Articles

The Effectiveness of Lime Juice (Citrus aurantifolia) in Preventing Calcium Oxalate Crystal Formation: An In Vitro Model

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Background: Calcium oxalate (CaOx) stones are the most prevalent type of urolithiasis and are associated with high recurrence rates. Preventive approaches targeting early crystallization stages, particularly nucleation and aggregation, are therefore crucial. Citrate is a recognized inhibitor of CaOx crystallization; however, pharmacological citrate therapy may face limitations in long-term use. Lime juice (Citrus aurantifolia), a natural source of citrate, may serve as an alternative preventive agent.

Objective: To evaluate the inhibitory effect of lime juice (Citrus aurantifolia) on calcium oxalate crystal formation in vitro.

Methods: A true experimental study with a post-test only control group design was conducted using a synthetic urine model. Five groups were assessed: negative control, positive control (potassium citrate 0.6%), and lime juice at concentrations of 2.5%, 5%, and 10% (v/v). Crystallization was monitored turbidimetrically at 620 nm for 60 minutes. Nucleation slope (SN), aggregation slope (SA), time to maximum absorbance (Tmax), and inhibition percentages were analyzed using one-way ANOVA and Tukey’s HSD test.

Results: All lime juice concentrations significantly reduced aggregation and prolonged Tmax compared with the negative control. The 5% concentration showed the strongest nucleation inhibition among natural treatments, while 2.5% demonstrated the highest aggregation inhibition.

Conclusion: Lime juice effectively inhibits CaOx crystallization in vitro and shows potential as a natural, accessible preventive strategy.

Evaluation of the Effectiveness of Tomato (Solanum lycopersicum L.) Juice in Inhibiting Calcium Oxalate Crystal Formation In Vitro

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Background: Nephrolithiasis is a major urological problem worldwide with a high recurrence rate, reaching approximately 50% within the first 5–10 years after the initial episode. Around 70–80% of kidney stones consist predominantly of calcium oxalate (CaOx). The imbalance between urinary promoters (calcium, oxalate) and inhibitors (citrate, magnesium) leads to supersaturation and crystal formation. Citrate functions as a strong natural inhibitor, although conventional medical therapy may involve considerable costs and adverse effects. Tomatoes (Solanum lycopersicum L.) are an affordable local commodity containing high levels of citrate and magnesium, and therefore hold potential as a natural antilithiasis agent.

Objective: To evaluate the effectiveness of tomato juice in inhibiting calcium oxalate crystal formation using a synthetic urine model.

Methods: An in vitro experimental study was carried out using a post-test only design with a control group. Samples were divided into five groups with three replications: Negative Control (no treatment), Positive Control (Potassium Citrate 0.5%), and three treatment groups of Tomato Juice at 25%, 50%, and 100% concentrations. Crystal formation was induced using CaCl₂ and Na₂C₂O₄ in synthetic urine. Absorbance was measured using a UV–Vis spectrophotometer (620 nm) at two-minute intervals for 60 minutes. Measured parameters included Slope of Nucleation (SN), Slope of Aggregation (SA), and percentage of inhibition.

Results: Tomato juice demonstrated statistically significant inhibitory activity against CaOx crystallization kinetics (p < 0.05 for SN and SA). The 25% concentration produced the highest inhibition rate (approximately 65%), comparable to the positive control (70%). The 50% and 100% concentrations yielded inhibition values of approximately 38% and 37%, respectively, indicating a dose–response pattern that did not increase proportionally with concentration.

Conclusion: Tomato juice effectively inhibited calcium oxalate crystal formation in vitro, particularly during the aggregation phase. The optimal effect was observed at the 25% concentration, suggesting a non-linear dose–response possibly influenced by the balance between citrate content and endogenous oxalate in tomatoes.