Neuroprotective Effects of Methyl Caffeate against Hydrogen Peroxide-Induced Cell Damage: Involvement of Caspase 3 and Cathepsin D Inhibition

Abstract

Finding effective neuroprotective strategies to combat various neurodegenerative disorders still remain a clinically unmet need. Methyl caffeate (MC), a naturally occurring ester of caffeic acid, possesses antioxidant and anti-inflammatory activities; however, its role in neuroprotection is less investigated. In order to better characterize neuroprotective properties of MC, we tested its effectiveness in various models of neuronal cell injury in human neuroblastoma SH-SY5Y cells and in mouse primary neuronal cell cultures. MC at micromolar concentrations attenuated neuronal cell damage induced by hydrogen peroxide (H2O2) in undifferentiated and neuronal differentiated SH-SY5Y cells as well as in primary cortical neurons. This effect was associated with inhibition of both caspase-3 and cathepsin D but without involvement of the PI3-K/Akt pathway. MC was neuroprotective when given before and during but not after the induction of cell damage by H2O2. Moreover, MC was protective against 6-OHDA-evoked neurotoxicity in neuronal differentiated SH-SY5Y cells via inhibition of necrotic and apoptotic processes. On the other hand, MC was ineffective in models of excitotoxicity (induced by glutamate or oxygen–glucose deprivation) and even moderately augmented cytotoxic effects of the classical apoptotic inducer, staurosporine. Finally, in undifferentiated neuroblastoma cells MC at higher concentrations (above 50 microM) induced cell death and when combined with the chemotherapeutic agent, doxorubicin, it increased the cell damaging effects of the latter compound. Thus, neuroprotective properties of MC appear to be limited to certain models of neurotoxicity and depend on its concentrations and time of administration.

Neuroprotective Properties of Kempferol Derivatives from Maesa membranacea against Oxidative Stress-Induced Cell Damage: An Association with Cathepsin D Inhibition and PI3K/Akt Activation

“…Interestingly, 0.7% ethanol did not change the extent of cell damage induced by the pro-apoptotic factor doxorubicin (Dox) ( Figure 4 c). Moreover, we confirmed the previous findings that the cell damage induced by H 2 O 2 or 6-OHDA in SH-SY5Y cells is oxidative stress-dependent [ 24 , 25 ] since the co-treatment with antioxidant (NAC) completely prevented the cell death evoked by these factors ( Figure 4 a,b).…”

“…Since our previous studies proved an involvement of caspase-3 and cathepsin D activation in the model of H 2 O 2 -evoked cell damage in SH-SY5Y cells [ 24 , 25 , 26 ], we examined whether or not the studied flavonols could affect these enzyme activities. IQ (50 µM), Krg (50 µM) and aRh (10 µM), when given alone, did not affect caspase-3 activity in UN- and RA-SH-SY5Y cells after 9 and 18 h of treatment, respectively ( Figure 6 a,b).…”

“…To the best of our knowledge, the compounds have never been investigated in this respect, until now. Undifferentiated (UN-SH-SY5Y) and retinoic acid-differentiated (RA-SH-SY5Y) neuroblastoma cell cultures were used for the purpose as a reliable experimental model in the initial screening for the potential neuroprotective agents [ 24 , 27 , 29 ]. Out of the three investigated compounds (IQ, Krg and aRh) only aRh at the concentration of 50 µM, after 48 or 72 h treatment, diminished proliferation of SH-SY5Y cells.…”

“…As H 2 O 2 -induced cell damage usually increases caspase-3 and cathepsin D (lysosomal aspartyl protease) activities in SH-SY5Y cells [ 24 , 25 , 26 ], the next step in our research was an examination on whether the tested compounds affected activities of the enzymes. Only aRh (1 µM) significantly reduced caspase-3 activity in both UN-SH-SY5Y and RA-SH-SY5Y cells.…”

Methyl Caffeate Isolated from the Flowers of Prunus persica (L.) Batsch Enhances Glucose-Stimulated Insulin Secretion

“…Interestingly, methyl caffeate ( 6 ) has a better effect than its free acid form, caffeic acid ( 5 ). Several studies on the biological activities of methyl caffeate ( 6 ) have reported its neuroprotective [ 36 ], anticancer [ 37 ], antioxidant [ 38 ], and anti-inflammatory effects [ 39 ] as well as antimicrobial and antimycobacterial activities [ 40 ]. Additionally, the induction of pancreatic islet β-cell regeneration by methyl caffeate ( 6 ) has also become clear [ 21 ], as its oral administration improved glucose tolerance in rats.…”