Biological and enzymatic treatment of bisphenol A and other endocrine disrupting compounds: a review

Bisphenol A is predominantly used as an intermediate in the production of polycarbonate plastics and epoxy resins. Traces of bisphenol A released into the environment can reach into the wastewater and soil via application of sewage sludge from wastewater treatment systems that receive water containing bisphenol A, or from leachate from uncontrolled landfills. In this study we have made an effort to review the work on the presence of bisphenol A and other related endocrine disrupting compounds in the environment and their impact on the life of living organisms including human beings. Bisphenol A has several implications on the health of human beings as well it can also affect the growth of plants and animals. Number of physicochemical methods such as adsorption, membrane based filtration, ozonation, fenton, electrochemical and photochemical degradation has been used for the removal of bisphenol A. However, these methods have some inherent limitations and therefore cannot be used for large scale treatment of such pollutants. The alternative procedures have attracted the attention of environmental scientists. Biological methods are looking quite promising and these procedures are helpful in the complete degradation of bisphenol A and related compounds. Several bacterial, fungal, and algal strains and mixed cultures have successfully been employed for the degradation of bisphenol A. Recently, enzymatic methods have attracted the attention of the environmentalists for the treatment of bisphenol A and other endocrine disrupting compounds. Numerous types of oxidoreductases; laccases, tyrosinases, manganese peroxidase, lignin peroxidase, polyphenol oxidases, horseradish peroxidase and bitter gourd peroxidase have exhibited their potential for the remediation of such types of compounds. The cytochrome P 450 monooxygenases and hemoglobin have also participated in the degradation of bisphenol A and other related endocrine disrupting compounds. Various redox mediators, surfactants and additives have also enhanced enzymatic oxidation of bisphenol A and other related endocrine disrupting compounds.     

Biological alternatives for termite control: A review

Termites are a serious menace to both plants and structures. They are the most problematic pest threatening agriculture and the urban environment. They cause significant losses to annual and perennial crops and damage to wooden components in buildings, especially in the semi-arid and sub-humid tropics. Chemical control has been a successful method of preventing termite attack, but the effects of these chemicals are of concern as they create problems for our health and the environment. Biological methods could be suitable alternatives in this regard. The present paper reviews the various methods (physical, chemical, and biological) for termite control. Recent advances and past research done on termite control emphasizing biological methods are reviewed. Biological methods described include botanicals (essential oil, seed, bark, leaf, fruit, root, wood, resin), as well as fungal, bacterial, and nematode approaches. The relationship between chemical structure of active components responsible for termite control and termiticidal activity is discussed. The plants reviewed show good insecticidal properties against termites. These botanicals can be used for termite control singly and in combination. The active component from biomass can be extracted to prepare efficacious and potent biocidal formulations.     

Organotin compounds and aquatic bacteria: A review

Organotins are toxic to microorganisms. Trisubstituted organotins (R₃SnX) are considered more toxic than disubstituted (R₂SnX₂) or monosubstituted (RSnX₃) compounds, and tetrasubstituted compounds (R₄Sn) are not considered toxic. In the R₃Sn series propyl-, butyl-, pentyl-, phenyl- and cyclohexyltins are the most toxic to microorganisms. Toxicity towards aerobes in the R₃Sn series is related to total molecular surface area and to the octanol: water partition coefficient,Kow, which is a measure of hydrophobicity. Care must be taken when testing the toxicity of tin compounds in the laboratory, for a number of biological, chemical and physical factors can influence the apparent toxicity. Although TBT is generally the most toxic of the butyltins, there are instances where monobutyltin (MBT) is as toxic, or more toxic, than TBT to microorganisms. Thus, debutylation in the sequence TBT→DBT→MBT→Sn does not detoxity TBT for all microorganisms. Some microorganisms can methylate inorganic or organic tins under aerobic or anaerobic conditions. Methylation can also occur by chemical means and the relative contributions of biotic and abiotic mechanisms are not clear. It is difficult to isolate a pure culture which can methylate tin compounds aerobically, and it is difficult to isolate a pure culture which degrades TBT, suggesting that microbial consortiums may be involved in transformations of organotins in the aquatic environment. Methylation and debutylation alter the adsorbtivity and solubility of tin compounds; thus microorganisms can influence the environmental mobility of tin. TBT-resistant microorganisms can be isolated, and in some of them resistance to TBT can be plasmid-mediated. The literature review for this paper was completed in July, 1992.     

