Disruption of Nongenomic Steroid Actions on Gametes and Serotonergic Pathways Controlling Reproductive Neuroendocrine Function by Environmental Chemicals
Rajesh K. Naz in Endocrine Disruptors, 2004
The finding that the majority of xenoestrogens that bind to the membrane progestin receptor in seatrout ovaries display little or no affinity for the nuclear progestin receptor in this species [97] suggests that localization of the receptor in the plasma membrane may be important for xenobiotic binding activity. Many of the xenoestrogens tested are highly lipophilic and readily interact with biological membranes, which are rich in lipids [103, 104]. Techniques to solubilize the membrane receptor and measure competition with 20β-S binding to the solubilized protein were developed to investigate this possibility. Removal of the receptor from the plasma membrane by solubilization did not alter the binding affinities of natural and synthetic steroids, whereas it resulted in a complete loss of binding to a variety of xenoestrogens such as DDT analogs and hydroxylated PCBs. In a separate study, the binding of organic compounds lacking estrogenic activity with different degrees of lipophilicity (octanol/water coefficients) to the membrane receptor was investigated in competition assays. The two most lipophilic compounds, dibenzofuran and biphenyl, caused significant displacement of 3H-20β-S at a concentration of 100 nM, whereas none of the other organic compounds were effective competitors at this concentration (unpublished observation).
Monographs of Chemicals Not Used as Fragrances Per Se But Present as Allergens in Botanical Products Used as Fragrances
Anton C. de Groot in Monographs in Contact Allergy, 2021
Usnic acid, a lichen acid, is a yellow crystalline solid (www.thegoodscentscompany.com). It is a monobasic acid (dibenzofuran) that accumulates in lichens. In nature, usnic acid occurs in D- and L-stereoisomers. Usnic acids have antimicrobial properties against bacteria, viruses, fungi, and protozoa (3). These properties have led to their use in personal care products including deodorants, creams, toothpaste, mouthwash, and sunscreens, especially in Europe (13). They also are used in clothing dyes and funeral wreaths. The dye used in litmus paper is derived from lichens (14).
Organic Chemicals
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
In one U.S. survey, almost all mothers nursing had PCB in their breast milk, with 30% having more than 0.05 ppm. Fifty percent of Michigan mothers had more than 1.35 ppm in their milk.306 Neurological and developmental impairments in children have been linked to exposure to PCBs through ingestion of mother's milk. Rats, rabbits, and guinea pigs exposed to PCBs showed liver damage with fatty infiltrates, central lobe atrophy, and necrosis.307 PCBs interfere with liver metabolism, with three major biochemical effects being the indicator of a mixed-function oxidase system. PCBs have major contaminants dibenzofuran and dibenzodioxine, both of which are potent mixed-function oxidase inducers. PCBs are potent immune suppressants and carcinogens.307 Following human exposure to PCBs, the neurological signs have included headache, fatigue, nervousness, dizziness, and decreased sensory nerve conduction.308 PCBs can cause lymphoid atrophy in rabbits, chickens, and guinea pigs. A splenic and/or thymic atrophy can occur in monkeys. PCBs affect vitamin A absorption; they inhibit the synthesis of retinal binding protein.309 Exposure to PCBs may cause selenium and/or vitamin E deficiency in chickens.310 PCBs are inducers of hepatic microsomal mixed-function oxidases and can affect selenium-induced growth functions of depleted rats by affecting their utilization.311 They are strong inducers of liver microsomal enzyme and possibly may affect selenium depletion. Hepatic biopsy in Yusho patients who have been accidentally exposed to PCBs in oil showed hypertrophy of the smooth endoplasmic reticulum, indicative of microsomal enzyme induction.312 Seven years after the accident, very high levels were still found in several Yusho patients, with 92.0 and 230 ppb being reported in two patients.312 Exposure to PCBs results in enlargement of the thyroid gland in rats.313 Clinical short-term responses of humans and monkeys to PCBs are summarized in Table 5.42.314
Radiosensitizer effect of usnic acid on Biomphalaria glabrata embryos
Published in International Journal of Radiation Biology, 2018
F. T. J. Santos, W. N. Siqueira, M. L. O. Santos, H. A. M. F. Silva, J. L. F. Sá, T. S. Fernandes, N. H. Silva, E. J. França, E. B. Silva, A. M. M. A. Melo
Lichens, symbiotic associations between fungi and algae, are the source of a variety of bioactive compounds, mainly derived from their secondary metabolism and having applications in medicine, the textile industry, cosmetics and food (Kosanić et al. 2012; Manojlovic et al. 2012; Paudel et al. 2012). Usnic acid, dibenzofuran found in several species of lichens, is one of the most studied lichen metabolites and one of the few commercially available today. A number of biological activities are attributed to this metabolite, and its analgesic, antiviral, antiparasitic, antimicrobial, anti-inflammatory, antiproliferative, antitumor and antioxidant effects are reported (Shang et al. 2014; Su et al. 2014). Such characteristics make usnic acid a promising candidate for bioassays that can verify its radiosensitizing activity.
