Anti-atherosclerotic and anti-inflammatory activities of catecholic xanthones and flavonoids isolated from Cudrania tricuspidata

Isoflavones with neuroprotective activities from fruits of Cudrania tricuspidata

Ten isoflavones, cudraisoflavones B-K (1-10), together with 27 known isoflavones, were isolated from the EtOAc soluble extract of fruits of Cudrania tricuspidata. The structures of compounds 1-10 were elucidated on the basis of MS and NMR spectroscopic data, including 2D NMR experiments. Compounds 7-9 and three known (11-13) compounds showed neuroprotective activity against 6-hydroxydopamine induced cell death in human neuroblastoma SH-SY5Y cells, with EC50 values of 0.5-9.2 μM.

Neuroprotective Xanthones from the Root Bark of Cudrania tricuspidata

Seventeen new prenylated xanthones (1-17) were isolated from an ethyl acetate-soluble extract of root bark of Cudrania tricuspidata together with 17 previously identified xanthones. The structures of the new compounds were elucidated by spectroscopic methods. Six new compounds (3, 7, 8, 9, 15, and 16) and six known compounds (18-23) showed neuroprotective effects against 6-hydroxydopamine-induced cell death in human neuroblastoma SH-SY5Y cells, with EC50 values of 0.7-16.6 μM.

Isocudraxanthone K induces growth inhibition and apoptosis in oral cancer cells via hypoxia inducible factor-1α

Isocudraxanthone K (IK) is a novel, natural compound from a methanol extract of the root bark of Cudrania tricuspidata. It has not been shown previously that IK possessed antitumor activity. We investigated the antitumor effects and molecular mechanism of IK and related signal transduction pathway(s) in oral squamous cell carcinoma cells (OSCCCs). The MTT assay revealed that IK had an antiproliferative effect on OSCCCs, in a dose- and time-dependent manner. IK induced apoptosis in OSCCCs, as identified by a cell-cycle analysis, annexin V-FITC and propidium iodide staining, and the nuclear morphology in cell death. IK caused time-dependent phosphorylation of Akt, p38, and ERK (extracellular signal-regulated kinase). In addition, IK increased the cytosolic to nuclear translocation of nuclear factor-κB (NF-κB) p65 and the degradation and phosphorylation of IκB-α in HN4 and HN12 cells. Furthermore, IK treatment downregulated hypoxia-inducible factor 1α (HIF-1α) and its target gene, vascular endothelial growth factor (VEGF). Cobalt chloride (CoCl₂), a HIF-1α activator, attenuated the IK-induced growth-inhibiting and apoptosis-inducing effects, and blocked IK-induced expression of apoptosis regulatory proteins, such as Bax, Bcl-2, caspase-3, caspase-8, and caspase-9, and cytochrome c. Collectively, these data provide the first evidence of antiproliferative and apoptosis-inducing effects of IK as a HIF-1α inhibitor and suggest it may be a drug candidate for chemotherapy against oral cancer.

A systematic review on biological activities of prenylated flavonoids

CONTEXT

Prenylated flavonoids are a unique class of naturally occurring flavonoids that exist especially for the plant's self-defensive strategy. This special class of flavonoids increases the bioactivities of their backbone flavonoids with non-prenylation; therefore, prenylated flavonoids have more potential to be developed and utilized.

OBJECTIVE

The number, position and type of the prenyl group on the flavonoids backbone structure may have close relationships with the bioactivities of flavonoids.

METHODS

PubMed and WEB OF KNOWLEDGE® were used to search articles published in English between 1 January 2002 and 31 December 2012, which discuss the structure-activity relationship between prenylated flavonoids and their bioactivities.

RESULTS

It is proposed that the prenyl-moiety makes the backbone compound more lipophilic, which leads to its high affinity with cell membranes. The prenylation brings the flavonoids with enhancement of antibacterial, anti-inflammatory, antioxidant, cytotoxicity, larvicidal as well as estrogenic activities. However, it is reported that the prenyl-moiety decreases the bioavailability and plasma absorption of prenylated flavonoids.

