Anti-Atopic Effect of Scutellaria baicalensis and Raphanus sativus on Atopic Dermatitis-like Lesions in Mice by Experimental Verification and Compound-Target Prediction.

Scutellaria baicalensis Georgi and Raphanus Sativus Linne herbal mixture (SRE) is a Chinese herbal medicine. In this study, we aimed to evaluate the therapeutic efficacy of SRE as an active ingredient for 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD) and to predict the underlying therapeutic mechanisms and involved pathways using network pharmacological analysis. Treatment with SRE accelerated the development of AD-like lesions, improving thickness and edema of the epidermis. Moreover, administering the SRE to AD-like mice suppressed immunoglobulin E and interleukin-4 cytokine and reduced T lymphocyte differentiation. In silico, network analysis was used to predict the exact genes, proteins, and pathways responsible for the therapeutic effect of the SRE against DNCB-induced AD. These results indicated that the SRE exerted protective effects on the DNCB-induced AD-like model by attenuating histopathological changes and suppressing the levels of inflammatory mediators. Therefore, the SRE can potentially be a new remedy for improving AD and other inflammatory diseases and predicting the intracellular signaling pathways and target genes involved. This therapeutic effect of the SRE on AD can be used to treat DNCB-induced AD and its associated symptoms.

Anticolon Cancer Effect of Korean Red Ginseng via Autophagy- and Apoptosis-Mediated Cell Death.

Ginseng (Panax ginseng Meyer) has been used in East Asian traditional medicine for a long time. Korean red ginseng (KRG) is effective against several disorders, including cancer. The cytotoxic effects of KRG extract in terms of autophagy- and apoptosis-mediated cell death and its mechanisms were investigated using human colorectal cancer lines. KRG induced autophagy-mediated cell death with enhanced expression of Atg5, Beclin-1, and LC3, and formed characteristic vacuoles in HCT-116 and SNU-1033 cells. An autophagy inhibitor prevented cell death induced by KRG. KRG generated mitochondrial reactive oxygen species (ROS); antioxidant countered this effect and decreased autophagy. KRG caused apoptotic cell death by increasing apoptotic cells and sub-G1 cells, and by activating caspases. A caspase inhibitor suppressed cell death induced by KRG. KRG increased phospho-Bcl-2 expression, but decreased Bcl-2 expression. Moreover, interaction of Bcl-2 with Beclin-1 was attenuated by KRG. Ginsenoside Rg2 was the most effective ginsenoside responsible for KRG-induced autophagy- and apoptosis-mediated cell death. KRG induced autophagy- and apoptosis-mediated cell death via mitochondrial ROS generation, and thus its administration may inhibit colon carcinogenesis.

Anti-tumor Properties of Picrasma quassioides Extracts in H-RasG12V Liver Cancer Are Mediated Through ROS-dependent Mitochondrial Dysfunction.

BACKGROUND: Picrasma quassioides (PQ) is a traditional Asian herbal medicine with anti-tumor properties that can inhibit the viability of HepG2 liver cancer cells. H-Ras is often mutated in liver cancer, however, the effect of PQ treatment on H-Ras mutated liver cancer is unclear. This study aimed to investigate the role of PQ on ROS accumulation and mitochondrial dysfunction in H-ras mutated HepG2 (HepG2G12V) cells. MATERIALS AND METHODS: PQ ethanol extract-induced HepG2G12V apoptosis was analyzed by the MTT assay, fluorescence microscopy, flow cytometry and western blotting. RESULTS: PQ treatment affected cell migration and colony formation in HepG2G12V cells. Cleaved-caspase-3, cleaved-caspase-9 and BCL2 associated agonist of cell death (BAD) expression levels were increased, while the levels of B-cell lymphoma-extra large (Bcl-xL) were decreased with PQ treatment. PQ treatment led to a reduction of H-Ras expression levels in liver cancer cells, thus reducing their abnormal proliferation. Furthermore, it led to increased expression levels of Peroxiredoxin VI, which regulates the redox signal in cells. CONCLUSION: Taken together these results provide a new functional significance for the role of PQ in treating HepG2G12V liver cancer.

Extract of Cornus officinalis Protects Keratinocytes from Particulate Matter-induced Oxidative Stress.

