Isolamento dos alcaloides (-)-cassina e (-)-espectalina das flores de Senna Spectabilis e preparação de dois derivados semissintéticos aromáticos

Abstract

The present work was designed from preliminary studies that verified the anticholinesterase activity related to (−)-cassine and (−)-spectaline alkaloids, isolated from Senna spectabilis flowers. Considering that there are few drugs to treat Alzheimer's disease, a neurodegenerative disease that mainly affects the elderly, several derivatives have been planned and two benzoylated analogs have been selected to be synthesized from the mixture of (−)-cassine and (−)-spectaline, order to obtain more potent compounds that can be used as models for the development of new anticholinesterase drugs. Initially, the mixture of (−)-cassine and (−)-spectaline was transformed into the respective hydrochlorides using a modified Kipp system and then subjected to reaction with benzoyl chloride to form the 3-O-benzoylcassine and 3-O-benzoylspectaline derivatives. Which were subjected to high resolution mass spectrometry to confirm the formed products. Then, they were submitted to an initial screening to evaluate the percentage of inhibition against anticholinesterase enzyme (AChE), the main target of anticholinesterase drugs. The results were not significant for the derivatives, presenting inhibition percentage lower than 5% at the highest concentration evaluated (300 μg mL–1), making the IC50 calculation unfeasible.