Reduction of five substituted octalones employing lithium tri-sec-butylborohydride (L-selectride®) in THF and ethyl ether led to allylic alcohols with moderate diastereoselectivity. The stereoselectivity of addition of bulky hydrides showed to be different from most examples in the literature and was strongly influenced by substitution on the octalone ring.

Natural products have been utilized by humans since ancient times and the relief and cure of their diseases was the first purpose for using natural products in medicine. The history of the oriental and occidental civilizations is very rich in examples of the utilization of natural products in medicine and health care. Chinese traditional medicine is one of the most important examples of how natural products can be efficient in the treatment of diseases, and it points to the importance of scientific research on natural products, concerning the discovery of new active chemical entities. The complexity, chemical diversity and biological properties of natural products always fascinated people, and during the last 200 years, this led to the discovery of important new drugs. In the last 30 years, the development of new bioassay techniques, biotechnology methods, bio-guided phytochemical studies, automated high throughput screening and high performance analytical methods, have introduced new concepts and possibilities of rational drug design and drug discovery. In this context, natural products have played an important and decisive role in the development of modern medicinal chemistry.

O padrão de fragmentação de uma série homóloga de alcalóides piperidínicos isolados de Senna spectabilis foi investigado utilizando-se espectrometria de massas tandem com ionização por electrospray (ESI-EM/EM). A análise dos extratos EtOH e frações das flores e dos frutos de S. spectabilis por ESI-EM e ESI-EM/EM permitiu elucidar a estrutura de quatro componentes pertencentes a uma série homóloga destes alcalóides, bem como de quatro co-metabólitos inéditos. A elucidação estrutural dos co-metabólitos, com base no padrão de fragmentação de alcalóides piperidínicos previamente isolados, e confirmados pelos dados de EM de alta resolução, demonstra a importância desta técnica para a determinação do "perfil metabolômico" de uma espécie de importância farmacológica.

The fragmentation pattern of a homologous series of piperidine alkaloids isolated from S. spectabilis was investigated using electrospray ionization tandem mass spectrometry (ESI-MS/MS). The ESI-MS and ESI-MS/MS analyses of EtOH extracts and fractions from flowers and fruits of S. spectabilis allowed to elucidate the structures of four new compounds. The identification of these co-metabolites, based on the fragmentation patterns of previously isolated compounds, and further confirmed by accurate mass spectrometry defines this technique as a powerful tool to determine the "metabolomic profile" of species which has pharmacological importance.