Seong-Il Heo

Free radical scavenging and total phenolic contents from methanolic extracts of Ulmus davidiana

A methanolic (MeOH) extract of Ulmus davidiana was analyzed for antioxidant activity using model systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, hydroxyl radical (OH) scavenging, reducing power, and total phenolic content. The MeOH extract exhibited strong antioxidant activity in the tested model systems. Among fractions using several solvents, the ethyl acetate (EtOAc)-soluble fraction, which exhibited strong antioxidant activity, was further purified by silica-gel and Sephadex LH-20 column chromatography. The (-)-Catechin (1) and (-)-catechin-7-O-β-d-apiofuranoside (2) were isolated as the active principles. Compounds 1 and 2 exhibited strong antioxidant activity on DPPH radicals, with IC50 values of 6.37±0.02μM and 6.41±0.03μM, respectively, and strong activity on OH radicals at 10μg/ml, with 53.65±0.01% and 52.56±0.01% inhibition. U. davidiana extracts may be exploited as biopreservatives in food applications as well as for health supplements of functional food, to alleviate oxidative stress.

Antioxidant and antidiabetic activities of extracts from Cirsium japonicum roots

This study investigated the antioxidant activity of methanol (MeOH) and water extracts from roots of Cirsium japonicum in vitro. MeOH extract showed a stronger free radical scavenging activity than water extract. However, both of extracts showed a concentration dependent hydroxyl radical scavenging activity, reducing power and metal chelating ability. MeOH extract had greater phenolic and flavonoid contents than water extract. The antidiabetic activity of these two extracts was evaluated by the α-glucosidase inhibition assay. The water extract showed a considerable α-glucosidase inhibitory activity. To our knowledge, this may be the first time to report the antioxidant and antidiabetic activities in Cirsium japonicum roots.

Induction of cell cycle arrest and apoptosis by the ethyl acetate fraction of Kalopanax pictus leaves in human colon cancer cells.

Kalopanax pictus is a deciduous tree used in traditional medicine; its leaves are also consumed as a vegetable. In this study, the ethyl acetate fraction of K. pictus leaves (EFK) was tested in vitro for anticancer activity against four cell lines: human colon cancer (HT-29) cells, human stomach cancer (NCI-N87) cells, human breast cancer (MDA-MB231) cells, and mouse melanoma (B16F1) cells. Results indicated that EFK showed the most potent tumor selective growth inhibitory activity against HT-29 cells with less cytotoxic effect on normal cell lines. Cytotoxicity of EFK on HT-29 cells was associated mainly with cell chromatin condensation, DNA fragmentation, and loss of membrane phospholipid asymmetry with appearance of G2/M phase arrest. Cell death induced by EFK displayed features characteristic of apoptosis, and was associated with generation of reactive oxygen species (ROS) and increase of Bax/Bcl-2 ratio. These findings suggest that K. pictus leaves have anticancer properties and may be valuable for application in pharmaceutical industry.

Antioxidant and Hepatoprotective Activities of Cirsium setidens NAKAI against CCl4-Induced Liver Damage

The antioxidant activity and hepatoprotective potential of Cirsium setidens Nakai, a widely used medicinal plant, were investigated. The n-butanol (n-BuOH) fraction of leaves and roots of C. setidens had a higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than the other soluble fractions. The n-BuOH fraction of roots of C. setidens had a significant hepatoprotective activity at a dose of 500 mg/kg compared to that of a standard agent. The biochemical results were confirmed by histological observations indicating that C. setidens extract decreased ballooning degeneration in response to CCl(4) treatment. The n-BuOH fraction reduced CCl(4)-induced liver injury in rats, and transcript levels of genes encoding antioxidant enzymes such as glutathione peroxidase 1 (GPO1), glutathione peroxidase 3 (GPO3) and superoxide dismutase (SOD1) were elevated in the livers of rats treated with this fraction (500 mg/kg). Based on these results, we suggest that the C. setidens extract has hepatoprotective effect related to its antioxidant activity.

Antioxidant effects and hepatoprotective activity of 2,5-dihydroxy-4,3′-di(β-d-glucopyranosyloxy)-trans-stilbene from Morus bombycis Koidzumi roots on CCl4-induced liver damage

We investigated hepatoprotective activity and antioxidant effect of the 2,5-dihydroxy-4,3′-di(β-d-glucopyranosyloxy)-trans-stilbene that purified from Morus bombycis Koidzumi roots against CCl4-induced liver damage in rats. The 2,5-dihydroxy-4,3′-di(β-d-glucopyranosyloxy)-trans-stilbene displayed dose-dependent superoxide radical scavenging activity (IC50 = 430.2 μg/ml), as assayed by the electron spin resonance (ESR) spin-trapping technique. The increase in aspartate aminotransferase (AST) activities in serum associated with carbon tetrachloride (CCl4)-induced liver injury was inhibited by 2,5-dihydroxy-4,3′-di(β-d-glucopyranosyloxy)-trans-stilbene and at a dose of 400 ∼ 600 mg/kg samples had hepatoprotective activity comparable to the standard agent, silymarin. The biochemical assays were confirmed by histological observations showing that the 2,5-dihydroxy-4,3′-di(β-d-glucopyranosyloxy)-trans-stilbene decreased cell ballooning in response to CCl4 treatment. These results demonstrate that the 2,5-dihydroxy-4,3′-di(β-d-glucopyranosyloxy)-trans-stilbene is a potent antioxidant with a liver protective action against CCl4-induced hepatotoxicity.