Synthesis and antiproliferative activity of some steroidal lactone compounds

Using cholesterol as starting material, some steroidal lactone compounds with the structures of 3-substituted-6-oxo-7-oxa-B-homo-cholestane or 3-substituted-7-oxo-6-oxa-B-homo-cholestane were synthesized by oxidation, reduction, Baeyer-Villiger reaction and condensation reaction. The cytotoxicity of these compounds against MGC 7901 (human gastric carcinoma), HeLa (human cervical carcinoma) and SMMC 7404 (human liver carcinoma) cells was investigated. Our results showed that the synthesized compounds displayed a distinct cytotoxicity against these cancer cells. In particular, compounds 8 and 9 have similar cytotoxic capability as cisplatin does. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.     

Omega-pyridiniumalkylethers of steroidal phenols: new compounds with potent antibacterial and antiproliferative activities

Novel omega-pyridiniumalkylethers of two steroidal phenols were synthesized as compounds with potential antimicrobial activity. 3-Hydroxy-estra-1,3,5(10)-triene-17-one and 1-hydroxy-4-methyl-estra-1,3,5(10)-triene-17-one were reacted with omega,omega'-dibromoalkanes to omega-bromoalkoxy-estra-1,3,5(10)-trienes followed by reaction with pyridine to obtain the desired steroidal omega-pyridiniumalkoxy compounds as bromides. Their antimicrobial activity against strains of multiresistant Staphylococcus aureus (MRSA), a vancomycin resistant Enterococcus faecalis and fast growing mycobacteria depends clearly on the length of the alkyl chain. A strong broadband activity has been found for the compounds with eight or 10 C-atoms; in some cases better than ciprofloxacin or cetylpyridinium salts. In addition, the antiproliferative and cytotoxic activity depends on the chain length, too. The differentiation between antibacterial and cytotoxic activity is better for the steroid hybrid molecules than the cetylpyridinium salts. These new compounds can serve as lead compounds for further optimization.     

Microbial transformations of tin and tin compounds

Summary The use of organotins for agricultural and industrial purposes and in the marine environment has been increasing steadily for more than 20 years. Recently, reliable methodologies have been developed to permit quantification of individual molecular species of organotins in cultures and in the environment. Particular attention has been given to methyltins which can be formed abiotically and by microorganisms, and to tributyltins which are toxic components of effective antifouling paints. In the aquatic environment tin, tributyltins and other organotins accumulate in the surface microlayer, in sediments, and on suspended particulates. Tin compounds are toxic to a variety of organisms and some aquatic organisms can bioaccumulate them. When tin compounds, particularly di-or tri-substituted tins, enter an ecosystem, a portion of the microbial population is killed. Among the survivors are organisms which can methylate inorganic or organic tins, but the relative contribution of biotic and abiotic mechanisms is not clear. While many details of methylations and demethylations need to be worked out, it is clear that transformations of tins can influence the toxicity, volatility and mobility of tin in natural ecosystems. Tributyltins can be debutylated by microorganisms, and hydroxybutyl tins may be intermediates, as they are in mammalian systems. Little is known of the potential and probable microbial transformations of other economically important organotins, but the transformations should be studied for they may have industrial and environmental importance.     

Biological aspects of orthodontic tooth movement: A review of literature

This review of literature describes the cellular and molecular biology of orthodontic tooth movement, including various theories and effect of chemical mediators on tooth movement. The better understanding of the tooth movement mechanism will inspire the clinicians to design and implement effective appliances that will result in maximum benefits and minimum tissue damage to the patients. This paper also emphasizes the applied aspect of different medication and hormones, during orthodontic treatment, on the signaling molecules which produce bone remodeling.     

Genotoxicity of chromium compounds. A review

This article reviews approximately 700 results reported in the literature with 32 chromium compounds assayed in 130 short-term tests, using different targets and/or genetic end-points. The large majority of the results obtained with Cr(VI) compounds were positive, as a function of Cr(VI) solubility and bioavailability to target cells. On the other hand, Cr(III) compounds, although even more reactive than Cr(VI) with purified nucleic acids, did not induce genotoxic effects in the majority of studies using intact cells. Coupled with the findings of metabolic studies, the large data-base generated in short-term test systems provides useful information for predicting and interpreting the peculiar patterns of Cr(VI) carcinogenicity.     

