Identification of pheophorbide a as an inhibitor of receptor for advanced glycation end products in Mallotus japonicus.

Accumulation of advanced glycation end products (AGEs) plays an important role in diabetes, immunoinflammation, and cardiovascular and neurodegenerative diseases. Since AGEs mediate their pathological effects through interaction with receptor for AGEs (RAGE), RAGE antagonists would provide a useful therapeutic option for various health disorders. Therefore, in this study, we aimed to identify phytochemicals that would inhibit binding of AGEs to RAGE, which may help develop new drug leads and/or nutraceuticals for AGE-RAGE-related diseases.

Synergic effect of curcumin and its structural analogue (Monoacetylcurcumin) on anti-influenza virus infection.

Curcumin (Cur), a polyphenolic compound extracted from spice and common food colourant turmeric, contains versatile bio-activities. Monoacetylcurcumin (MAC), a structural analogue of Cur, differs from Cur by acetyl modification, but retains enone groups. Comparative analysis revealed MAC effectively inhibited influenza virus infection (IAV) to a similar extent as, if not superior to, curcumin.

MGDG extracted from spinach enhances the cytotoxicity of radiation in pancreatic cancer cells.

Background: In our previous study, monogalactosyl diacylglycerol (MGDG) purified from spinach was found to have cytotoxic effects in human cancer cell lines. This study further assessed whether MGDG can enhance the cytotoxic effects of radiation in human pancreatic cancer cells in vitro and in vivo.

Methods: Glycoglycerolipids from spinach including MGDG were extracted from dried spinach.

Polyprenylated Benzoylphloroglucinols with DNA Polymerase Inhibitory Activity from the Fruits of Garcinia schomburgkiana.

Chemical investigation of the fruits of Garcinia schomburgkiana collected in Vietnam led to the isolation of eight new schomburgkianones, A-H (1-8), four known (9-12) polyprenylated benzoylphloroglucinols, and four known biflavonoids. The structures of these compounds were elucidated by spectroscopic and chemical means. The absolute configuration at C-40 of 1 and 2 was determined by (1)H NMR analyses of their MPA esters.

The Establishment of an Assay to Measure DNA Polymerase-Catalyzed Repair of UVB-Induced DNA Damage in Skin Cells and Screening of DNA Polymerase Enhancers from Medicinal Plants.

An in vitro assay method was established to measure the activity of cellular DNA polymerases (Pols) in cultured normal human epidermal keratinocytes (NHEKs) by modifying Pol inhibitor activity. Ultraviolet (UV) irradiation enhanced the activity of Pols, especially DNA repair-related Pols, in the cell extracts of NHEKs. The optimal ultraviolet B (UVB) exposure dose and culture time to upregulate Pols activity was 100 mJ/cm² and 4-h incubation, respectively.

Screening of mammalian DNA polymerase and topoisomerase inhibitors from Garcinia mangostana L. and analysis of human cancer cell proliferation and apoptosis.

We purified and identified eight xanthones from mangosteen (Garcinia mangostana L.) and investigated whether these compounds inhibited the activities of mammalian DNA polymerases (Pols) and human DNA topoisomerases (Topos). β-Mangostin was the strongest inhibitor of both mammalian Pols and human Topos among the isolated xanthones, with 50% inhibitory concentration (IC50) values of 6.

Rose myrtle (Rhodomyrtus tomentosa) extract and its component, piceatannol, enhance the activity of DNA polymerase and suppress the inflammatory response elicited by UVB‑induced DNA damage in skin cells.

A number of naturally occurring agents are hypothesized to protect against ultraviolet (UV)‑induced skin damage. The present study screened >50 plant extracts for inhibitors of UVB‑induced cytotoxicity, using cultured normal human epidermal keratinocytes (NHEK), and identified that the fruit of rose myrtle (Rhodomyrtus tomentosa) was the most marked inhibitor of cell death. The protective effect of rose myrtle extract and the two key components, piceatannol and piceatannol‑4'‑O‑β‑D‑glucopyranoside, on UVB‑induced damage and inflammation in cultured NHEK was investigated.

3-O-Acyl-epicatechins Increase Glucose Uptake Activity and GLUT4 Translocation through Activation of PI3K Signaling in Skeletal Muscle Cells.

Tea catechins promote glucose uptake in skeletal muscle cells. In this study, we investigated whether the addition of an acyl group to the C-3 position of catechins to generate 3-O-acyl-catechins promoted glucose uptake in L6 myotubes. 3-O-Myristoyl-(-)-epicatechin (EC-C14) and 3-O-palmitoyl-(-)-epicatechin (EC-C16) promoted glucose uptake and translocation of glucose transporter (GLUT) 4 in the cells.

