RESUMEN
A series of 10,13-disubstituted 16-membered macrolides was synthesized using nitroso Diels-Alder reactions of leucomycin A7. Despite the extensive constituent functionalities in leucomycin, the hetero cycloaddition reactions proceeded in a highly regio- and stereoselective fashion. Subsequent chemical modifications of the nitroso cycloadducts, including N-O bond reduction, were also conducted. Most leucomycin derivatives retained antibiotic profiles similar to leucomycin A7, and, in contrast to leucomycin itself, several exhibited moderate antiproliferative and cytotoxic activity.
Asunto(s)
Antibacterianos/química , Antibacterianos/farmacología , Kitasamicina/análogos & derivados , Kitasamicina/farmacología , Compuestos Nitrosos/química , Animales , Antibacterianos/síntesis química , Antibacterianos/toxicidad , Bacterias/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Humanos , Kitasamicina/síntesis química , Kitasamicina/química , Kitasamicina/toxicidad , Ratones , Relación Estructura-ActividadRESUMEN
This review concerns the definitions and appropriate analytical characterisations of herbal reference standards within the framework of regulatory requirements. It describes currently applicable rules and regulations, as well as future issues relating to the European Pharmacopoeia and United States Pharmacopoeia. It provides an update on the use and availability of pharmacopoeial (EP and USP) herbal reference standards since our last review was published in 2009. The continuing challenges facing manufacturers, suppliers and analysts are discussed on the basis of exemplary reference substances for herbal products in medicinal and food products. The article also reviews the special aspects of Brazilian stipulations (Brazilian Pharmacopoeia, Anvisa) by comparison with European regulations. The term herbal products as used throughout this article refers to herbal drugs, herbal preparations and finished herbal medicinal products unless a different meaning is obvious from the context. More specific terms are used where necessary.
RESUMEN
An efficient procedure for the highly selective oxidation of leucomycines to the corresponding 16-membered 9- and 13-oxo macrolides using hypervalent iodinates is presented. Both the Dess-Martin periodinane (DMP) and polymer-bound 2-iodoxybenzoic acid (IBX) show clear advantages over the previously employed manganese dioxide. Key intermediates for a variety of further chemical derivatization methods (2a, 2b) are obtained in very good yields without the requirement of protecting groups.