Mi Kyeong Lee

Dibenzocyclooctadiene lignans from Schisandra chinensis protect primary cultures of rat cortical cells from glutamate-induced toxicity.

A methanolic extract of dried Schisandra fruit (Schisandra chinensis Baill.; Schisandraceae) significantly attenuated the neurotoxicity induced by L‐glutamate in primary cultures of rat cortical cells. Five dibenzocyclooctadiene lignans (deoxyschisandrin, gomisin N, gomisin A, schisandrin, and wuweizisu C) were isolated from the methanolic extract; their protective effects against glutamate‐induced neurotoxicity were then evaluated. Among the five lignans, deoxyschisandrin, gomisin N, and wuweizisu C significantly attenuated glutamate‐induced neurotoxicity as measured by 1) an inhibition in the increase of intracellular [Ca2+]; 2) an improvement in the glutathione defense system, the level of glutathione, and the activity of glutathione peroxidase; and 3) an inhibition in the formation of cellular peroxide. These results suggest that dibenzocyclooctadiene lignans from Schisandra chinensis may possess therapeutic potential against oxidative neuronal damage induced by excitotoxin.

Protection of Rat Hepatocytes Exposed to CCl4 In‐vitro by Cynandione A, a Biacetophenone from Cynanchum wilfordii

To identify hepatoprotective agents from plant sources we use primary cultures of rat hepatocytes injured by CCl4. The hepatoprotective agents are the compounds that mitigate the injury caused by CCl4. Using this system we have investigated the biochemical mechanisms involved in the hepatoprotective activity of cynandione A, a biacetopherone, isolated from the roots of Cynanchum wilfordii Hemsley (Asclepiadaceae). Cynandione A (50 μm) significantly reduced (approximately 50%) the release into the culture medium of glutamic pyruvic transaminase and sorbitol dehydrogenase from the primary cultures of rat hepatocytes exposed to CCl4. Glutathione, superoxide dismutase, catalase and glutathione reductase play important roles in the cellular defence against oxidative stress. Cynandione A appeared to protect primary cultured rat hepatocytes exposed to CCl4 from significant drops in the levels of each of these four specific markers. Cynandione A also ameliorated lipid peroxidation by up to 50% as demonstrated by a reduction in the production of malondialdehyde.

Antifibrotic activity of diterpenes from Biota orientalis leaves on hepatic stellate cells

Antifibrotic effect of twelve diterpenes (1–12) from the 90% methanolic fraction of Biota orientalis leaves was evaluated employing HSC-T6 cells by assessing cell proliferation and morphological change. Among these diterpenes, totarol (8) and isopimara-8(14),15-dien-19-oic acid (9) dramatically reduced cell proliferation in dose-and time-dependent manner. Furthermore, treatment with these compounds resulted in the different pattern of morphological changes of HSC-T6 cells. Taken together, antiproliferative activity of diterpenes from B. orientalis might suggest therapeutic potentials against liver fibrosis.

Stimulatory constituents of Eclipta prostrata on mouse osteoblast differentiation

One flavonoid, diosmetin (1), and two isoflavonoids, 3′‐hydroxybiochanin A (2) and 3′‐O‐methylorobol (3), were isolated from the methanol extract of Eclipta prostrata L. by a bioactivity‐guided fractionation technique using primary cultures of mouse osteoblasts as an in vitro assay system. All three compounds significantly increased osteoblast differentiation as assessed by the alkaline phosphatase activity. Copyright

Asiatic acid derivatives enhance cognitive performance partly by improving acetylcholine synthesis

Thirty‐six semi‐synthesized derivatives of asiatic acid were examined to determine if they had cognitive‐enhancing activity in a passive avoidance test. Among the compounds tested, AS‐2, AS‐2–9–006 and AS‐9–006 significantly alleviated scopolamine‐induced memory impairment at doses of 1 and 10 mg kg−1. Furthermore, AS‐2 and AS‐2–9–006 (1 mg kg−1 administered four times daily) enhanced cognitive performance as determined in a water maze test. These three asiatic acid derivatives did not show any significant effect on the learning process in active avoidance tests. AS‐2, AS‐2–9–006 and AS‐9–006 enhanced cholineacetyltransferase activity in a cholinergic neuroblastoma cell line, S‐20Y, in‐vitro. Therefore, AS‐2, AS‐2–9–006 and AS‐9–006 may have therapeutic value in alleviating certain memory impairment observed in dementia.

meso-Dihydroguaiaretic acid attenuates the neurotoxic effect of staurosporine in primary rat cortical cultures

The effect of meso-dihydroguaiaretic acid (MDGA) on the staurosporine-induced neuronal apoptosis and its potential mechanism were investigated using primary cultures of rat cortical cells as an assay system. Treatment of MDGA at the concentrations of 0.1, 1.0 and 10 microM significantly protected neuronal cells against Staurosporine-induced apoptosis. The neuroprotective activity of MDGA was the most potent at the concentration of 1.0 microM and was not increased at higher concentration. MDGA reduced apoptotic characteristics induced by STS; MDGA reduced the condensed nuclei in staurosporine-injured rat cortical cells. MDGA diminished the calcium influx that accompanies the staurosporine-induced apoptosis, and inhibited the subsequent overproduction of reactive oxygen species and peroxide to the level of control cells. It also preserved cellular activity of superoxide dismutase, an antioxidative enzyme reduced by staurosporine insult. In addition, MDGA significantly inhibited caspase-3/7 activation and cytochrome c release. Taken together, these results suggested that MDGA protected neuronal cells against staurosporine-induced apoptosis through the inhibition of Ca(2+) influx, cellular oxidation, cytochrome c release and caspase-3/7 activation.

Modification of C2 functional group on asiatic acid and the evaluation of hepatoprotective effects.

For the development of novel hepatoprotective agents, C2 functional group on asiatic acid was modified, and evaluated for their hepatoprotective effects. Among prepared compounds, com-pounds10 and14 showed better hepatoprotective effects compared to Silymarin.

A Comparison between Water and Ethanol Extracts of Rumex acetosa for Protective Effects on Gastric Ulcers in Mice

Rumex acetosa is a perennial herb that is widely distributed across eastern Asia. Although the hot water extract of R. acetosa has been used to treat gastritis or gastric ulcers as a folk medicine, no scientific report exists for the use of this plant to treat gastric ulcers. Hence, the present study was undertaken to assess the anti-ulcer activity of water and 70% ethanol extracts obtained from R. acetosa, using an HCl/ethanol-induced gastric ulcer model in mice. Anti-inflammatory and free radical-scavenging activities of these two extracts were also evaluated and compared. As a result, the administration of R. acetosa extracts significantly reduced the occurrence of gastric ulcers. However, significant differences in protective activity against gastric ulcers were observed between the two samples. In the case of the group pretreated with an ethanol extract dosage of 100 mg/kg, the protective effect (90.9%) was higher than that of water extract (41.2%). Under histological evaluation, pretreatment with R. acetosa extracts reversed negative effects, such as inflammation, edema, moderate hemorrhaging and loss of epithelial cells, presented by HCl/ ethanol-treated stomachs. Meanwhile, R. acetosa extracts showed potent DPPH radical-scavenging activity and decreased NO production in a murine macrophage cell line, RAW 264.7, in a dose-dependent manner without affecting cellular viability. The greater anti-ulcer and NO production inhibitory activities exhibited by ethanol extracts compared to water extracts could be ascribed to the higher emodin levels, a major anthraquinone component of this plant.