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PubMedDate not supplied

Qualitative detection of Volatile Organic Compounds in outdoor and indoor air.

The present work attempts to identify VOC's in outdoor and indoor air in Mumbai City India. Ambient air was adsorbed on especially fabricated stainless steel cartridge packed with activated coconut charcoal at uniform flow rate. Qualitative identification of VOC's was done by thermally desorbing air from the cartridges and subsequent analysis on Varian GC-MS using NIST Library. The outdoor monitoring locations include residential area, commercial area, industrial, airport, petrol pumps, traffic junctions, arterial roads, highways, slums, parking area, service garages and municipal dump sites. The indoor locations comprised of air-conditioned and non air-conditioned offices, bedrooms, shops and instrumentation laboratory. The identified VOC's include aldehydes, ketones, polynuclear aromatic hydrocarbons, aromatic acids, oxygenated hydrocarbons, amines, esters and halogenated compounds. Thirteen VOCs in outdoor air and seven in indoor air amongst those identified, figure in the list of Hazardous Air Pollutants listed in Title III of the U.S. EPA Clean Air Act Amendments of 1990.

Air Pollutants↗

PubMed2026

Marine-derived Bioactive Compounds: A Promising Frontier against Multidrug-resistant Microbial Infections.

The global escalation of Multidrug-Resistant (MDR) bacterial infections poses a serious and growing threat to public health, contributing to increased morbidity, mortality, and substantial economic burden worldwide. The widespread and often indiscriminate use of antibiotics in clinical and agricultural settings has accelerated the emergence of resistance, significantly diminishing the efficacy of conventional antimicrobial therapies. This pressing challenge necessitates the exploration of alternative sources for novel antibiotics. Marine ecosystems-renowned for their immense biodiversity and ecological complexity-have gained attention as a rich and largely untapped reservoir of bioactive natural products with potent antimicrobial activity. Marine organisms, such as sponges, tunicates, algae, and bacteria and fungi derived from marine sources, produce structurally diverse and pharmacologically active metabolites, including peptides, polyketides, alkaloids, terpenoids, sterols, lactones, and halogenated compounds. Many of these marine-derived molecules possess unique chemical scaffolds and novel mechanisms of action, offering the potential to circumvent existing resistance pathways. Some compounds have shown promising activity against MDR pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii. However, challenges such as low natural abundance, difficulty in cultivation, and structural complexity have limited their clinical translation. Recent advancements in marine biotechnology, genomics, metagenomics, and synthetic biology have opened new avenues for the discovery, biosynthesis, and structural optimization of these compounds. These innovative approaches not only facilitate sustainable production but also enhance the pharmacological properties.

Humans↗

PubMed1989

[Microbial degradation of aromatic compounds].

Benzene degrading bacteria can be isolated easily. In this contribution, the degradation pathway of benzene has been described. It shows a formation of catechol as an intermediate product which can be split oxidatively between hydroxyl groups (an ortho-splitting) as well as beside the hydroxyl groups (a meta-splitting). The participation of plasmids in the degradation process has been brought out. The herbicide PyraminR becomes metabolized by Phenylobacterium immobile in a way which is typical for the degradation of other aromatics, too. The characteristics of a Pseudomonas strain which could become enriched in the presence of 4-chlorobenzoic acid has been quoted: it offers four different ways of dehalogenation. The degradation pathways of aniline and its derivatives go towards catechol and its derivatives. The possible degradation of natural occurring aromatics has been shown by the examples of chloramphenicol, ephedrine, papaverin, juglone and lawsone. The formation of halogenated compounds under natural conditions has been discussed.

Benzene↗

PubMed1989

Chloromethane, a Novel Methyl Donor for Biosynthesis of Esters and Anisoles in Phellinus pomaceus.

Chloromethane (CH(3)Cl), a gaseous natural product released as a secondary metabolite by many woodrotting fungi of the family Hymenochaetaceae, has been shown to act as a methyl donor for biosynthesis of methyl esters of benzoic and furoic acid in the primary metabolism of Phellinus pomaceus. The broad-specificity methylating system could esterify a wide range of aromatic and aliphatic acids. In addition to CH(3)Cl, both bromo- and iodomethanes acted as methyl donors. Methylation did not appear to proceed via methanol or a coenzyme A intermediate. The initial growth-related accumulation of methyl benzoate during culture of P. pomaceus was paralleled by an increase in activity of the methylating system in the mycelium. Changes in percent incorporation of CH(3) from exogenous CH(3)Cl during growth indicated that although utilization of CH(3)Cl was initially closely coupled to biosynthesis of the compound, the system became less tightly channeled later in growth. This phase coincided with release of gaseous CH(3)Cl by the fungus. A biochemically distinct CH(3)Cl-utilizing system capable of methylating phenols and thiophenol was also identified in the fungus, but in contrast with the carboxylic acid-methylating system, it attained maximum activity in the idiophase. Preliminary investigations of a non-CH(3)Cl-releasing fungus, Fomitopsis pinicola, have shown the presence of a CH(3)Cl-utilizing system capable of methylating benzoic acid, suggesting that CH(3)Cl biosynthesis may occur in non-hymenochaetaceous fungi. Halogenated compounds hitherto found in nature are mainly stable end products of metabolism. The participation of CH(3)Cl in primary fungal metabolism demonstrates that some halometabolites may have a previously unrecognized role as intermediates in the biosynthesis of nonhalogenated natural products.

