The invention relates to a Flatstem Milkvetch Seed extract for preventing melanin precipitation. It is extracted from Flatstem Milkvetch Seed by at least one step with organic solvent. The Flatstem Milkvetch Seed extract is with abilities of inhibiting tyrosinase activity and extracellular melanin formation. Therefore, the present invention can achieve the goal of whitening by preventing melanin precipitation, and can further be used as the pharmaceutical composition for ameliorating melanin precipitation.本發明有關於一種用於防止黑色素沉澱之沙苑子萃取物,係以至少一步驟之有機溶劑萃取沙苑子製得,此沙苑子萃取物具有抑制酪胺酸酶活性之能力,以及抑制細胞外黑色素生成之能力;藉此,本發明可達到防止黑色素沉澱之美白目的,進而可利用本發明作為改善黑色素沉澱之組成物。(101)‧‧‧沙苑子材料(103)‧‧‧第一萃取物(105)‧‧‧第二萃取物(107)‧‧‧第一剩餘物(109)‧‧‧第三萃取物(111)‧‧‧第二剩餘物(113)‧‧‧第四萃取物(115)‧‧‧第三剩餘物(S1)‧‧‧步驟一(S2)‧‧‧步驟二(S3)‧‧‧步驟三(S4)‧‧‧步驟四
