Development of an Efficient Extraction Method for Separating Solasodine, an Steroidal Alkaloid, From an Oily Matrix: A Comparison Between LLE and SPE

Aims: In many references of Traditional Iranian Medicine (TIM), there are methods to produce medicinal products from plant fruit based on extraction of active substances into oils. One of these recommendations is to import cucurbit or pumpkin seed oil into an entirely ripe fruit of Solanum melongena plant. In this study for the first time, the extraction of solasodine from the oily matrix has been investigated to find a precise method with suitable extraction recovery.

Study Design: Original Research Article.

Place and Duration of Study: The study took place in herbal and traditional medicines research center of Kerman, Iran from February 2015 to November 2017.

Methodology: Solasodine, an active steroidal alkaloid metabolite of the plant, was used for standardization of the product. Two methods of (Liquid-liquid extraction) LLE and (Solid phase extraction) SPE were evaluated and their conditions were optimized by assessment of seven effective factors at five levels using HPLC as the method of choice for solasodine determination.

Results: Results showed that LLE and SPE in optimized conditions had recoveries of about 76.5 and 94.7%, respectively. For the extraction of low concentrations of the analyte, the SPE method had better accuracies (88 to 105%), but its precision was less than that of LLE method. In contrast, the LLE method had a higher precision in the whole range while its relevant accuracy was lower. The LOD and LOQ of SPE-HPLC method were 0.2 and 0.6 μg/ml and those of the LLE-HPLC method were 0.2 and 0.7 μg/ml, respectively.

Conclusion: In general, both methods of LLE-HPLC and SPE-HPLC showed acceptable validation parameters including linearity, precision, accuracy, LOD, and LOQ; and they can be used for routine extraction and determination of solasodine in traditional medicine products.