CONCLUSION

The prenyl group affects the bioactivities of flavonoids in certain ways, while the action mechanisms and the structure-activity relationship as well as more in vivo studies even clinical validation trials need to be further investigated.

Preliminary assessment of mutagenic and anti-mutagenic potential of some aminoalkanolic derivatives of xanthone by use of the Vibrio harveyi assay

The Vibrio harveyi assay was used to evaluate mutagenic and anti-mutagenic effects of four new aminoalkanolic derivatives of xanthone with anticonvulsant activity, to select the potentially safe compounds for further in vivo studies in animal models. The study showed that at a concentration of 40 ng/ml the test compounds were not mutagenic. Additionally, two of the investigated compounds, namely the (R,S)-N-methyl-1-amino-2-propanol derivative of 6-methoxyxanthone (compound III) and the (R)-N-methyl-2-amino-1-butanol derivative of 7-chloroxanthone (compound IV) were strong inhibitors of the mutagenicity induced by 4-nitroquinoline-N-oxide (4-NQO) in V. harveyi strains BB7M and BB7XM. The inhibition percentages for compound IV were 49 (in BB7M) and 69 (in BB7XM), whereas for compound III these percentages were 47 (in BB7M) and 42 (in BB7XM), respectively. The present study demonstrates that four bioactive derivatives of xanthone display no mutagenic activity in the V. harveyi assay. In addition, compounds III and IV demonstrated considerable anti-mutagenic activity in this test. Based on the results obtained here, these compounds could be selected for further studies in animal models, while compounds III and IV should be tested further for their anti-mutagenic properties.

Separation and purification of flavonoid from Taxus remainder extracts free of taxoids using polystyrene and polyamide resin

An efficient separation process of flavonoid from Taxus wallichiana var. mairei remainder extracts free of taxoids was developed in this study. AB-8 macroporous resin and polyamide resin offered the fine adsorption capacity, and its adsorption rate at 30°C fitted well to the Langmuir and Freundich isotherms. Resin dynamic adsorption and desorption experiments were conducted to optimize the separation process of total flavonoids from T. wallichiana var. mairei remainder extracts free of taxoids. The optimum parameters for adsorption by AB-8 resin were as follows: (1) the concentration of flavonoids in a sample solution of 5.61 mg/mL with a processing volume of 2 bed volume (BV) (60 mL); (2) for desorption, ethanol-water (80:20, v/v), with 6 BV as an eluent at a flow rate of 2 BV/h. After a one-run treatment with AB-8 resin, the content of flavonoids was increased 5.10-fold from 4.05 to 20.65%. The optimum parameters for adsorption by polyamide resin were as follows: processing volume of 2 BV (30 mL); for desorption, ethanol-water (70:30, v/v), with 8 BV as an eluent at a flow rate of 2 BV/h. After one-run treatment with polyamide resin, the content of total flavonoids increased from 20.65 to 65.21%. The method will provide a potential approach for large-scale separation and purification of flavonoid for its wide pharmaceutical use.

Indirect homologous competitive enzyme-linked immunosorbent assay for the detection of a class of glycosylated dihydrochalcones

Hesperetin dihydrochalcone 4'-glucoside, 1, and phloretin 4'-glucoside, 2, belong to a family of dihydrochalcone glycosides that exhibit flavorant properties. In this study was developed a competitive, indirect homologous ELISA for the detection of targets 1 and 2 in fermentation media. Immunogen and coating antigen were prepared by conjugating hapten, 4-(3-oxo-3-(2,6-dihydroxy-4-glucoside phenyl)propyl) benzoic acid, to thyroglobulin and bovine serum albumin, respectively. Antibodies raised in rabbits M6122, M6123, and M6124 and the coating antigen were screened and characterized to determine their optimum concentrations. The optimized ELISA, developed with antibody M6122, gave IC50 values of 27.8 and 21.8 ng/mL for 1 and 2, respectively. Selectivity of the assay was assessed by measuring cross-reactivity of antibody M6122 to related congeners such as aglycones and the 2'-glycosides of hesperetin dihydrochalcone, 5 and phloretin, 6. Antibody M6122 showed very low recognition of 5 and virtually no recognition of the aglycones and 6.

