Figure 1: Dose-response effect of noni leaf extract on hPDL cell proliferation. Cell proliferation of hPDL cells treated with noni leaf extract (0.025%, 0.625%, 1.25%, 2.5%, and 5% g/ml) for 24 hours was measured by MTT assay. All concentrations of noni leaf extract except 5% (g/ml) significantly enhanced cell proliferation (* p < 0.05), compared to the control group. Values are displayed as percentage of control ± SD from three independent experiments.