Synthesis, Photochemical Properties, and Cytotoxicities of 2H-Naphtho[1,2-b]pyran and Its Photodimers.

A 2H-naphtho[1,2-b]pyran, prepared by dimerization of 2-bromo-3-methyl-1,4-naphthoquinone and O-methylation, readily undergoes solid-state [2 + 2] photodimerization to give a photodimer in excellent yield and with excellent selectivity. Retro [2 + 2] cycloaddition can be achieved by irradiation of a solution of the photodimer in chloroform. Interestingly, the 2H-naphtho[1,2-b]pyran dimerizes with a skeletal rearrangement to afford 2,5-dihydro-1-benzoxepin dimers upon irradiation in methanol or via irradiation with hexamethylditin.

Influence of particle size on the in vitro and in vivo anti-inflammatory and anti-allergic activities of a curcumin lipid nanoemulsion.

The polyphenolic compound, curcumin, is a natural yellow pigment component of turmeric. It exerts various biological effects, such as anti-inflammatory effects, and we have previously demonstrated that curcumin is a specific inhibitor of DNA polymerase λ. Curcumin is characterized by poor bioavailability as it is water-insoluble, is poorly absorbed and is systemically eliminated.

5-O-Acyl plumbagins inhibit DNA polymerase activity and suppress the inflammatory response.

We previously found that vitamin K3 (menadione, 2-methyl-1,4-naphthoquinone) inhibits the activity of human mitochondrial DNA polymerase (pol) γ. In this study, we focused on plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone), and chemically synthesized novel plumbagins conjugated with C2:0 to C22:6 fatty acids (5-O-acyl plumbagins). These chemically modified plumbagins displayed enhanced mammalian pol inhibition, with plumbagin conjugated to docosahexaenoic acid (C22:6-acyl plumbagin) exhibiting the strongest inhibition of pol λ among the ten 5-O-acyl plumbagins synthesized.

Bioactive dihydronaphthoquinone derivatives from Fusarium solani.

New dihydronaphthoquinone derivatives, karuquinone A (1), karuquinone B (2), and karuquinone C (3), were isolated from a fungal culture broth of Fusarium solani. The structures were determined by interpretation of spectroscopic data (1D/2D NMR, MS, and IR). Three known compounds, javanicin (4), 2,3-dihydro-5-hydroxy-8-methoxy-2,4-dimethylnaphtho[1,2-b]furan-6,9-dione (5), and 5-hydroxydihydrofusarubin C (6), were also isolated.

Inhibition of mammalian DNA polymerases and the suppression of inflammatory and allergic responses by tyrosol from used activated charcoal waste generated during sake production.

The components adsorbed onto activated charcoal following the fermentation process of the Japanese rice wine "sake" have been studied with the aim of identifying suitable applications for this industrial food waste product. The absorbed materials were effectively extracted from the charcoal, and inhibited the activity of several mammalian DNA polymerases (pols). Subsequent purification of the extract afforded tyrosol [4-(2-hydroxyethyl)phenol] as the active component, which selectively inhibited the activity of 11 mammalian pols with IC50 values in the range of 34.

Polyketides from the cultured lichen mycobiont of a Vietnamese Pyrenula sp.

A spore-derived mycobiont of a crustose Pyrenula sp. lichen collected in Vietnam was cultivated on a malt-yeast extract medium supplemented with 10% sucrose. Chemical investigation of the cultivated colonies led to the isolation of eight new alkylated decalin-type polyketides (1-8) along with three known compounds.

Cytotoxic alkylated hydroquinone, phenol, and cyclohexenone derivatives from Aspergillus violaceofuscus Gasperini.

New alkylated hydroquinones violaceoid A (1), violaceoid B (2), and violaceoid C (3), an alkylated phenol violaceoid D (4), and a cyclohexenoid violaceoid E (5) were isolated from a culture broth of Aspergillus violaceofuscus Gasperini isolated from moss. The structures were identified by interpretation of spectroscopic data (1D and 2D NMR, MS, and IR). Two known compounds, the cyclohexenoid 6 and eupenoxide (7), were also isolated.

Suppression of allergic and inflammatory responses by essential oils derived from herbal plants and citrus fruits.

