Oxomollugin, an oxidized substance in mollugin, inhibited LPS-induced NF-κB activation via the suppressive effects on essential activation factors of TLR4 signaling.

Oxomollugin is a degraded product of mollugin and was found to be an active compound that inhibits LPS-induced NF-κB activation. In this study, we investigated the inhibitory activity of oxomollugin, focusing on TLR4 signaling pathway, resulting in NF-κB activation. Oxomollugin inhibited the LPS-induced association of essential factors for initial activation of TLR4 signaling, MyD88, IRAK4 and TRAF6. Furthermore, oxomollugin showed suppressive effects on LPS-induced modification of IRAK1, IRAK2 and TRAF6, LPS-induced association of TRAF6-TAK1/TAB2, and followed by IKKα/ß phosphorylation, which critical in signal transduction leading to LPS-induced NF-κB activation. The consistent results suggested that oxomollugin inhibits LPS-induced NF-κB activation via the suppression against signal transduction in TLR4 signaling pathway.The activities of oxomollugin reported in this study provides a deeper understanding on biological activity of mollugin derivatives as anti-inflammatory compounds.

Cyclolinopeptide F, a cyclic peptide from flaxseed inhibited RANKL-induced osteoclastogenesis via downergulation of RANK expression.

Previously, we reported that cyclolinopeptides (CLs) extracted from flaxseed inhibited receptor activator of nuclear factor κ-B ligand (RANKL)-induced osteoclastogenesis from mouse bone marrow cells in vitro. However, mode of action involved in CLs-inhibited osteoclastogenesis has been yet unknown. Therefore, in this study, we investigated the details of inhibitory activity of cyclolinopeptide-F (CL-F) in osteoclastogenesis, as a representative of CLs. CL-F dose-dependently inhibited RANKL-induced osteoclastogenesis (IC50 0.58 µM) without cytotoxic effects. The inhibition by CL-F was mainly observed in macrophage colony-stimulating factor (M-CSF)-induced proliferation/differentiation phase from M-CSF responsive immature myeloid cells to monocyte/macrophage (M/Mϕ) lineage. Additionally, CL-F also slightly inhibited RANKL-induced differentiation phase from M/Mϕ to mature osteoclasts. Expression of RANKL receptor, RANK, in M-CSF-induced M/Mϕ, i.e. osteoclast progenitor cells, was decreased by CL-F treatment. Furthermore, RT-PCR analysis revealed that CL-F inhibited c-fos gene expression, which is reported to be crucial for RANK expression in osteoclast progenitor cells induced with M-CSF from myeloid lineage cells. These results suggested that CL-F inhibits osteoclastogenesis via down regulation of c-fos expression, which leads to the down-regulation of RANK expression in M-CSF-induced osteoclast progenitors.

Oxomollugin, a potential inhibitor of lipopolysaccharide-induced nitric oxide production including nuclear factor kappa B signals.

Mollugin, a naphthoquinone derivative, was reported to possess various biological activities such as anti-inflammatory and anti-tumor activity. Mollugin isolated from Rubia tinctorum roots inhibited lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 macrophages. However, mollugin synthesized for further investigation of its anti-inflammatory mechanism showed weak activity in addition to unstable assay results. From the result of analysis on a degradation product of mollugin, oxomollugin was found to be the main active substance of mollugin degradation, showing a potent inhibitory activity on NO-production including nuclear factor kappa B signals.

Inhibitory effects of low molecular weight polyphenolics from Inonotus obliquus on human DNA topoisomerase activity and cancer cell proliferation.