The skin is one of the large organs in the human body and the most exposed to outdoor contaminants such as particulate matter < 2.5 µm (PM2.5). Recently, we reported that PM2.5 induced cellular macromolecule disruption of lipids, proteins, and DNA, via reactive oxygen species, eventually causing cellular apoptosis of human keratinocytes. In this study, the ethanol extract of Cornus officinalis fruit (EECF) showed anti-oxidant effect against PM2.5-induced cellular oxidative stress. EECF protected cells against PM2.5-induced DNA damage, lipid peroxidation, and protein carbonylation. PM2.5 up-regulated intracellular and mitochondrial Ca2+ levels excessively, which led to mitochondrial depolarization and cellular apoptosis. However, EECF suppressed the PM2.5-induced excessive Ca2+ accumulation and inhibited apoptosis. The data confirmed that EECF greatly protected human HaCaT keratinocytes from PM2.5-induced oxidative stress.

Horse Oil Mitigates Oxidative Damage to Human HaCaT Keratinocytes Caused by Ultraviolet B Irradiation.

Horse oil products have been used in skin care for a long time in traditional medicine, but the biological effects of horse oil on the skin remain unclear. This study was conducted to evaluate the protective effect of horse oil on ultraviolet B (UVB)-induced oxidative stress in human HaCaT keratinocytes. Horse oil significantly reduced UVB-induced intracellular reactive oxygen species and intracellular oxidative damage to lipids, proteins, and DNA. Horse oil absorbed light in the UVB range of the electromagnetic spectrum and suppressed the generation of cyclobutane pyrimidine dimers, a photoproduct of UVB irradiation. Western blotting showed that horse oil increased the UVB-induced Bcl-2/Bax ratio, inhibited mitochondria-mediated apoptosis and matrix metalloproteinase expression, and altered mitogen-activated protein kinase signaling-related proteins. These effects were conferred by increased phosphorylation of extracellular signal-regulated kinase 1/2 and decreased phosphorylation of p38 and c-Jun N-terminal kinase 1/2. Additionally, horse oil reduced UVB-induced binding of activator protein 1 to the matrix metalloproteinase-1 promoter site. These results indicate that horse oil protects human HaCaT keratinocytes from UVB-induced oxidative stress by absorbing UVB radiation and removing reactive oxygen species, thereby protecting cells from structural damage and preventing cell death and aging. In conclusion, horse oil is a potential skin protectant against skin damage involving oxidative stress.

3-Bromo-4,5-dihydroxybenzaldehyde Enhances the Level of Reduced Glutathione via the Nrf2-Mediated Pathway in Human Keratinocytes.

A natural bromophenol found in seaweeds, 3-bromo-4,5-dihydroxybenzaldehyde (BDB), has been shown to possess antioxidant effects. This study aimed to investigate the mechanism by which BDB protects skin cells subjected to oxidative stress. The effect of BDB on the protein and mRNA levels of glutathione-related enzymes and the cell survival of human keratinocytes (HaCaT cells) was investigated. BDB treatment increased the protein and mRNA levels of glutathione synthesizing enzymes and enhanced the production of reduced glutathione in HaCaT cells. Furthermore, BDB activated NF-E2-related factor 2 (Nrf2) and promoted its localization into the nucleus by phosphorylating its up-stream signaling proteins, extracellular signal-regulated kinase and protein kinase B. Thus, BDB increased the production of reduced glutathione and established cellular protection against oxidative stress via an Nrf2-mediated pathway.

3-Hydroxy-4,7-megastigmadien-9-one, isolated from Ulva pertusa, attenuates TLR9-mediated inflammatory response by down-regulating mitogen-activated protein kinase and NF-κB pathways.

CONTEXT: Seaweeds are rich in bioactive compounds in the form of vitamins, phycobilins, polyphenols, carotenoids, phycocyanins and polysaccharides; many of these are known to have advantageous applications in human health. 3-Hydroxy-4,7-megastigmadien-9-one (comp) was isolated from Ulva pertusa (U. pertusa) Kjellman (Ulvaceae), which is a familiar edible green seaweed. OBJECTIVE: This study evaluates the anti-inflammatory activity of comp in CpG DNA-stimulated bone marrow-derived dendritic cells (BMDCs). MATERIALS AND METHODS: For evaluating the effect of comp on cytokines production, BMDCs were treated with doses of comp (0, 0.5, 1, 2, 5, 10, 25 and 50 µM) for 1 h before stimulation with CpG DNA (1 µM). Cytokine production was measured by ELISA. Western blotting was conducted for evaluating effect of comp (50 µM) on MAPKs and NF-κB pathways. Luciferase reporter gene assay was conducted for effect of comp (0, 5, 10 and 25 µM) on transcriptional activity of AP-1 and NF-κB. RESULTS: Comp exhibited strong inhibition of interleukin (IL)-12 p40, IL-6 and TNF-α cytokine production with IC50 values of 6.02 ± 0.35, 27.14 ± 0.73, and 7.56 ± 0.21 µM, respectively. It blocked MAPKs and NF-κB pathways by inhibiting the phosphorylation of ERK1/2, JNK1/2, p38 and IκBα. In addition, it strongly inhibited the transcriptional activity of AP-1 and NF-κB with IC50 values of 8.74 ± 0.31 and 12.08 ± 0.24 µM, respectively. DISCUSSION AND CONCLUSION: Taken together, these data suggest that comp has a significant anti-inflammatory property and warrants further studies concerning the potential of comp for medicinal use.

