數種花果萃出物及 stilbenoids 化合物之抗氧化活性與線蟲模式下之抗老化功效

Abstract

Aging is a progressive phenomenon of losing physiological function, behavior and cognitive ability over time. Previous studies have pointed out that oxidative stress is an important factor that causes aging. Therefore, some previously shown antioxidative materials were chosen, including water extract of Longan flower (Dimocarpus longan Lour.) (L-W), water extract of mulberry (Morus alba Linn.) (M-W), water extract of roselle (Hibiscus sabdariffa Linn.) (R-W), water fraction from ethanol extract of embryo of Nelumbo nucufera Gaertn.(N-E-W), stilbene glycoside from Polygonum multiflorum Thunb.(PM-SG) and pterostilbene. The objective is to investigate the anti-aging ability of these materials in the Caenorhabditis elegans model. The first part of this study was the chemical in vitro antioxidative experiments, including DPPH free radicals scavenging assay, trolox equivalent antioxidant capacity assay, oxygen radical absorbance capacity assay, reducing power assay and total polyphenols analysis. Results showed that L-W, PM-SG and pterostilbene had excellent activities followed by N-E-W, M-W and R-W. The second part of this study was the cellular antioxidant activity assay. The concentrations of each sample used in the assay were determined according to the cytotoxicity of each sample on Hep G2 cell. Results showed that L-W had the best cellular antioxidant activity with EC50 value 25.51 ± 2.17 μg/mL, followed by PM-SG (EC50 = 211.35 ± 34.11 μg/mL), N-E-W (EC50 = 457.83 ± 34.33 μg/mL) and M-W (EC50 = 776.66 ± 28.20 μg/mL). At 500 μg/mL R-W still did not have apparent activity while the cytotoxicity of pterostilbene was too high to express its antioxidant activity. Compared with the results of chemical antioxidant experiments, there were large differences in the activities of PM-SG and pterostilbene, indicating that the cellular antioxidant activity of these two compounds were influencesd by the structure. The third part of this study was the anti-aging tests in C. elegans model. We first investigated the lifespan prolonging effects of different samples. Results showed that only PM-SG、L-W and N-E-W had apparent anti-aging activities, with greatest degree of lifespan extention of 15.8%, 17.1% and 15.5%, respectively. Compared with the results of chemical antioxidant experiments, only samples exhibiting cellular antioxidant activities demonstrated anti-aging effects. Further examination of the effects of PM-SG、L-W and N-E-W on age-related changes of physiological processes, the results showed that PM-SG, L-W and N-E-W did not influence the self-fertile reproductive span, but did delay the decrease of pharyngeal pumping rate. This finding indicated that the lifespan prolonging effects of the three samples were not via influencing reproduction ability. On the other hand, since pharyngeal pumping rate had already been proved as one of the aging index, the finding of pharyngeal pumping rate test can be another evidence of the anti-aging ability of these samples. In addition, experiments to test if PM-SG, L-W and N-E-W are helpful to worms to resist the environmental pressure were also conducted, and the results showed that PM-SG, L-W and N-E-W can improve the survival rate of worms under thermal-stress, with greatest degree of lifespan extention of 46.8%, 53.6% and 32.3%, respectively. Only PM-SG and L-W, however, are helpful to worms to resist the oxidative-stress from H2O2, with greatest degree of lifespan extention of 81.7% and 113.7%, respectively. We speculated that the oxidative-stress was too high in this system, so that N-E-W with less antioxidant activity, can not express its antioxidant ability. In summery, samples, which showed better in vitro antioxidant activity, seemed to be the more effective ones in anti-aging tests in C. elegans model as well. This indicated that antioxidant activities correlate closely to anti-aging effects.