Table 3. Inhibition of nitric oxide production by the flavanol monomers.
| Compound | Abbreviation | Molecular weight | IC50 (μM) | IC50 (μg/ml) |
| (+)-Catechin | 290.27 | NA | NA | |
| (−)-Epicatechin | EC | 290.27 | 128.5 | 37.3 |
| (−)-Epicatechin gallate | ECG | 442.37 | 75.7 | 33.5 |
| (−)-Epigallocatechin | EGC | 306.27 | 91.9 | 28.1 |
| (−)-Epigallocatechin gallate | EGCG | 458.37 | 89.4 | 41.0 |
| Gallic acid (positive control) | 170.12 | 212 | 36.1 | |
| Flavanol-rich lychee fruit extract | FRLFE | --- | --- | 28.3 |
| Unprocessed lychee fruit extract | --- | --- | ND | |
| Green tea extract | --- | --- | NA |
When IL-1β increased nitric oxide (NO) in the medium, the NO level in the presence of IL-1β was set to 100%, whereas the NO level in the absence of IL-1β was set to 0%. Gallic acid was used as a positive control to monitor the suppression of IL-1β-indcuced NO production.
IC50, half-maximal (50%) inhibitory concentration of NO production in IL-1β-treated hepatocytes.
NA, not applied because 50% suppression of NO production was not observed.
ND, not determined because NO levels increased.