Anti-wrinkle effects of Sargassum muticum ethyl acetate fraction on ultraviolet B-irradiated hairless mouse skin and mechanistic evaluation in the human HaCaT keratinocyte cell line.

The present study investigated the photoprotective properties of the ethyl acetate fraction of Sargassum muticum (SME) against ultraviolet B (UVB)­induced skin damage and photoaging in a mouse model. HR­1 strain hairless male mice were divided into three groups: An untreated control group, a UVB­irradiated vehicle group and a UVB­irradiated SME group. The UVB­irradiated mice in the SME group were orally administered with SME (100 mg/kg body weight in 0.1 ml water per day) and then exposed to radiation at a dose of 60­120 mJ/cm2. Wrinkle formation and skin damage were evaluated by analysis of skin replicas, epidermal thickness and collagen fiber integrity in the dermal connective tissue. The mechanism underlying the action of SME was also investigated in the human HaCaT keratinocyte cell line following exposure of the cells to UVB at a dose of 30 mJ/cm2. The protein expression levels and activity of matrix metalloproteinase­1 (MMP­1), and the binding of activator protein­1 (AP­1) to the MMP­1 promoter were assessed in the HaCaT cells using western blot analysis, an MMP­1 fluorescent assay and a chromatin immune­precipitation assay, respectively. The results showed that the mean length and depth of the wrinkles in the UVB­exposed hairless mice were significantly improved by oral administration of SME, which also prevented the increase in epidermal thickness triggered by UVB irradiation. Furthermore, a marked increase in collagen bundle formation was observed in the UVB­treated mice with SME administration. SME pretreatment also significantly inhibited the UVB­induced upregulation in the expression and activity of MMP­1 in the cultured HaCaT keratinocytes, and the UVB­enhanced association of AP­1 with the MMP­1 promoter. These results suggested that SME may be useful as an anti-photoaging resource for the skin.

4-Hydroxy-2,3-Dimethyl-2-Nonen-4-Olide Has an Inhibitory Effect on Pro-Inflammatory Cytokine Production in CpG-Stimulated Bone Marrow-Derived Dendritic Cells.

This study was intended to assess the anti-inflammatory properties of 4-hydroxy-2,3-dimethyl-2-nonen-4-olide (Comp) isolated from Ulva pertusa Kjellman on production of pro-inflammatory cytokines. Comp revealed remarkable inhibitory effects on production of pro-inflammatory cytokines in bone marrow-derived dendritic cells (BMDCs). Comp pre-treatment in the CpG DNA-stimulated BMDCs exhibited strong inhibition of interleukin (IL)-12 p40 and IL-6 production with IC50 values ranging from 7.57 ± 0.2 to 10.83 ± 0.3, respectively. It revealed an inhibitory effect on the phosphorylation of ERK1/2, JNK1/2, and p38, and on activator protein (AP)-1 reporter activity. Comp displayed noteworthy inhibitory effects on phosphorylation and degradation of IκBα, and on NF-κB reporter activity. In summary, these data propose that Comp has substantial anti-inflammatory properties and warrants further study concerning its potential use as a therapeutic agent for inflammation-associated maladies.

Hwang-Heuk-San induces apoptosis in HCT116 human colorectal cancer cells through the ROS-mediated activation of caspases and the inactivation of the PI3K/Akt signaling pathway.

