Inhibition of LPS-stimulated ROS production by fluorinated and hydroxylated chalcones in RAW 264.7 macrophages with structure-activity relationship study

Based on the importance of the previous fluorinated and/or hydroxylated chalcones studies, thirty-six compounds were designed as phenyl or hydroxyphenyl bearing fluoro, trifluoromethyl or trifluoromethoxy phenyl propenones and synthesized by applying modified Claisen-Schmidt condensation reaction as a single step. Inhibitory effects of the synthesized compounds on ROS production stimulated by LPS in RAW 264.7 macrophage were evaluated. Structure-activity relationship (SAR) study revealed that the compounds possessing para-hydroxyphenyl group combined with meta-fluoro or meta-trifluoromethyl phenyl group, and meta/para-hydroxyphenyl group combined with ortho-trifluoromethoxyphenyl group have an essential role in inhibiting the LPS-stimulated ROS production in RAW 264.7 macrophages. The most significant inhibitory effect on LPS-stimulated ROS production in RAW 264.7 macrophages was observed in compound 30 that possessed para-hydroxyphenyl group along with ortho-trifluoromethoxyphenyl group.     

Synthesis,topoisomerase I and II inhibitory activity,cytotoxicity, and structure–activity relationship study of hydroxylated 2,4-diphenyl-6-aryl pyridines

A new series of 2,4-diphenyl-6-aryl pyridines containing hydroxyl group(s) at the ortho, meta, or para position of the phenyl ring were synthesized, and evaluated for topoisomerase I and II inhibitory activity and cytotoxicity against several human cancer cell lines for the development of novel anticancer agents. Structure–activity relationship study revealed that the substitution of hydroxyl group(s) increased topoisomerase I and II inhibitory activity in the order of meta > para > ortho position. Substitution of hydroxyl group on the para position showed better cytotoxicity.     

Synthesis, characterization and in vitro anti-cancer activity of N-(ferrocenyl)benzoyl tri- and tetrapeptide esters

N-ortho, N-meta and N-para-(ferrocenyl)benzoyl tri- and tetrapeptide esters (2-7) were prepared by coupling ortho, meta and para-ferrocenyl benzoic acids to the tri- and tetrapeptide ethyl esters of GlyGlyGly(OEt) and GlyGlyGlyGly(OEt) in the presence of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole. The compounds were characterized by a range of NMR spectroscopic techniques, mass spectrometry and cyclic voltammetry. The anti-proliferative effects of the ortho derivatives 2 and 5 were measured in vitro against H1299 lung cancer cells and both gave IC₅₀ values greater than 50 μM. Therefore, extending the length of the peptide chain had a negative effect on activity, relative to N-(ferrocenyl)benzoyl amino acid and dipeptide derivatives.     

Relative hepatotoxicity of ortho and meta mono substituted thiobenzamides in the rat

Thiobenzamide is known to be hepatotoxic in the rat and the relative hepatotoxicity of para-substituted thiobenzamides has previously been shown to depend strictly on the electronic character of the para substituent. We have now extended this study to include ortho and meta monosubstituted thiobenzamides. Among the meta-substituted compounds, hepatotoxicity varies in strict accordance with the electronic character of the substituent, whereas the ortho-substituted compounds show no toxicity at comparable doses regardless of the nature of the substituent. Explanations for these substituent effects are provided in terms of the chemical reactivity of the compounds and their corresponding S-oxide and S,S-dioxide metabolites.     

