Tridax procumbens flavonoids promote osteoblast differentiation and bone formation

Abstract

Background: Tridax procumbens flavonoids (TPFs) are well known for their medicinal properties among local natives. Besides traditionally used for dropsy, anemia, arthritis, gout, asthma, ulcer, piles, and urinary problems, it is also used in treating gastric problems, body pain, and rheumatic pains of joints. TPFs have been reported to increase osteogenic functioning in mesenchymal stem cells. Our previous study showed that TPFs were significantly suppressed the RANKL-induced differentiation of osteoclasts and bone resorption. However, the effects of TPFs to promote osteoblasts differentiation and bone formation remain unclear. TPFs were isolated from Tridax procumbens and investigated for their effects on osteoblasts differentiation and bone formation by using primary mouse calvarial osteoblasts.

Results: TPFs promoted osteoblast differentiation in a dose-dependent manner demonstrated by up-regulation of alkaline phosphatase and osteocalcin. TPFs also upregulated osteoblast differentiation related genes, including osteocalcin, osterix, and Runx2 in primary osteoblasts. TPFs treated primary osteoblast cells showed significant upregulation of bone morphogenetic proteins (BMPs) including Bmp-2, Bmp-4, and Bmp-7. Addition of noggin, a BMP specific-antagonist, inhibited TPFs induced upregulation of the osteocalcin, osterix, and Runx2.

Conclusion: Our findings point towards the induction of osteoblast differentiation by TPFs and suggested that TPFs could be a potential anabolic agent to treat patients with bone loss-associated diseases such as osteoporosis.

Fig. 1

The effects of TPF on osteoblast differentiation in primary osteoblast cells. The cells were treated with TPF for 6 days and stained for ALP (a), measured ALP activity (b, c). After then the cells were treated with TPF for 21 days, osteoblastic mineralization was determined by Alizarin red S staining (d) and the concentrations of osteocalcin in the culture media were measured (e, f). Effects of TPF on Alp and Osteocalcin mRNA expression in calvarial osteoblast cells (g, h). The data are expressed as the mean ± SD (n = 3) for each group. *p < 0.05

Fig. 2

Effects of TPF on Osterix Runx2, Bmp2, Bmp4 and Bmp7 mRNA expression in calvarial cells (a–e). The cells were cultured for 6 days in the presence or absence of TPF treatment. The data are expressed as the mean ± SD (n = 3) for each group. *p < 0.05

Fig. 3

The effects of TPF with noggin on osteoblast differentiation in primary osteoblast cells. The cells were treated with TPF for 6 days and stained for ALP (a), measured ALP activity (b, c). After then the cells were treated with TPF for 21 days, osteoblastic mineralization was determined by Alizarin red S staining (d) and the concentrations of osteocalcin in the culture media were measured (e, f). The data are expressed as the mean ± SD (n = 3) for each group. *p < 0.05

Fig. 4

Effects of TPF with noggin on Alp, Osteocalcin, Osterix and Runx2, mRNA expression in calvarial cells (a–d). The cells were cultured for 6 days in the presence or absence of TPF treatment. The data are expressed as the mean ± SD (n = 3) for each group. *p < 0.05