Effects of phenanthridine derivatives on skin tissue of HQ-treated C57bl/6 mice
After the pharmacodynamic evaluation, all experimental mice were euthanized, and the skin of the test area was removed, stained with haematoxylin eosin (HE), and observed under a microscope. The tyrosinase in the blood of drug-treated mice recovered remarkably and the MDA content decreased significantly in a dose-dependent manner (Fig 4b) compared to that in mice from the NC group. The results indicated that in comparison to the skin of the blank control, there were considerably fewer melanin granules and a thicker (10–20 layers of reticular structure) stratum corneum in the skin of the negative control. In contrast, skin samples from drug-treated groups displayed significantly different clinical features, with considerably more melanin granules and thinner (3-10 layers of reticular structure) stratum corneum (Fig. 4b). Similar to the aforementioned situation, the number of melanin granules in the skin of the compound-treated groups was significantly increased, even with a low treatment dose.