Journal Article↗

PubMed1977

Carcinogenicity studies on halogenated hydrocarbons.

A series of halogenated compounds was tested by oral intubation in 200 Osborne-Mendel rats and 200 B6C3F1 mice of both sexes. Carbon tetrachloride, used as a positive control, induced liver and adrenal tumors in mice and neoplastic nodules in the livers of rats. 1,2-Dibromoethane and 1,2-dibromo-3-chloropropane caused stomach tumors with many metastases in both rats and mice. Chloroform, known to cause hepatocellular carcinomas in mice, led in addition to kidney tumors in male rats. 1,2-Dichloroethane was much weaker than the analog, 1,2-dibromoethane, and induced only a few stomach tumors in rats. It increased liver and lung tumors in mice. Most of the compounds, namely, trichloroethylene, 1,1-dichloroethane, 1,1,2-trichloroethane, hexachloroethane, and tetrachloroethylene, increased hepatocellular carcinomas in mice but had little or no action in rats. Iodoform tended to increase thyroid tumors in male rats and hepatocellular carcinomas in male mice. The action of 3-chloropropene was questionable. No tumors could be attributed to 1,1,1-trichloroethane (methyl-chloroform).

Animals↗

PubMed2003

A combination of ultrasound and oxidative enzyme: sono-biodegradation of substituted phenols.

Sonolysis, enzyme treatment, and a combination of the two processes were tested for the degradation of substituted phenols (phenol, p-chlorophenol, p-bromophenol, p-iodophenol, p-methoxyphenol, p-cresol and p-nitrophenol) in aqueous medium. These organic pollutants are divided into three groups according to their degradation behaviour. In group (I), p-nitrophenol, horseradish peroxidase (HRP) in presence of hydrogen peroxide had a negligible effect on its decomposition. The combined method showed the same effect as sonolysis. Therefore, it is convenient to degrade p-nitrophenol by ultrasonic waves alone. In group (II), p-methoxyphenol and p-cresol, the combined method was approximately the same as enzyme treatment. It means that, the ultrasound had a negligible effect and the enzyme treatment alone was more favourable. Phenol and its halogenated compounds (choloro, bromo and iodo) were placed in group (III) and showed different behaviour than the two mentioned cases. The combined method was more efficient than the sonolysis and enzyme treatment individually. It should be noted that the effect of enzyme on this group (III) was in the medium level in compare of the two other groups (I and II) which the enzyme had a lower and higher effects respectively.

Biodegradation, Environmental↗

PubMed2006

Mechanism of enhanced conversion of 1,2,3-trichloropropane by mutant haloalkane dehalogenase revealed by molecular modeling.

1,2,3-Trichloropropane (TCP) is a highly toxic, recalcitrant byproduct of epichlorohydrin manufacture. Haloalkane dehalogenase (DhaA) from Rhodococcus sp. hydrolyses the carbon-halogen bond in various halogenated compounds including TCP, but with low efficiency (k (cat)/K (m )= 36 s(-1) M(-1)). A Cys176Tyr-DhaA mutant with a threefold higher catalytic efficiency for TCP dehalogenation has been previously obtained by error-prone PCR. We have used molecular simulations and quantum mechanical calculations to elucidate the molecular mechanisms involved in the improved catalysis of the mutant, and enantioselectivity of DhaA toward TCP. The Cys176Tyr mutation modifies the protein access and export routes. Substitution of the Cys residue by the bulkier Tyr narrows the upper tunnel, making the second tunnel "slot" the preferred route. TCP can adopt two major orientations in the DhaA enzyme, in one of which the halide-stabilizing residue Asn41 forms a hydrogen bond with the terminal halogen atom of the TCP molecule, while in the other it bonds with the central halogen atom. The differences in these binding patterns explain the preferential formation of the (R)- over the (S)-enantiomer of 2,3-dichloropropane-1-ol in the reaction catalyzed by the enzyme.