Hwang-Heuk-San (HHS) is a polyherbal formulation that has been used in traditional Korean medicine for hundreds of years to treat gastrointestinal malignancy. However, to date, the mechanisms responsible for the anticancer effects remain unclear. In the present study, we investigated the anticancer effects of HHS using HCT116 human colorectal cancer (CRC) cells. Our results showed that HHS treatment significantly reduced cell survival and increased apoptotic cell death in a concentration-dependent manner. The treatment of HCT116 cells with HHS also significantly elevated the accumulation of reactive oxygen species (ROS), which was followed by the attenuation of the mitochondrial membrane potential through the upregulation of Bax and the downregulation of Bcl-2, which was accompanied by the release of cytochrome c to the cytosol. In addition, HHS treatment caused the truncation of Bid and activated the caspases (caspase-8, -9 and -3), which was associated with the induction of the Fas ligand, the death receptors (DRs), DR4 and DR5, downregulation of the inhibitors of protein expression in the apoptosis protein family, and the degradation of poly(ADP-ribose)-polymerase. However, a pan-caspase inhibitor reversed the HHS-induced apoptosis and growth suppression, indicating that HHS induces apoptosis though a caspase-dependent intrinsic and extrinsic apoptotic pathway in HCT116 cells. Moreover, HHS treatment inhibited the activation of phosphatidylinositol-3-kinase (PI3K)/Akt signaling, and a pharmacological inhibitor of PI3K significantly potentiated the apoptotic effects of HHS when employed in combination in HCT116 cells. Furthermore, the blocking of ROS generation by antioxidant N-acetyl cysteine attenuated the HHS-induced release of cytochrome c, caspase activation and PI3K/Akt inactivation, thereby preventing HHS-induced apoptosis and reduction in cell viability. These findings suggest that HHS-induced ROS generation is required for caspase-dependent apoptotic cell death involving inhibition of the PI3K/Akt signaling pathway in HCT116 cells. Overall, our findings suggest that HHS may be an effective treatment for CRC cancer, and further studies are required to identify the active compounds in HHS.

Isorhamnetin Protects Human Keratinocytes against Ultraviolet B-Induced Cell Damage.

Isorhamnetin (3-methylquercetin) is a flavonoid derived from the fruits of certain medicinal plants. This study investigated the photoprotective properties of isorhamnetin against cell damage and apoptosis resulting from excessive ultraviolet (UV) B exposure in human HaCaT keratinocytes. Isorhamnetin eliminated UVB-induced intracellular reactive oxygen species (ROS) and attenuated the oxidative modification of DNA, lipids, and proteins in response to UVB radiation. Moreover, isorhamnetin repressed UVB-facilitated programmed cell death in the keratinocytes, as evidenced by a reduction in apoptotic body formation, and nuclear fragmentation. Additionally, isorhamnetin suppressed the ability of UVB light to trigger mitochondrial dysfunction. Taken together, these results indicate that isorhamnetin has the potential to protect human keratinocytes against UVB-induced cell damage and death.

Hepatoprotective effects of Lycium chinense Miller fruit and its constituent betaine in CCl4-induced hepatic damage in rats.

The hepatoprotective activities of Lycium chinense Miller (LC) fruit extract and its component betaine were investigated under carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. The treatment of LC fruit extract significantly suppressed the increase of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the sera of CCl4 injured rats, and restored the decreased levels of anti-oxidant enzymes such as total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) and suppressed the expression of inflammatory mediators including inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-1 and -2. To visualize the potential activity of betaine, a component of LC fruit, betaine was substituted for LC extract in CCl4 injured rats. The biochemical profile in CCl4 injured rats co-treated with betaine matched those of LC fruit treated CCl4 injured rats. The ameliorative effects of LC extract, as well as betaine, were also confirmed by histopathological examination. Collectively, the present findings imply that LC fruit, via its component betaine, mitigate CCl4-induced hepatic injury by increasing antioxidative activity and decreasing inflammatory mediators including iNOS and COX-1/COX-2.

Gracilaria bursa-pastoris (Gmelin) Silva extract attenuates ultraviolet B radiation-induced oxidative stress in human keratinocytes.

The purpose of this study was to assess the protective effects of an ethanol extract derived from the red alga Gracilaria bursa-pastoris (Gmelin) Silva (GBE) on ultraviolet B (UVB)-irradiated human HaCaT keratinocytes. GBE exhibited scavenging activity against intracellular reactive oxygen species that were induced by either hydrogen peroxide or UVB radiation. In addition, both the superoxide anion and the hydroxyl radical were scavenged by GBE in cell-free systems. GBE absorbed light in the UVB range (280-320 nm) of the electromagnetic spectrum and lessened the extent of UVB-induced oxidative damage to cellular lipids, proteins, and DNA. Finally, GBE-treated keratinocytes showed a reduction in UVB-induced apoptosis, as exemplified by fewer apoptotic bodies. These results suggest that GBE exerts cytoprotective actions against UVB-stimulated oxidative stress by scavenging ROS and absorbing UVB rays, thereby attenuating injury to cellular constituents and preventing cell death.

