Two fast screening methods (GC-MS and TLC-ChEI assay) for rapid evaluation of potential anticholinesterasic indole alkaloids in complex mixtures

Abstract

The pharmacotherapy for Alzheimer's disease (AD) includes the use of acetylcholinesterase inhibitors (AChEI). Recent investigations for novel AD therapeutic agents from plants suggested that Tabernaemontana genus is a promising source of novel anticholinesterasic indole alkaloids. In this work two fast screening techniques were combined in order to easily identify novel cholinesterase inhibitors (ChEI). Gas chromatography-mass spectrometry (GC-MS) of the less polar alkaloidic fractions obtained from the acid-base extraction of the stalk of T. laeta revealed thirteen monoindole alkaloids, four of them confirmed by co-injection with previously isolated alkaloids. The others were tentatively identified by mass fragmentation analysis. By gas chromatography with flame ionization detection (GC-FID) and using isatin as internal standard, affinisine and voachalotine were determined as major compounds. These fractions and fourteen previously isolated alkaloids, obtained from root bark of T. laeta and T. hystrix were investigated for acetyl (AChE) and butyrylcholinesterase (BuChE) inhibitory activities by the modified Ellman's method in thin layer chromatography (TLC-ChEI). Results showed selective inhibition of the alkaloids heyneanine and N b -methylvoachalotine for BuChE, and 19-epi-isovoacristine for AChE, whereas olivacine, affinisine, ibogamine, affinine, conodurine and hystrixnine inhibited both enzymes. In addition to confirming that monoterpenoid indole alkaloids can be novel therapeutic agents for AD, this is the first report of the ChEI activity of olivacine, a pyridocarbazole alkaloid.

Chemical Constituents Antioxidant and Anticholinesterasic Activity of Tabernaemontana catharinensis

“…Of the compounds identified in the raw extract of T. catharinensis , affinisine was previously described in T. catharinensis extracts [24] as well as in extracts from T. buchtieni [25], T. fuchsiaefolia [17], and T. histrix [9]. In turn, 16-epi-affinine was identified in T. catharinensis , T. latea , T. pachysiphon and T. psychotrifolia [18], and T. fuchsiaefolia [22].…”

“…Tabernaemontana catharinensis ADC is a small tree of the Apocynaceae family currently found in Brazil, Argentina, Uruguay, Paraguay, and Bolivia [4]. The genus Tabernaemontana has evoked interest due to the important biologic activity of its extracts, particularly, antimicrobial [5, 6], anti-tumoral [7], antioxidant [8], anti-cholinesterasic [9], and anti-inflammatory [10] activities, most of which have been associated with indole alkaloids. Although several biological activities of T. catharinensis extracts have been reported, few substances with anticholinesterase activity able to minimize damage caused by oxidative stress have been described in T. catharinensis .…”

Cytotoxicity and genotoxicity of coronaridine from Tabernaemontana catharinensis A.DC in a human laryngeal epithelial carcinoma cell line (Hep-2)

“…The genus Tabernaemontana is rich in monoterpene indole alkaloids such as coronaridine, voacangine, hydroxycoronaridine, isovoacangine, 11-hydroxycoronaridine, voacristine, 19-epi-voacristine, isovoacristine, ibogamine, 10-metoxyibogamine, 11-metoxyibogamine, and 19-epi-heyneanine (Kam and Sim, 2002; Prakash Chaturvedula et al , 2003). These indole alkaloids have numerous biological activities, including central nervous system-stimulating activity, antihypertensive, anticholinesterase, antimicrobial and antimalarial properties, and especially antitumor activity (van Beek et al , 1984; Perera et al , 1985; Delorenzi et al , 2001; Prakash Chaturvedula et al , 2003; de Almeida et al , 2004; Kam et al , 2004; Andrade et al , 2005; Vieira et al , 2008; Medeiros et al , 2011). …”

Isolamento, identificação e avaliação da atividade antileucêmica de alcaloides indólicos monoterpênicos de Tabernaemontana salzmannii (A. DC.), Apocynaceae

“…Em publicações anteriores relatamos o isolamento e identificação de alcaloides indólicos monoterpênicos das espécies T. laeta (Medeiros et al, 1999(Medeiros et al, , 2001(Medeiros et al, , 2003 e T. hystrix (Monnerat et al, 2005a), bem como a atividade anticolinesterásica de dezessete alcaloides indólicos (Vieira et al, 2008).…”