Aldose reductase inhibitors from the fruits of Caesalpinia ferrea Mart.

Aldose reductase inhibitors were isolated from an extract of the dry fruits of Caesalpinia ferrea Mart. (Leguminosae). Compound 2 was identified as ellagic acid by comparison with a reference sample. The structure of compound 1 was elucidated as 2-(2,3,6-trihydroxy-4-carboxyphenyl) ellagic acid on the basis of spectral evidence, especially 2D-NMR data (HMQC, HMBC and NOESY). These two compounds inhibited aldose reductase in a non-competitive manner.