The aim of the present study was to investigate the biological activity of 20 essential oils (EOs) derived from herbal plants and citrus fruits. The in vitro anti-allergic and anti-inflammatory activities of these oils were investigated, and the EO which was found to have the strongest activity of the 20 EOs examined, was investigated further to identify its components and bioactive compounds. The in vitro anti-allergic activity was determined by measuring the release of β-hexosaminidase from rat basophilic leukemia (RBL-2H3) cells treated with the calcium ionophore, A23187.

Anti-tumor effects of novel 5-O-acyl plumbagins based on the inhibition of mammalian DNA replicative polymerase activity.

We previously found that vitamin K3 (menadione, 2-methyl-1,4-naphthoquinone) inhibits the activity of human mitochondrial DNA polymerase γ (pol γ). In this study, we focused on plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone), and chemically synthesized novel plumbagins conjugated with C2:0 to C22:6 fatty acids (5-O-acyl plumbagins). These chemically modified plumbagins enhanced mammalian pol inhibition and their cytotoxic activity.

Inhibition of DNA polymerase λ and associated inflammatory activities of extracts from steamed germinated soybeans.

During the screening of selective DNA polymerase (pol) inhibitors from more than 50 plant food materials, we found that the extract from steamed germinated soybeans (Glycine max L.) inhibited human pol λ activity. Among the three processed soybean samples tested (boiled soybeans, steamed soybeans, and steamed germinated soybeans), both the hot water extract and organic solvent extract from the steamed germinated soybeans had the strongest pol λ inhibition.

Formosusin A, a novel specific inhibitor of mammalian DNA polymerase β from the fungus Paecilomyces formosus.

Variotin (1) and three novel compounds, formosusin A (2), B (3), and C (4), were isolated from the cultures of the fungus Paecilomyces formosus, and their structures were determined by spectroscopic analyses. Compound 2 is (6Z,8E,10E)-variotin, a new cis-olefin analog of compound 1. Compound 2 selectively inhibited the activity of mammalian DNA polymerase β (pol β) in vitro, with an IC50 of 35.

Three acetophenones from Acronychia pedunculata.

Phytochemical investigation of the leaves and twigs of Acronychia pedunculata has led to the isolation of three new acetophenone monomers 1-3 as well as 1-[2',4'-dihydroxy-3',5'-di-(3″-methyl-2″-butenyl)-6'-methoxy]phenylethanone (4), acronyculatin E (5), a mixture of β-sitosterol and stigmasterol, and sesamin. The structures of these new compounds were elucidated spectroscopically. The inhibitory activities of the isolated acetophenone derivatives against mammalian DNA polymerases and human cancer cell growth were also assessed.

Structure-activity relationship analysis of curcumin analogues on anti-influenza virus activity.

Curcumin (Cur) is a commonly used colouring agent and spice in food. Previously, we reported that Cur inhibits type A influenza virus (IAV) infection by interfering with viral haemagglutination (HA) activity. To search for a stable Cur analogue with potent anti-IAV activity and to investigate the structure contributing to its anti-IAV activity, a comparative analysis of structural and functional analogues of Cur, such as tetrahydrocurcumin (THC) and petasiphenol (Pet), was performed.

Synthesis, structure, and cytotoxicity studies of some fungal isochromanes.

Ustusorane D and penicisochromans B-D are natural isochromans isolated from Aspergillus ustus 094102 and Penicillium sp. PSU-F40, respectively. Herein, we report the syntheses of (-)-ustusorane D and (+)-penicisochroman B and the structures of penicisochromans C and D.

Inhibitory effects of a major soy isoflavone, genistein, on human DNA topoisomerase II activity and cancer cell proliferation.

The inhibitory activity of 3 soy isoflavones (daidzein, genistein and glycitein) and their glycosides (daidzin, genistin and glycitin) on mammalian DNA polymerases (pols) and topoisomerases (topos) was investigated. Of the compounds tested, only genistein selectively inhibited human topo II activity and had an IC50 value of 37.5 µM.

Inhibitory effects of α-mangostin on mammalian DNA polymerase, topoisomerase, and human cancer cell proliferation.

We found that the ethanol extract of mangosteen (Garcinia mangostana L.) fruit rind had a strong inhibitory effect on mammalian DNA polymerase (pol) activity and isolated α-mangostin as a potent pol inhibitor from the extract. In this study, the inhibitory activities against mammalian pols by α-mangostin and its related five compounds, 3-isomangostin, xanthone, 9,10-anthraquinone, 9-anthracenecarboxylic acid, and anthracene, were investigated.