Mechanistic approaches for evaluating the toxicity of reactive organochlorines and epoxides in green algae

Abstract

Reactive electrophilic chemicals, such as reactive organochlorine compounds or epoxides, react specifically with a broad spectrum of nucleophilic biomolecules, including proteins and DNA. Conventional toxicity tests for algae, involving the observation of growth inhibition, i.e., the inhibition of cell multiplication, after several days, yield unreliable information for risk assessment because reactive compounds hydrolyze to different extents during the exposure period. The diversity of their modes of toxic action further complicates effect assessment and calls for methods yielding additional information on the mechanisms of toxicity. One of the primary targets of reactive chemicals in cells is the tripeptide glutathione (GSH), which is important for detoxification but can also be regarded as a toxicity sensor because changes in glutathione levels indicate stress. A vital system for algae is the photosynthetic system, which is indirectly affected by reactive chemicals. The test systems developed in this study for the assessment of reactive toxicity toward algae were therefore based not only on nonspecific toxicity indicators like growth inhibition but also on indicators for disturbance of photosynthesis (inhibition of photosystem II quantum yield) and glutathione metabolism. The application of the developed test systems on Scenedesmus vacuolatus after short-term exposure of 2 h showed that these tests can be used as fast screening tests for algal toxicity and in mode-of-action-based test batteries.

4′‐Phenyl‐2,2′:6′,2′′‐terpyridine Derivatives Containing 1‐Substituted‐2,3‐Triazole Ring: Synthesis, Characterization and Anticancer Activity

“…Compound A1 is least active among tested, which could be intriguing regarding its potential high reactivity. Constrained oxirane ring being capable to interact with various proteins and biological structures may generate oxidative stress, DNA damage which in turn reflects non‐specific toxicity . Such mechanism is usually involved in the environmental toxicity of oxirane intermediates that are broadly utilized in industry.…”

“…Constrained oxirane ring being capable to interact with various proteins and biological structures may generate oxidative stress, DNA damage which in turn reflects non-specific toxicity. [24] Such mechanism is usually involved in the environmental toxicity of oxirane intermediates that are broadly utilized in industry. Cancer cells, however, are known for their higher basal oxidative potential emerging from high-level glycolysis and connected with upregulation of antioxidant proteins like superoxide dismutase MnSOD.…”

Mutations of Toluene-4-Monooxygenase That Alter Regiospecificity of Indole Oxidation and Lead to Production of Novel Indigoid Pigments

“…However, the accumulation of the nearly colorless compound isoindigo, purportedly formed via the dimerization of 2-oxindole (38), could account for the elevated levels of cell-associated radioactivity. Another potential cause of elevated levels of cell-associated radioactivity is the covalent linkage of reactive indole oxidation products, such as indoxyl and epoxides, to cellular material (1,32).…”

“…For therapeutic applications, the cost of product separation would be less of a concern than for textile applications. The 7-hydroxyindole produced by the G103L::A107G mutant, and the derivatives thereof, can be used as a keratin fiber dye (6), as antagonists of the insulinstimulating hormone calmodulin (4,41), or as a stimulants of dopamine production (32). Similarly, the F196L mutant is potentially useful as a catalyst for the production of 2-oxindole or for converting indoles with aromatic ring substitutions into derivatives of 2-oxindole such as 5-chloro-2-oxindole, a precursor to the antirheumatic drug Tenidap (5).…”

Screening test battery for pharmaceuticals in urine and wastewater

“…After exposure, 1 ml of the cell suspension was transferred to the glass cuvette of a ToxY-PAM fluorometer (prototype manufactured by Gademann Instruments, Würzburg, Germany; series production by Heinz Walz, Effeltrich, Germany), and the effective quantum yield of energy conversion at photosystem II reaction centers, Y, was assessed using Equation 2, where F is the momentary fluorescence yield and is the FЈ M maximum fluorescence yield induced by a saturation pulse [17]. The inhibition of photosystem II quantum yield was calculated using Equation 3 [18]:…”