Figure 2: Noni leaf extract increases alkaline phosphatase activity in hPDL cells. ALP activity was measured in hPDL treatment groups over the course of 6 weeks in culture. ALP activity of untreated cells slowly increased over the course of 6 weeks in culture. The hPDL cells treated with 2.5% (g/ ml) of noni leaf extract demonstrated increased ALP activity at the end of 2nd week, peaking during the 3rdand 4th weeks, before gradually decreasing by the end of 6th week. In the group treated by β-GP and ascorbic acid, ALP activity approximately increased during the 2nd and 3rd weeks, compared to the untreated group. The ALP activity of noni treated cells significantly increased (* p < 0.05), compared to both untreated and β-GP plus ascorbic acid treated cells, particularly from the 3rd to the 5th week. Values are displayed as mean ± SD from three independent experiments.