Dichloromethane Soluble Fraction Research Articles

Isolation of flavonoids from the bark of Entada rheedii Spreng

The methanol extract of the bark of Entada rheedii has been fractionated to afford petroleum ether, dichloromethane, ethyl acetate and aqueous soluble fraction through modified Kupchan partitioning protocol and those fractions has been subjected to repeated-chromatographic separation by Sephadex size exclusion chromatography and purification processes to isolate the secondary metabolites. A total of seven compounds have been isolated from the bark of E. rheedii, which were identified as epicatechin (1), liquiritigenin (2), glabridin (3), 4′-O-methylglabridin (4), isoliquiritigenin (5), hispaglabridin A (6) and shinflavanone (7). This is the first report of isolation of these compounds from E. rheedii.

In vitro antiprotozoal activity and cytotoxicity of extracts and fractions from the leaves, root bark and stem bark of Isolona hexaloba

Ethnopharmacological relevanceIsolona hexaloba (Pierre) Engl. and Diels (Annonaceae) is traditionally used in D.R. Congo against parasitic diseases including malaria. Materials and methodsTwo crude aqueous extracts, 3 crude methanol extracts and 3 crude 80% ethanol extracts from the leaves, root bark and stem bark together with 12 subfractions from the crude 80% ethanol extracts were evaluated in vitro for their antiprotozoal activity against Trypanosoma brucei brucei, T. cruzi, Leishmania infantum and the chloroquine and pyrimethamine resistant K1 strain of Plasmodium falciparum. Their cytotoxic effects against MRC-5 cell lines were also assessed. ResultsResults indicated that the most pronounced activities against T. b. brucei were recorded for the crude methanol extracts of root bark (IC50=1.97µg/ml; SI>32.49) and leaves (IC50=2.65µg/ml; SI>24.15). Three samples displayed good activity against T. cruzi: the 80% methanol extract of leaves (IC50=8.33µg/ml; SI>3.92), its petroleum ether fraction (IC50=8.50µg/ml; SI=2.52) and the crude aqueous extract of the stem bark (IC50=9.31µg/ml; SI=3.46). The crude aqueous extract of the leaves exhibited a pronounced and selective activity against L. infantum (IC50=2.00µg/ml; SI>32). The crude methanol extract of leaves (IC50=6.35µg/ml; SI>10.10) and the 2 dichloromethane soluble fractions of the 80% ethanol extracts from root bark (IC50=6.96µg/ml; SI=6.1) and stem bark (IC50=8µg/ml; SI>8.00) showed good activity and selectivity against L. infantum. The most active samples against Plasmodium falciparum K1 were the leaves crude 80% ethanol extract (0.92µg/ml) and its fractions: alkaline aqueous (IC50=0.27µg/ml), 90% methanol (0.90µg/ml) and dichloromethane (1.04µg/ml), respectively, with promising selectivity indexes of 35<SI<237. None of all the tested crude extracts and fractions was found to be cytotoxic against MRC-5 cell lines except the petroleum ether soluble fraction from the leaves which displayed a cytotoxic effect (CC50=21.40µg/ml). ConclusionOverall, extracts of I. hexaloba tested here, showed good results concerning parasitic infections such as Chagas' disease, leishmaniasis, malaria and/or sleeping sickness without considerable toxicity. The 80% ethanol extracts from leaves and their fractions turned out to be of special interest as they were the most useful in the treatment of malaria.

Chemical constituents from Belamcanda chinensis and their inhibitory effects on nitric oxide production in RAW 264.7 macrophage cells.

Belamcanda chinensis (L.) DC., which belongs to the family of Iridaceae, has been used as a folk medicine for the treatment of inflammation, asthma, tonsillitis, and many other throat disorders. Bioactivity-guided purification of the methylene chloride-soluble fraction of the rhizomes of B. chinensis based on the inhibition of nitric oxide production led to the identification of seventeen known compounds. Their structures were elucidated on the basis of extensive spectroscopic measurement such as NMR and ESI-MS. All of the isolated compounds were evaluated for their inhibitory effects on nitric oxide production in LPS-induced RAW 264.7 macrophage cells.

