Lichen-derived caperatic acid and physodic acid inhibit Wnt signaling in colorectal cancer cells

Lichens are a source of secondary metabolites which possess important biological activities, including antioxidant, antibacterial, anti-inflammatory, and cytotoxic effects. The anticancer activity of lichens was shown in many types of tumors, including colorectal cancers (CRC). Several studies revealed that the application of lichen extracts diminished the proliferation of CRC cells and induced apoptosis. Colon carcinogenesis is associated with aberrations in Wnt signaling. Elevated transcriptional activity of β-catenin induces cell survival, proliferation, and migration. Thus, the inhibition of Wnt signaling is a promising therapeutic strategy in colorectal cancer. The aim of this study was the evaluation of the effects of lichen-derived depsides (atranorin, lecanoric acid, squamatic acid) and depsidones (physodic acid, salazinic acid) and a poly-carboxylic fatty acid-caperatic acid, on Wnt signaling in HCT116 and DLD-1 colorectal cancer cell lines. HCT116 cells were more sensitive to the modulatory effects of the compounds. PKF118-310, which was used as a reference β-catenin inhibitor, dose-dependently reduced the expression of the classical β-catenin target gene-Axin2 in both cell lines. Lecanoric acid slightly reduced Axin2 expression in HCT116 cells while caperatic acid tended to reduce Axin2 expression in both cell lines. Physodic acid much more potently decreased Axin2 expression in HCT116 cells than in DLD-1 cells. Physodic acid and caperatic acid also diminished the expression of survivin and MMP7 in a cell line and time-dependent manner. None of the compounds affected the nuclear translocation of β-catenin. This is the first report showing the ability of caperatic acid and physodic acid to modulate β-catenin-dependent transcription.

Depsidones from Lichens as Natural Product Inhibitors of M-Phase Phosphoprotein 1, a Human Kinesin Required for Cytokinesis

M-Phase Phosphoprotein 1 (MPP1), a microtubule plus end directed kinesin, is required for the completion of cytokinesis. Previous studies have shown that MPP1 is upregulated in various types of bladder cancer. This article describes inhibitor screening leading to the identification of a new class of natural product inhibitors of MPP1. Two compounds with structural similarity, norlobaridone (1) and physodic acid (2), were found to inhibit MPP1. Physodic acid is not competitive with ATP, indicating the presence of an allosteric inhibitor-binding pocket. Initial drug-like property screening indicates that physodic acid is more soluble than norlobaridone and has more favorable lipophilicity. However, both suffer from high clearance in human microsomal stability assays mediated by the lability of the lactone ring as well as hydroxylation of the alkyl chains as shown by metabolite identification studies. In cell-based assays physodic acid is a weak inhibitor with EC50 values of about 30 μM in a range of tumor cell lines. The two depsidones identified and characterized here could be used for future improvement of their activity against MPP1 and will be useful chemical probes for studying this unique molecular motor in more depth.

Antimicrobial Activity of Extracts of Chemical Races of the Lichen Pseudevernia furfuracea and their Physodic Acid, Chloroatranorin, Atranorin, and Olivetoric Acid Constituents

The antimicrobial activity and the MIC values of the ethanol, chloroform, diethyl ether, and acetone extracts of the chemical races of Pseudevernia furfuracea (var. furfuracea and var. ceratea) and their physodic acid, chloroatranorin, atranorin, and olivetoric acid constituents have been investigated against some microorganisms. Nearly all extracts of both chemical races showed antimicrobial activity against Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Proteus vulgaris, Staphylococcus aureus, Streptococcus faecalis, Yersinia enterocolitica, Candida albicans, Candida glabrata, Alternaria alternata, Ascochyta rabiei, Aspergillus niger, Fusarium culmorum, Fusarium moniliforme, Fusarium oxysporum, Fusarium solani, and Penicillium notatum. There was no antimicrobial activity of the extracts against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Pseudomonas syringae, Salmonella typhimurium, Alternaria citri, Alternaria tenuissima, and Gaeumannomyces graminis. Chloroatranorin and olivetoric acid were active against the same microorganisms with few exceptions. Physodic acid was active against about the same bacteria and yeasts and inactive against all of the filamentous fungi tested. Also no activity of atranorin against the filamentous fungi was observed.

