Is melatonin water soluble

at 20ºC solubility in water is 2g/L and at 50ºC solubility is 5g/L. There is data showing that even with refrigeration, solutions of melatonin are only stable for about a week when containing ethanol. Ethanol is used in preparing solutions due to the higher solubility of melatonin in ethanol. Solubility data is from teh EC report and the stability data is from the Sigma-Aldrich Product Info Sheet.