Synthesis and biological evaluation of 2-phenol-4-chlorophenyl-6-aryl pyridines as topoisomerase II inhibitors and cytotoxic agents

A new series of 2-phenol-4-chlorophenyl-6-aryl pyridines were designed, synthesized, and evaluated for topoisomerase (topo) I and II inhibitory activities as well as cytotoxic activity against four different human cancer cell lines such as HCT15, T47D, DU145, and Hela. Most of the tested compounds exhibited stronger topo II inhibitory activity at 100 μM as compared to etoposide. All the compounds, except 39, did not show topo I inhibitory activity. Interestingly, compounds that showed better topo II inhibition than etoposide have ortho- or para-chlorophenyl at 4-position of central pyridine, and none of the compounds possess meta-chlorophenyl. SAR study revealed the importance of ortho- or para-chlorophenyl at 4-position of the central pyridine for selective topo II inhibitory activity. Similarly, all compounds possessing meta- or para-hydroxyphenyl moieties showed moderate to significant cytotoxic effects. Particularly, compounds 27–37, and 39 which showed excellent cytotoxicity (IC₅₀ = 0.68–1.25 μM) against T47D breast cancer cells suggest the importance of meta- or para-hydroxyphenyl moiety at 2-position of the central pyridine for the design of anticancer agents with related scaffolds.     

Spectrum of the Reductive Dehalogenation Activity of Desulfitobacterium frappieri PCP-1

Desulfitobacterium frappieri PCP-1 was induced for ortho- and para-dechlorinating activities by different chlorophenols. Dehalogenation rates ranging from 25 to 1,158 nmol/min/mg of cell protein were observed according to the chlorophenol tested and the position of the chlorine removed. D. frappieri shows a broad substrate specificity; in addition to tetrachloroethylene and pentachloropyridine, strain PCP-1 can dehalogenate at ortho, meta, and para positions a large variety of aromatic molecules with substituted hydroxyl or amino groups. Reactions of O demethylation and reduction of nitro to amino substituents on aromatic molecules were also observed.     

Establishment of a Polychlorinated Biphenyl-Dechlorinating Microbial Consortium, Specific for Doubly Flanked Chlorines, in a Defined, Sediment-Free Medium

Estuarine sediment from Charleston Harbor, South Carolina, was used as inoculum for the development of an anaerobic enrichment culture that specifically dechlorinates doubly flanked chlorines (i.e., chlorines bound to carbon that are flanked on both sides by other chlorine-carbon bonds) of polychlorinated biphenyls (PCBs). Dechlorination was restricted to the para chlorine in cultures enriched with 10 mM fumarate, 50 ppm (173 μM) 2,3,4,5-tetrachlorobiphenyl, and no sediment. Initially the rate of dechlorination decreased upon the removal of sediment from the medium. However, the dechlorinating activity was sustainable, and following sequential transfer in a defined, sediment-free estuarine medium, the activity increased to levels near that observed with sediment. The culture was nonmethanogenic, and molybdate, ampicillin, chloramphenicol, neomycin, and streptomycin inhibited dechlorination activity; bromoethanesulfonate and vancomycin did not. Addition of 17 PCB congeners indicated that the culture specifically removes double flanked chlorines, preferably in the para position, and does not attack ortho chlorines. This is the first microbial consortium shown to para or meta dechlorinate a PCB congener in a defined sediment-free medium. It is the second PCB-dechlorinating enrichment culture to be sustained in the absence of sediment, but its dechlorinating capabilities are entirely different from those of the other sediment-free PCB-dechlorinating culture, an ortho-dechlorinating consortium, and do not match any previously published Aroclor-dechlorinating patterns.     

Alkenyl substituted bicyclic nucleoside analogues retain nanomolar potency against Varicella Zoster Virus

Novel alkenyl substituted aryl bicyclic furano pyrimidines have been prepared and evaluated in vitro against Varicella Zoster Virus (VZV). The para-substituted analogues retain the nanomolar potency we have reported for p-alkyl analogues, while the ortho- and meta-alkenyl systems lose 3–4 orders of potency.     

