Asiatic acid

β-Amyrin, α-amyrin, lupeol, erythrodiol, uvaol, oleanolic acid, ursolic acid, and asiatic acid were purchased from Extrasynthese (Genay, France). Betulin and MeJA were purchased from Sigma-Aldrich (St. Louis, MO, USA). Betulinic acid was purchased from Tokyo Chemical Industry (Tokyo, Japan). Soyasapogenol B and soyasapogenol A were purchased from Tokiwa Phytochemical (Chiba, Japan). Sophoradiol, 24-hydroxy-β-Amyrin, and soyasapogenol E were kindly provided by Dr. Kiyoshi Ohyama (Tokyo Institute of Technology, Japan).

Methanol, acetonitrile, formic acid, rutin, phloridzin and catechin were obtained from Sigma-Aldrich (Milan, Italy). Procyanidin B2, oleanolic acid, asiatic acid were obtained from Extrasynthese (Genay Cedex, France). An Agilent Eclipse XDB C-18 3.0 × 150 mm (3.5 µm) was used as stationary phase for analytical procedures. For semipreparative HPLC separation of triterpene acids, an Agilent Eclipse C-18 30 × 210 mm (5 µm) stationary phase was used. An Agilent 1100 system equipped with 1100 series diode array, Sedex 60 Evaporative Light Scattering Detector (ELSD) and Agilent 1260 series fraction collector was used for purification of triterpene acids. For LC-DAD-MS analysis an Agilent 1260 chromatograph equipped with 1260 series diode array was used (Agilent, Santa Clara, CA, USA). After the chromatography column a “T” junction split the flow to DAD and Varian MS 500 mass spectrometer (Varian, Santa Clara, CA, USA). MS spectra were acquired using two different approaches, one using Electrospray (ESI) and one Atmospheric Pressure Chemical Ionization (APCI) sources for polyphenols and triterpenes, respectively. For both analyses the spectrometer operated in negative ion mode acquiring spectra in the range m/z 50–2000.