Cleistochlamys kirkii constituents with antibacterial activity

The main aim of this work was to find new antibacterial compounds from the African medicinal plant Cleistochlamys kirkii (Annonaceae) that is used in African traditional medicine for the treatment of infectious diseases [1,2]. To achieve this goal, the root bark used by native populations was collected and a bioassay-guided phytochemical study was performed on the methanol extract. From the dichloromethane soluble fraction of the methanol extract several compounds were isolated, namely C-benzylated flavanones, a dioxopiperazine alkaloid, α,β-unsaturated lactones and an acetogenine. Their structures were assigned based on spectroscopic methods namely 1D and 2D-NMR (COSY, HMBC, HMQC) experiments. The evaluation of the antibacterial activity was carried out by using the microdilution method on a selected bacteria panel that included Gram-positive bacteria: Staphylococcus aureus (sensitive, MRSA and VISA strains), vancomycin-resistant Enterococcus faecalis and Bacillus subtilis and Gram-negative Salmonella typhimurium and Pseudomonas aeruginosa. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for all the compounds. Promising results were obtained with some of the isolated compounds displaying antibacterial activity against Gram positive strains, with MIC values ranging from 1 to 8 µg/mL. Moreover, when combined with ampicillin, some of the isolated compounds displayed a remarkable synergism, lowering the antibiotic MIC value up to 200 times. Based on these results, the most active compounds might be promising hits/leads for the development of new antibiotics against resistant bacterial strains.

Research on Physical and Chemical Properties of Blended Bio-Oil Based on Fractionation

To improve the properties of bio-oil, a new method was proposed that does not involve introduction of any energy medium. An ether-soluble fraction (ES), a dichloromethane soluble fraction (DCMS), and a dichloromethane insoluble fraction (DCMIS) of bio-oil were obtained using ether and dichloromethane as extraction solvents. The same amount of each fraction (10 g) was blended into bio-oil with a certain quantity of 100 g. The three samples were then placed in sealed vials and heated for 12, 60, and 180 h at both 60 °C and 80 °C in an oil bath. Based on the aging properties of the three fractions, blended bio-oil was prepared using ES and DCMS in certain volume ratio. The total yield of the three fractions combined was around 90 wt%; the weight loss was thought to be due to the volatilization of low molecular weight matter and water during the process of solvent evaporation using a rotary evaporator. The aging test results indicated that the DCMIS fraction had the poorest properties compared with ES and DCMS such as acid number, water content and viscosity. In order to get the best properties of blended bio-oil, the optimal volume ratio of ES/DCMS was 1/2 according to the aging test.

Induction of Anticarcinogenic Enzymes by Dichloromethane-soluble Fraction of Physalis alkekengi var. francheti Hort. in Mouse Hepatoma Cells

Physalis alkekengi var. francheti Hort. is known as an insecticide and traditional remedy for liver related diseases. Therefore, this study investigated the chemopreventive effects of extracts and several solvent fractions (n-hexane, dichloromethane, n-butanol, water) of Physalis alkekengi var. francheti Hort. First, their cytotoxicity and NQO1 activity were measured using an MTT assay, plus a quinone reductase [NAD(P)H dehydrogenase (quinone); NAD(P)H: (quinone acceptor) oxidoreductase, EC 1.6.99.2]-inducing activity assay was performed using cultured murine hepatoma cells (Hepa1c1c7) and its mutant cells(BpRc1). The reduction of electrophilic quinones by NQO1 is an important detoxification pathway and major mechanism of chemoprevention. When compared with the other solvent soluble fractions with different polarities, the dichloromethane fraction of Physalis alkekengi var. francheti Hort. showed a higher NQO1-inducing activity that was also dose-dependent. Moreover, the dichloromethane fraction of Physalis alkekengi var. francheti Hort. induced ARE-luciferase activities in HepG2-C8 cells that were generated by transfecting the ARE-luciferase gene construct, suggesting the Nrf2-ARE-mediated induction of anti-oxidative enzymes. In conclusion, the dichloromethane-soluble fraction of Physalis alkekengi var. francheti Hort. showed a relatively strong induction of detoxifying enzymes, thereby meriting further study to identify the active components and evaluate their potential as cancer preventive agents.

