Provided are a plant extract composition and a pharmaceutical composition for inhibiting tyrosinase activity, preventing melanogenesis or treating melanogenesis, wherein the plant extract composition contains curcumin and resveratrol by weight ratio from 4:1 to 1:4. The plant extract composition and the pharmaceutical composition are useful for preventing and treating pigmentation for skin whitening, and achieve the effect of whitening skin and reducing pigmentation for a subject in topical site.本發明提供一種可用於抑制酪胺酸酶的酵素活性並減少或預防黑色素生成之植物萃取組合物及其醫藥品，其中該植物萃取組合物含有重量比例為4：1至1：4之薑黃萃取物與白藜蘆醇。本發明植物萃取組合物及其醫藥品可用於預防和治療淡化皮膚顏色及黑色素沉澱，以使受體局部部位達到皮膚顏色淡化及減少黑色素沉澱之效果。
