本研究分析九節木（Psychotria rubra）枝條與葉子萃取物的抗酪胺酸酶活性，以及萃取物對斑馬魚黑色素生成的影響，評估九節木枝葉萃取物的美白功效。結果顯示九節木葉子萃取物對酪胺酸酶的抑制效果優於枝條萃取物，葉子萃取物中四個可溶部的抗酪胺酸酶活性，以乙酸乙酯可溶部的效果最佳。進一步評估九節木萃取物對斑馬魚黑色素生成的抑制成效，同樣以葉子萃取物的效果較枝條萃取物為佳。葉子萃取物各可溶部中，亦以乙酸乙酯可溶部抑制斑馬魚黑色素生成的效果最佳；其次為正丁醇可溶部。綜合上述結果顯示九節木葉子萃取物與乙酸乙酯可溶部具有抑制酪胺酸酶的活性，同時可降低斑馬魚黑色素的生成。

This study evaluated the antityrosinase activity and the melanogenesis inhibitory activity of twig and leaf extracts from Psychotria rubra in zebrafish (Dania rerio). In the antityrosinase assay, the leaf extract showed a better tyrosinase inhibitory activity than the twig extract. Among four soluble fractions of leaf extract, the ethyl acetate soluble fraction presented the best tyrosinase inhibitory activity. As for the melanogenesis inhibitory activity in zebrafish, the leaf extract also exhibited better efficacy than the twig extract. The ethyl acetate soluble fraction of leaf extract had the best antimelanogenesis activity in zebrafish, followed by the n-butanol soluble fraction. These results demonstrated that P. rubra leaf extract and ethyl acetate soluble fraction exhibit the antityrosinase activity and melanogenesis inhibitory effect in zebrafish.