Hydrolases↗

PubMed1992

[A study of the relationships between exposure periods and no-effect doses in repeated dose toxicity tests].

In the risk assessment of chemicals to humans, it is a very important step to determine no-observed-adverse-effect-levels (NOAEL) or lowest-observed-adverse-effect-levels (LOAEL) from animal experiments. Recently, short-term screening tests, such as 28-day repeated dose toxicity test, are carried out in accordance with the regulative guidelines for the safety evaluation of chemicals. However, many problems still remain in the risk assessment to human based on short-term toxicity studies. For this reason, we studied the relationships between the exposure periods and NOAELs or LOAELs in repeated dose toxicity tests using available test results of 18 halogenated compounds. The ratios between each NOAEL or LOAEL of short-term tests (14, 28 days, 13 weeks and 6 month) and those of long-term tests (longer than one year) were calculated on the basis of same animal species, route and toxic effect. From this study, it was considered that exposures above 13 weeks were needed to satisfy the present safety factor considerations for setting an acceptable daily intake (ADI).

Administration, Inhalation↗

PubMed1997

Atmospheric degradation of HFCs and HCFCs: chemistry and noxiousness.

Hydrohaloalkanes are potential alternatives to the fully halogenated compounds (CFCs) that are believed to be responsible for depletion of the stratospheric ozone. In order to establish whether hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are actually more environmentally acceptable, it is extremely important to know, in addition to ODP and HGWP, their atmospheric degradation mechanism, tropospheric lifetime, and toxicity and noxiousness of their atmospheric degradation products. The primary atmospheric sink for hydrohaloalkanes is the reaction with hydroxyl radicals (OH), so that laboratory measurements or a reliable estimation of the rate constants (kOH) of these reactions is essential in order to assess their atmospheric lifetimes. The previsional models for kOH developed in our laboratory allow the estimation of the atmospheric lifetimes of as many as 449 halocarbons (i.e., all the halocarbons containing F and/or Cl with one, two, and three carbon atoms). The harmful character of some degradation products halogenated and oxygenated is also discussed.

Air Pollutants↗

PubMed1996

High yield conversion of doxorubicin to 2-pyrrolinodoxorubicin, an analog 500-1000 times more potent: structure-activity relationship of daunosamine-modified derivatives of doxorubicin.

A convenient, high yield conversion of doxorubicin to 3'-deamino-3'-(2''-pyrroline-1''-yl)doxorubicin is described. This daunosamine-modified analog of doxorubicin is 500-1000 times more active in vitro than doxorubicin. The conversion is effected by using a 30-fold excess of 4-iodobutyraldehyde in anhydrous dimethylformamide. The yield is higher than 85%. A homolog of this compound, 3'-deamino-3'-(1'',3''-tetrahydropyridine-1''-yl)doxorubicin, was also synthesized by using 5-iodovaleraldehyde. In this homolog, the daunosamine nitrogen is incorporated into a six- instead of a five-membered ring. This analog was 30-50 times less active than its counterpart with a five-membered ring. A similar structure-activity relationship was found when 3'-deamino-3'-(3''-pyrrolidone-1''-yl)doxorubicin (containing a five-membered ring) and 3'-deamino-3'-(3''-piperidone-1''-yl)doxorubicin (with a six-membered ring) were tested in vitro, the former being 5 times more potent than the latter. To further elucidate structure-activity relationships, 3'-deamino-3'-(pyrrolidine-1''-yl)doxorubicin, 3'-deamino-3'-(isoindoline-2''-yl)doxorubicin, 3'-deamino-3'-(2''-methyl-2''-pyrroline-1''-yl)doxorubicin, and 3'-deamino-3'-(3''-pyrroline-1''-yl)doxorubicin were also synthesized and tested. All the analogs were prepared by using reactive halogen compounds for incorporating the daunosamine nitrogen of doxorubicin into a five- or six-membered ring. These highly active antineoplastic agents can be used for incorporation into targeted cytotoxic analogs of luteinizing hormone-releasing hormone intended for cancer therapy.

Aldehydes↗

PubMed2006

Measuring and modelling experimental densities and ultrasonic velocities of aromatic and halogenated environmental pollutants.