Low molecular weight (LMW) polyphenolics containing a polyhydroxylated benzyl moiety are abundant in medicinal plants. In the present study, we report on the activities of seven LMW polyphenolics isolated from Inonotus obliquus, a medicinal mushroom. The isolated compounds included caffeic acid (CA), 3,4-dihydroxybenzalacetone (DBL), gallic acid, syringic acid, protocatechuic acid, 3,4-dihydroxybenzaldehyde and 2,5-dihydroxyterephthalic acid. We analyzed their inhibitory effects on DNA polymerase (pol) and DNA topoisomerase (topo), and their effects on human cancer cell growth. All isolated compounds inhibited human topo II activity; the most potent were DBL and CA, which contain a catechol propanoid moiety. CA and DBL inhibited the activity of human topo I, whereas other compounds had no effect. No compound modulated the activities of 11 mammalian pol species or other DNA metabolic enzymes, including T7 RNA polymerase, mouse IMP dehydrogenase (type II), T4 polynucleotide kinase and bovine deoxyribonuclease I. CA and DBL markedly suppressed the proliferation of human colon HCT116 carcinoma cells with an LD50 of 70.0 and 49.4 µM, respectively, and halted the cell cycle in the G2/M phase. The suppressive effect of these compounds on cancer cell growth correlated with their ability to inhibit topo II. These results suggest that CA- and DBL-dependent decreases in cell proliferation are due to the inhibition of cellular topo II. The mechanism of action of these catechol propanoid compounds and the implication for their use as anticancer agents are discussed.

Manipulation of DNA damage checkpoint signaling in cancer cells by antioxidant biofactor (AOB).

Antioxidant biofactor (AOB) is one of the fermented grain food supplements commercially available in Japan and other countries. Herein, we investigated the effect of AOB on the UVC (254 nm) induced DNA damage in A549 cells. Both distilled water and MeOH extracts of AOB did not show any significant cell toxicity. However, the UV (25-75 J m(-2)) induced cell death was amplified in the presence of these extracts, especially the MeOH extract. When the DNA damage was evaluated by comet assay, the AOB water extract prevented the UV induced DNA damage at the initial stage but significantly inhibited the repair process, especially in the cells exposed to a high dose of UV. The retardation of DNA repair was significantly higher in the presence of the MeOH extract, concentrating such components as caffeine and polyphenols, and thus the damage was enhanced both in the cells irradiated by low and high doses of UV. The DNA damage profile was consistent with the inhibitory profile of ATR, a key kinase of DNA damage checkpoint signaling. The AOB MeOH extract markedly reduced the phosphorylation level of the checkpoint proteins activated by UV, such as p53, SMC1 and Chk1, together with ATR. The inhibitory effect of the AOB water extract was less effective as compared to the MeOH extract, but was dose-dependent both in the cells irradiated with high and low doses of UV. The dual role of AOB as an antioxidant and a checkpoint modulator suggests its beneficial use in complementary medicine as a potential sensitizer of anticancer treatment.

Persimmon leaf extract inhibits the ATM activity during DNA damage response induced by Doxorubicin in A549 lung adenocarcinoma cells.

Persimmon leaf (PL) has been commonly recognized for its wide variety of health benefits. A previous study has reported that persimmon leaf extract (PLE) contained flavonols with the 2″-galloly moiety (PLEg). Galloylated homologues generically show stronger activity in their biological function, so enhanced functions can be expected for PLEg. We investigated in this present study the effect of PLEg on the cellular DNA damage checkpoint signaling to sensitize cancer chemotherapy. Treatment with PLE and PLEg significantly increased the cytotoxicity of doxorubicin (DOX) in A549 adenocarcinoma cells. PLE and PLEg reduced the phosphorylation of checkpoint proteins such as structural maintenance of chromosomes 1 (SMC1), checkpoint kinase 1 (Chk1), and p53 in DOX-treated cells. Moreover, PLE decreased the phosphorylation of ATM (ataxia telangiectasia mutated) in a dose-dependent manner. PLE, and especially PLEg, abrogated the G2/M checkpoint during DOX-induced DNA damage. These results suggest that PLEg specifically inhibited ATM-dependent checkpoint activation by DOX, and that PLEg might be a useful sensitizer in cancer chemotherapy.

