Analysis parameters
LC-MS analyses were performed on a LC-MS 2020 system
(Shimadzu, Tokyo, Japan) associated to an electrospray ioniza-
tion source (ESI). Separation was carried on a 150 × 4.6 mm
i.d. C18 reverse phase Gemini column(Phenomenex,Torrance,
CA, USA) with particle size of 3 μm and pore size of130 Å.
The column oven was fixed at 30 °C. The mobile phase
consisted of(A) 0.5%formic acid in water and (B) acetonitrile.