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Korean ginseng (Panax ginseng C.A. Meyer) has been extensively used as a functional food for thousands of years. This study with the aim to evaluate the potential of P. ginseng flower components as a functional food with medicinal properties resulted in the identification of three new dammarane-type saponins, named floralginsenosides Ka-Kc (1-3), along with seventeen known ones (4-20). Their structures were elucidated on the basis of chemical and spectroscopic methods, and their antioxidant activities were evaluated by the intracellular ROS radical scavenging DCF-DA assay. Among them, floralginsenoside Ka (1) displayed potent scavenging activity with the inhibition value of 64% at 10 microM; and ginsenoside Rb(1) (13), floralginsenoside Kc (3), floralginsenoside Kb (2), vinaginsenoside R(9) (11), majoroside F(1) (12), ginsenoside I (17), and ginsenoside II (18) showed moderate scavenging capacity with the inhibition rate of 28, 33, 35, 35, 35, 38, and 38% at 10 microM, respectively. These results warrant further studies concerning the potential of saponin extracts of P. ginseng flowers for functional foods.

alphaB-crystallin is a member of the small heat shock proteins, which is abundantly expressed in various vertebrate tissues including the central nervous system. In our previous report, we showed alphaB-crystallin induction in activated astrocytes in the postischemic brain and in H2O2-treated primary astrocyte cultures. To investigate the functional significance of alphaB-crystallin induction in astrocytes, we generated a stable C6 astroglioma cell line overexpressing alphaB-crystallin. In these cells, hydrogen peroxide-induced apoptosis was reduced by 60% compared to parent cells. Furthermore, the repression of alphaB-crystallin expression by alphaB-crystallin siRNA transfection suppressed this protective effect, indicating that alphaB-crystallin is responsible for the protection against H2O2-induced apoptosis in C6 astroglioma cells. Similar level of aggravation in H2O2-induced apoptosis was observed in primary astrocyte cultures when alphaB-crystallin expression was suppressed by alphaB-crystallin siRNA transfection, confirming the importance of alphaB-crystallin. In addition, the induction of caspase-3 activity after H2O2 treatment was markedly suppressed in alphaB-crystallin-overexpressing cells, and immunoprecipitation proved binding between alphaB-crystallin and partially processed caspase-3 (a p24 intermediate). These results indicate that alphaB-crystallin confers protection against hydrogen peroxide-induced astrocytes apoptosis in part by inhibiting caspase-3 activation.

AlphaB-crystallin, known as a vertebrate lens protein, is a member of the small heat shock proteins (sHSP). AlphaB-crystallin is abundantly expressed in the vertebrate lens and striated muscles and it is also expressed constitutively in other tissues including the central nervous system (CNS). In our previous report, we showed alphaB-crystallin induction in activated astrocytes, which are enriched in the penumbra after transient focal cerebral ischemia. We also reported that alphaB-crystallin is significantly induced in astrocytes in the CA3 region of the hippocampus following KA-induced seizure. Here, we report that the expression of alphaB-crystallin is upregulated in H2O2-treated primary astrocyte cultures, which was prepared from newborn male Sprague-Dawley rats and that the proximal 408 bp of the alphaB-crystallin promoter harboring stress response element (STRE) is responsible for this induction. This effect of H2O2 was found to be virtually abolished by introducing mutations into STRE, and these mutations also impaired increased lens epithelial derived growth factor (LEDGF) binding to STRE after H2O2 treatment. Moreover, LEDGF was induced in primary astrocyte cultures after H2O2 treatment and alphaB-crystallin induction was significantly suppressed by transfecting small interfering RNA (siRNA) targeting LEDGF. Together these results indicate that the H2O2-induced upregulations of alphaB-crystallin in astrocytes are mediated by the LEDGF-STRE interaction on alphaB-crystallin promoter.