Investigation of the Anti-Proliferative Effect and the Underlying Mechanism of the Crude Extract of Celastrus Orbiculatus on Human HaCaT Keratinocytes

Traditional Chinese Medicine (TCM) has a long history in treating a variety of skin diseases, including psoriasis. In this present study, the anti-proliferative effect of the crude extract of Celastrus orbiculatus (also known as Nan She Teng, or NST) and its underlying mechanism were investigated. SRB and MTT assays were employed and confirmed an IC50 value of 29.4μg/ml for NST on HaCaT cells treated for 48h. In addition, cellular morphology was examined with Hoechst 33342 stain, which detected chromosomal condensation with changes in cell membrane shape. Cell cycle analysis by propidium iodide (PI) staining displayed significant sub-G1 peaks(49.4%) at 45μg/ml(1.5×IC50) of NST compared to less than 11% in Control. Moreover, flow cytometric analysis by Annexin-V PI staining revealed dose-dependent apoptosis due to NST application, 60.1% in the 45μg/ml while only 6.0% in Control. Similarly, flow cytometry with JC-1 staining yielded 6.7% of cells in Control had a low mitochondrial membrane potential (MMP/ΔΨm), whereas cells treated with 30μg/ml (IC50) presented 57.2% low MMP. In conclusion, our experimental data validate the anti-proliferative effect of the crude extract of NST, and the observed inhibition on cell growth was attributed to the induction of apoptosis.