Novel dibenzo[b,e]oxepinones from the freshwater-derived fungus Chaetomium sp. YMF 1.02105

Six new dibenzo[b,e]oxepinone metabolites, chaetones A-F (1-6), as well as three known compounds, 1-hydroxy-6-methyl-8-hydroxymethylxanthone (7), citreorosein (8), and emodin (9), were obtained from a freshwater-derived fungal strain Chaetomium sp. YMF 1.02105. Their structures were established on the basis of extensive spectroscopic data analysis and comparison with spectroscopic data reported. Compounds 1-6 are further additions to the small group of dibenzo[b,e]oxepinones represented by arugosins A-H. Compounds 1-7 were tested for their cytotoxic activities against A549, Raji, HepG2, MCF-7, and HL-60 cell lines. The results showed that compound 3 had significant cytotoxicity with IC50 values of 1.2, 1.8, 1.9, 2.3, and 1.6 µg/mL, respectively, against the five cancer cell lines. All compounds showed modest antimicrobial activity against Staphylococcus aureus (ATCC 6538) in standard disk assays.

New dihydrodibenzoxepins from Bulbophyllum kwangtungense

Three new dihydrodibenzoxepins 7,8-dihydro-5-hydroxy-12,13-methylenedioxy-11-methoxyldibenz[ B,F]oxepin (1), 7,8-dihydro-4-hydroxy-12,13-methylenedioxy-11-methoxyldibenz[ B,F]oxepin (2), and 7,8-dihydro-3-hydroxy-12,13-methylenedioxy-11-methoxyldibenz[ B,F]oxepin (3), were isolated from Bulbophyllum kwangtungense Schlecht, along with three known compounds, cumulatin (4), densiflorol A (5) and plicatol B (6). Their structures were established by a combination of 1D and 2D NMR spectroscopic techniques. All new compounds (1-3) and the known compound densiflorol A (5) exhibited anti-tumor activities against HeLa and K562 human tumor cell lines.

A robust hybrid peptide crystal formed with weak hydrogen bonds

In the course of our work relating to the design of a bihelical structure (I) from diphenic anhydride by tethering with cystine di-OMe, stable, hard, and rigid crystals, mp 215-218 degrees C were isolated in low yields ( approximately 2%). The crystal structure established that it was a bis amide (II) arising from diphenic acid and cystine di-OMe [(II), C(22)H(22)N(2)O(6)S(2) (a = 9.897 (1) A, b = 12.210 (1) A, c = 18.192 (1) A, sp. gr. P2(1)2(1)2(1))]. An authentic sample of (II) was subsequently prepared in 47% yields by condensation of diphenic acid dichloride with cystine di-OMe. A most surprising feature of II was, despite its high density, rigidity, and hardness, it did not exhibit any normal hydrogen bonds. The nearest approximation to a "usual" hydrogen bond was the single NH...OC linkage that occurred between molecules along a twofold screw axis. In this linkage, N...O = 3.265 A and H...O = 2.43 A, values that are at least 10% longer than those usually observed in peptides. The rigidity of the crystals appears to depend upon many weak hydrogen bonds of the type CH...O, CH...pi, CH...S, and NH...S working in concert. Even these attractions have separations that are at the high end of the range of previously observed values, although some of the weak hydrogen bonds have been rarely reported and have poorly defined ranges. The attractive effect of each of these weak bonds may be enhanced by the occurrence of a number of them in a parallel fashion like rungs in a ladder.

The antimicrobial activity of extracts of the lichen Hypogymnia tubulosa and its 3-hydroxyphysodic acid constituent

The antimicrobial activity and the MIC values of the diethyl ether, acetone, chloroform, petroleum ether, and ethanol extracts of the lichen Hypogymnia tubulosa and its 3-hydroxyphysodic acid constituent have been investigated against some microorganisms. At least one of the extracts or 3-hydroxyphysodic acid showed antimicrobial activity against Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes, Proteus vulgaris, Salmonella typhimurium, Staphylococcus aureus, Streptococcus faecalis, and Candida albicans. No antifungal activity of the extracts has been observed against ten filamentous fungi.

A flavanone and a dihydrodibenzoxepin from Bauhinia variegata

Phytochemical analysis of the root bark of Bauhinia variegata Linn yielded a new flavanone, (2S)-5,7-dimethoxy-3',4'-methylenedioxyflavanone (1) and a new dihydrodibenzoxepin, 5,6-dihydro-1,7-dihydroxy-3,4-dimethoxy-2-methyldibenz [b,f]oxepin (2) together with three known flavonoids (3-5). The structures of the new compounds were determined on the basis of spectral studies.