Prevention of hydrogen peroxide-induced oxidative stress in PC12 cells by 3,4-dihydroxybenzalacetone isolated from Chaga (Inonotus obliquus (persoon) Pilat).

Chaga (Inonotus obliquus (persoon) Pilat) is a mushroom traditionally used as a folk medicine for tumors and stomach ulcers in Russia. Previously, we reported the antioxidant potential of Chaga extracts and seven isolated phenolic ingredients. In the present study, we investigated the protective effects of Chaga extracts and other isolated phenolic ingredients against H(2)O(2)-induced oxidative stress in PC12 cells. Intracellular generation of reactive oxygen species (ROS) leads to oxidative stress and subsequent damage of cellular and nuclear components. Chaga extracts and the phenolic ingredients, 3,4-dihydroxybenzalacetone (DBL) and caffeic acid (CA), effectively suppressed intracellular ROS level in H(2)O(2)-treated cells. The H(2)O(2)-induced cell death was more pronounced, effectively prevented in the cells treated with DBL than in cells treated with CA. In addition, ROS activate various signal transduction pathways including the mitogen-activated protein kinase (MAPK) cascade. Therefore, we examined the potentially beneficial effects of DBL on extracellular signal-regulated protein kinase (ERK), c-Jun NH(2)-terminal kinase (JNK), and p38-MAPK signaling activated by H(2)O(2) stimulation. DBL selectively inhibited the phosphorylation of p38-MAPK, without affecting JNK and ERK.

Cancer cell cytotoxicity of extracts and small phenolic compounds from Chaga [Inonotus obliquus (persoon) Pilat].

Previously, we studied the antioxidant potential of Chaga mushroom [Inonotus obliquus (persoon) Pilat] extracts and isolated several small (poly)phenolic compounds as the major antioxidant components in the 80% methanol (MeOH) extract. In the present study, these isolated phenolic ingredients together with several other types of Chaga extracts were examined for cytotoxic effects against normal (IMR90) and cancer (A549, PA-1, U937, and HL-60) cell lines. Results revealed decoctions from both the fruiting body (FB) and sclerotium (ST) parts of Chaga, especially the ST part, showed considerable cytotoxicity toward tumor cells, but the cytotoxicity appeared to be stronger against normal cells than cancer cells. The 80% MeOH ST extract also showed the same trend. On the other hand, the 80% MeOH extract of FB showed significant cytotoxicity towards tumor cell lines without affecting normal cells, for example, the 50% lethal dose was 49.4 +/- 2.9 microg/mL for PA-1 cells versus 123.6 +/- 13.8 microg/mL for normal cells. The phenolic components isolated from the 80% MeOH extracts had markedly greater cancer cell toxicity than the extracts themselves. In particular, two out of seven compounds showed strong cytotoxicity towards several tumor cell lines without giving rise to significant cell toxicity toward normal cells. For example, the 50% lethal dose for 3,4-dihydroxybenzalacetone was 12.2 micromol/L in PA-1 cells but was 272.8 micromol/L in IMR90 cells. Fluorescence-activated cell sorting analysis further revealed these phenolic ingredients have high potentiality for apoptosis induction in PA-1 cells.

Identification of a novel blocker of IkappaBalpha kinase activation that enhances apoptosis and inhibits proliferation and invasion by suppressing nuclear factor-kappaB.

