Morphological Inhibition of Calcium Oxalate Monohydrate by Roselle (Hibiscus sabdariffa L.)

Abstract

Calcium oxalate (CaOx) can be crystallized in several forms and morphologies. In this research, we investigated the crystallization of CaOx by the precipitation of calcium chloride and sodium oxalate in the absence and presence of roselle (Hibiscus sabdariffa L.). The effects of roselle concentration and [Ca2+]/[C2O42-] concentration on CaOx crystal forms and morphologies were studied. The crystals were characterized by scanning electron microscopy (SEM), and the quantities of Ca2+ in aqueous solution were detected by atomic absorption spectrometry (AAS). The results show that roselle concentration and [Ca2+]/[C2O42-] concentration affected the crystal morphologies that mainly were hexagonal, octahedral and dendritic. Higher roselle concentration increased the formation of calcium oxalate dihydrate (COD) crystals as the octahedral shape. Roselle may act as a good inhibitor for kidney stones since it induces the COD crystals that are easily excreted in urine. This research may ensure the application of roselle as herbal medicine to prevent kidney stones.