دانلود مقاله ترجمه شده سنتز یک پلیمر قالبِ مولکولی، جهت استخراج فاز جامدِ بتولین و بتولینیک اسید از پوست درخت چنار

Abstract

Introduction  –  Plant  extracts  are  usually  complex  mixtures  of  various  polarity  compounds  and  their  study  often  includes  a purification step, such as solid-phase extraction (SPE), to isolate interest compounds prior analytical investigations. Molecularly imprinted polymers (MIPs) are a new promising type of SPE material which offer tailor-made selectivity for the extraction of trace active components in complex matrices. Numerous specific cavities that are sterically and chemically complementary of the target molecules, are formed in imprinted polymers. A molecularly imprinted polymer (MIP) was synthesised in order to trap a specifi  c class of triterpene, including betulin and betulinic acid from a methanolic extract of plane bark. Methodology  –  Imprinted  polymers  were  synthesised  by  thermal  polymerisation  of  betulin  as  template,  methacrylic  acid (MAA)  or  acrylamide  (AA)  as  functional  monomer,  ethylene  glycol  dimethacrylate  as  crosslinking  agent  and  chloroform  as porogen.  Afterwards,  MAA-  and  AA-MIPs  were  compared  with  their  non-imprinted  polymers  (NIPs)  in  order  to  assess  the  selectivity vs betulin and its derivatives. Recovered triterpenes were analysed by HPLC during MIP-SPE protocol. Results – After SPE optimisation, the MAA-imprinted polymer exhibited highest selectivity and recovery (better than 70%) for betulin  and  best  affinity  for  its  structural  analogues.  Thus,  a  selective  washing  step  (chloroform,  acetonitrile)  removed unwanted matrix compounds (fatty acids) from the SPE cartridge. The elution solvent was methanol. Finally, the MAA-MIP was applied to fractionate a plane bark methanolic extract containing betulin and betulinic acid. Conclusion  – This  study  demonstrated  the  possibility  of  direct  extraction  of  betulin  and  its  structural  analogues  from  plant extracts by MIP technology.