A MIP FOR THE EXTRACTION OF AILANTHONE FROM LEAVES OF AILANTHUS ALTISSIMA

Ailanthus altissima, known as the ‘tree of heaven’, is used in traditional chinese medicine to treat cold and gastric diseases. The biological activity of leaf and stem bark extracts is mainly due to the presence of ailanthone, a compound belonging to the quassinoid class. Over the past two decades, some studies have clearly demonstrated the strong herbicidal activity of its extracts. Besides, anti-tuberculosis and anti-malarial activity has also been described. Recently, a lot of special attention has been paid to the cytostatic activity of ailanthone itself. In spite of the spread of A. altissima in a wide variety of soil conditions and environments, the extraction of ailanthone is based on very long and demanding procedures which keep the price of the commercial product very high.

In this work, we describe a preliminary screening of a polymeric library of non-imprinted polymers in order to select monomers and crosslinkers capable of significant interactions towards ailanthone. Starting from the five monomer-crosslinker combinations selected, we prepared two MIPS, 4-vinylpyridine-co-divinylbenzene (4VP-DVB) and 4-vinylpyridine-co-trimethylpropantrimethacrylate (4VP-TRIM) by using acetonitrile and dichloromethane as polymerisation solvents.

The binding properties were investigated by equilibrium binding experiments performed in acetonitrile, methanol and water. The best binding properties compared with the correspondent non-imprinted polymer were obtained with 4VP-TRIM polymer.

The selected MIP was applied to set up a MISPE procedure for the extraction of ailanthone from leaf extracts. A complete extraction protocol was developed first on a standard of ailanthone and then on sample extracts by optimizing sample loading, washing steps and elution conditions to recover ailanthone quantitatively. In order to investigate the matrix effect in different extraction conditions, aliquots of dried leaves were extracted in different solvents as water, methanol, ethyacetate and dichloromethane. In the optimized extraction protocol, the organic extract was evaporated and re-dissolved in water. After precipitation of tannins by addition of polyethylenglycole, the aqueous sample was loaded on the MISPE cartridge that was subsequently washed with water. Finally, ailanthone was recovered by elution with methanol and quantified by HPLC.

In conclusion, through the screening of a non-imprinted library it was possible to identify an optimal formulation to prepare an ailanthone-imprinted polymer, and a simple and rapid approach to solid phase extraction of ailanthone from A. altissima was successfully achieved.