Involvement of the p38 MAPK and ERK signaling pathway in the anti-melanogenic effect of methyl 3,5-dicaffeoyl quinate in B16F10 mouse melanoma cells.

Methyl 3,5-dicaffeoyl quinate (MDQ), an active compound present in Kalopanax pictus, Salicornia herbacea L., Aster oharai and Solidago virga-aurea var. gigantean, is a dicaffeoylquinic acid derivative esterified by methanol. Recent studies have revealed that MDQ possesses multiple pharmacological activities, such as antitumor, antioxidative and cytoprotective activities. To date, there has been no attempt to test the action of MDQ in melanocytes. In this study, we investigated the effect of MDQ on melanogenesis in B16F10 mouse melanoma cells. MDQ inhibited melanin production and tyrosinase activity in B16F10 mouse melanoma cells without a direct inhibitory effect on mushroom tyrosinase activity. Furthermore, we also found that MDQ decreased protein expression levels of microphthalmia-associated transcription factor (MITF) and tyrosinase in B16F10 melanin cells. Meanwhile, phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) was significantly reduced after 6h MDQ treatment, and this expression recovered at 48 h. The phosphorylation of extracellular signal-regulated kinase (ERK) was significantly enhanced at 12-48 h, whereas no effect was observed in the phosphorylation of Akt. In addition, MDQ treatment did not significantly alter the expression levels of total p38 MAPK, ERK, and Akt. Thus, it seems that inhibition of phospho-p38 MAPK and activation of phospho-ERK may lead to the suppression of melanogenesis in MDQ-treated B16F10 mouse melanoma cells.

Biological Activities of Fractions from Methanolic Extract of Picrasma quassioides

Antioxidant, antidiabetes, and anticancer activities of fractions (water, hexane, EtOAc, and BuOH) from methanolic (MeOH) extract of Picrasma quassioides were evaluated in vitro. Among the four fractions, BuOH fraction showed cytotoxic activity on the human stomach carcinoma cells (NCI-N87) without cytotoxic effect on the human normal kidney cells (293) by MTT assay. Considering these results, we adapted BuOH fraction of MeOH extract to the assessment of apoptosis by flow cytometry and mRNA expression levels of established apoptotic-related genes on NCI-N87 cells. The experiments showed that BuOH fraction could induce apoptosis on NCI-N87 cells significantly. Take together these results, P. quassioides showed that it could be used for potential pharmaceutical products.

Free radical scavenging and hepatoprotective actions of Quercus aliena acorn extract against CCl4-induced liver

In the present study, we investigated the protective effect of Quercus aliena acorn extracts against CCl4-induced hepatotoxicity in rats, and the mechanism underlying the protective effects. Aqueous extracts of Quercus aliena acorn had higher superoxide radical scavenging activity than other types of extracts. The Quercus aliena acorn extracts displayed dose-dependent superoxide radical scavenging activity (IC50 = 4.92 μg/ml), as assayed by the electron spin resonance (ESR) spin-trapping technique. Pretreatment with Quercus aliena acorn extracts reduced the increase in serum aspartate aminotransferase (AST) and serum alanine aminotransferase (ALT) levels. The hepatoprotective action was confirmed by histological observation. The aqueous extracts reversed CCl4-induced liver injury and had an antioxidant action in assays of FeCl2- ascorbic acid induced lipid peroxidation in rats. Expression of cytochrome P450 2E1 (CYP2E1) mRNA, as measured by RT-PCR, was significantly decreased in the livers of Quercus aliena acorn-pretreated rats compared with the livers of the control group. These results suggest that the hepatoprotective effects of Quercus aliena acorn extract are related to its antioxidative activity and effect on the expression of CYP2E1.

The effects of exogenous hormones on genetic tumor formation in Nicotiana hybrids

The effect of exogenous auxin and cytokinin on cell proliferation and differentiation varies with the tissue system, and depends on the endogenous levels of the two hormones in the tissue. In this report, cytokinin (N 6 -benzyladenine, BA) and auxin (indole-3-acetic acid, IAA) were used to treat young seedlings, leaf explants, and genetic tumors of a Nicotiana hybrid. Exogenous BA markedly accelerated genetic tumor formation in young seedlings, while exogenous IAA inhibited it on young seedlings but not on leaf explants. Genetic tumors showed low sensitivity to exogenous BA and IAA. RAPD analysis of the genomes of the genetic tumors and normal tissue suggested that tumor formation is related to genomic instability.