Figure 10.

Chromatographic fractionation of green tea extract and AKR1B1 differential inhibition. Panel (A): A water-soluble fraction of a green tea extract (see Materials and Methods) was loaded onto a Bondelut C18 column. The elution was performed at the indicated points by a series of isocratic steps of % methanol in water (v:v) as follows: a, 10; b, 20; c, 30; d, 50; and e, 100 (see Methods for details). The separation profile monitored at 254 nm (red line) and the % inhibition exerted by individual fractions measured using L-idose (blue area) and HNE (yellow area) as substrates, are reported. The green area refers to the overlap of blue and yellow areas. The percentage inhibition refers to the activity measured in the presence of the eluted fraction with respect to the activity measured in the absence of the fraction. Panels (B–D) refer to the chromatographic analysis performed in the conditions described in Panel (A) of commercial standards of EGCG, GA, and EGC, respectively. The standards were dissolved (10 mM) in water and loaded (5 µmoles) on the column.