Aspidosperma species: A review of their chemistry and biological activities.

Ethnopharmacological Relevance: Species of Aspidosperma are known popularly as "peroba, guatambu, carapanaúba, pau-pereiro" and "quina". The genus can be found in the Americas, mainly between Mexico and Argentina. Many species of Aspidosperma are used by the population in treating cardiovascular diseases, malaria, fever, diabetes and rheumatism. The phytochemical aspects of the species of the genus Aspidosperma have been studied extensively. The monoterpene indole alkaloids are the main secondary metabolites in Aspidosperma species, and about 250 of them have been isolated showing a considerable structural diversity. Several of them have showed some important pharmacological activities. Aspidosperma subincanum Mart. and Aspidosperma tomentosum Mart. (Apocynaceae) are Brazilian species widely used by the population to treat diabetes mellitus, hypercholesterolemia. The pharmacological activities of both species have been investigated and the biological properties described can be related to their isolated indole alkaloids. However, more pharmacological studies are needed in order to justify the use of these species in folk medicine. In this review, we present reports mainly focused on chemical and biological studies and their relationship with the ethnopharmacological use of both Aspidosperma species.

Aim Of The Study: The aim of this review is to present their ethnopharmacological use as correlated to their biological activities as described for the extracts and isolated compounds from Aspidosperma subincanum Mart. and Aspidosperma tomentosum Mart. In addition, some aspects related to the biosynthetic pathways are discussed, also NMR assignments and some synthesis information about indole alkaloids from both Aspidosperma species are included.

Material And Methods: The bibliographic search was made in theses and dissertations using some databases such as NDLTD (Networked Digital Library of Theses and Dissertations), OATD (Open Access Theses and Dissertations) and Google Scholar. More data were gathered from books, Brazilian journals and articles available on electronic databases such as, Google Scholar, PubChem, Scifinder, Web of Science, SciELO, PubMed and Science Direct. Additionally, the Google Patents and Espacenet Patent Search (EPO) were also consulted. The keywords Aspidosperma, A. subincanum, A. tomentosum, indole alkaloids were used in the research. The languages were restricted to Portuguese, English and Spanish and references were selected according to their relevance.

Results: A. subincanum Mart. and A. tomentosum Mart. (Apocynaceae) are Brazilian species widely used by the population to treat a few diseases. Extracts and isolated compounds of both species have shown antitumor and antimalarial activities. The antitumor activity of isolated compounds has been extensively studied. However, the antiplasmodial activity needs to be investigated further as well as the anti-inflammatory, anti-hyperlipidemic and anorexigenic activities. From A. subincanum twenty-one indole alkaloids were isolated and some of them have been extensively studied. From the leaves and bark of A. tomentosum four alkaloids and one flavonoid were isolated. Furthermore, CG-MS analysis of seeds, branches, leaves and arils identified nine indole alkaloids. Stemmadenine has been proposed as a precursor of indole alkaloids obtained from some species of Aspidosperma. Many of the biosynthetic steps have been characterized at the enzymatic level and appropriate genes have been identified, however, other steps have yet to be investigated and they are still controversial. Some isolated alkaloids from A. subincanum and A. tomentosum were identified only by mass spectrometry. In many cases, their NMR data was either not available or was incomplete. The described meta-analysis of the available NMR data revealed that the chemical shifts belonging to the indole ring might be used to characterize this class of alkaloids within complex matrices such as plant extracts. The biological activities and the structural complexity of these compounds have stimulated the interest of many groups into their synthesis. In this review, some information about the synthesis of indole alkaloids and their derivatives was presented.

Conclusions: A. subincanum and A. tomentosum are used by the population of Brazil to treat many diseases. A few biological activities described for the extracts and isolated compounds of both species are in agreement with the ethnopharmacological use for others species of Aspidosperma, such as, antimalarial, the treatment of diabetes and other illnesses. These species are sources of leading compounds which can be used for developing new drugs. In addition, other biological activities reported and suggested by ethnopharmacological data have yet to be investigated and could be an interesting area in the search for new bioactive compounds.