Taurine prevents oxidative damage of high glucose-induced cataractogenesis in isolated rat lenses.

Diabetic cataract is an ocular disease represented as blindness by lens opacification. Oxidative as well as osmotic stress caused by accumulation of polyols within the lens has been shown to be associated with glucose-induced cataractogenesis. Taurine has an antioxidant capacity and its level in diabetic cataractous lens is markedly decreased. Therefore, we investigated whether taurine is a part of antioxidative defense mechanism involved in protecting the lens against high glucose-induced oxidative stress and tissue damage. Lenses were isolated from male Sprague-Dawley rats weighing about 180-200 g and cultured in high glucose medium (55.6 mM) for 6 d as a model of high glucose-induced cataractogenesis. To investigate the antioxidative effect of taurine, 30 mM taurine was added in normal medium for 2 d before the addition of high glucose. The culture of lenses in high glucose medium increased the weight and opacity of lenses of and the carbonylated protein level, and decreased glutathione (GSH) content. Although there were no significant effects of taurine on the weight or opacity of lenses, pretreatment of lenses with 30 mM taurine significantly reversed the level of protein carbonylation and GSH to those of controls. Therefore, taurine might spare GSH and protect the lens from oxidative stress induced by a high concentration of glucose.

Apoptotic effect of IP(6) was not enhanced by co-treatment with myo-inositol in prostate carcinoma PC3 cells.

Inositol hexaphosphate (IP(6)) is a major constituent of most cereals, legumes, nuts, oil seeds and soybean. Previous studies reported the anticancer effect of IP(6) and suggested that co-treatment of IP(6) with inositol may enhance anticancer effect of IP(6). Although the anticancer effect of IP(6) has been intensively studied, the combinational effect of IP(6) and inositol and involved mechanisms are not well understood so far. In the present study, we investigated the effect of IP(6) and myo-inositol (MI) on cell cycle regulation and apoptosis using PC3 prostate cancer cell lines. When cells were co-treated with IP(6) and MI, the extent of cell growth inhibition was significantly increased than that by IP(6) alone. To identify the effect of IP(6) and MI on apoptosis, the activity of caspase-3 was measured. The caspase-3 activity was significantly increased when cells were treated with either IP(6) alone or both IP(6) and MI, with no significant enhancement by co-treatment. To investigate the effect of IP(6) and MI of cell cycle arrest, we measured p21 mRNA expression in PC3 cells and observed significant increase in p21 mRNA by IP(6). But synergistic regulation by co-treatment with IP(6) and MI was not observed. In addition, there was no significant effect by co-treatment compared to IP(6) treatment on the regulation of cell cycle progression although IP(6) significantly changed cell cycle distribution in the presence of MI or not. Therefore, these findings support that IP(6) has anticancer function by induction of apoptosis and regulation of cell cycle. However, synergistic effect by MI on cell cycle regulation and apoptosis was not observed in PC3 prostate cancer cells.

Water extract of Aralia elata prevents cataractogenesis in vitro and in vivo.

The water extract of Aralia elata (Aralia extract) has been used in Korean traditional medicine to treat diabetes mellitus. Here, we investigated the aldose reductase inhibitory activity, antioxidant activity and anticataract capacity of Aralia extract using various experimental systems. To determine its aldose reductase inhibitory activity and its antioxidant effect, we used rat lens homogenates. Rat lens cultures and a rat model were used to observe anticataract activity. The resulting IC50 value of Aralia extract in vitro as an aldose reductase inhibitor was 11.3 microg/ml and as an antioxidant was 25.1 microg/ml. Rat lenses in media containing 20 mM xylose developed a distinctly opaque ring in 9h, and treatment with Aralia extract at a concentration of 1mg/ml lowered lens opacity by 36.4 and 31.3% after 24 and 48 h, respectively. In vivo experiments were performed with streptozotocin (STZ) induced diabetic rats. The diabetic control animals developed cataracts at 11 weeks after STZ injection, while oral Aralia extract administered at 300 and 600 mg/kg body weight for 11 weeks reduced cataract formation by 15 and 12%, respectively. The present study shows that Aralia extract inhibits aldose reductase and acts in vitro as an antioxidant, and suggests that these activities have a preventive effect on cataractogenesis in xylose containing lens organ cultures and in in vivo in STZ induced diabetic rats.