Abstract
- Background
Dietary herbs and plants rich in bioactive flavonoids—such as parsley (Petroselinum crispum), which contains high concentrations of the flavone apigenin—have been widely investigated for their potential systemic antioxidant properties and health-promoting benefits. This randomized crossover clinical trial was designed to evaluate the metabolic fate, renal excretion kinetics, and systemic antioxidant efficacy of dietary apigenin derived from fresh parsley intake in healthy human subjects consuming a strictly controlled, low-flavone background diet.
- Methods
A rigorous randomized crossover trial design was implemented involving seven healthy men and seven healthy women. Participants completed two 2-week intervention periods consuming a strictly controlled baseline diet low in flavones and naturally occurring antioxidants. During one of the intervention weeks, the basic diet was supplemented with fresh parsley providing a standardized apigenin content of 3.73–4.49 mg per megajoule (MJ) of energy intake. Timed 24-hour urine collections were obtained to quantify the renal excretion of apigenin using high-performance liquid chromatography. Fasting blood samples were analyzed to assess erythrocyte antioxidant enzyme activities—specifically glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)—alongside plasma protein 2-adipic semialdehyde residues as a specific biomarker of plasma protein oxidation. Between-condition differences were evaluated using appropriate statistical tests.
- Results
Urinary excretion of apigenin increased significantly during the parsley-supplemented intervention, ranging from 1.59 to 409.09 $\mu$g/MJ per 24 hours, compared to 0 to 112.27 $\mu$g/MJ per 24 hours during the low-flavone basic diet ($P < 0.05$). The mean fraction of ingested apigenin excreted renally during the parsley intervention was 0.58% ($\text{SE } 0.16\%$). Regarding systemic antioxidant markers, erythrocyte glutathione reductase (GR) and superoxide dismutase (SOD) activities increased significantly during the parsley intervention ($P < 0.005$) relative to the baseline diet levels, whereas erythrocyte catalase and glutathione peroxidase activities showed no significant alterations. No statistically significant changes were detected in plasma protein 2-adipic semialdehyde residues. Across the short-term study duration, an overall downward trend in baseline antioxidant enzyme activity was observed, with decreased SOD activity strongly correlated at the individual level with increased oxidative damage to plasma proteins. However, dietary supplementation with parsley effectively counteracted this decline, preserving and enhancing GR and SOD activities.
- Conclusions
Dietary supplementation with parsley (Petroselinum crispum) significantly enhances urinary apigenin excretion, confirming systemic bioavailability, and successfully counteracts the declining trend of key erythrocyte antioxidant enzymes (GR and SOD) during a low-antioxidant diet. These findings demonstrate the physiological efficacy of parsley-derived flavonoids in supporting human endogenous antioxidant defenses.
https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effect-of-parsley-petroselinum-crispum-intake-on-urinary-apigenin-excretion-blood-antioxidant-enzymes-and-biomarkers-for-oxidative-stress-in-human-subjects/7BE52CFEA3D028BF1FEFC820B3F6CC5F