Genotoxicity and interference with cell cycle activities by an ethanolic extract from Thai Plumbago indica roots in human lymphocytes in vitro

In Thai traditional medicine, Plumbago indica has been known to have health benefit especially for anti-inflammatory, antibacterial, and antitumor activities. However, the mechanisms of its action are still uncertain. One of which might be its genotoxic effect. In the present study, we investigated the genotoxicity of an ethanolic extract of Plumbago indica root (EEPIR) by sister chromatid exchange (SCE) assay in human lymphocytes in vitro. Dried EEPIR was prepared from percolation with 95% ethanol. Human lymphocytes were treated with EEPIR at concentrations of 12.5, 25, 50, 100 and 500 µg/ml in plain RPMI 1640 medium for 3h at 37^OC. The result indicated that EEPIR at the concentration of 12.5 – 100 µg/ml could induce cell cycle delay as shown by the significant increase in the number of metaphase cells in the first cell cycle but neither in the later cell cycles. Genotoxicity was found at 25 – 100 µg/ml EEPIR. Cytotoxicity was found at concentrations of > 500 µg/ml. Therefore, these activities of the EEPIR could serve its potential therapeutic effects, especially as anticancer. Further study of EEPIR in vivo is still needed to support this evidence.