The ethyl acetate fraction of Sargassum muticum attenuates ultraviolet B radiation-induced apoptotic cell death via regulation of MAPK- and caspase-dependent signaling pathways in human HaCaT keratinocytes.

CONTEXT: Our previous work demonstrated that an ethyl acetate extract derived from Sargassum muticum (Yendo) Fenshol (SME) protected human HaCaT keratinocytes against ultraviolet B (UVB)-induced oxidative stress by increasing antioxidant activity in the cells, thereby inhibiting apoptosis. OBJECTIVE: The aim of the current study was to further elucidate the anti-apoptotic mechanism of SME against UVB-induced cell damage. MATERIALS AND METHODS: The expression levels of several apoptotic-associated and mitogen-activated kinase (MAPK) signaling proteins were determined by western blot analysis of UVB-irradiated HaCaT cells with or without prior SME treatment. In addition, the loss of mitochondrial membrane potential (Δψm) was detected using flow cytometry or confocal microscopy and the mitochondria membrane-permeate dye, JC-1. Apoptosis was assessed by quantifying DNA fragmentation and apoptotic body formation. Furthermore, cell viability was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. RESULTS: SME absorbed electromagnetic radiation in the UVB range (280-320 nm) of the UV/visible light spectrum. SME also increased Bcl-2 and Mcl-1 expression in UVB-irradiated cells and decreased the Bax expression. Moreover, SME inhibited the UVB-induced disruption of mitochondrial membrane potential and prevented UVB-mediated increases in activated caspase-9 and caspase-3 (an apoptotic initiator and executor, respectively) levels. Notably, treatment with a pan-caspase inhibitor enhanced the anti-apoptotic effects of SME in UVB-irradiated cells. Finally, SME reduced the UVB-mediated phosphorylation of p38 MAPK and JNK, and prevented the UVB-mediated dephosphorylation of Erk1/2 and Akt. DISCUSSION AND CONCLUSION: The present results indicate that SME safeguards HaCaT keratinocytes from UVB-mediated apoptosis by inhibiting a caspase-dependent signaling pathway.

Anti-inflammatory and antioxidant activities of phenolic compounds from Desmodium caudatum leaves and stems.

Four flavanonols (1-4), one xanthone (5), and three flavonoid glycosides (6-8), were isolated from the leaves and stems of Desmodium caudatum. Their structures were elucidated by comparing spectroscopic data with reported values. The anti-inflammatory activity of the isolated compounds was investigated in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells. Among them, compounds 1 and 2 exhibited inhibitory effects on LPS-induced IL-6, IL-12 p40, and TNF-α production with IC50 values ranging from 6.0 to 29.4 µM. Compound 5 exhibited 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species scavenging activity in human HaCaT keratinocytes. These results warrant further studies of the potential anti-inflammatory and antioxidant benefits of compounds from D. caudatum.

6'-o-galloylpaeoniflorin protects human keratinocytes against oxidative stress-induced cell damage.

6'-O-galloylpaeoniflorin (GPF) is a galloylated derivate of paeoniflorin and a key chemical constituent of the peony root, a perennial flowering plant that is widely used as an herbal medicine in East Asia. This study is the first investigation of the cytoprotective effects of GPF against hydrogen peroxide (H2O2)-induced cell injury and death in human HaCaT keratinocytes. GPF demonstrated a significant scavenging capacity against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, H2O2-generated intracellular reactive oxygen species (ROS), the superoxide anion radical (O2 (-)), and the hydroxyl radical (•OH). GPF also safeguarded HaCaT keratinocytes against H2O2-provoked apoptotic cell death and attenuated oxidative macromolecular damage to DNA, lipids, and proteins. The compound exerted its cytoprotective actions in keratinocytes at least in part by decreasing the number of DNA strand breaks, the levels of 8-isoprostane (a stable end-product of lipid peroxidation), and the formation of carbonylated protein species. Taken together, these results indicate that GPF may be developed as a cytoprotector against ROS-mediated oxidative stress.

