In vitro response of human gingival epithelial S-G cells to resveratrol

Abstract

Resveratrol, a natural hydroxystilbene found in grapes and wine, may play an active role in the prevention of heart disease and cancer. Little is known of the biological activity of this molecule to cells of the oral cavity. The data presented herein provide an in vitro cytotoxicity profile of resveratrol to human gingival epithelial S-G cells. For comparative purposes, initial studies were performed with various human cell types. Based on midpoint cytotoxicity values with the neutral red (NR) assay, the sequence of sensitivity to resveratrol was: tongue squamous carcinoma SCC-25 cells>S-G cells>RHEK-1 keratinocytes≫fibroblasts (gingiva, periodontal ligament, and pulp). The neoplastic (SCC-25) and immortal, nonmalignant (S-G and RHEK-1) cells were one to three times more sensitive to resveratrol than were the low-passaged normal human fibroblasts. For the short-term assays, the sequence of sensitivity of the S-G cells to resveratrol was: BrdU ELISA (DNA synthesis)>NR (lysosomal integrity)>alamarBlue (redox status of the cell)>WST-1 (mitochondrial dehydrogenase activities). Arrest of cell growth, due to inhibition of DNA synthesis, may explain the leveling of toxicity between day 2 and 3 for a 3-day continuous exposure to resveratrol. Irreversible damage to cell proliferation was noted in S-G cells exposed to 75–150 μM resveratrol for 2 days and then subsequently maintained for another 3 days in resveratrol-free medium. The cytotoxicity of resveratrol was neither potentiated nor ameliorated in the presence of an hepatic S9 microsomal fraction. The cytotoxicity of hydrogen peroxide to S-G cells was lessened by N-acetyl- l-cysteine and quercetin, but not by resveratrol. For nitric oxide, only N-acetyl- l-cysteine reduced toxicity. The ability of resveratrol to function as an antioxidant was, therefore, not noted under these test conditions.