Extraction and Radiochemical Labeling of Licorice Root Extract and Investigation of Its Bioaffinity Using In Vitro Methods

In recent years, increasing attention has been directed toward plant-derived extracts as potential agents for diagnostic and therapeutic applications in nuclear medicine. Breast cancer remains one of the most frequently diagnosed malignancies among women, highlighting the need for novel molecular imaging approaches. In this context, technetium-99m (99mTc), a cornerstone radionuclide for single-photon emission computed tomography (SPECT), offers favorable physical characteristics for diagnostic imaging. This study aimed to extract and chemically characterize licorice root extract (LRE) and to investigate its in vitro bioactivity on breast cancer cell lines following labeling with 99mTc. Chemical characterization of LRE was performed using high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC), and liquid chromatography–quadrupole time-of-flight mass spectrometry (LC–QTOF–MS). Radiolabeling of LRE with 99mTc was achieved using the stannous chloride reduction method, and the resulting radiochemically labeled compound ([99mTc]LRE) was evaluated for radiochemical purity by thin-layer radiochromatography (TLRC). The in vitro bioactivity of [99mTc]LRE was assessed using MCF-7 and MDA-MB-231 breast cancer cell lines. The radiolabeling procedure yielded [99mTc]LRE with a radiochemical yield of 98.91 ± 1.27% (n = 4). These findings indicate that [99mTc]LRE is a stable radiolabeled compound and suggest its potential applicability as a novel plant-based radiotracer for SPECT imaging in breast cancer research.