Biochanin a

The acetonitrile and methanol were of HPLC grade and were purchased from Roth GmbH (Karlsruhe, Germany). The reference compounds (chlorogenic acid, caffeic acid, ferulic acid, t-cinnamic acid, mangiferin, kaempferol, tectoridin, iristectorigenin B, nigricin, irigenin, isoorientin, genistein-7-glucoside, and biochanin A) were purchased from ChromaDex (Santa Ana, CA, USA), Sigma-Aldrich (Saint Louis, MO, USA), HWI ANALYTIK GmbH, and Roth GmbH (Karlsruhe, Germany). All other chemicals were of analytical grade.

Solvents used for extraction and phytochemical standardization were of analytical or chromatographic/LC-MS grade and were provided by Avantor Performance Materials (Gliwice, Poland) and J.T. Baker (Gross-Gerau, Germany), respectively. Ultrapure water (resistance of 18.2 MΩ) was obtained from a Direct-Q system (Millipore, Molsheim, France). Isoflavone reference substances (purity ≥ 95%), namely, genistin, genistein, formononetin, biochanin A, ononin, and sissotrin, were purchased from ChromaDex Inc. (Santa Ana, CA, USA). Stock isoflavone standard solutions, prepared at the concentration range of 0.1–0.2 mg/mL, were properly diluted in methanol (LC-grade) and stored at 4–8 °C.