Figure 7.
Effects of NNFE on the proteasomal degradation of tyrosinase in melan-a cells. (A) Cells (3 × 105 cells/mL) were pre-treated with 25 μg/mL cycloheximide (a protein synthesis inhibitor) for 1 h. Separately, cells were pre-treated with 10 μM MG-132 (a proteasomal inhibitor) for 1 h. Cycloheximide and MG-132-pretreated cells were then treated with NNFE for 6 h. Whole cell lysates were subjected to western blot analysis using anti-tyrosinase antibodies. Equal protein loadings were confirmed using β-actin antibodies. (B) Melanin contents were determined in triplicate, and results are expressed as the means ± SDs. *p < 0.05, versus the non-treated controls, Student’s t-test. NNFE, ethyl acetate fraction of N. nouchali flower extract.