The effect of plum juice on the prevention of struvite calculus formation in vitro.
OBJECTIVE
To evaluate the effect of plum juice on struvite calculus formation in vitro and to explore the effect of plum juice on urease-producing bacteria and urease activity. The compliance of available drugs is low for struvite calculus after surgical treatment and functional food may represent a good choice as an alternative therapy.


METHODS
Antibacterial activity was assessed using a microdilution antimicrobial susceptibility test. Urease activity was determined by measuring ammonia production. Struvite crystals were induced by Proteus mirabilis in artificial urine with natural and pH-adjusted plum juice. The optical density (OD)(600) and pH of artificial urine were examined, as well the shape and weights of crystals.


RESULTS
Natural plum juice showed an antibacterial effect on urease-producing bacteria, whereas the pH-adjusted juice did not. A concentration-dependent inhibition on urease activity was found for both natural and pH-adjusted juice. Natural plum juice at a high concentration of 0.5% showed an obvious inhibition on the increase of OD(600) and pH of the artificial urine, and crystal formation was prevented by up to or more than 8 h, depending on the concentration of juice. Crystal weight in the natural plum juice groups was decreased in a concentration-dependent manner. The pH-adjusted plum juice did not show any effect on OD(600) and pH, although the presence of juice changed the crystal habit, indicating that the juice slowed the growth rate of crystals.


CONCLUSIONS
Natural plum juice at high and moderate concentrations prevented the formation of P. mirabilis-induced crystals for up to 8 h in artificial urine. Although pH-adjusted and low-concentration natural juice did not prevent the occurrence of crystals, both types of juice slowed their growth rate.
Division of Clinical Pharmacy, Department of Pharmacy, The Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
Huaijun
H
Zhu
Xizhao
X
Sun
Jianlin
J
Lu
Meihua
M
Wang
Yun
Y
Fang
Weihong
W
Ge
D001628:Beverages; D002137:Calculi / Q000517:prevention & control*; D003460:Crystallization; D007711:Klebsiella pneumoniae / Q000201:enzymology; D017616:Magnesium Compounds; D008826:Microbial Sensitivity Tests; D010710:Phosphates; D011513:Proteus mirabilis / Q000201:enzymology; D027861:Prunus; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D013211:Staphylococcus aureus / Q000201:enzymology; D000069877:Struvite; D014510:Urease / Q000096:biosynthesis
D017616:Magnesium Compounds; D010710:Phosphates; D000069877:Struvite; D014510:Urease