Ethno-Pharmacological Survey, In Vitro Anti-Sickling and Free Radical Scavenging Activities of Carapa Procera DC. Stem Bark (Meliaceae)

Drepanocytosis is a genetic and neglected disease, endemic in negroids population. One of the main characteristics of this pathology is the production of a large amount of free radicals, leading to a severe oxidative stress and the consumption of NO by free oxygen radicals, and/or by cell-free plasma heme. The consequences of this defect are hemolytic anemia and tissue damage brought about by the blockage of blood vessels by the sickled cells. The present study evaluated the antisickling and radical scavenging activities of extracts from Carapa procera stem bark using Emmel’s test and the DPPH assay. Carapa procera was selected through an ethno-pharmacological. The results showed that methanolic, ethyl acetate and dichloromethane soluble fractions, anthocyanins and organic acids exhibited a significant antisickling as revealed by the observed normal biconcave form of sickle erythrocyte (normalization rate > 70%) in hypoxic conditions. Methanolic extract exhibited a good radical scavenging activity (ED 50 = 1.698 ± 0.079 µg/mL). The chemical screening performed on the plant revealed the presence of anthocyanins and organic acids which were then extracted. Total anthocyanins and organic acids revealed interesting antisickling and antioxidant properties that could justify the integration of Carapa procera in Congolese pharmacopoeia for the management of sickle cell disease. Bioactive extracts from this plant species could increase nitric oxide by scavenging free oxygen radicals. For the best our knowledge, Carapa procera has not been yet previously reported as antisickling plant in the traditional medicine database of Democratic Republic of the Congo.

Multidimensional and comprehensive two-dimensional gas chromatography of dichloromethane soluble products from a high sulfur Jordanian oil shale

A high sulfur Jordanian oil shale was converted into liquid hydrocarbons by reaction at 390 °C under N2, and the dichloromethane soluble fraction of the products was isolated then analyzed by using gas chromatography (GC). Comprehensive two-dimensional GC (GC×GC) and multidimensional GC (MDGC) were applied for component separation on a polar - non-polar column set. Flame-ionization detection (FID) was used with GC×GC for general sample profiling, and mass spectrometry (MS) for component identification in MDGC. Multidimensional GC revealed a range of thiophenes (th), benzothiophenes (bth) and small amounts of dibenzothiophenes (dbth) and benzonaphthothiophenes (bnth). In addition, a range of aliphatic alkanes and cycloalkanes, ethers, polar single ring aromatic compounds and small amounts of polycyclic aromatics were also identified. Some of these compound classes were not uniquely observable by conventional 1D GC, and certainly this is true for many of their minor constituent members. The total number of distinct compounds was very large (ca.>1000). GC×GC was shown to be appropriate for general sample profiling, and MDGC-MS proved to be a powerful technique for the separation and identification of sulfur-containing components and other polar compounds.

Catalytic Pyrolysis of Forest Thinnings with ZSM-5 Catalysts: Effect of Reaction Temperature on Bio-oil Physical Properties and Chemical Composition

In this study, noncatalytic and catalytic fast pyrolysis of forest thinnings was carried out in a bench-scale bubbling fluidized bed reactor using two commercial ZSM-5 catalysts. After the initial comparison experiments at 475 °C, the catalyst which showed a clearly higher activity was further tested at reaction temperatures of 400 and 550 °C. The yield of organic liquids, which was 39 wt % in the noncatalytic experiment, decreased to 14–24 wt % depending on the reaction temperature. Varying the reaction temperature while using the ZSM-5 catalyst also caused significant changes in the elemental composition, viscosity, and pH, as well as the chemical composition of bio-oil. In general, the use of the catalyst resulted in a less viscous bio-oil with an oxygen content as low as 19 wt %. The catalytically produced bio-oil contained less carbohydrate degradation products and more aromatic compounds. Based on the chemical characterization results (13C nuclear magnetic resonance spectroscopy, gas chromatography–flame ionization detector, gas chromatography–mass spectrometry, and solvent fractionation) obtained in this study, a new supplementary procedure for the existing solvent fractionation method was suggested to be used as an initial screening tool for aromatic hydrocarbon content in bio-oil samples. In this procedure, a water-insoluble, dichloromethane-soluble fraction containing low molecular mass lignin compounds and aromatic hydrocarbons is first isolated using solvent fractionation. When the dichloromethane is allowed to evaporate at room temperature, the consequent mass loss of the pyrolysis products exhibits a linear correlation with the content of aromatic hydrocarbons in bio-oil, as quantified by gas chromatographic methods.