Separation of (Z)- and (E)-isomers of thioxanthene and dibenz[b,e]oxepin derivatives with calixarenes and resorcinarenes as additives in nonaqueous capillary electrophoresis

Five acidic calix[4]arenes with carboxylic or sulfonic groups at either the upper or lower rim of the cavity and one resorc[4]arene were investigated to separate three thioxanthenes (flupentixol, clopenthixol, chlorprothixene) and a dibenz[b,e]oxepin derivative (doxepin) with cis-/trans-isomerism by nonaqueous capillary electrophoresis (NACE). Partial filling of the capillary with the UV-absorbing selectors led to a low detection limit and an advantageous signal-to-noise ratio (S/N). A sufficient electrophoretic mobility of the calixarenes towards the anode was necessary to outweigh the oppositely directed electroosmotic flow (EOF). This depended from the functional groups, the dissociation and the hydrodynamic radius of the cyclophanes. In contrast, the resorcinarene was useable only by addition of sodium dodecyl sulfate (SDS) because only the complex of the two selectors had an anodic apparent electrophoretic mobility. p-Sulfonyl-calix[4]arene (ss-a1) was the most capable selector for all E/Z-isomers with maximal alpha-values ranging from 1.056 for doxepin to 1.224 for chlorprothixene. This was due to the sufficient migration in reversed direction to the EOF even at low pH* values of 3.0. Otherwise, electrostatic as well as hydrophobic interactions with the positively charged isomers seem to contribute to a superior recognition. Increasing the concentration up to 15 mM ss-a1 and using acidic media (pH* 5.0) led to high separation efficiency. Changing the organic solvent provides a powerful tool to improve selectivity with N,N-dimethylformamide-methanol (DMF-MeOH)-mixtures for thioxanthenes. Further electrophoretic parameters were optimized, such as the concentration of the electrolytes, the addition of SDS, the kind of electrolytes and the voltage. Distinct differences in selectivities were found between the derivatives with thioxanthene and dibenzo[b,e]oxepin ring system, respectively. Further, the different basic side chain was responsible for the different selectivity at higher pH* values. In contrast, the substitution at position 2 of the thioxanthenes played a secondary role. Based on the studies of single parameters a method for a simultaneous separation of the four pairs of isomers within 13 min was developed.

Effects of olopatadine, a new antiallergic agent, on human liver microsomal cytochrome P450 activities

Olopatadine, a new histamine H(1) receptor-selective antagonist, is a tricyclic drug containing an alkylamino moiety. Some compounds containing a similar alkylamino group form a cytochrome p450 (p450) -iron (II)-nitrosoalkane metabolite complex [metabolic intermediate complex (MIC)], thereby causing quasi-irreversible inhibition of the p450. There was concern that olopatadine might also form MICs, therefore, the present investigation was undertaken to explore this possibility. We identified the enzymes catalyzing olopatadine metabolism and investigated the effect of olopatadine on human p450 activities. During incubation with human liver microsomes in the presence of a NADPH-generating system, olopatadine was metabolized to two metabolites, M1 (N-monodemethylolopatadine) and M3 (olopatadine N-oxide) at rates of 0.330 and 2.50 pmol/min/mg protein, respectively. Troleandomycin and ketoconazole, which are both selective inhibitors of CYP3A, significantly reduced M1 formation but specific inhibitors of other p450 isozymes did not decrease M1 formation. Incubation of olopatadine with cDNA-expressed human p450 isozymes confirmed that M1 formation was almost exclusively catalyzed by CYP3A4. The formation of M3 was enhanced by N-octylamine and was inhibited by thiourea. High specific activity of M3 formation was exhibited by cDNA-expressed flavin-containing monooxygenase (FMO)1 and FMO3. Olopatadine did not inhibit p450 activities when it was simultaneously incubated with substrates for different p450 isozymes. Also, p450 activities in human liver microsomes were unaffected by pretreatment with olopatadine or M1. Furthermore, spectral analysis revealed that neither olopatadine nor M1 formed an MIC. Therefore, it is unlikely that olopatadine will cause drug-drug interactions involving p450 isozymes.