Effect of Sulfate and Organic Carbon Supplements on Reductive Dehalogenation of Chloroanilines in Anaerobic Aquifer Slurries

When di-, tri-, and tetrachloroaniline were incubated in methanogenic groundwater slurries, they were reductively dehalogenated by the aquifer microbiota. 2,3,4-Trichloroaniline was metabolized by two pathways. Primary dehalogenation occurred at either the meta or ortho position of this substrate to form 2,4- and 3,4-dichloroaniline, respectively. The latter chemical could be stoichiometrically converted to 3-chloroaniline. 2,3,4,5-Tetrachloroaniline was degraded by the sequential removal of halogens from the para and then the ortho position to form 3,5-dichloroaniline. An additional pathway was observed with this substrate when the aquifer slurries were amended with butyrate. That is, halogens could be removed from both the meta and ortho positions of tetrachloroaniline. The amendment of sulfate to methanogenic aquifer slurries slowed the rate of 2,3,4,5-tetrachloroaniline degradation and increased the amount of substrate channeled through the additional pathway. The reported intermediates or end products are identified by their chromatographic mobility and mass-spectral profiles.     

Structural motives controlling the binding affinity of 9,10-bis(methylpyridinium)anthracenes towards DNA

In the search of new DNA groove binding agents a series of substituted 9,10-methylpyridiniumanthracenes have been synthesized and their interactions with DNA have been studied by UV/vis absorption, CD and fluorescence spectroscopy. A minor groove binding mode is confirmed by DNA melting studies, strong CD effects, the dependence of the binding affinity on ionic strength, and the differentiation between AT and GC base pairs. No binding occurs to GC sequences. Binding constants to calf thymus DNA (ct-DNA) and poly(dA:dT) in the range between 1 × 10⁴ and 3 × 10⁵ M⁻¹ have been determined. The binding strength decreases with the size of substituents attached at the anthracene site. Variation of the substitution pattern of the charged groups shows that methyl groups in meta position cause slightly stronger binding than methyl groups in para position. In contrast, with these groups in ortho position, no binding interaction has been observed. The strongest binding is achieved with an expansion of the peripheral heterocycle from pyridine to quinoline. Molecular modeling reveals the pivotal role of the substitution pattern: Anthracenes with para and meta pyridines align along the minor grooves. On the other hand, the ortho derivative adopts no groove-alignment.     

Hydroxylation of beta-phenylethylamine in the rat

$\text{ortho}$, $\text{meta}$ and $\text{para}$ Tyramine, as their dansyl derivatives, have been identified and quantitated by mass spectrometry in rat urine. After intraperitoneal injection of phenylethylamine labelled either with deuterium or tritium in the presence of pargyline, the amount of urinary tyramines excreted was 0.8% ($\text{para}$, 0.74%; $\text{meta}$, 0.12%; $\text{ortho}$, 0.008%) of the injected dose. The advantages of involving stable isotopes and mass spectrometry in metabolic studies of pharmacologically active compounds is discussed.     

Biotransformation of organic sulfides: Part. 10. Formation of chiral ortho- and meta-substituted benzyl methyl sulfoxides by biotransformation using Helminthosporium species NRRL 4671

Benzyl methyl sulfides substituted with methyl, chloro, cyano, bromo, methoxy, nitro and amino groups in the ortho or meta positions of the aromatic ring have been converted to (S) sulfoxides by biotransformation using the fungal biocatalyst Helminthosporium species NRRL 4671. The enantiomeric excesses for meta-substituted examples were high in those cases where the substituent was of a polar nature, and comparable to those observed for the corresponding para-substituted substrates. With one exception (o-amino), the ortho-substituted examples gave sulfoxides of lower enantiomeric purity. The role of a suitably located polar substituent on an aryl ring of the substrate in ensuring a high enantiomeric excess in sulfoxidation by Helminthosporium species has been confirmed by the biotransformations of 4-(methylthiomethyl)benzyl alcohol and 2-(4-nitrophenyl) ethyl methyl sulfide, which give sulfoxides of much higher optical purity than those obtained from the corresponding unsubstituted substrates.     

