ABSTRACT
The toxicity of viologens can be significantly reduced by including them in tight [2]rotaxane structures alongside ß-cyclodextrin, thus turning them into candidates of pharmaceutical interest. Here, we report a synthesis pathway for a benign viologen, by capping a small ß-cyclodextrin-caged molecule, the 4,4'-bipyridine, with minimal-length presynthesized axle-stopper segments of the propyl-3-pentamethyldisiloxane type. After 90 min from the oral administration to laboratory mice, the product concentration in the bloodstream reaches a value equivalent to 0.634% of the initial dose of 800 mg·kg(-1). As compared to the nude viologen having the same structure, which proved to be lethal in doses of 40 mg·kg(-1), the product induces reversible morphological changes in the liver, kidney, lung, and cerebellum, up to a dose of 400 mg·kg(-1), with higher dosages giving rise to a chronic slow evolution.
Subject(s)
Pyridines/toxicity , Siloxanes/toxicity , beta-Cyclodextrins/chemistry , Administration, Oral , Animals , Cerebellum/drug effects , Kidney/drug effects , Liver/drug effects , Lung/drug effects , Mice , Proton Magnetic Resonance Spectroscopy , Pyridines/chemistry , Siloxanes/chemical synthesis , Siloxanes/chemistryABSTRACT
The compatibility of wood from mountain pine beetle (Dendroctonus ponderosa) killed lodgepole pine (Pinus contorta var. latifolia) with Portland cement was investigated based on time-since-death as a quantitative estimator, and the presence of blue-stained sapwood, brown rot, or white rot as qualitative indicators. The exothermic behavior of cement hydration, maximum heat rate, time to reach this maximum, and total heat released within a 3.5-24 h interval were used for defining a new wood-cement compatibility index (CX). CX was developed and accounted for large discrepancies in assessing wood-cement compatibility compared to the previous methods. Using CX, no significant differences were found between fresh or beetle-killed wood with respect to the suitability for cement; except for the white rot samples which reached or exceeded the levels of incompatibility. An outstanding physicochemical behavior was also found for blue-stained sapwood and cement, producing significantly higher compatibility indices.