Interaction of S100 proteins with the antiallergic drugs, olopatadine, amlexanox, and cromolyn: identification of putative drug binding sites on S100A1 protein

S100 proteins are a multigenic family of low-molecular-weight Ca(2+)-binding proteins comprising 19 members. These proteins undergo a conformational change by Ca(2+)-binding and consequently interact with their target proteins. Recently, we reported that two antiallergic drugs, Amlexanox and Cromolyn, bind to S100A12 and S100A13 of the S100 protein family. In the present study, we used a newly developed antiallergic drug, Olopatadine, as a ligand for affinity chromatography and examined binding specificity of the drug to S100 protein family. Olopatadine binds specifically to S100 proteins, such as S100A1, S100B, S100L, S100A12, and S100A13, in a Ca(2+)-dependent manner but not to calmodulin. Mutagenesis study showed that amino acid residues 76-85 in S100A1 are necessary for its binding to Olopatadine. In contrast, residues 89-94 were identified as an Amlexanox-binding site in S100A1. Moreover, Olopatadine did not competitively inhibit S100A1-binding site of Amlexanox. Furthermore, we showed that Olopatadine inhibited the binding of S100A1 target protein's binding site peptides to S100A1. These results indicate that C-terminal region of S100A1 is important for antiallergic drug binding, although the drug binding sites are different according to each antiallergic drug. Differences in the binding sites of S100A1 to antiallergic drugs suggest that the regulatory functions of S100 proteins may exist in several regions. Therefore, these drugs may serve as useful tools for evaluating the physiological significance of S100 protein family.

Separation of cis- and trans-isomers of thioxanthene and dibenz[b,e]oxepin derivatives on calixarene- and resorcinarene-bonded high-performance liquid chromatography stationary phases

The chromatographic behavior of six calix[n]arene phases (n=4, 6, 8) and one calix[4]resorcinarene phase is described for the separation of cis- and trans-isomers of three thioxanthene (flupentixol, clopenthixol, chlorprothixene) and one benz[b,e]oxepin derivative (doxepin). The influences of two different organic modifiers (MeOH, MeCN) for the separation of the isomers on every column are described. Different selectivities of the stationary phases exist as a function of the ring size of the calixarenes and their substitution at the "upper rim" with p-tert.-butyl groups. Furthermore, the influence of free phenol groups on the resorcinarene phase is discussed. Relations between structural elements of the analytes and the retention behavior on the stationary phases are found. The selectivity of the calixarene and resorcinarene stationary phases is compared with a RP-C18 phase containing the same base silica. Advantages of the resorcinarene as well as of the calixarene columns exist for the separation of cis- and trans-isomers of three compounds dependent from the substitution in position 2 of the thioxanthenes, respectively the kind of the basic side chain of all substances.

Production of phenolics by immobilized cells of the lichen Pseudevernia furfuracea: the role of epiphytic bacteria

Immobilized lichen cells from the thalli of the lichen Pseudevernia furfuracea, supplied with acetate as the only source of carbon, continuously produced phenolic substances, atranorin and physodic acid, over 23 days. Epiphytic bacteria associated with the lichen thallus grew actively, probably using both acetate and reduced compounds supplied by lichen cells, since their active growth was avoided by including 10 microM 3,3'-dichlorophenyl-1,1'dimethylurea in the bath solution. Penicillin largely impeded the growth of epiphytic bacteria and decreased phenolic production, which was recovered only at the end of the experimental period, just when the bacteria started a slow, but active growth. We suggest the cooperation of epiphytic bacteria in the biosynthesis of both atranotrin and physodic acid.

Dibenzoxepinone hydroxylamines and hydroxamic acids: dual inhibitors of cyclooxygenase and 5-lipoxygenase with potent topical antiinflammatory activity

Hydroxylamine and hydroxamic acid derivatives of a known nonsteroidal antiinflammatory dibenzoxepine series display both cyclooxygenase (CO) and 5-lipoxygenase (5-LO) inhibitory properties. Many of these new dual CO/5-LO inhibitors also exhibit potent topical antiinflammatory activity in the arachidonic acid-induced murine ear edema model. On the basis of their promising profile of in vitro and in vivo activities, hydroxamic acids 24h, 3-(6,11-dihydro-11-oxodibenz[b,e]oxepin-2-yl)-N-hydroxy-N-++ +methylpropanamide (HP 977), and 25, 3-(6,11-dihydrodibenz[b,e]oxepin-2-yl)-N-hydroxy-N- methylpropanamide (P10294), were selected as developmental candidates for the topical treatment of inflammatory skin disorders.

