Osteoblastic inductivity of Equisetum telmateia extract and fractions on human osteoblast cells

Equisetum species contains high amounts of silicon, potassium, zinc, sulfur, carbon, and polyphenolic derivatives as flavonoids. Furthermore, these genus-derived extracts have potential osteoconductive and osteoinductive activities. Therefore, we can use this genus for bone-regeneration applications. We conducted the current study to determine the osteoinductive potential of Equisetum telmateia (ET) ethanol extract and its fractions on the human foetal osteoblast (hfOB) cell line in a time- and dose-dependent manner. The ethanol extract of the plant was applied to the osteoblast cells with a dose range of 12.5–100 µg/mL for 7, 14, and 21 days of treatment. Moreover, the osteoblast cells were treated with water, ethyl acetate, hexane, and chloroform fractions at different concentrations (5–500 µg/mL for water and ethyl acetate fractions, 5–250 µg/mL for hexane and chloroform fractions) for 7 days. We found a significant reduction in the hFOB cell viability treated with hexane, and chloroform fractions for 7 days with the applied doses. Furthermore, a significant reduction was acquired with high doses of water and ethyl acetate fractions. Thus, we only tested the water and ethyl acetate fractions (10–200 µg/mL), for 7, 14 and 21 days respectively. We used the Sulforhodamine B (SRB) assay to determine the cell viability. Additionally, we measured the alkaline phosphatase (ALP) activity in hfOB cells treated with ethanol extract and water fractions for 7, 14, and 21 days. SRB findings revealed that ET's ethanol extract increased cell viability in a dose- and time-dependent manner. For a 100 µg/mL dose and 21 days, we found that the cell viability value in ET-treated cells was 20% higher than the control one. Only the water extract, among the fractions, enhanced osteoblast proliferation at even a small dose for 21 days. Moreover, the ethanol extract and water fraction treatment increased ALP activity for 21 days. The results of this study indicated the osteoblastic inductivity of E. telmateia's ethanol extract and water fraction.