Anti-leishmanial activity of alkaloidal extracts obtained from different organs of Aspidosperma ramiflorum.

The present study was designated to evaluate semi-quantitative antileishmanial activity of alkaloidal extracts that were obtained from 1g of different parts of Aspidosperma ramiflorum (leaves, roots, seeds, and stem barks). Alkaloidal extracts of barks and leaves presented a good activity against the extracellular form (promastigotes) of Leishmania (L.) amazonensis. It is known that compounds responsible for the antileishmanial activity in the alkaloidal extracts from A. ramiflorum are the monoterpenoid indole alkaloids ramiflorine A and ramiflorine B, therefore extracts obtained from different plant parts were analyzed by electrospray ionization mass spectrometry (ESI-MS) in order to evidence the presence of these bioactive alkaloids. Based on these findings, alkaloidal extract from leaves was fractionated on preparative thin-layer chromatography in a bioassay-guided fractionation affording individual purified ramiflorines A and B. Both ramiflorines A and B showed significant activity against Leishmania (L.) amazonensis (LD(50) values of 18.5±6.5µg/ml and 12.63±5.52µg/ml, respectively). Our results are showing that alkaloidal extract from leaves is a promising alternative to the use of stem barks from A. ramiflorum.

Comparação de diferentes metodologias para obtenção de cultura de calos de Stevia rebaudiana (Bertoni) Bertoni / Comparison of different methodologies for obtaining callus cultures from Stevia rebaudiana (Bertoni) Bertoni

As folhas de Stevia rebaudiana (Bertoni) Bertoni (Asteraceae) contêm glicosídeos diterpenóides (GDS), que são cerca de 300 vezes mais doce que a sacarose a 4%. O objetivo deste estudo foi avaliar a formação de calos, a partir de folhas obtidas in vivo e in vitro de S. rebaudiana em dois meios já descritos na literatura: Murashige e Skoog (MS), suplementado com 3 mg L-1 de ácido 2,4-diclorofenóxiacético (2,4-D), e o MS suplementado com 1 mg L-1 de ácido naftalenoacético (ANA) e 0,5 mg L-1 de 6-benzilaminopurina 6-BAP) e um desenvolvido em nosso laboratório o Woody Plant Medium (WPM), suplementado com 6 mg L-1 de ANA e 4 mg L-1 de cinetina (CIN). Os explantes obtidos in vitro iniciaram a formação de calos um pouco mais rapidamente que os das folhas de plantas advindas da natureza. A utilização dos nutrientes do meio WPM, associada a uma combinação de fitorreguladores adequada, proporcionou velocidade de indução e multiplicação de calos bem maiores que as apresentadas nos meios que empregaram os nutrientes do MS. Novos experimentos serão realizados, depois de alcançada a estabilidade genética dos calos, visando avaliar a capacidade destes em biossintetizar os GDS

The leaves from Stevia rebaudiana (Bertoni) Bertoni (Asteraceae) contain diterpenoid glycosides (GDS), which are almost 300 times sweeter than sucrose at 4%. The subject of this study was to evaluate the callus-formation from in vivo and in vitro leaves of Stevia rebaudiana in two already described in literature: Murashige and Skoog (MS) supplemented with 3 mg L-1 of 2,4-dichlorophenoxyacetic acid (2,4-D); MS supplemented with 1 mg L-1 of naphthaleneacetic acid (NAA) and 0.5 mg L-1 of 6-benzylaminopurine (6-BAP) and other developed in our laboratory the Woody Plant Medium (WPM) with 6 mg L-1 of NAA and 4 mg L-1 of Kinetin (KIN). The explants obtained in vitro initiated callus formation faster than leaves from natural plants. The utilization of WPM nutrients, associated with an adequate combination of phytoregulators, provided greater callus induction velocity and multiplication than the media that using MS nutrients. New experiments will be conducted after reaching genetic stability of the calluses, seeking to evaluate the capacity of these calluses to biosynthesize GDS