Changes of mineralogical characteristics and osteoblast activities of raw and processed pyrites

Pyrite, a commonly used mineral medicine in traditional Chinese medicine (TCM), is normally prescribed in the form of calcined or processed pyrite to ensure clinical safety and efficacy. We herein compared the changes of mineral phase characteristics of raw and processed pyrites and their effects on osteoblast proliferation. Processed pyrite was fragile and crispy compared to the raw one. Its main component changed from FeS2 to Fe7S8. After calcination and quenching in vinegar, the concentrations of Fe and Zn increased in the decoction of processed pyrite, whereas that of As decreased. Serum containing processed pyrite enhanced the alkaline phosphatase activity of osteoblasts compared to blank serum, and serum containing raw pyrite also increased such activity. The osteogenesis-enhancing function of processed pyrite was manifested as increased numbers and areas of formed mineralized nodules. The findings are helpful to unveil the clinical mechanism of processed pyrite which has commonly been used to treat bone fracture in TCM practice.