Prenylated Flavonoids from Morus alba L. Cause Inhibition of G1/S Transition in THP-1 Human Leukemia Cells and Prevent the Lipopolysaccharide-Induced Inflammatory Response

Morus alba L. (MA) is a natural source of many compounds with different biological effects. It has been described to possess anti-inflammatory, antioxidant, and hepatoprotective activities. The aim of this study was to evaluate cytotoxicity of three flavonoids isolated from MA (kuwanon E, cudraflavone B, and 4′-O-methylkuwanon E) and to determine their effects on proliferation of THP-1 cells, and on cell cycle progression of cancer cells. Anti-inflammatory effects were also determined for all three given flavonoids. Methods used in the study included quantification of cells by hemocytometer and WST-1 assays, flow cytometry, western blotting, ELISA, and zymography. From the three compounds tested, cudraflavone B showed the strongest effects on cell cycle progression and viability of tumor and/or immortalized cells and also on inflammatory response of macrophage-like cells. Kuwanon E and 4′-O-methylkuwanon E exerted more sophisticated rather than direct toxic effect on used cell types. Our data indicate that mechanisms different from stress-related or apoptotic signaling pathways are involved in the action of these compounds. Although further studies are required to precisely define the mechanisms of MA flavonoid action in human cancer and macrophage-like cells, here we demonstrate their effects combining antiproliferative and anti-inflammatory activities, respectively.

Characterization of tyrosinase inhibitors in the twigs of Cudrania tricuspidata and their structure-activity relationship study

The twigs of Cudrania tricuspidata were found to show strong tyrosinase inhibitory activity, and further detailed component analysis resulted in the isolation of a new flavanol glucoside, (2S,3S)-2,3-trans-dihydromorin-7-O-β-d-glucoside (1), plus twenty-seven known compounds (2-28). Their structures were elucidated on the basis of ESI-MS and NMR spectral data. Among the isolated compounds, trans-dihydromorin (8), oxyresveratrol (9), and steppogenin (12) were found to exhibit significant tyrosinase inhibition activities. Moreover, the structure-activity relationship of these isolated compounds was also discussed.

Antioxidant activities of extracts from teas prepared from medicinal plants, Morus alba L., Camellia sinensis L., and Cudrania tricuspidata , and their volatile components

The antioxidant activity of essences of teas prepared from mulberry ( Morus alba L.), Camellia sinensis L., and Cudrania tricuspidata (Carr.) Burea plant was examined using two antioxidant assays. Selected volatile chemicals identified in these plants were also tested for antioxidant activity. All extracts exhibited antioxidant activity with a clear dose response in the aldehyde/carboxylic acid and the malonaldehyde/gas chromatography (MA/GC) assays. Antioxidant activity of extracts at the level of 500 μg/mL ranged from 77.02 ± 0.51% (stems of Burea plant) to 52.57 ± 0.92% (fermented tea of Camellia and stems of Mulberry tea) in the aldehydes/carboxylic acid assay. Their antioxidant activity at the level of 160 μg/mL ranged from 76.17 ± 0.27% (roots of Burea plant) to 59.32 ± 0.27% (stems of Mulberry tea) in the MA/GC assay. Among the positively identified compounds (11 terpenes and terpenoids, 15 alkyl compounds, 26 nitrogen containing heterocyclic compounds, 9 oxygen containing heterocyclic compounds, 18 aromatic compounds, 7 lactones, 6 acids, and 4 miscellaneous compounds), eugenol, 2,5-dihydroxyl acetophenone, and isoeugenol exhibited antioxidant activity comparable to that of BHT in both assays. Vanillin and 2-acetylpyrrole showed potent antioxidant activity in the aldehydes/carboxylic acid assay but only moderate activity in the MA/GC assay. These results suggest that consumption of antioxidant-rich beverages prepared from these plants may be beneficial to human health.

