Bone-Enhancing Effects of Equisetum: From Traditional Use to Scientific Validation

Equisetum species have been used in traditional medicine for various purposes such as wound healing, kidney stone reduction, and healing of bone fractures. There are no studies to clarify the effects of different Equisetum species on bone metabolism and structure. In this study, we aimed to investigate the effects of different Equisetum species on bone cell proliferation and molecular changes in bone tissue, bone turnover biomarkers, and vitamin D metabolism using in vivo models.

According to the first part of the study, the most effective species [E. ramosissimum (ER) and E. telmateia (ET)] on bone cell proliferation were determined in vitro, and then the molecular effects of these species on rat bone tissues (femur and tibia) were examined in vivo by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy.

Moreover, biomarkers of bone turnover were determined by ELISA and tissue levels of enzymes involved in vitamin D metabolism were examined by the western blot technique. When the molecular changes in bone structure were analyzed, it was observed that ER plant extract strengthened both the mineral and collagen content of femur and tibia bone tissues, while ET plant extract had a significant effect on the mineral phase in only femur tissues. It was observed that both Equisetum species significantly decreased bone resorption biomarker levels implying a decrease in the rate of bone resorption. Moreover, both ER and ET plant extracts decreased the CYP24A1 enzyme levels that inactivate vitamin D in the kidney. In addition, we observed that 25(OH)D production, which is the first step of vitamin D activation in the liver, accelerated by increasing the protein amounts of the enzymes that perform this reaction.

Considering the effects on bone molecular structure, bone turnover biomarkers, and vitamin D metabolism, it was found that E. ramosissmum was the most active plant species for bone development by showing its effects mostly at high doses.