IN-VITRO PHARMACOLOGICAL INVESTIGATIONS OF THE PLANT BOERHAVIA REPENS (FAMILY: NYCTAGINACEAE)

Boerhavia repens is an important medicinal plant having application in jaundice, fever and various other disorders. The whole plant Boerhavia repens was sun dried and extracted using methanol. Later the crude methanolic extract was fractionated into four different fractions using Petroleum ether, carbon tetrachloride, Di-chloromethane and Ethyl acetate. The anti-oxidant activity of the different fractions was measured by the DPPH free radical scavenging activity. The ethyl acetate and the di-chloro methane soluble fractions showed very potent anti-oxidant activity by the DPPH free radical scavenging method. The antimicrobial activity of the different fractions was measured by disc diffusion method. The antimicrobial screening of the plant showed that the carbon tetrachloride soluble fractions and the Petroleum ether soluble fractions showed mild antimicrobial activity. Evaluation of cyto-toxic activity was done using the brine-shrimp lethality bio-assay. The petroleum ether soluble fraction and the ethyl acetate soluble fractions showed significant cyto-toxic activity.

Roles of Tobacco Fractions in the Formation of Polycyclic Aromatic Amines in Tobacco Pyrolysis

Abstract The aim of the present study was to gain further understanding of the precursors in tobacco of four polycyclic aromatic amines (PAAs) - 1- and 2-aminonaphthalene, 3- and 4-aminobiphenyl. We carried out non-isothermal pyrolysis of the residues, which were obtained after extraction of tobacco cut filler with methylene chloride followed by extraction with water, under three different pyrolysis conditions (target temperature 800 °C / 800 °C / 400 °C and O2 concentration in carrier gas 0% / 20% / 3%, resp.). The yields of the four PAAs obtained by the pyrolysis of each sample were evaluated. Several nitrogenous components in the sample were also analyzed. The results under all these pyrolysis conditions showed that 1) the methylene chloride-soluble fraction, in which 50-60% of nicotine was extracted, did NOT contribute significantly contribution to the yields of the four PAAs; 2) the watersoluble fraction, in which most of the nitrogenous inorganic ions and amino acids were extracted, contributed at an average of about 30% to total PAA yield; and 3) the insoluble residue, in which only protein was detected during the investigation of the nitrogenous components in the present study, showed the highest contribution, 50-60% of the four PAAs formed. Consequently, it is concluded that protein-like components in tobacco contribute highly to the formation of the four PAAs by tobacco pyrolysis.

Immunosuppressive Effects of the Traditional Chinese Herb Qu Mai on Human Alloreactive T Cells

Current therapies for transplant rejection are suboptimally effective. In an effort to discover novel immunosuppressants we used cytokine ELISPOT and ELISAs to screen extracts from 53 traditional Chinese herbs for their ability to suppress human alloreactive T cells. We identified a dichloromethane-soluble fraction (Qu Mai fraction AD [QMAD]) of Qu Mai (Dianthus superbus) as a candidate. High-performance liquid chromatography (HPLC) analysis of QMAD revealed three dominant peaks, each with a MW ~600 Daltons and distinct from cyclosporine and rapamycin. When we added QMAD to human mixed lymphocyte cultures, we observed dose-dependent inhibition of proliferation and IFNγ production, by naïve and memory alloreactive T cells, and observed an increased frequency of Foxp3(+) CD4(+) T cells. To address whether QMAD induces regulatory T cells we added QMAD to anti-CD3/CD28-stimulated naïve CD4 T cells and observed a dose-dependent upregulation of Foxp3 associated with new suppressive capacity. Mechanistically, QMAD did not induce T cell IL-10 or TGFβ but blocked T cell AKT phosphorylation, a key signaling nexus required for T cell proliferation and expansion, that simultaneously prevents Foxp3 transcription. Our findings provide novel insight into the antiinflammatory effects of one traditional Chinese herb, and support the need for continued isolation, characterization and testing of QMAD-derived components as immune suppressants for transplant rejection.

Antioxidant and cytotoxic activities of Parabaena sagitatta Miers

A methanolextract of the leaves of Parabaena sagitatta Miers and its petroleum ether, carbon tetrachloride, dichloromethane, ethylacetate and aqueous soluble partitionates were evaluated for antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), Folin-Ciocalteau reagent and phosphomolybdenum total antioxidant assays by using butylated hydroxytolune (BHT) and ascorbic acid as standards. The dichloromethane soluble fraction demonstrated the presence of significant amount of phenolic compounds 61.06 ± 0.54 mg GAE/g of extract and also has moderate antioxidant activity IC50 50.62 ± 0.25 ?g/ml. A positive correlation (R2), 0.969 was observed between total phenolic content and total antioxidant activity of P. sagitatta. The general toxicity was determined by brine shrimp lethality bioassay where the dichloromethane LC50DOI: http://dx.doi.org/10.3329/bjb.v41i2.13441 Bangladesh J. Bot. 41(2): 155-158, 2012 (December)

