Toxicity Of Polyphenols Research Articles

In silico approach towards polyphenols as targeting glucosamine-6-phosphate synthase for Candida albicans

Candida albicans is one of the most common species of fungus with life-threatening systemic infections and a high mortality rate. The outer cell wall layer of C. albicans is packed with mannoproteins and glycosylated polysaccharide moieties that play an essential role in the interaction with host cells and tissues. The glucosamine-6-phosphate synthase enzyme produces N-acetylglucosamine, which is a crucial chemical component of the cell wall of Candida albicans. Collectively, these components are essential to maintain the cell shape and for infection. So, its disruption can have serious effects on cell growth and morphology, resulting in cell death. Hence, it is considered a good antifungal target. In this study, we have performed an in silico approach to analyze the inhibitory potential of some polyphenols obtained from plants. Those can be considered important in targeting against the enzyme glucosamine-6-phosphate synthase (PDB-2VF5). The results of the study revealed that the binding affinity of complexes theaflavin and 3-o-malonylglucoside have significant docking scores and binding free energy followed by significant ADMET parameters that predict the drug-likeness property and toxicity of polyphenols as potential ligands. A molecular dynamic simulation was used to test the validity of the docking scores, and it showed that the complex remained stable during the period of the simulation, which ranged from 0 to 100 ns. Theaflavins and 3-o-malonylglucoside may be effective against Candida albicans using a computer-aided drug design methodology that will further enable researchers for future in vitro and in vivo studies, according to our in silico study. Communicated by Ramaswamy H. Sarma

Cytometric Analysis of Cytotoxicity of Polyphenols and Related Phenolics to Rat Thymocytes: Potent Cytotoxicity of Resveratrol to Normal Cells

The chemopreventive and chemotherapeutic actions of polyphenols and related phenolics have received considerable attention since these compounds induce apoptosis in several types of cancer cells in vitro. A plausible criterion for the use of such compounds is that they should not exert any toxic effect on normal cells. However, information about the toxicity of polyphenols and related phenolics to normal cells is limited. In this study, the effects of polyphenols and related phenolics on rat thymocytes were examined by flow cytometric analysis with appropriate fluorescent probes. The compounds examined in this study were caffeic acid, rosmarinic acid, chlorogenic acid, (+)-catechin, 6-gingerol, sesamol, resveratrol, and eugenol. Of these, resveratrol was the most cytotoxic on rat thymocytes incubated for 24 hrs with 100 microM of this compound. Resveratrol at a concentration of 10 microM or more (up to 100 microM) led to a significant dose-dependent increase in the population of dead cells, shrunken living cells, annexin V-positive cells and cells with hypodiploidal DNA. In the presence of benzyloxycarbonyl-Val-Ala-Asp (OMe) fluoromethylketone (Z-VAD-FMK), a pan-inhibitor of caspases, the resveratrol-induced increase in the population of cells with hypodiploidal DNA was partially inhibited. Overall, it is suggested that resveratrol at a concentration of 10 microM or more induces apoptosis in normal cells as well as cancer cells (previously reported elsewhere). Thus, at concentrations that are suitable for chemopreventive and chemotherapeutic actions, resveratrol may exert a cytotoxic effect on normal cells.

CYTOTOXIC AND CYTOSTATIC EFFECTS OF POLYPHENOLS AGAINST RAT 3Y1 FIBROBLASTS TRANSFORMED BY E1A GENE OF HUMAN ADENOVIRUS-TYPE-12

Toxicity of polyphenols against rat 3Y1 fibroblasts and the cells transformed by human adenovirus (Ad12-3Y1), its EIA gene (EIA-3Y1), or simian virus 40 (SV-3Y1) was examined. Among the diphenol compounds examined, pyrocatechol (o-diphenol) and hydroquinone (p-diphenol) showed selective toxicity against Ad12-3Y1 and EIA-3Y1 cells, while resorcinol (m-diphenol) showed a much weaker non-specific toxicity against these cells. Another o-diphenol (dopamine) and triphenols (gallic acid and pyrogallol) were less toxic but showed selective toxicity. At lower concentrations where they were not toxic, all polyphenols attenuated toxicity of phosphatidylcholine against EIA-3Y1 cells. Among antioxidants examined, ascorbic acid reduced the toxicity of pyrocatechol, but alpha-tocopherol and butyrated hydroxytoluene did not. Oxidation of pyrocatechol was not enhanced in the presence of 3Y1 or EIA-3Y1 cells and their homogenates. These results suggest that the selective toxicity of polyphenols against Ad12-3Y1 and E1A-3Y1 cells is not related to their oxidation velocity but other factors such as the activity of active oxygen-scavenging enzymes.