Osteogenic Activity of New Dammarane-Type Saponins From Gynostemma pentaphyllum

Five dammarane-type saponins (1-5) were isolated from the aerial parts of Gynostemma pentaphyllum, including two new compounds, 2α,3β,12β,19,20(S)-pentahydroxydammar-24-ene 3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside]-20-O-[β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside] (1) and 12-oxo-2α,3β,20(S)-trihydroxydammar-24-ene 3-O-(β-D-glucopyranoside)-20-O-[β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside] (2). The structures were elucidated through various spectroscopic analyses (IR, HRESIMS, 1D and 2D NMR). Compounds 1-3 and 5 exhibited osteogenic activity by stimulating alkaline phosphatase (ALP) activity, collagen synthesis, and calcium mineralization in mouse osteoblastic MC3T3-E1 cells. Among these, compound 2 increased ALP activity by 1.30 ± 0.07- and 1.59 ± 0.16-fold at 2 and 1 µg/mL, respectively, whereas compound 1 increased collagen synthesis and calcium mineralization by 1.14 ± 0.05- and 1.24 ± 0.06-fold at 1 µg/mL, and compound 3 increased these parameters by 1.25 ± 0.07- and 1.14 ± 0.03-fold at 2 µg/mL, respectively.