Active substances and in vitro anti-diabetic effects of a traditional folk remedy Bian-Que Triple-Bean Soup as affected by the boiling time

Bian-Que Triple-Bean Soup (Bian-Que San Dou Yin in Chinese) is a folk remedy which has been used for thousands of years in the practices of traditional Chinese medicine. The objectives of the current study were aimed to determine in vitro anti-diabetic effects and to find out the optimal cooking time for retaining active substances. α-Glycosidase in vitro inhibitory capacities and DPPH free radical scavenging capacities, and contents of active substances including total phenolics, saponin, tannin and monomeric anthocyanin, were determined with colorimetric methods. The results revealed that Bian-Que Triple-Bean Soup boiled for 30 min has the most effective impact on α-glycosidase inhibition. n-Butanol-soluble and water extract fractions showed relatively higher α-glycosidase inhibitory activity (17.4% and 11.2%, respectively) than that (2.56% and 5.32%, respectively) of hexane-soluble and dichloromethane-soluble fractions. Degradation was observed for those thermally unstable substances (TPC, tannin, and anthocyanin) by extending the boiling time; however, there were no obvious changes for thermo-stable substances (saponin).

Antioxidant, Antimicrobial and Cytotoxic Activities of &lt;i&gt;Desmodium Motorium&lt;/i&gt; Merr.

The n-hexane, carbon tetrachloride, dichloromethane soluble fractions of methanol extract of the whole plant of Desmodium motorium were subjected to antioxidant activity by indicated method, inhibition of microbial growth by disc diffusion method and cytotoxicity by brine shrimp lethality bioassay. The methanol i.e., crude extract showed highest antioxidant activity having IC50 9.5 ?g/ml as compared to 9.0 ?g/ml for standard agent BHT. The n-hexane, carbon tetrachloride and dichloromethane soluble fraction showed moderate inhibitory activity to microbial growth, while all the extractive exhibited strong cytotoxic property with the carbon tetrachloride soluble materials revealed the strongest cytotoxicity with LC50 1.54 ?g/ml.© 2013 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v5i1.10955 J. Sci. Res. 5 (1), 201-205 (2013)

우방자에서 분리한 주름개선 화합물

This study was carried out to discover the skin wrinkle reducing components in the seeds of Arctium lappa. The isolation of a methylene chloride-soluble fraction of 70% ethanol extract from the seeds of Arctium lappa using a procollagen type-1 synthesis and MMP-1 activity resulted in the isolation and identification of four lignin compounds: arctiin, arctigenin, matairesinol, and diarctigenin. All structures were confirmed via NMR and MS spectroscopic data. To determine cell viability and procollagen type-1 synthesis, human dermal fibroblasts were treated with 10-100 μM. As a result, none of the four compounds showed cytotoxicity up to 50 μM. We also investigated their procollagen type-1 synthesis and MMP-1 inhibition activity and found that arctiin had the highest activity in terms of both procollagen synthesis and MMP-1 inhibition among all four compounds. Putting all the data together, we suggest that arctiin be used in cosmetics as an anti-wrinkle material.

In vitro Anti‐diabetic Activity and Chemical Characterization of an Apolar Fraction of Morus alba Leaf Water Extract

The tea from the white mulberry (Morus alba L.) leaf is a worldwide known traditional medicine of type II diabetes. Here, we report the investigation of the dichloromethane-soluble fraction obtained in a 0.24% m/m yield from the hot water extract of mulberry leaves. A significant, dose-dependent activity was found by means of the 24-h glucose consumption of fully differentiated adipocytes both in the absence and presence of insulin. The fraction was characterized by HPLC-DAD, GC-MS and GC-FID. The main constituent (40.3% by means of GC-FID) was isolated and identified as loliolide by EIMS, HRESIMS and NMR spectroscopy. In the active fraction benzyl alcohol, ethyl benzoate, t-cinnamic acid, p-hydroxyacetophenone, t-coniferyl alcohol and synapil alcohol were also identified by GC-MS and quantified by GC-FID (0.7, 1.3, 1.5, 2.9, 7.5 and 2.6%, respectively).

