Diastereomeric Separation of Free and Conjugated Silibinin in Plasma by Reversed Phase HPLC After Specific Extraction

Pharmacokinetics and Metabolic Profile of Free, Conjugated, and Total Silymarin Flavonolignans in Human Plasma after Oral Administration of Milk Thistle Extract

“…The results demonstrated that all six silymarin flavonolignans were rapidly eliminated, and the conjugated silymarin flavonolignans had relatively longer half-lives and much higher AUC 03ϱ values than their free forms (Table 2). These results are in agreement with the previous observations after administration of silybin to humans ( (Barzaghi et al, 1990;Mascher et al, 1993;Gatti and Perucca, 1994;Schandalik and Perucca, 1994;Rickling et al, 1995), although the individual silymarin flavonolignans were not completely characterized in the earlier studies. Our data also demonstrate that, at the peak times (1-3 h), the fractions of the free, sulfated, and glucuronidated silymarin in human plasma were approximately 17, 28, and 55% of the total (Table 3), respectively.…”

“…Some previous studies have reported the plasma concentrations of the free and total silybin isomers in animals and humans after an oral dose of silybin or silymarin (Barzaghi et al, 1990;Mascher et al, 1993;Morazzoni et al, 1993;Gatti and Perucca, 1994;Schandalik and Perucca, 1994;Rickling et al, 1995). However, the pharmacokinetics and metabolism of individual silymarin flavonolignans in humans have not been reported previously.…”

“…Before systematic evaluation of the safety, efficacy, and tolerability of orally administrated silymarin in patients with liver disease and other disorders, it is necessary to estimate the actual contents of the six principal isomers in the standardized silymarin extracts and obtain some preliminarily information about the pharmacokinetics of silymarin in humans. The plasma pharmacokinetics and metabolism of silybin (a mixture of SB A and SB B ) in humans (Barzaghi et al, 1990;Mascher et al, 1993;Gatti and Perucca, 1994;Schandalik and Perucca, 1994;Rickling et al, 1995) and rats (Morazzoni et al, 1993;Rickling et al, 1995) have been reported previously, showing the fast elimination of both free and conjugated silybin. In this study, we investigated the pharmacokinetics and metabolic profile of the free (unconjugated), conjugated (sulfated and glucuronidated), and total (free and conjugated) silymarin flavonolignans in human plasma after a single oral dose of 600 mg of standardized milk thistle extracts to healthy volunteers.…”

Effect of &#946-Glucuronidase on Extraction Efficiency of Silymarin from Human Plasma Samples Using Validated HPLC-UV Analysis

“…Other flavonolignans present in silymarin extract are isosilybin A, isosilybin B, dehydrosilybin, silychristin, silydianin, and a few flavonoids, mainly taxifolin [4]. Silymarin contains silybin as a major component, therefore, most of the studies are based on the assessment of silybin in plasma [5][6][7]. Silymarin flavonolignans are rapidly metabolized after its oral administration and mainly form glucuronide conjugates.…”

Silymarin: What is in the name …? An appeal for a change of editorial policy

“…Simple analytical procedures (HPLC, capillary electrophoresis) make possible an unequivocal determination of silymarin components. [19][20][21] We strongly recommend that investigators should either (1) give the exact composition of the "silymarin complex" or "the principle" used, or (2) use pure, chemically defined compounds. Implementation of these changes would greatly clarify the literature describing the biology of silymarin and its constituents.…”