Figure 2: Effects of milk thistle extract (MTE) and soybean extract (SBE) on alkaline phosphatase (ALP) activity of osteoblasts ((a) and (b)) and tartrate-resistant acid phosphatase (TRAP) activity of osteoclasts ((c) and (d)). After differentiation of MC3T3-E1 cells to osteoblasts and of RAW264.7 cells to osteoclasts, MTE ((a) and (c)) and SBE ((b) and (d)) were treated individually or in combination at the doses indicated. To detect activity of ALP in MC3T3-E1 cell media on day 6, a colorimetric enzyme assay was employed. Absorbance was measured at λ = 405 nm and compared with p-nitrophenol (PNP) standard (mean ± SEM, ). The ALP enzyme activity was expressed as nmol PNP/min/mg protein. For the measurement of TRAP activity, RAW 264.7 cells were exposed to 50 ng/mL RANKL for 5 days. After 5-day culture, TRAP-positive activity was determined at λ = 405 nm (mean ± SEM, ). Values in bar graphs not sharing a letter indicate significant difference at .