Table 3.
Inhibitory effects of constituents from plants of the genus Salacia on rat lens aldose reductase
| IC50 (μM) | |
|---|---|
| Friedelan-3-one-29-ol (17) | 98 |
| Maytenfolic acid (23) | 72 |
| 3β,22 β-Dihydroxyolean-12-en-29-oic acid (24) | 26 |
| Tingenine B (32) | 7.0 |
| Tingenone (33) | 13 |
| Regeol A (34) | 30 |
| Triptocalline A (35) | 14 |
| Celahin C (38) | 95 |
| Mangiferin (41) | 3.2 |
| Epalrestat | 0.0072 |
Aldose reductase inhibitory activity: The supernatant fluid of a rat lens homogenate was used as a crude enzyme. The incubation mixture contained 180 mM Na, K-phosphate buffer (pH 7.0), 100 mM Li2SO4, 0.03 mM NADPH, 1 mM dL-glyceraldehyde as a substrate, and 100 μL of enzyme fraction, with or without 25 μL of sample solution, in a total volume of 0.5 mL. The reaction was initiated by the addition of NADPH at 30 °C. After 30 min, the reaction was stopped by the addition of 150 μL of 0.5 M HCl. Then, 0.5 mL of 6 M NaOH containing 10 mM imidazole was added, and the solution was heated at 60 °C for 20 min to convert NADP to a fluorescent product. Fluorescence was measured using a fluorophotometer (luminescence spectrometer LS50B, Perkin-Elmer, UK) at an excitation wavelength of 360 nm and an emission wavelength of 460 nm. Each test sample was dissolved in DMSO. Measurements were made in duplicate, and the IC50 value was determined graphically by plotting the percent inhibition versus log of the test compound. An aldose reductase inhibitor epalrestat was used as a reference compound
Reproduced with permission from J. Nat. Prod., 66, 1191–1196. Copyright [2003] ACS