Characterization of Red Pine Pyrolysis Bio-oil by Gas Chromatography–Mass Spectrometry and Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

A red pine fast pyrolysis bio-oil was subjected to sequential solvent fractionation into n-hexane soluble (HS), ether soluble (ES), ether insoluble (EIS), dichloromethane soluble (DS), and methanol soluble (MeS) fractions. The volatile components of bio-oil were analyzed by gas chromatography–mass spectrometry (GC–MS), indicating the presence of acids, aldehydes, ketones, alcohols, phenols, and anhydromonosaccharides, which consisted of methoxy, hydroxy, and carbonyl functional groups. These results imply that the bio-oil was similar to the most reported fast pyrolysis bio-oil samples in molecular composition. The bio-oil and its five subfractions were analyzed by negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The predominant compounds in bio-oil were O2–O17 class species with 1–22 double-bond equivalent (DBE) values and 4–39 carbon numbers. The most abundant class species in biocrude oil, HS, ES, EIS, DS, and MeS subfractions were O7, O...

Chemopreventive Potential of an Ethyl Acetate Fraction from Curcuma Longa is Associated with Upregulation of p57kip2and Rad9 in the PC-3M Prostate Cancer Cell Line

Turmeric (Curcuma longa) has been shown to possess anti-inflammatory, antioxidant and antitumor properties. However, despite the progress in research with C. longa, there is still a big lacuna in the information on the active principles and their molecular targets. More particularly very little is known about the role of cell cycle genes p57(kip2) and Rad9 during chemoprevention by turmeric and its derivatives especially in prostate cancer cell lines. Accordingly, in this study, we have examined the antitumor effect of several extracts of C. longa rhizomes by successive fractionation in clonogenic assays using highly metastatic PC-3M prostate cancer cell line. A mixture of isopropyl alcohol: acetone: water: chloroform: and methanol extract of C. longa showed significant bioactivity. Further partition of this extract showed that bioactivity resides in the dichloromethane soluble fraction. Column chromatography of this fraction showed presence of biological activity only in ethyl acetate eluted fraction. HPLC, UV-Vis and Mass spectra studies showed presence three curcuminoids in this fraction besides few unidentified components. From these observations it was concluded that the ethyl acetate fraction showed not only inhibition of colony forming ability of PC-3M cells but also up-regulated cell cycle genes p57(kip2) and Rad9 and further reduced the migration and invasive ability of prostate cancer cells.

A source mixing model to apportion PAHs from coal tar and asphalt binders in street pavements and urban aquatic sediments

Present-day and more than 30 years old road and footpath pavements from Auckland, New Zealand were analysed for PAHs to test the hypothesis that coal tar based pavement binders contribute to unusually high PAH concentrations in adjacent stream and estuarine sediments. Total PAH (∑ 28PAH) concentrations in the dichloromethane-soluble fraction (“binder”), comprising 5–10% of pavement mass, were as high as 200 000 mg kg −1 (10 000 mg kg −1 in binder + aggregate). Older and deeper pavement layers were strongly pyrogenic, whereas pavement layers from recently sealed roads had a more petrogenic composition and more than 1000 times lower ∑ 28PAH concentrations. Source identification analysis using three PAH isomer ratio pairs (benz(a)anthracene/(benz(a)anthracene + chrysene); benzo(a)pyrene/(benzo(a)pyrene + benzo(e)pyrene); and indeno(1,2,3-cd)pyrene/(indeno(1,2,3-cd)pyrene + benzo(g,h,i)perylene) revealed low PAH (bitumen) pavements to have consistently lower isomer ratios than high PAH (coal tar) samples. Moreover, pavement data for one isomer ratio (e.g. benzo(a)pyrene/(benzo(a)pyrene + benzo(e)pyrene) were highly correlated with those of another isomer ratio (e.g. benz(a)anthracene/(benz(a)anthracene + chrysene) and were bounded at their lower and higher extremes by the characteristics of pure bitumen and coal tar, respectively, suggesting that PAH composition of a given pavement sample could be accounted for by conservative mixing between coal tar and bitumen as source materials. A concentration-weighted mixing model, with coal tar and bitumen as source materials, explained more than 80% of the variance in isomer ratios and enveloped the entire PAH compositional and concentration range encountered. PAH composition and concentrations in adjacent stream sediments (> 15 mg kg −1 dry weight) were consistent with diluted coal tar material as a principal PAH source. Due to the very high PAH concentrations of coal tar, a coal tar content of as little as 0.01% of total sediment mass can account for more than 90% of PAH concentrations in adjacent stream sediments.