Investigating the in-vivo effects of silymarin flavonolignans on serum bilirubin concentration and platelet characteristics

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Thesis (Masters)
Master of Medical Research (MMedRes)
School of Medical Science
Griffith Health
Introduction: Elevation in serum bilirubin concentration is associated with reduced risk of cardiovascular disease (CVD). Silymarin, an extract of the Milk Thistle plant, inhibits UGT1A1 enzymes, the main enzyme responsible for the conjugation and elimination of bilirubin from the body. This effect of elevated serum bilirubin may potentially protect against CVD. Aim/Objective: Using a single-blind, placebo-controlled crossover trial to investigate the in-vivo effects of Legalon®, on circulating bilirubin concentrations, platelet characteristics, and coagulation, recognised CVD biomarkers. Method: The effects of Milk Thistle (Silibinin) On circulating unconJugated bilirubin levels and markers of Oxidative stress and inflammation (MOJO) study was a randomised single-blind, crossover, placebo-controlled trial. The required number of participants, based on power calculation and basis of the trial was sixty-five participants. Participants were provided Legalon® and placebo during two supplementation phases, each of 14 days duration with a 28 day washout period in between. Demographic data and blood samples were collected during seven participant visits (screening, Day 0, Day 7, and Day 14 for each arm). Light transmission aggregometry, flow cytometry, clinical biochemistry, haematology, coagulation analysis, and high-pressure liquid chromatography (HPLC) were performed for collecting blood samples. Subsequent statistical analysis was conducted for seventeen participants who had satisfactory compliance (> 80% compliance for both study arms). Results: Twenty-five male participants were enrolled into the MOJO trial. Seventeen male participants completed the trial with satisfactory compliance (>80% for both the Legalon® and placebo capsules). Circulating total bilirubin (TB) and direct bilirubin (DB) showed no significant difference between time points, and between the study arms (TB ANOVA time p=0.8773, treatment p=0.8971; DB ANOVA time p=0.9210, treatment p=0.9849). This w