Conditional Inhibition of Hemozoin Formation by Chloroquine in vitro
- VernacularTitle:氯喹在体外对疟色素形成的条件性抑制
- Author:
Jun SUN
;
Bo CHEN
;
Yanyu LONG
- Publication Type:Journal Article
- Keywords:
Malaria parasite;
Hemozoin;
Chloroquine;
Threshold pH;
X-ray diffraction
- From:
Chinese Journal of Parasitology and Parasitic Diseases
1987;0(02):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study the characteristics of inhibition on hemozoin formation by chloroquine under in vitro condition.Methods Under different concentrations(0.5-2 mol/L) of sodium acetate(NaAc) and at the pH range of 4.0-5.0, chloroquine was tested for inhibition of ?-hematin(hemozion) formation by using the HPIA(heme polymerization inhibitory activity) assay.The morphology of ?-hematin crystals was determined by light microscopy.Ultraviolet spectrophotometry was employed to measure ?-hematin content, and the size of ?-hematin crystal was analyzed by X-ray diffraction(XRD) .Results Chloroquine exhibited varied effect on ?-hematin formation, depending on pH value and Na+ concentration.When the NaAc concentration increased from 0.5 mol/L(pH 4.2) to 2 mol/L(pH 4.8), the chloroquine inhibitory effect also increased.Results suggested that there exists a threshold pH, below which the ?-hematin formation escalates and chloroquine inhibition declines, and at or above which chloroquine exerts a stronger inhibitory effect on ?-hematin formation.With the increase of pH from 4.4 to 4.8, the crystallinity and the size of crystal changed from 6.93% and 357 to 6.32% and 264 , respectively.When pH reached to 5, no more ?-hematin formed.Chloroquine could reduce the crystallinity and crystal size of ?-hematin at same pH value.Morphology analysis on the samples was consistent with the above results.Conclusion Chloroquine inhibits hemozoin formation only when the pH value is at or above threshold pH.
