Application of small caltrops (Tribulus terrestris) to inhibit calcium oxalate monohydrate crystallization

Calcium oxalate (CaOx) can be crystallized in several forms and morphologies. Here we studied the crystallization of CaOx by the precipitation of calcium chloride and sodium oxalate in the absence and presence of small caltrops (Tribulus terrestris). The effects of small caltrops concentration and [Ca(2+)]/[C(2)O(4)(2-)] on CaOx crystal forms and morphologies were investigated. The crystals were characterized by scanning electron microscopy, and the quantities of Ca(2+) in aqueous solution were detected by atomic absorption spectrometry. The results show that small caltrops concentration and [Ca(2+)]/[C(2)O(4)(2-)] affected the crystal morphologies that were mainly hexagonal, octahedral, and dendritic. Higher small caltrops concentration raised the formation of calcium oxalate dihydrate (COD) crystals in an octahedral shape. It was concluded that small caltrops acts as a good inhibitor for kidney stones since they induce COD crystals which are easily excreted in urine.