Table 3.
α-Glucosidase Inhibition by Tea and Grape Seed Extracts and Individual Catechins
| Extracts | IC50 (μg/mL) | IC90 (μg/mL) | Catechins | IC50 (μg/mL) | IC90 (μg/mL) | ||
|---|---|---|---|---|---|---|---|
| Acarbose (positive control) | (n=7) | 91.0 ± 10.8a | >645* | C | (n=2) | ~31 | > 290* |
| Grape seed extract | (n=3) | 1.2 ± 0.2b | 2.1 ± 0.2f | EC | (n=2) | > 290* | N.D. |
| Green tea extract | (n=3) | 0.5 ± 0.1c | 0.8 ± 0.2g | EGC | (n=2) | N.D. | N.D. |
| Teavigo® | (n=3) | 0.3 ± 0.1d | 0.4 ± 0.1g | ECG | (n=3) | 3.5 ± 1.1b,e | 13.9 ± 4.1h |
| White tea extract | (n=3) | 2.5 ± 0.4e | 5.7 ± 1.8f,h,i | EGCG GCG |
(n=3) (n=3) |
0.3 ± 0.1d 1.4 ± 0.1b,e |
0.4 ± 0.1g 2.9 ± 0.2i |
Different letter superscripts denote significant differences in IC50 or IC90 values as determined by unpaired t-test (p < 0.05)
*
Exceeds maximum concentration tested
N.D. = value not determined
Values presented are mean ± standard error or approximate values if weak inhibition was observed