The pyranoxanthone inophyllin A induces oxidative stress mediated-apoptosis in Jurkat T lymphoblastic leukemia cells

Inophyllin A (INO-A), a pyranoxanthone isolated from the roots of Calophyllum inophyllum represents a new xanthone with potential chemotherapeutic activity. In this study, the molecular mechanism of INO-A-induced cell death was investigated in Jurkat T lymphoblastic leukemia cells. Assessment of phosphatidylserine exposure confirmed apoptosis as the primary mode of cell death in INO-A-treated Jurkat cells. INO-A treatment for only 30 min resulted in a significant increase of tail moment which suggests that DNA damage is an early apoptotic signal. Further flow cytometric assessment of the superoxide anion level confirmed that INO-A induced DNA damage was mediated with a concomitant generation of reactive oxygen species (ROS). Investigation on the thiols revealed an early decrease of free thiols in 30 min after 50 μM INO-A treatment. Using tetramethylrhodamine ethyl ester, a potentiometric dye, the loss of mitochondrial membrane potential (MPP) was observed in INO-A-treated cells as early as 30 min. The INO-A-induced apoptosis progressed with the simultaneous activation of caspases-2 and -9 which then led to the processing of caspase-3. Taken together, these data demonstrate that INO-A induced early oxidative stress, DNA damage and loss of MMP which subsequently led to the activation of an intrinsic pathway of apoptosis in Jurkat cells.

IgE, COX-2, and IL-4 are expressed by DEHP through p38 MAPK and suppressed by plant glycoprotein (75 kDa) in ICR mice

The aim of the present study was to evaluate the inhibitory effect of glycoprotein isolated from Cudrania tricuspidata Bureau (CTB glycoprotein) on di(2-ethylhexyl) phthalate (DEHP)-induced allergic inflammatory response in mice. We evaluated the activity of β-hexosaminidase, expression of cyclooxygenase (COX)-2, p38 mitogen-activated protein kinase (MAPK), and activator protein (AP)-1, and production of immunoglobulin (Ig)E and interleukin (IL)-4 in DEHP-treated RBL-2H3 cells and ICR mice. Our results revealed that the CTB glycoprotein inhibited the activity of β-hexosaminidase and production of IgE and IL-4 in serum from DEHP-treated mice. We also found that the CTB glycoprotein reduced arachidonic acid release, COX-2 expression, and AP-1 transcriptional activation through p38 MAPK phosphorylation in DEHP-treated RBL-2H3 cells. The activation of AP-1 was completely blocked by treatment with p38 MAPK inhibitor (SKF86002). The results from these experiments indicate that CTB glycoprotein effectively protects against the allergic inflammation response, mainly through downregulation of MAPK/AP-1 in the mast cell degranulation stage. In conclusion, we suggest that the CTB glycoprotein may be one component of health supplements for the prevention of allergic inflammation.

The fruits of Cudrania tricuspidata suppress development of atopic dermatitis in NC/Nga mice

The fruits of Cudrania tricuspidata are a medicinal herb in Korea, known for its antiatherosclerotic and antiinflammatory effects. Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by the influx of lymphocytes into the dermis. Using an animal model of AD, we assessed whether C. tricuspidata suppresses the development of AD-like skin lesions. Cudrania tricuspidata was administered orally to NC/Nga mice with Dermatophagoides-farinae-induced AD-like lesions for 49 days. The effects of C. tricuspidata were assessed by measuring clinical symptoms, swelling of the skin on the back and ears, and plasma concentrations of mTARC (mouse thymus and activation regulated chemokine), histamine and immunoglobulin E (IgE). We found that C. tricuspidata (60 mg/kg/day) inhibited the development of AD-like skin lesions, reduced skin dermatitis scores and inhibited the histological changes induced by repeated application of D. farinae. In addition, C. tricuspidata inhibited the increases in plasma concentrations of mTARC, histamine and IgE induced by D. farinae. These findings indicate that C. tricuspidata inhibits the development of AD-like skin lesions induced by repeated applications of D. farinae in sensitized NC/Nga by suppressing plasma concentrations of mTARC, histamine and IgE.

