Described is a method of treating a skin condition in a subject. The method includes applying topically to the subject an effective amount of an aqueous Astragalus seed extract solution to a skin area in need of reducing or slowing the skin condition. The aqueous Astragalus seed extract solution is prepared by a procedure including the steps of: soaking dried seeds of Astragalus seed in an aqueous solvent to form a suspension; boiling the suspension for at least 30 minutes; and filtering the suspension so as to obtain the Astragalus seed aqueous extract solution, the weight ratio of the dried seeds of Astragalus seed to the extract solution being 1:100 to 75:100.