Prelog and anti-Prelog stereoselectivity of two ketoreductases from Candida glabrata

Two ketoreductases from Candida glabrata were used for the asymmetric reduction of prochiral substituted acetophenones displayed different enantiopreference toward para-, meta-substituted and ortho-halogen substituted acetophenones with excellent enantioselectivity. Homology modeling and docking analysis were in conformity with this interested enantiopreference obtained from experimental tests. The reduction of a series of other substituted aryl ketones was also investigated using the two ketoreductases.     

Regiospecificity of Chlorophenol Reductive Dechlorination by Vitamin B12s

Vitamin B₁₂, reduced by titanium (III) citrate to vitamin B_12s, catalyzes the reductive dechlorination of chlorophenols. Reductive dechlorination of pentachlorophenol and of all tetrachlorophenol and trichlorophenol isomers was observed. Reaction of various chlorophenols with vitamin B₁₂ favored reductive dechlorination at positions adjacent to another chlorinated carbon, but chlorines ortho to the hydroxyl group of a phenol were particularly resistant to reductive dechlorination, even if they were also ortho to a chlorine. This resulted in a reductive dechlorination pattern favoring removal of para and meta chlorines, which differs substantially from the pattern exhibited by anaerobic microbial consortia.     

A novel aryl-hydrazide from the marine lichen Lichina pygmaea: Isolation,synthesis of derivatives,and cytotoxicity assays

A new aryl-hydrazide l-glutamic acid derivative, pygmeine (3), was isolated from a methanolic extract of Lichina pygmaea, a marine lichen. Synthetic derivatives obtained via a two-step coupling of l-glutamic acid with phenylhydrazine moieties were useful to elucidate the structure of 3 and to carry out biological assays. Thus, the cytotoxicity of the ortho-, meta-, and para-hydroxyl isomers along with their respective benzyl intermediates, and a natural methoxylated analog, were evaluated on murine and human melanoma cells (B16, A375). The para-hydroxyl isomer 6 was found to be the most active (IC₅₀ = 1.6 μM) on B16 cells.     

Diaryl-1,2,4-oxadiazole antioxidants: Synthesis and properties of inhibiting the oxidation of DNA and scavenging radicals

Six 1,2,4-oxadiazole derivatives were prepared in order to compare their abilities to protect DNA against radical-mediated oxidation and to scavenge radicals. These derivatives had a structure based on disubstituted 1,2,4-oxadiazole, in which a vanillin group (A ring) and a substituted benzene group (B ring) were the substituents. The functional group at B ring was assigned as ortho- or meta-hydroxylbenzene group, ortho-chlorobenzene group, no group contained, and pyridine group or vanillin group at B ring. It was found that the compound with two vanillin groups attaching to oxadiazole can trap 2.05 radicals in protecting DNA against 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH)-induced oxidation, and the compound with an ortho-hydroxylbenzene group at B ring can trap 1.78 radicals. The compound with an ortho-chlorobenzene group at B ring exhibited the highest ability to inhibit ^·OH-induced oxidation of DNA, while the compound with a meta-hydroxylbenzene group at B ring inhibited Cu²⁺/glutathione (GSH)-induced oxidation of DNA efficiently. The ortho- and para-hydroxylbenzene groups at B ring made the compounds possess the highest rate constant (k) in scavenging 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS^+.) and 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH). Therefore, only a few hydroxyl groups can markedly enhance the activity of the core-branched antioxidant, which may be a novel structural feature in designing antioxidant.     

Photodynamic effects of novel 5,15-diaryl-tetrapyrrole derivatives on human colon carcinoma cells