3,4-dihydroxybenzalacetone (DBL) is a polyphenol derived from the medicinal plant Chaga [Inonotus obliquus (persoon) Pilat]. Although Chaga is used in Russia folk medicine to treat tumors, very little is known about its mechanism of action. Because most genes involved in inflammation, antiapoptosis, and cell proliferation are regulated by the transcription factor nuclear factor-kappaB (NF-kappaB), we postulated that DBL activity is mediated via modulation of the NF-kappaB activation pathway. We investigated the effects of DBL on NF-kappaB activation by electrophoretic mobility shift assay and on NF-kappaB-regulated gene expression by Western blot analysis. We found that DBL suppressed NF-kappaB activation by a wide variety of inflammatory agents, including tumor necrosis factor (TNF), interleukin-1beta, epidermal growth factor, okadaic acid, phorbol 12-myristate 13-acetate, and lipopolysaccharide. The suppression was not cell type specific and inhibited both inducible and constitutive NF-kappaB activation. DBL did not interfere with the binding of NF-kappaB to DNA but rather inhibited IkappaBalpha kinase activity, IkappaBalpha phosphorylation and degradation, p65 phosphorylation, and translocation. DBL also suppressed the expression of TNF-induced and NF-kappaB-regulated proliferative, antiapoptotic, and metastatic gene products. These effects correlated with enhancement of TNF-induced apoptosis and suppression of TNF-induced invasion. Together, our results indicate that DBL inhibits NF-kappaB activation and NF-kappaB-regulated gene expression, which may explain the ability of DBL to enhance apoptosis and inhibit invasion.

Antioxidant small phenolic ingredients in Inonotus obliquus (persoon) Pilat (Chaga).

Inonotus obliquus (persoon) Pilat (Chaga, in Russia, kabanoanatake in Japan) is a fungus having been used as a folk medicine in Russia and said to have many health beneficial functions such as immune modulating and anti-cancer activities. In the present study, the antioxidant activity of hot water extract (decoction) of Chaga was precisely compared with those of other medicinal fungi (Agaricus blazei Mycelia, Ganoderma lucidum and Phellinus linteus) showing Chaga had the strongest antioxidant activity among fungi examined in terms of both superoxide and hydroxyl radicals scavenging activities. Further determination of the antioxidant potential of isolated fruiting body (brown part) and Sclerotium (black part) revealed the 80% MeOH extract of fruiting body had the highest potential as high as that of Chaga decoction. Finally, seven antioxidant components were isolated and purified from the 80% MeOH extract of Chaga fruiting body, and their chemical structures were determined as small phenolics as follows: 4-hydroxy-3,5-dimethoxy benzoic acid 2-hydroxy-1-hydroxymethyl ethyl ester (BAEE), protocatechic acid (PCA), caffeic acid (CA), 3,4-dihybenzaladehyde (DB), 2,5-dihydroxyterephtalic acid (DTA), syringic acid (SA) and 3,4-dihydroxybenzalacetone (DBL). Notably, BAEE was assigned as the new compound firstly identified from the natural source in the present study.

Amyloid-beta-induced cytotoxicity of PC-12 cell was attenuated by Shengmai-san through redox regulation and outgrowth induction.

Neurodegenerative brain disorders such as Alzheimer's disease (AD) have been well investigated. However, significant methods for the treatment of the promotion and progression of AD are unavailable to date. Recent studies suggested that the redox imbalance and the accumulation of amyloid-beta (Abeta) peptide occurring in the brain of AD patients lead to oxidatively-induced apoptotic cell death. Here, we show the effects of Shengmai-san (SMS) on Abeta-induced cytotoxicity in PC-12 cells. SMS dose-dependently attenuated the cytotoxicity by Abeta incubation and also prevented the morphological damage in neurites of the PC-12 cells. Hemeoxygenase-1 and glutathione peroxidase-1 expressions were increased by SMS pretreatment. SMS decreased the phosphorylation level of c-jun amino-terminal kinase (JNK) and the activity of caspase-3, which were enhanced by Abeta incubation. Of importance, SMS treatment promoted neurite outgrowth. These data demonstrated dual roles of SMS in PC-12 cells. SMS prevents the apoptosis through the enhancement of anti-oxidant enzymes and inhibition of the JNK signaling pathway with the promotion of nerve cell maturation, thus suggesting benefits of SMS for the treating of neurodegenerative diseases. It may also be beneficial not only for the treatment of brain disorders but also for other diseases caused by oxidative stress.