*2.7. Statistical Analysis*

Statistical differences were evaluated using a two-tailed Student *t*-test or Mann-Whitney U-test. A *p*-value of <0.05 was considered statistically significant. Statistical analyses were conducted primarily using GraphPad Prism software (GraphPad Software Inc., La Jolla, CA, USA). The combination index (CI) was calculated by the Chou–Talalay method. A combination index (CI) < 1 indicates synergism, CI = 1 an additive effect, and CI > 1 an antagonistic effect [21].