Natural compound cudraflavone B shows promising anti-inflammatory properties in vitro

Cudraflavone B (1) is a prenylated flavonoid found in large amounts in the roots of Morus alba, a plant used as a herbal remedy for its reputed anti-inflammatory properties. The present study shows that this compound causes a significant inhibition of inflammatory mediators in selected in vitro models. Thus, 1 was identified as a potent inhibitor of tumor necrosis factor α (TNFα) gene expression and secretion by blocking the translocation of nuclear factor κB (NF-κB) from the cytoplasm to the nucleus in macrophages derived from a THP-1 human monocyte cell line. The NF-κB activity reduction resulted in the inhibition of cyclooxygenase 2 (COX-2) gene expression. Compound 1 acts as a COX-2 and COX-1 inhibitor with higher selectivity toward COX-2 than indomethacin. Pretreatment of cells by 1 shifted the peak in an regulatory gene zinc-finger protein 36 (ZFP36) expression assay. This natural product has noticeable anti-inflammatory properties, suggesting that 1 potentially could be used for development as a nonsteroidal anti-inflammatory drug lead.

Antioxidant xanthone derivatives induce cell cycle arrest and apoptosis and enhance cell death induced by cisplatin in NTUB1 cells associated with ROS

In an effort to develop novel antioxidant as anticancer agents, a series of xanthones were prepared. In vitro screening, the synthetic xanthones revealed significant inhibitory effects on xanthine oxidase and ABTS radical-cation scavenging activity. The selective compounds 2 and 8 induced an accumulation of NTUB1 cells in the G(1) phase arrest and cellular apoptosis by the increase of ROS level. The combination of cisplatin and 2 significantly enhanced the cell death in NTUB1 cells. Compounds 2 and 8 did not show cytotoxic activity in selected concentrations against SV-HUC1 cells. The present results suggested that antioxidants 2 and 8 may be used as anticancer agent for enhancing the therapeutic efficacy of anticancer agents and to reduce their side effect.

Anti-inflammatory effect of glycoprotein isolated from Cudrania tricuspidata Bureau: involvement of MAPK/NF-κB signaling

The aim of this study was to evaluate inhibitory effect of glycoprotein isolated from Cudrania tricuspidata Bureau (CTB glycoprotein) on allergic responses. We evaluated the activities of mitogen-activated protein kinase (MAPK), transcriptional factor, and production of immunoglobulin (Ig)E and interleukin (IL)-4 in RBL-2H3 cells and BALB/c mice. Our results showed that CTB glycoprotein inhibited the production of IgE and IL-4 in serum from ovalbumin (OVA)-treated BALB/c mice. We also found that CTB glycoprotein inhibited the phosphorylation of p38 MAPK, and transcriptional activation of nuclear factor (NF)-κB in RBL-2H3 cells. The activation of NF-κB was effectively blocked by treatment with p38 MAPK inhibitor (SKF86002). The results from these experiments indicate that the CTB glycoprotein inhibits release of β-hexosaminidase, and production of IgE and IL-4 via down regulation of MAPK/ NF-κB on the stage of mast cell degranulation. In conclusion, we suggest that the CTB glycoprotein might be a potent preventive agent in allergic responses.

Modulatory effects of phytoglycoprotein (75 kDa) on allergic inflammatory cytokines in Di(2-ethylhexyl) phthalate (DEHP)-stimulated RBL-2H3 cells