Novel angiotensin II receptor antagonists. Design, synthesis, and in vitro evaluation of dibenzo[a,d]cycloheptene and dibenzo[b,f]oxepin derivatives. Searching for bioisosteres of biphenylyltetrazole using a three-dimensional search technique

Three-dimensional substructure searching (3D search), using the program MACCS-3D, was utilized for designing novel angiotensin II receptor antagonists which contain a bioisostere of the biphenylyltetrazole moiety of DuP 753. A 3D query was prepared from an overlay model of substructures of several potent AII antagonists. The search system retrieved 139 compounds from the database MDDR-3D, which consisted of 29,400 medicinal patent compounds. A tricyclic compound was selected from the retrieved compounds and then evolved by considering steric fitness to the overlay model and synthetic feasibility. Finally, various novel AII antagonists having dibenzo[a,d]cycloheptene or dibenzo[b,f]oxepin were designed and synthesized. The receptor binding activity (Ki) for several members of this series was in the 10(-10) M range, demonstrating the ability of 3D search technique to explore new lead structures.

Binding of 5H-dibenzo[a,d]cycloheptene and dibenz[b,f]oxepin analogues of clozapine to dopamine and serotonin receptors

Series of 5,11-dicarbo- and 11-carbo-5-oxy-10-(1-alkyl-1,2,3,6-tetrahydro-4 pyridinyl) analogues and a 11-carbo-5-oxy-10-(1-methyl-4-piperidinyl) analogue of the atypical antipsychotic agent clozapine were prepared and tested for binding to the dopamine D-2L and D-4 and serotonin S-2A and S-2C receptors. Some of these analogues were found to have dopamine D-2L and D-4 and serotonin S-2A and S-2C receptor binding activities as high as or higher than those of clozapine, indicating that neither the diazepine structure nor the piperazine ring present in clozapine is essential for high antidopamine activity and or for high dopamine D-4 selectivity (Ki for the dopamine D-2L receptor/Ki for the dopamine D-4 receptor). Increasing in the effective size of the alkyl substituent at the tertiary amine nitrogen atom in the 1,2,3,6-tetrahydro-4-pyridinyl moiety in the 5H-dibenzo[a,d]cycloheptene series reduces the affinity for the dopamine D-4 receptor, but in the dibenz[b,f]oxepin series, no significant change in binding affinity to the dopamine D-4 receptor was observed. Equal or slightly higher affinity for the serotonin S-2A and S-2C receptors was observed for the 10-(1-ethyl-1,2,3,6-tetrahydro-4- pyridinyl) analogues in both series, but for the 10-[1,2,3,6-tetrahydro-1-(2-propenyl)-4- pyridinyl] analogues, any favourable steric factor is overshadowed by an unfavorable electronic effect as a result of change in the basicity of the tertiary amino group in the pyridinyl moiety. Replacement of three of the four nitrogen atoms in clozapine with three carbon or two carbon atoms and an oxygen atom and removal of the chlorine atoms gives 10-(1,2,3,6-tetrahydro-1- methyl-4-pyridinyl)dibenzo[a,d]cycloheptene and 10-(1-methyl-4-piperidinyl)dibenz[b,f]oxepin, each having twice the binding activity to the dopamine D-4 receptor as does clozapine and a dopamine D-4 selectivity equal to that of clozapine.

Enzymatic optical resolution of dibenzoxepins and its application to an optically active antiallergic agent with thromboxane A2 receptor antagonistic activity

Methyl (+/-)-11-(2-hydroxyethyl)thio-6,11-dihydrodibenz[b,e]oxepin- 2- carboxylate (5) was enantio-selectively acylated with acetic anhydride in an organic medium by Lipase Amano P to give methyl (-)-11-(2-acetoxyethyl)thio-6,11-dihydrodibenz[b,e]oxepin-2- carboxylate (8), and the (+)-enantiomer by Lipase Sigma Type VII. Using Lipase Amano P, (+)- and (-)-(5) could be prepared with high optical purity (84-94% e.e.). These products were respectively converted to (+)- and (-)-KW-4099, which had antiallergic activity with complete retention of the optical purity.

Synthesis and optical resolution of an antiallergic agent KW4099 with thromboxane A2 antagonistic activity

A new antiallergic agent with thromboxane A2 antagonistic activity, KW4099, was synthesized by a simple method. Its optical resolution was accomplished with the use of (+)- or (-)-2,2'-(1,1'-binaphthyl)phosphoric acid as a resolving agent.