Meclocycline Sulfosalicylate

β-III-Spectrin is a key cytoskeletal protein that localizes to the soma and dendrites of cerebellar Purkinje cells and is required for dendritic arborization and signaling. A spinocerebellar ataxia type 5 L253P mutation in the cytoskeletal protein β-III-spectrin causes high-affinity actin binding. Previously we reported a cell-based fluorescence assay for identification of small-molecule actin-binding modulators of the L253P mutant β-III-spectrin. Here we describe a complementary, in vitro, fluorescence resonance energy transfer (FRET) assay that uses purified L253P β-III-spectrin actin-binding domain (ABD) and F-actin. To validate the assay for high-throughput compatibility, we first confirmed that our 50% FRET signal was responsive to swinholide A, an actin-severing compound, and that this yielded excellent assay quality with a Z' value > 0.77. Second, we screened a 2684-compound library of US Food and Drug Administration-approved drugs. Importantly, the screening identified numerous compounds that decreased FRET between fluorescently labeled L253P ABD and F-actin. The activity and target of multiple Hit compounds were confirmed in orthologous cosedimentation actin-binding assays. Through future medicinal chemistry, the Hit compounds can potentially be developed into a spinocerebellar ataxia type 5-specific therapeutic. Furthermore, our validated FRET-based in vitro high-throughput screening platform is poised for screening large compound libraries for β-III-spectrin ABD modulators.

The thermal behavior of the antibiotics doxycycline (Dox) and meclocycline (Meclo) in the monohydrate and sulfosalicylate forms was investigated by TG/DTG, TG/DTA, DSC and TG-FTIR.Dox decomposed in three steps after its melting at 174°C, with no evidence of crystallization on cooling.According to thermogravimetry associated with evolved gas anal., it was suggested that decomposition begins with the release of: water, isocyanic acid, dimethylamine, as well as carbon dioxide and ammonia, resulting from the decomposition of isocyanic acid.At 535°C carbon monoxide, methane and water were identified in gaseous phase.Meclo decomposed in two steps and did not presented melting and crystallization events.The gases released by Meclo during thermal decomposition were sulfur dioxide (from sulfosalicylate), carbon dioxide, isocyanic acid, carbon monoxide and ammonia.A mechanism for the thermal degradation of both antibiotics in nitrogen, has been proposed.