Water soluble extract from plant of Solanum genus and the preparation process thereof, and pharmaceutical composition containing the water soluble extract

A process for preparing a water-soluble extract from a plant of Solanum genus, comprising the steps of:

• (a) subjecting a plant material of a plant of Solanum genus to an extraction treatment using an acidic aqueous solution with a pH value of 3˜5, such that an aqueous solution is obtained;
• (b) adjusting the pH value of the aqueous solution obtained in step (a) to pH 8˜10 with a base, such that a precipitate is formed;
• (c) washing the precipitate formed in step (b) with water, followed by drying, such that a dried product is obtained;
• (d) admixing the dried product obtained in step (c) with chloroform, followed by addition of a suitable amount of a 100% alcohol, such that a chloroform-alcohol mixture is formed;
• (e) mixing the chloroform-alcohol mixture formed in step (d) with a water/alcohol solution having a predetermined water:alcohol ratio, such that a mixture containing a chloroform-based layer and a non-chloroform-based layer is obtained;
• (f) removing the chloroform-based layer from the mixture obtained in step (e), followed by addition of a suitable amount of water;
• and
• (g) obtaining a supernatant from the resultant mixture of step (f), followed by drying the supernatant, wherein the resultant dried product is able to be directly dissolved in water to form a yellowish clear and transparent aqueous solution.