation of nerve impulses in myelinated nerve fibers depends on a number of factors involving the myelin and neural axons. In several neurodegenerative diseases, nerve impulses can be affected by the structural and biochemical characteristics of the myelin sheath and the activity of ion channels located in the nodes of Ranvier. Though it is generally accepted that lipid disorders are involved in the development of neurodegenerative diseases, little is known about their impact on nerve impulses. Cholesterol oxide derivatives (also called oxysterols), which are either formed enzymatically or as a result of cholesterol auto-oxidation or both, are often found in abnormal levels in the brain and body fluids of patients with neurodegenerative diseases. This leads to the question of whether these molecules, which can accumulate in the plasma membrane and influence its structure and functions (fluidity, membrane proteins activities, signaling pathways), can have an impact on nerve impulses. It is currently thought that the ability of oxysterols to modulate nerve impulses could be explained by their influence on the characteristics and production of myelin as well as the functionality of Na+ and K+ channels