Compound K, a metabolite of ginseng saponin, inhibits colorectal cancer cell growth and induces apoptosis through inhibition of histone deacetylase activity.

In this study, we investigated the molecular mechanisms underlying the anti-proliferative effects of Compound K, with specific reference to histone modification. Exposure of HT-29 human colon cancer cells to Compound K resulted in time-dependent inhibition of histone deacetylase (HDAC) activity, mRNA and protein expression. Compound K treatment induced unmethylation of the RUNX3 promoter region such as TSA treatment and an accumulation of acetylated histones H3 and H4 within the total cellular chromatin, resulting in an enhanced ability of these histones to bind to the promoter sequences of the tumor suppressor gene Runt-related transcription factor 3 (RUNX3). Treatment of cells with Compound K increased the mRNA and protein expression of RUNX3, as well as p21, a downstream target of RUNX3. These alterations were consistent with cell cycle arrest at the G0/G1 phases and induction of apoptosis. Our results provide new insights into the mechanisms of Compound K action in human colorectal cancer cells and suggest that HDAC inhibition presents a novel approach to prevent or treat colorectal cancer.

Apo-9'-fucoxanthinone, isolated from Sargassum muticum, inhibits CpG-induced inflammatory response by attenuating the mitogen-activated protein kinase pathway.

Sargassum muticum (S. muticum) is a brown edible alga and widely distributed in Korea. This report was designed to evaluate the anti-inflammatory properties of apo-9'-fucoxanthinone (APO-9') isolated from S. muticum on pro-inflammatory cytokine production. S. muticum extract (SME) exhibited significant inhibitory effects on pro-inflammatory cytokine production in bone marrow-derived macrophages (BMDMs) and dendritic cells (BMDCs). APO-9' pre-treatment in the CpG DNA-stimulated BMDMs and BMDCs showed a strong dose-dependent inhibitory effect on interleukin (IL)-12 p40, IL-6 and tumor necrosis factor (TNF)-α production with IC50 values ranging from 5.31 to 13.79. It exhibited a strong inhibitory effect on the phosphorylation of ERK1/2 and on activator protein (AP)-1 reporter activity. APO-9' pre-treatment exhibited significant inhibition of CpG DNA-induced production of inducible nitric oxide synthase. Taken together, these data suggest that SME and APO-9' have a significant anti-inflammatory property and warrant further studies concerning the potentials of SME and APO-9' for medicinal use.

Anti-melanogenesis constituents from the seaweed Dictyota coriacea.

This study was conducted to identify the anti-melanogenesis constituents from a seaweed Dictyota coriacea (Holmes). Three known compounds, viz. 1,9-dihydroxycrenulide (1), epiloliolide (2) and D-mannitol (3), were isolated from the ethanol extract. The melanin synthesis inhibition activities were evaluated using B16F10 melanoma cells for the isolates. Compared with the positive control, arbutin, compounds 1 and 2 exhibited more potency, showing 27.8 and 22.6% inhibition activities at a substrate concentration of 30 microg/mL. Our studies also indicate that these compounds are not cytotoxic. Hence, they might prove to be useful therapeutic agents for treating hyperpigmentation and effective components of whitening cosmetics.

The role of a ginseng saponin metabolite as a DNA methyltransferase inhibitor in colorectal cancer cells.

Hypermethylation of runt-related transcription factor 3 (RUNX3) promoter regions occurs in at least 65% of colorectal cancer cell lines. Compound K, the main metabolite of ginseng saponin, induced demethylation of a RUNX3 promoter in HT-29 human colorectal cancer cells, assessed by methylation-specific PCR and the quantitative pyrosequencing analysis. The demethylation of RUNX3 in compound K-treated cells resulted in the re-expression of RUNX3 mRNA, protein and the localization into the nucleus. Demethylation of the RUNX3 gene by compound K occurred via inhibition of the expression and activity of DNA methyltransferase 1 (DNMT1). Compound K also significantly induced RUNX3-mediated expression of Smad4 and Bim. DNMT1 inhibitory activity by compound K was related to extracellular signal-regulated kinase (ERK) inhibition, assessed by siRNA transfection on DNMT1 and ERK. In conclusion, compound K significantly inhibits the growth of colorectal cancer cells by inhibiting DNMT1 and reactivating epigenetically-silenced genes. Ginseng saponin is a potential candidate as DNMT1 inhibitor in the chemoprevention of cancer.