Effects of three diterpenoids on tumour cell proliferation and telomerase activity

Xerophilusin B (XB), macrocalin B (MB) and eriocalyxin B (EB) belong to ent-kaurene diterpenoids. The inhibition effects of three ent-kaurane compounds on the proliferation of six tumour lines (K562, HL-60, A549, MKN, HCT and CA) were estimated by methyl-thiazol-tetrazolium, and the telomerase activity in K562 cells was measured by the telomeric repeat amplification protocol-enzyme-linked immunosorbent assay. We found that XB, MB and EB could significantly inhibit the proliferation of tumour cells. Within the concentration range of 10(-4)-10(-8) mol L(-1), three ent-kaurane compounds could markedly inhibit the telomerase activity in K562 cells, and their effects on telomerase were exhibited in a dose-dependent manner. Our results demonstrate that XB, MB and EB can inhibit the proliferation of tumour cells and the telomerase activity, which provides data for developing ent-compounds as antitumour drugs.