Abstrait

Effect Of Medicinal Plants OnThe Brushite Crystallization At pH=6.5

Aissa Belouatek, Brahim Kacem, Mohamed Beghalia, Ahmed Addou, Ahmed Semmoud

In this work, we performed an in vitro crystallization study enabling the specification of kinetic and thermodynamic conditions of formation and growth of crystalline calcic phosphates species by changing the pH. We used inhibitors, which are medicinal plants which prevent, slow down or reduce crystallization phases. We chose the classical model for the study of phosphate crystallization without inhibitor and with it, in order to assess the inhibiting capacity of any chemical species used. The precipitation of the solid phase of phosphates from artificial urine at different initial pH values was the object of our investigation. The crystal size development was monitored by polarized microscopy at different time intervals. After crystallization time, the mixture was filtered, the recovered dried precipitates were analysed by FTIR spectroscopy and X-rays diffraction technique and chemical analysis. In the absence of inhibitor, the crystallization of phosphates at pH=6.5, led to the formation of brushite(DCPD) and amorphous carbonated calcium phosphates(ACCP), after 6 hours. In presence of inhibitor at pH=6.5, at lower concentrations of sage inhibition was partial. The addition of 1ml of sage to the mixture decreases the size of crystal, after 4 hours the size of crystals stabilized at 20.67m. The complete disappearance of brushite crystals was obtained after addition of 10mL of sage, only Pentahydrated octocalcic phosphates(POP) and ACCP were formed. In the presence of camomile, the inhibition of brushite growth and aggregation increased. The addition of up to a volume of 20mL of camomile resulted in total inhibition and crystalline transformation of the ACCP into carbapatite(CA). Phosphate compounds encountered in urine can be dangerous and the use of inhibitors to prevent, slow down or reduce crystallization phases might be very helpful. In this investigation, sage and camomile proved to be good inhibitors. Their effect increases with solution pH but they are more efficient in less acidic or neutral urine than in alkaline one.