The potential environmental impact of aromatic and halogenated chemicals from the petrochemical and steel industry is of growning concern. The present paper deals with the modelling and experimental determination of density and speed of sound at the range 278.15-323.15 of six aromatic and halogenated compounds (Benzene, Toluene, Ethylbenzene, Fluorobenzene, 2-Fluorotoluene and Chlorobenzene). Fitting equations were applied to the data in order to correlate for later computer based design. The estimation of the studied properties was made by the application of different theoretical procedures. The Mchaweh-Nasrifar-Moshfeghian model (MNM), an equation of state based on the generalized van der Waals theory which combines the Staverman-Guggenheim combinatorial term of lattice statistics with an attractive lattice gas expression and the Free Length Theory showed a good response at the studied conditions.

Benzene Derivatives↗

PubMedDate not supplied

Luciferase-dependent, cytochrome P-450-catalyzed dehalogenation in genetically engineered Pseudomonas.

To investigate the possibility of luciferase-dependent photoreduction of cytochrome P-450's in vivo, Vibrio harveyi luciferase was coexpressed with the bacterial cytochrome P-450cam in Pseudomonas putida. Luciferase expression was under the control of the Pm promoter from the meta-cleavage TOL operon, incorporated into the chromosome by a mini Tn5-mediated transposition. Cytochrome P-450cam expression was controlled by the Ptac-lac promoter on the broad host range vector pMMB206. Both proteins were expressed in Pseudomonas putida strain MTCC 102 (PpW). This strain does not harbor the cam plasmid, which encodes the enzymes responsible for degradation of the terpene camphor. The metabolic activity of the resulting strain (PpW-lux-cam) toward model halogenated compounds was studied. In the absence of the natural cytochrome P-450cam, electron transfer partners putidaredoxin (PR) and putidaredoxin reductase (Fp), and at low oxygen tension, the bacterial cells efficiently dehalogenate model chlorinated hydrocarbons in a light-independent reaction. Hexachloroethane and pentachloroethane were metabolized to tetrachloroethylene and trichloroethylene, respectively, at rates comparable to that of strain PpG786, which carries the scam plasmid. Reductive dehalogenation required the expression of both luciferase and cytochrome P-450 in the same cells. These results indicate that alternative electron transfer partners may be exploited for cytochrome P-450-dependent bioremediation strategies.

Camphor↗

PubMed2000

Emissions of methyl halides and methane from rice paddies.

Methyl halide gases are important sources of atmospheric inorganic halogen compounds, which in turn are central reactants in many stratospheric and tropospheric chemical processes. By observing emissions of methyl chloride, methyl bromide, and methyl iodide from flooded California rice fields, we estimate the impact of rice agriculture on the atmospheric budgets of these gases. Factors influencing methyl halide emissions are stage of rice growth, soil organic content, halide concentrations, and field-water management. Extrapolating our data implies that about 1 percent of atmospheric methyl bromide and 5 percent of methyl iodide arise from rice fields worldwide. Unplanted flooded fields emit as much methyl chloride as planted, flooded rice fields.

Atmosphere↗

PubMed2004

Measurement and numerical analysis of flammability limits of halogenated hydrocarbons.

Flammability limits measurement was made for a number of halogenated compounds by the ASHRAE method. Most of compounds measured are the ones for which discrepancy was noted between the literature values and predicted values of flammability limits. As a result, it has been found that most of the newly obtained values of flammability limits are not in accordance with the literature values. Numerical analysis was carried out for a set of flammability limits data including the newly obtained ones using a modified analytical method based on F-number scheme. In this method, fitting procedure was done directly to flammability limits themselves instead of fitting to F-number. After the fitting process, the average relative deviation between the observed and calculated values is 9.3% for the lower limits and 14.6% for the upper limits.

Fires↗

PubMed1979

Gas-liquid chromatographic and mass spectrometric indentification of chlorinated trifluorotoluene residues in Niagara River fish.

Several unknown halogenated compounds were detected in Niagara River fish using a method similar to the AOAC multiresidue method for chlorinated pesticides in high-moisture foods. From gas-liquid chromatographic-mass spectrometric (GLC/MS) data and GLC retention times on 3 columns, 7 of the compounds were identified as 4-chloro-alpha,alpha,alpha-trifluorotoluene (0.17--2.0 ppm), 2-chloro-alpha,alpha,alpha-trifluorotoluene (0.002--0.1 ppm), 3,4-dichloro-alpha,alpha,alpha-trifluorotoluene (0.02--0.28 ppm), 2,4-dichloro-alpha,alpha-alpha-trifluorotoluene (0.02--0.17) ppm), 2,3-dichloro-alpha,alpha,alpha-trifluorotoluene (trace-0.005 ppm), 2,6-dichlorotoluene (not quantitated), and 2,4,5-trichlorotoluene (0.31 ppm was found in the only sample quantitated). Other isomers of tri- and tetrachloro-alpha,alpha,alpha-trifluorotoluene and di-,tri-, and tetrachlorotoluene were also present in these samples. Recoveries of the specific chlorinated trifluorotoluenes identified in these samples ranged from 86 to 108%.

