RESUMO
Two new structurally unique compounds bearing a nitrogen- and sulfur-containing tricyclic ring system, ulbactin F (1) and its diastereomeric isomer ulbactin G (2), were isolated from the culture extract of a sponge-derived Brevibacillus sp. The structures and absolute configurations of 1 and 2 were determined by NMR analysis and X-ray crystallographic analysis. These compounds inhibit the migration of tumor cells in the submicromolar to micromolar range.
Assuntos
Antineoplásicos/química , Brevibacillus/química , Carcinoma de Células Escamosas/química , Movimento Celular/efeitos dos fármacos , Neoplasias Esofágicas/química , Compostos Heterocíclicos com 3 Anéis/química , Compostos Heterocíclicos com 3 Anéis/farmacologia , Tiazolidinas/química , Tiazolidinas/farmacologia , Animais , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Carcinoma de Células Escamosas/tratamento farmacológico , Linhagem Celular Tumoral , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Neoplasias Esofágicas/tratamento farmacológico , Carcinoma de Células Escamosas do Esôfago , Compostos Heterocíclicos com 3 Anéis/isolamento & purificação , Humanos , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , PoríferosRESUMO
Continuous, coherent subterahertz radiation arises when a dc voltage is applied across a stack of the many intrinsic Josephson junctions in a Bi2Sr2CaCu2O(8+δ) single crystal. The active junctions produce an equal number of I-V characteristic branches. Each branch radiates at a slightly tunable frequency obeying the Josephson relation. The overall output is broadly tunable and nearly independent of heating effects and internal cavity frequencies. Amplification by a surrounding external cavity to allow for the development of a useful high-power source is proposed.
