Conflicting actions of 4-vinylcatechol in rat lymphocytes under oxidative stress induced by hydrogen peroxide

Abstract

4-Vinylcatechol (4VC) has been identified as an aroma compound in roasted foods, especially coffee. It is also a component in traditional herbal medicines. This compound may be subconsciously ingested through foods and herbs. Recent experimental evidence has shown that 4VC possesses an antioxidative action. However, the antioxidative action of 4VC at cellular levels is not well characterized. The effects of 4VC (0.1-100 µM) were examined on rat thymic lymphocytes without and with oxidative stress induced by 300 µM hydrogen peroxide (HO). Cell treatment with 100 µM 4VC alone for 4 h significantly increased the population of dead cells. Thus, 4VC at 100 µM or above elicits cytotoxicity. However, 4VC at sublethal concentrations (1-10 µM) significantly attenuated the HO-induced increase in cell lethality in a concentration-dependent manner. While application of 10 µM 4VC slowed the process of cell death induced by HO, 4VC did not antagonize the HO-induced reduction of cellular nonprotein thiols. Although 4VC at 10 µM did not affect intracellular Ca and Zn levels, the agent potentiated the HO-induced increases in these levels. These actions of 10 µM 4VC are adverse to the cells under the oxidative stress. However, 10 µM 4VC partly attenuated the cell death induced by 100 nM A23187, a calcium ionophore. There are conflicting actions of 4VC at 1-100 µM on the cells under oxidative stress although the agent is used for an antioxidant. Thus, caution is required when using 4VC as a therapeutic agent.

Bioactivity of alginetin, a caramelization product of pectin: Cytometric analysis of rat thymic lymphocytes using fluorescent probes

“…Each cell suspension (100 μL) was analyzed using flow cytometry to assess alginetin-induced changes in cellular parameters. Fluorescence data acquisition from 3 × 10 3 cells required 10–15 s. In our previous study to examine the cytotoxicity of H 2 O 2 as oxidative stress and A23187 (Calcimycin), a divalent cation ionophore (Sigma-Aldrich Co, St. Louis, MO, USA) as Ca 2+ overload [ 6 ], the cells were incubated with H 2 O 2 or A23187 for 3–4 h to induce cell death in 20–40% of cells. Change in [NPT] i by alginetin was examined 2 h after the application in order to suggest the [NPT]i before the occurrence of cell death induced by H 2 O 2 .…”