This study investigated the inhibitory effect of a glycoprotein isolated from Cudrania tricuspidata Bureau (CTB glycoprotein) on di(2-ethylhexyl) phthalate (DEHP)-induced mast cell degranulation and related signaling cascade in RBL-2H3 cells. This experiment evaluated the intracellular Ca(2+) level, and the activities of protein kinase C (PKC), mitogen-activated protein kinase (MAPK), transcription factor, and the cytokines in DEHP-treated RBL-2H3 cells. Our results revealed that the CTB glycoprotein in the presence of DEHP inhibits the release of histamine and expression of interleukin (IL)-4, IL-6, and TNF-alpha in RBL-2H3 cells. We also found that the CTB glycoprotein inhibits the intracellular Ca(2+) level, translocation of PKC from cytosol to membrane and the phosphorylation of ERK1/2 in cells. Moreover, the CTB glycoprotein (100 microg/ml) has suppressive effects on transcriptional activation of nuclear factor (NF)-kappaB in DEHP-treated RBL-2H3 cells. The activation of NF-kappaB was collectively blocked by treatment with PKC inhibitor (staurosporine) as well as ERK1/2 inhibitor (PD98059), respectively. The results from these experiments indicated that the CTB glycoprotein inhibits release of histamine and expressions of IL-4, IL-6, and TNF-alpha via down regulations of PKC/MAPK and NF-kappaB on the stage of mast cell degranulation induced by DEHP. Moreover, oral administration of CTB glycoprotein (10-20 mg/kg) inhibited compound 48/80-mediated systemic reaction in mice. In conclusion, we speculated that the CTB glycoprotein might be one component for preparation of health supplements for prevention of allergic immune disorders.

Cytotoxicity, apoptosis-inducing effects and structure-activity relationships of four natural xanthones from Gentianopsis paludosa Ma in HepG2 and HL-60 cells

Four xanthones were isolated from Gentianopsis paludosa Ma and were identified by modern spectroscopic methods. Cytotoxicity of the four xanthones was tested on HepG2 cells and HL-60 cells by sulphorhodamine B (SRB) assay. Clonogenic survival assay, trypan blue exclusion method, AO/EB staining and DNA fragmentation assay were conducted to investigate the effect on growth inhibition and apoptosis in the two cell lines in vitro. At the same time, structure-activity relationships (SARs) of the xanthones were investigated. The results showed that the xanthones had significant cytotoxicity and inhibition of proliferation in both HepG2 cells and HL-60 cells, and could induce apoptosis in these two cell lines. SARs indicated that the methoxy group had more cytotoxic contribution than the hydroxyl group at site C-8 in the structural scaffold of xanthone. The glycosidea at site C-1 may aggravate the stereospecific blockade of compound 4 and reduced its cytotoxic activity.

Anti-inflammatory action of Cudrania tricuspidata on spleen cell and T lymphocyte proliferation

This study examined whether an extract of Cudrania tricuspidata shows anti-proliferative effects in anti-CD3/CD28-mediated spleen and CD4+CD25− T cells and decreases the production of the pro-inflammatory cytokines interleukin-2 (IL-2) and interferon-γ (IFN-γ) in anti-CD3/CD28-mediated CD4+CD25− T cells. The proliferation of anti-CD3/CD28-mediated spleen cells and CD4+CD25− T cells was effectively suppressed by C. tricuspidata. This extract, however, did not show cytotoxicity in spleen cells under conditions where the antigen was not stimulated using CCK-8 analysis. C. tricuspidata also decreased the production of the pro-inflammatory cytokines IL-2 and IFN-γ by selective inhibition of this extract on proliferating cells in anti-CD3/CD28-mediated CD4+CD25− T cells. These results suggest that C. tricuspidata may be useful in the treatment of autoimmune diseases and organ transplantation through the inhibitory action of T cells in inflammation.

Antioxidant activities of new flavonoids from Cudrania tricuspidata root bark

Two new flavonoids, hydroxybenzyl flavonoid glycosides (6-p-hydroxybenzyl kaempferol-7-O-beta-D-glucopyranoside named cudranian 1 and 6-p-hydroxybenzyl quercetin-7-O-beta-D-glucopyranoside named cudranian 2), and 3 known flavonoids (kaempferol-7-O-beta-D-glucopyranoside, quercetin-7-O-beta-D-glucopyranoside and aromadendrin) were isolated from root bark of Cudrania tricuspidata and their structures were elucidated by spectroscopic methods. These compounds showed remarkable radical scavenging effects against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and anti-lipid peroxidation efficacy on human low-density lipoprotein by TBARS assay.

