Nutritional and Bioactive Evaluation of Quercetin Isolated from Taraxacum officinale: Antioxidant and DNA Protective Properties

Taraxacum officinale (Dandelion) is a commonly used medicinal plant rich in bioactive compounds, including flavonoids. However, evidence supporting the DNA-protective effects of flavonoids is limited. The present study aimed to quantify the total amount of flavonoids in the dandelion aqueous-ethanolic extract, isolate quercetin, and evaluate its antioxidant activity and its ability to protect human genomic DNA from oxidative stress.

Dandelion leaves were extracted using an aqueous-ethanol solution, and the total amount of flavonoids was determined by an aluminum chloride colorimetric method. Quercetin was isolated and identified using reversed-phase HPLC, and its antioxidant activity was evaluated with vitamin C as the standard antioxidant using the DPPH radical scavenging assay. The capability of quercetin to protect DNA from oxidative stress was estimated using human leukocyte DNA and gel electrophoresis. Molecular docking analysis was performed to examine the binding affinity of quercetin with DNA.

The total flavonoid content was 0.69 mg quercetin equivalents per gram of extract. HPLC confirmed quercetin presence with a retention time of 4.03-4.3 min. Quercetin showed antioxidant activity with an IC50 of 8.40 µg/mL. Interestingly, quercetin at different concentrations (25, 50, and 100 µg/mL) showed DNA protection compared to treating DNA with damaging agents. Molecular docking indicated a strong binding energy of -8.0 kcal/mol of quercetin with DNA, with an electrostatic energy of -0.26 kcal/mol.

The study highlights quercetin as a key contributor to the antioxidant and DNA-protective effects of dandelion. The moderate effect of DNA protection suggests that quercetin may work in combination with other phytochemicals present in the plant. The strong DNA-binding affinity observed in molecular docking investigates the mechanistic support for the in vitro results, highlighting the therapeutic potential of dandelion-derived compounds.

The quercetin isolated from dandelion showed potent antioxidant activity with a moderate ability to protect DNA from damaging agents. The finding of the DNA protection assay was further confirmed by its strong binding energy observed in a molecular docking analysis.