Preliminary in vitro cytotoxicity studies on a panel of meso diaryl-substituted tetrapyrrole derivatives newly synthesized in our laboratory have shown that these compounds are photodynamically active on the human colon carcinoma cell line HCT116. In the present study, we investigate some mechanistic aspects of the photodynamic action of the most active compounds in the series, namely the 5-phenyl-15-(3-methoxyphenyl)porphyrin (1), the 5-phenyl-15-(3-hydroxyphenyl)porphyrin (2) and the 5,15-diphenylporphyrin (3). The results of the cytotoxicity studies indicate that the novel photosensitisers (PSs) are more potent in vitro than m-THPC (Foscan^®), a powerful PS already approved for clinical use in photodynamic therapy (PDT). A series of experiments were performed to elucidate a number of aspects in the mechanism of PS-induced phototoxicity, including, intracellular accumulation and subcellular localization of the PSs, induction of apoptosis, and generation of reactive oxygen species (ROS) and NO. All the compounds tested exhibit similar singlet oxygen quantum yields; differential intracellular accumulation can contribute to the observed differences in phototoxicity. Flow cytometric studies indicate that all the tested compounds induce apoptosis; however, their cytotoxic effect does not seem to rely solely on this process. Generation of significant amounts of reactive oxygen species (ROS) and NO were also observed; however, the contribution of this latter effect to the overall phototoxicity is unclear. Taken together, our observations suggest that the diaryl derivatives included in the present study could represent promising leads for the development of novel photosensitizing agents.     

Microbial Reductive Dechlorination of Aroclor 1260 in Baltimore Harbor Sediment Microcosms Is Catalyzed by Three Phylotypes within the Phylum Chloroflexi

The specific dechlorination pathways for Aroclor 1260 were determined in Baltimore Harbor sediment microcosms developed with the 11 most predominant congeners from this commercial mixture and their resulting dechlorination intermediates. Most of the polychlorinated biphenyl (PCB) congeners were dechlorinated in the meta position, and the major products were tetrachlorobiphenyls with unflanked chlorines. Using PCR primers specific for the 16S rRNA genes of known PCB-dehalogenating bacteria, we detected three phylotypes within the microbial community that had the capability to dechlorinate PCB congeners present in Aroclor 1260 and identified their selective activities. Phylotype DEH10, which has a high level of sequence identity to Dehalococcoides spp., removed the double-flanked chlorine in 234-substituted congeners and exhibited a preference for para-flanked meta-chlorines when no double-flanked chlorines were available. Phylotype SF1 had similarity to the o-17/DF-1 group of PCB-dechlorinating bacteria. Phylotype SF1 dechlorinated all of the 2345-substituted congeners, mostly in the double-flanked meta position and 2356-, 236-, and 235-substituted congeners in the ortho-flanked meta position, with a few exceptions. A phylotype with 100% sequence identity to PCB-dechlorinating bacterium o-17 was responsible for an ortho and a double-flanked meta dechlorination reaction. Most of the dechlorination pathways supported the growth of all three phylotypes based on competitive PCR enumeration assays, which indicates that PCB-impacted environments have the potential to sustain populations of these PCB-dechlorinating microorganisms. The results demonstrate that the variation in dechlorination patterns of congener mixtures typically observed at different PCB impacted sites can potentially be mediated by the synergistic activities of relatively few dechlorinating species.     

Anaerobic Degradation of Benzene, Toluene, Ethylbenzene, and Xylene Compounds by Dechloromonas Strain RCB

Dechloromonas strain RCB has been shown to be capable of anaerobic degradation of benzene coupled to nitrate reduction. As a continuation of these studies, the metabolic versatility and hydrocarbon biodegradative capability of this organism were investigated. The results of these revealed that in addition to nitrate, strain RCB could alternatively degrade benzene both aerobically and anaerobically with perchlorate or chlorate [(per)chlorate] as a suitable electron acceptor. Furthermore, with nitrate as the electron acceptor, strain RCB could also utilize toluene, ethylbenzene, and all three isomers of xylene (ortho-, meta-, and para-) as electron donors. While toluene and ethylbenzene were completely mineralized to CO₂, strain RCB did not completely mineralize para-xylene but rather transformed it to some as-yet-unidentified metabolite. Interestingly, with nitrate as the electron acceptor, strain RCB degraded benzene and toluene concurrently when the hydrocarbons were added as a mixture and almost 92 μM total hydrocarbons were oxidized within 15 days. The results of these studies emphasize the unique metabolic versatility of this organism, highlighting its potential applicability to bioremediative technologies.