A novel thin-layer chromatography-based method for Brazilin quantification

Brazilin, a constituent of the Chinese medicine heartwood, exhibits pronounced anti-tumor effects. To date, brazilin quantification mostly relies on high-performance liquid chromatography (HPLC), which is not accurate enough because of an easily oxidizable structure. Herein, a thin-layer chromatography (TLC)-based method was developed for the quantitative analysis of brazilin. A water solution of purified brazilin was spotted on a GF254 silica gel plate and developed using a mixture of chloroform‒acetone‒formic acid (8:4:1, V/V). After ammonia vaporing, AlCl3 solution (90 mg/mL) was sprayed to form a stable compound. Detection was performed at 508 nm using a dual-beam TLC scanner, and brazilin was quantitatively analyzed by using an external standard. The optimal time for ammonia vaporing was 6 min. Sample stability remained for 10‒200 min. At 508 nm, brazilin absorbance showed a good linear relationship in the range of 0‒6 μg (R2 = 0.9962). Precision RSD was no more than 3.40%, and recovery was between 100 and 105%. This novel TLC-based method has great potential for the quantitative assessment of brazilin. It is simpler, more reliable, and faster than HPLC-based analysis.