RESUMEN
A combination of flash chromatography, solid phase extraction, high-performance liquid chromatography, and in vitro bioassays was used to isolate phytocomponents endowed with anticholinesterase activity in extract from Phyllanthus muellarianus. Phytocomponents responsible for the anti-cholinesterase activity of subfractions PMF1 and PMF4 were identified and re-assayed to confirm their activity. Magnoflorine was identified as an active phytocomponent from PMF1 while nitidine was isolated from PMF4. Magnoflorine was shown to be a selective inhibitor of human butyrylcholinesterase-hBChE (IC50 = 131 ± 9 µM and IC50 = 1120 ± 83 µM, for hBuChE and human acetylcholinesterase-hAChE, respectively), while nitidine showed comparable inhibitory potencies against both enzymes (IC50 = 6.68 ± 0.13 µM and IC50 = 5.31 ± 0.50 µM, for hBChE and hAChE, respectively). When compared with the commercial anti-Alzheimer drug galanthamine, nitidine was as potent as galanthamine against hAChE and one order of magnitude more potent against hBuChE. Furthermore, nitidine also showed significant, although weak, antiaggregating activity towards amyloid-ß self-aggregation.
Asunto(s)
Acetilcolinesterasa , Butirilcolinesterasa/química , Inhibidores de la Colinesterasa , Simulación del Acoplamiento Molecular , Phyllanthus/química , Corteza de la Planta/química , Extractos Vegetales/química , Acetilcolinesterasa/química , Inhibidores de la Colinesterasa/química , Inhibidores de la Colinesterasa/aislamiento & purificación , Proteínas Ligadas a GPI/antagonistas & inhibidores , Proteínas Ligadas a GPI/química , Humanos , Estructura MolecularRESUMEN
Phyllanthus muellerianus (Kuntze) Excell (family Euphorbiaceae) stem bark methanol extract inhibited the growth of Clostridium sporogenes and Streptococcus pyogenes, responsible for gas gangrene and suppurative and non suppurative diseases, respectively. After the HPLC fingerprint acquisition a bioguided fractionation of the defatted methanol extract allowed the isolation of six fractions whose activity was evaluated against the two pathogen bacteria. A further purification of the most active fraction afforded a pure compound responsible for the very interesting inhibitory activity against C. sporogenes and S. pyogenes (MIC 0.91 µM, MIC 3.64 µM). (1)H NMR and MS analytical techniques allowed the identification of the bioactive as Nitidine; this quaternary ammonium alkaloid was observed in the genus Phyllanthus for the first time. A study on Nitidine counter ion, performed using energy dispersive spectroscopy (EDS) coupled with scanning electron microscopy (SEM) was also carried out.