Development of Isocratic RP-HPLC Method for Separation and Quantification of L-Citrulline and L-Arginine in Watermelons.

抄録

Watermelons (Citrullus lanatus) are known to have sufficient amino acid content. In this study, watermelons grown and consumed in Malaysia were investigated for their amino acid content, L-citrulline and L-arginine, by the isocratic RP-HPLC method. Flesh and rind watermelons were juiced, and freeze-dried samples were used for separation and quantification of L-citrulline and L-arginine. Three different mobile phases, 0.7% H₃P0₄, 0.1% H₃P0₄, and 0.7% H₃P0₄ : ACN (90 : 10), were tested on two different columns using Zorbax Eclipse XDB-C₁₈ and Gemini C₁₈ with a flow rate of 0.5 mL/min and a detection wavelength at 195 nm. Efficient separation with reproducible resolution of L-citrulline and L-arginine was achieved using 0.1% H₃P0₄ on the Gemini C₁₈ column. The method was validated and good linearity of L-citrulline and L-arginine was obtained with R² = 0.9956, y = 0.1664x + 2.4142 and R² = 0.9912, y = 0.4100x + 3.4850, respectively. L-citrulline content showed the highest concentration in red watermelon of flesh and rind juice extract (43.81 mg/g and 45.02 mg/g), whereas L-arginine concentration was lower than L-citrulline, ranging from 3.39 to 11.14 mg/g. The isocratic RP-HPLC method with 0.1% H₃P0₄ on the Gemini C₁₈ column proved to be efficient for separation and quantification of L-citrulline and L-arginine in watermelons.