Standardized silymarin, silybin (48% SA and 52% SB), β-glucuronidase (type B-10 from bovine liver), β-glucuronidase (from Escherichia coli), sulfatase (type H-1 from Helix pomatia), and naringenin (NG) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Ultra Pool human liver microsomes (150 donors) and recombinant UGT1A1 were purchased from BD Biosciences (Bedford, MA, USA). Reference standards of silychristin and silydianin were purchased from ChromaDex (Santa Ana, CA, USA) and U.S. Pharmacopoeia (Rockville, MD, USA), respectively. Reference standards of SA and SB, isosilybin A and isosilybin B were obtained as a generous gift from Ulrich Mengs (Madaus GmbH, Cologne, Germany). The purity of all six silymarin flavonolignan standards was between 97% and 99%. All other chemicals and reagents were of analytical grade or higher and were purchased from commercial sources.
Silymarin (Legalon®, Lot No. 0418901) and matching placebo were manufactured in hard capsules by Madaus Rottapharm Group (Cologne, Germany). The flavonolignan content of each capsule was 23.2 mg, silybin A; 32.0 mg, silybin B; 11.8 mg, isosilybin A; 6.6 mg, isosilybin B; 24.9 mg, silychristin; and 29.0 mg, silydianin [21 (link)]. These six flavonolignans account for 70.8% (127.5 mg silymarin equivalent to 140 mg of silymarin) of the 180 mg milk thistle extract contained in each capsule.
Silymarin (Legalon®, Lot No. 0418901) and matching placebo were manufactured in hard capsules by Madaus Rottapharm Group (Cologne, Germany). The flavonolignan content of each capsule was 23.2 mg, silybin A; 32.0 mg, silybin B; 11.8 mg, isosilybin A; 6.6 mg, isosilybin B; 24.9 mg, silychristin; and 29.0 mg, silydianin [21 (link)]. These six flavonolignans account for 70.8% (127.5 mg silymarin equivalent to 140 mg of silymarin) of the 180 mg milk thistle extract contained in each capsule.