Table 3.
Enzyme kinetics of caffeic acid (CA) and syringic acid (SA) against α-amylase, α-glucosidase and aldose reductase enzymes.
| Enzymes | Compound | Treatment | Mode of Inhibition x | Km (µM) | Vmax (103(µM/min)−1 |
Ki (mg) y,z |
|---|---|---|---|---|---|---|
| α-Amylase | CA | Control | Competitive | 0.79 | 25.25 | 1.03 ± 0.15 |
| IC20 10.75 µg | 0.91 | 26.15 | ||||
| IC40 21.50 µg | 1.82 | 25.75 | ||||
| IC60 32.25 µg | 3.02 | 26.10 | ||||
| SA | Control | Competitive | 0.94 | 50.55 | 1.25 ± 0.04 | |
| IC20 10.10 µg | 1.55 | 51.10 | ||||
| IC40 20.20 µg | 2.88 | 51.11 | ||||
| IC60 30.30 µg | 3.99 | 50.95 | ||||
| α-Glucosidase | CA | Control | Competitive | 1.01 | 40.05 | 0.52 ± 0.02 |
| IC20 3.20 µg | 2.44 | 39.98 | ||||
| IC40 6.40 µg | 3.33 | 40.40 | ||||
| IC60 9.60 µg | 5.01 | 40.37 | ||||
| SA | Control | Competitive | 1.22 | 34.00 | 0.96 ± 0.22 | |
| IC20 3.0 µg | 3.58 | 33.55 | ||||
| IC40 6.0 µg | 5.54 | 33.43 | ||||
| IC60 9.0 µg | 8.80 | 33.79 | ||||
| Aldose reductase | CA | Control | Non-competitive | 0.79 | 27.71 | 1.11 ± 0.36 |
| IC20 1.25 µg | 0.81 | 13.35 | ||||
| IC40 2.50 µg | 0.81 | 10.15 | ||||
| IC60 3.75 µg | 0.80 | 5.05 | ||||
| SA | Control | Non-competitive | 0.81 | 78.60 | 1.64 ± 0.65 | |
| IC20 1.20 µg | 0.91 | 34.47 | ||||
| IC40 2.40 µg | 0.92 | 20.05 | ||||
| IC60 3.60 µg | 0.92 | 11.50 |
x inhibition mode was performed from double reciprocal plot. y Ki = dissociation constant. z Values are expressed as mean ± SE.