Preparation of Naringenin Solution for <em>In Vivo</em> Application

The preparation of a compound (phytochemical) solution is an overlooked but critical step prior to its application in studies such as drug screening. The complete solubilization of the compound is necessary for its safe use and relatively stable results. Here, a protocol for preparing naringenin solution and its intraperitoneal administration in a high-fat diet and streptozotocin (STZ)-induced diabetic model is demonstrated as an example. A small amount of naringenin (3.52-6.69 mg) was used to test its solubilization in solvents, including ethanol, dimethylsulfoxide (DMSO), and DMSO plus Tween 80 reconstituted in physiological saline (PS), respectively. Complete solubilization of the compound is determined by observing the color of the solution, the presence of precipitates after centrifugation (2000 x g for 30 s), or allowing the solution to stand for 2 h at room temperature (RT). After obtaining a stable compound/phytochemical solution, the final concentration/amount of the compound required for in vivo studies can be prepared in a solvent-only (no PS) stock solution, and then diluted/mixed with PS as desired. The antidiabetic osteoporotic effects of naringenin in mice (intraperitoneal administration at 2 mg/mL) were assessed by measuring blood glucose, bone mass (micro-CT), and bone resorption rate (TRAP staining and ELISA). Researchers looking for detailed organic/phytochemical solution preparations will benefit from this technique.