A review of spectroscopic methods for characterizing microbial transformations of minerals

Over the past decade, advances in surface-sensitive spectroscopic techniques have provided the opportunity to identify many new microbiologically mediated biogeochemical processes. Although a number of surface spectroscopic techniques require samples to be dehydrated, which precludes real-time measurement of biotransformations and generate solid phase artifacts, some now offer the opportunity to either isolate a hydrated sample within an ultrahigh vacuum during analysis or utilize sources of radiation that efficiently penetrate hydrated specimens. Other nondestructive surface spectroscopic techniques permit determination of the influence of microbiological processes on the kinetics and thermodynamics of geochemical reactions. The ability to perform surface chemical analyses at micrometer and nanometer scales has led to the realization that bacterial cell surfaces are active sites of mineral nucleation and propagation, resulting in the formation of both stable and transient small-scale surface chemical heterogeneities. Some surface spectroscopic instrumentation is now being modified for use in the field to permit researchers to evaluate mineral biotransformations under in situ conditions. Surface spectroscopic techniques are thus offering a variety of opportunities to yield new information on the way in which microorganisms have influenced geochemical processes on Earth over the last 4 billion years.     

Biological degradation of cyanide compounds

Cyanide compounds are produced as waste products of a number of industrial processes and several routes for their removal from the environment are under investigation, including the use of biodegradation. The most recent developments in this area have come from studies of the hydrolytic and oxidative pathways for biodegradation and the conditions that affect their activity. The biodegradation of cyanide under anaerobic conditions has also recently demonstrated the feasibility for concomitant biogas generation, a possible economic benefit of the process. Significant advances have been reported in the use of plants for the phytoremediation of cyanide compounds and evidence for the biodegradation of thiocyanate and metal-cyanide complexes has become available. Despite these advances, however, physical and economic factors still limit the application of cyanide biodegradation, as do competing technologies.     

有机物生物降解性评价方法综述

评价有机物生物降解性的方法和文献很多,但缺乏系统性介绍评价方法及指导方法选择的综述性文献.本文围绕有机物的生物降解性评价,简要介绍了评价有机物生物降解性的指示性参数及厌、好氧有机物生物降解性评价方法,着重介绍了评价方法选择的标准和原则,并详细分析了不同试验方法使用过程中产生有机物生物降解率差异的原因.最后,以世界经济合作与发展组织(OECD)制定的标准为例,全面介绍了该评价方法的选择使用过程并整合这一评价体系绘制了方法选择路线图,指出了各项试验方法的优越性.     

Biological activity of vanadium compounds

Vanadium compounds are characterised by a broad spectrum of action in vivo and in vitro. Their insulin-mimetic activity is manifested in their ability to normalize changes observed in both clinical and experimental diabetes (i.e. hyperglycaemia, hyperlipidaemia, lowered cell sensitivity to insulin) through the regulation of carbohydrate and lipid metabolism and the removal of secondary symptoms of this disease (as e.g. retinopathy, cardiomyopathy, nephropathy). Nevertheless, vanadium is considered to be a toxic element in both cationic and anionic form, although the latter type has more serious side effects. This is accounted for by the faster absorption of anionic forms, although the chemical structure, geometry, and the manner of synthesis of its derivatives also contributes to this elevated toxicity. Besides their antidiabetic properties, vanadium derivatives have also been observed to influence processes related to mitogenic cell responses (apoptosis, proliferation, neoplastic transformation). However, both anti-and pro-neoplastic properties of vanadium are reported.     

Biological detoxification of mycotoxins: a review

Mycotoxins are secondary fungal metabolites and are reported to be carcinogenic, genotoxic, teratogenic, dermato-, nephro- and hepatotoxic. Several studies have shown that economic losses due to mycotoxins occur at all levels of food and feed production, including crop and animal production, processing and distribution. Therefore, there is a great demand for a novel approach to prevent both the formation of mycotoxins in food and feed and the impact of existing mycotoxin contamination. Recently, investigators have reported that many microorganisms including bacteria, yeast, moulds, actinomycetes and algae are able to remove or degrade mycotoxins in food and feed. We have reviewed various strategies for the detoxification of mycotoxins using microorganisms such as bacteria, yeast and fungi.     

Synthesis and antiproliferative activity of A-ring aromatised and conduritol-like steroidal compounds

A simple approach to aromatization of steroidal quinols and epoxyquinols using a catalytic amount of TMSOTf is reported. Beside acetylation of the angular OH, the acid-catalyzed (TfOH) dienone-phenol rearrangement occurred affording "para" products, or in the case of blocked position 4, the acetoxy group 1,2-migration leads to the formation of "meta" products. Using epoxyquinol derivative as a substrate, the acetoxy group elimination was observed, followed by acid-catalyzed epoxy-ring opening and subsequent double bond migration, giving as a final product Delta(9,11)A-ring aromatized compounds. Synthesis of conduritol-like compounds and structure confirmation by X-ray crystallography of the precursor of steroidal conduritol is also described. In addition, the results of extensive antiproliferative screening against a panel of 60 cancer cell lines are presented.