Animals↗

PubMed1976

Evaluation of chlorine compounds for surface disinfection by laboratory and in-use testing.

The disinfecting properties of chloramine and compounds containing chlorinated trisodium phosphate and potassium bromide or sodium dichlorisocyanurate and detergents were studied by laboratory and in-use tests and compared with a phenolic disinfectant containing detergents. In a modified Kelsey test all the preparations were effective in the recommended dilutions in clean conditions. The effectiveness of the chlorine-bromine disinfectant substantially decreased in the presence of organic material. The in-use testing was performed in infectious disease and intensive care wards. Chloramine was so disliked that the in-use test could not be carried out. In the infectious disease ward the total bacterial colony counts of the floors (disinfected once a day) were twice as high as those of the intensive care ward (disinfected 3 times a day) during the use of the phenolic and chlorine-bromine disinfectants. The frequent cleaning routine seemed thus to have an effect on the microbial contamination of the floors. The same difference was found in the contamination of the other non-vertical surfaces although they were disinfected only once a day in both wards. In both wards the total bacterial colony counts of all non-vertical surfaces were lower during the use of halogen compounds than during the use of the phenolic disinfectant. The staff, however, complained of the irritation of the skin and the mucous membranes when using chlorine disinfectants.

Chloramines↗

PubMed2000

Examination of lacZ mutant induction in the liver and testis of Muta Mouse following injection of halogenated aliphatic hydrocarbons classified as human carcinogens.

Possible induction of lacZ mutation was examined in the liver and testis of Muta Mouse following the administration of carcinogenic halogenated compounds, namely 1,2-dichloroethane (DCE), 1,2-dibromoethane (DBE), carbon tetrachloride, or 1,2-dibromo-3-chloropropane (DBCP). Slight increases were observed on the mutant frequency in the testis DNA isolated from the mice 14 days after treatment with DBCP at 40 mg/kg or with DBE at 60 mg/kg but not in the liver. Further investigation was necessary to confirm the mutation induction by these chemicals in the testis including experiments with longer sampling intervals. No increase was detected in the frequency following DCE administration of single doses of up to 150 mg/kg or of consecutive injections of up to 280 mg/kg. Marginal but biologically insignificant responses were observed in the liver from the carbon tetrachloride exposed mice. The present results suggest that these carcinogenic chemicals are less efficient for induction of gene mutation in the liver of Muta Mouse.

Animals↗

PubMed2003

Polybrominated diphenyl ethers (PBDEs): new pollutants-old diseases.

Polybrominated diphenyl ethers (PBDEs) are a class of recalcitrant and bioaccumulative halogenated compounds that have emerged as a major environmental pollutant. PBDEs are used as a flame-retardant and are found in consumer goods such as electrical equipment, construction materials, coatings, textiles and polyurethane foam (furniture padding). Similar in structure to polychlorinated biphenyls (PCBs), PBDEs resist degradation in the environment. Less brominated PBDEs like tetra-, penta- and hexa- demonstrate high affinity for lipids and can accumulate in the bodies of animals and humans. Breast milk from North American women contained much higher amounts of PBDEs than levels in breast milk from Swedish women, indicating that North American exposures to PBDEs may be particularly high. Evidence to date suggests that tetra- and penta-BDEs are likely to be the more toxic and bioaccumulative of the PBDE compounds, compared to octa- and deca-congeners. PBDEs are sold as mixtures, under names such as "pentabromodiphenyl ether" and "octabromodiphenyl ether." The pentabromo product is a mixture of tetra-BDEs and penta-BDEs in approximately equal amounts. Pentabromo consists of PBDEs that are believed to be the most toxic. This mixture has been banned by the European Union, but is still used in North America. The United States is the leading producer and user of pentabromo. In August 2003, the State of California passed a bill to phase out the use of penta- and octa-PBDE by 2008. The toxicology of PBDEs is not well understood, but PBDEs have been associated with tumors, neurodevelopmental toxicity and thyroid hormone imbalance. The neurotoxic effects of PBDEs are similar to those observed for PCBs. Children exposed to PBDEs are prone to subtle but measurable developmental problems. It is presumed that PBDEs are endocrine disruptors, but research in this area is scant. Further studies are imperative in a multitude of health and environmental disciplines to determine the adverse effects and mode of action of this widespread emerging pollutant on human health.

Animals↗