APPLICATIONS, FERRIER REARRANGEMENT AND REACTIONS. In carbohydrate chemistry, the O-glycoside is an organic molecule in which sugar is bound to another functional group via a glycosidic bond. In the last few years, considerable progress has been made in the synthesis and applications of O-glycosides. Despite their challenging chemistry, due to their versatility, O-glycosides play a pivotal role the development of the chemistry of novel materials and bioactive molecules. This review summarizes recent developments, in the last twenty years, about the Ferrier rearrangement reaction involving synthesis, mechanistic proposal and application of 2,3-unsaturated O-glycosides.
Species of the genus Begonia are expensive ornamental plants. There have been few reports of chemical studies with the Begonia species. Here we report the first chemical and biological study of essential oil for a species of Begonia. The essential oil of the Begonia reniformis leaf obtained by hydrodistillation was analyzed via GC-MS and twenty-one compounds were identified. Sesquiterpenes silphiperfol-4,7(14)-diene and β-vetispirene were the major ones with a percentage of 15.7 and 21.0%, respectively. The oil showed weak activity against bacteria Bacillus subtilis and Pseudomonas aeruginosa with minimum inhibitory concentrations of 625μg/mL for each of the two bacteria.
Medicinal plants are used for primary health care in many countries. In Brazil, there are hundreds of street markets selling a wide variety of herbs for medicinal purposes without quality control or scientific evidence; instead, their purported efficacy is based exclusively on empirical ethnobotanical knowledge. The present study evaluated the effectiveness of five medicinal plants widely utilized in Brazil to treat infections, as well as determined their chemical profiles. The results revealed that the five plants investigated (Anacardium occidentale L., Handroanthus impetiginosus Mart., Bumelia sartorum Sw., Zornia brasiliensis Vogel and Cnidosculus urens Pohl) demonstrated moderate to strong antimicrobial activity against most fungi and bacteria tested, principally for infections caused by gram-negative bacteria. The extracts of four plants exhibited MIC of 19.5 µg mL-1 against the bacterium Escherichia coli. The results also confirmed that these five traditional medicinal plants are efficient and inexpensive alternative sources of substances to treat infections. The samples of the commercially marketed plants did not have consistent chemical compositions in at least one type of HPLC, GC/MS, UV or 1H NMR analysis.
Os compostos que contêm sistemas de anéis heterocíclicos são de grande importância tanto na medicina quanto na indústria. O anel heterocíclico de 1,2,4-oxadiazol de cinco membros tem recebido atenção considerável por causa de suas propriedades bioisostéricas únicas e um espectro excepcionalmente amplo de atividades biológicas. Este estudo teve como objetivo a síntese, a caracterização e a avaliação da atividade antimicrobiana de uma série de 2-(3-aril-1,2,4-oxadiazol-5-il)-trans-3,4-(metilenodioxi)-cinamila usando modelos experimentais in vitro. A síntese dos 1,2,4-oxadiazóis foi desenvolvida, com duração de 5 min, usando irradiação de micro-ondas fornecendo os compostos em rendimentos moderados (34-50%). Suas estruturas foram determinadas usando espectroscopia de IV (Infravermelho), Resonância magnética nuclear de hidrogênio (RMN 1H) () eRessonancia magnética nuclear de carbono 13 (RMN 13C). As atividades antibacterianas dos novos derivados de 1,3,4-oxadiazóis foram testado contra Gram positivo (Bacillus subtilis, Enterococcus faecalis e Staphylococcus aureus) e Gram negativo (Escherichia coli e Klebsiella pneumoniae) bactérias usando o método de difusão em disco. Os 2-(3-m-toluil-1,2,4-oxadiazol-5-il)-3,4-(metilenodioxi)-cinamila e o 2-(3-pirimidil-1,2,4-oxadiazol-5-il)-3,4-(metilenodioxi)- cinamila apresentaram resultados contra S. aureus, com valor de CIM de 19,5 μg mL-1 quatro vezes mais potente que o metronidazol padrão (CIM=78 μg mL-1).
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