Anti-proliferation, cell cycle arrest and apoptosis induced by a natural xanthone from Gentianopsis paludosa Ma, in human promyelocytic leukemia cell line HL-60 cells

1-hydroxy-3,7,8-trimethoxyxanthone (xanthone 1) was isolated from Gentianopsis paludosa Ma and identified by MS and NMR in our laboratory. In this study, the results showed that xanthone 1 is a potent inducer of anti-proliferation and apoptosis in HL-60 cells. When the cells treated with lower concentrations of xanthone 1 (12.4-74.4microM), significant proliferation inhibition was detected by cell viability assay and morphological analyses, and conspicuous G1 and G2/M cell cycle arrest were observed by flow cytometric (FCM) analysis. However, when the cells treated with higher doses of xanthone 1 (82.7-330.8microM), significant apoptosis was observed by double sequential AO/EB staining, DNA fragmentation assay and FCM analysis. In addition, conspicuous DNA damage was detected by comet assay. In short, all the results showed that xanthone 1 had a significant cytotoxic effect and could induce proliferation inhibition and apoptosis in HL-60 cells in a time- and dose-dependent manner. It was possible that xanthone 1 could induce DNA damage in HL-60 cells, which resulted in G1 phase arrest at the lower concentrations and G2/M phase arrest at the higher concentrations, thus inhibiting the cell proliferation, and irreparable DNA damage at the higher concentrations might be responsible for the occurrence of apoptosis.

Low density lipoprotein (LDL)-antioxidant flavonoids from roots of Sophora flavescens

Oxidation of low density lipoprotein (LDL) is strongly implicated as a key process in the onset of atherosclerosis. In this study, nine alkylated (C10-C5) flavonoids from Sophora flavescens were examined for their inhibitory effects on copper-induced LDL oxidation. Of the flavonoids tested, sophoraflavanone G (1), kurarinone (2), kurarinol (3), norkurarinol (4), and kuraridin (9) inhibited the generation of thiobarbituric acid reactive substances (TBARS) with IC50s of 7.9, 14.5, 22.0, 26.9, and 17.5 microM, respectively. The most potent inhibitor, compound 1, also demonstrated significant activities in complementary in vitro investigations, such as lag time (130 min at 5 microM), relative electrophoretic mobility (REM) of ox-LDL (80% inhibition at 20 microM), and fragmentation of apoB-100 (inhibition of 71% at 20 microM). Analysis of the structures of these compounds reveals that a resorcinol moiety in the B-ring is strongly correlated with protection of LDL-oxidation.

Prenylated and benzylated flavonoids from the fruits of Cudrania tricuspidata

Three new prenylated isoflavones, 5,7-dihydroxy-6-(2''-hydroxy-3''-methylbut-3''-enyl)-4'-methoxylisoflavone (1), 5,4'-dihydroxy-6-(3''-methylbut-2''-enyl)-2'''-(4'''-hydroxy-4'''-methylethyl)-3'''-methoxydihydrofurano-[4''',5''';7,8]isoflavone (2), and 5,4'-dihydroxy-8-(3''-methylbut-2''-enyl)-2'''-(4'''-hydroxy-4'''-methylethyl)furano-[4''',5''';6,7]isoflavone (3), a benzylated dihydroflavonol, 5,7,4'-trihydroxy-8-p-hydroxybenzyldihydroflavonol (4), and eight known flavonoids (5-12) were isolated from the fruits of Cudrania tricuspidata. The structures of these compounds were determined on the basis of MS and (1)H and (13)C NMR spectroscopic data, including 2D NMR experiments. Compounds 2, 3, 6, 7, 8, 10, 11, and 12 inhibited LPS-induced nitric oxide production, with IC(50) values of 11.8-41.8 microM.

1-(1,3-Benzodioxol-5-ylmethyl)-3-[4-(1H-imidazol-1-yl)phenoxy]-piperidine analogs as potent and selective inhibitors of nitric oxide formation

A new series of 1-(1,3-benzodioxol-5-ylmethyl)-3-[4-(1H-Imidazol-1-yl)phenoxy]-piperidine analogs were designed and identified as potent and selective inhibitors of NO formation based both on the crystal structure of a murine iNOS Delta114 monomer domain/ inhibitor complex and inhibition of the NO formation in human A172 cell assays. Compound 12S showed high potency and high iNOS selectivity versus nNOS and eNOS.