A systematic review on biomonitoring of individuals living near or working at solid waste incinerator plants
Published in Critical Reviews in Toxicology, 2019
Laura Campo, Petra Bechtold, Lucia Borsari, Silvia Fustinoni
Waste incineration is a thermal process leading to the combustion of organic substances contained in waste material. Solid waste incinerators (SWIs) can treat both municipal (MSWI) and industrial/hospital hazardous waste (HSWI). Waste materials feeding the plant may be thus crude urban waste, residual from differentiated waste collection and treated or untreated waste from industrial processes or hospitals. As a consequence of the combustion process, emissions are spread into the environment containing both inorganic and organic substances, among which carbon oxide (CO), carbon dioxide (CO2), sulfur and nitrogen oxides (SOX, NOX), soot, metal elements, and their oxides and salts, volatile organic compounds (VOC), dioxins [polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofuran (PCDFs), together PCDD/Fs)], polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), particulate matter (PM) and ultrafine particles (World Health Organization 2007). These substances may be emitted as vapors (i.e. Hg, VOC, 2-, and 3-ring-PAHs) or adsorbed onto particulate matters; as such, they can be present as airborne pollutants and enter the human body through inhalation, or they can deposit on the ground. Ground contaminants can be directly ingested with contaminated food, that is vegetables or animals grown in the deposition area of the incineration plume, or with contaminated water, after dissolution by atmospheric precipitations and leaching into the groundwater.
Usnic acid and its derivatives for pharmaceutical use: a patent review (2000–2017)
Published in Expert Opinion on Therapeutic Patents, 2018
Olga A. Luzina, Nariman F. Salakhutdinov
It has been demonstrated that natural products play a dominant role in the discovery of leads for the development of drugs for the treatment of human diseases [1]. Most of them belong to the domain of plant-derived compounds, and much of nature’s ‘treasure trove of small molecules’ remains to be explored from marine, microbial, and fungal environments. Lichens are composite organisms consisting of a symbiotic association of a fungus (the mycobiont) with a photosynthetic partner (the phytobiont), usually either a green alga or cyanobacterium. The morphology, physiology, and biochemistry of lichens are very different from those of isolated fungi and alga in culture. Over the past two decades, there has been renewed and growing interest in lichens as a source of novel, pharmacologically active biomolecules [2]. Of the hundreds of known secondary lichen metabolites, the dibenzofuran derivative, usnic acid (UA), is without doubt the most extensively studied. Usnic acid is widely distributed in species of Cladonia (Cladoniaceae), Usnea (Usneaceae), Lecanora (Lecanoraceae), Ramalina (Ramalinaceae), Evernia, Parmelia (Parmeliaceae), and other lichen genera. Lichens produce much UA, up to 8% of the dry weight of thalli. Its content in thalli undergoes broad seasonal variation, reaching a maximum in the late spring and early summer and low levels in autumn and winter. The usnic acid content depends on geographic locality, correlating with the time of summer solstice, insolation, and temperature [3]. Since Usnea spp. synthesize and excrete UA in response to an environmental influence, the UA content may be increased artificially up to 31% [4].
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