摘要或動機

目的：紫色桿菌（Chromobacterium sp.）是一種生活在土壤及水域環境的革蘭氏陰性菌，它會產生紫黑色的紫色桿菌素（Violacein），因而使菌體與培養液皆呈紫色。Violacein是一種由兩個L-色胺酸（L-tryptophan）分子所聚合成的五環化合物，已被證實具有抗菌以及抑制腫瘤細胞生長的活性。本實驗的目的在探討紫色桿菌是否會利用不同官能基的L-色胺酸，合成不同的Violacein衍生物，並分析這些Violacein衍生物的生物活性。方法：將紫色桿菌培養於液態LB培養基中，分別加入不同濃度的L-tryptophan、1-CH₃-L-tryptophan與5-OH-L-tryptophan，於室溫下培養48小時，再用乙酸乙酯萃取Violacein及其衍生物，將萃取出來的紫色桿菌素，用紫外光/可見光分光光譜計和質譜儀進行分析。最後，再將這些萃取物打入斑馬魚受精卵做胚胎毒性測試，並進行試管外DNA剪切能力分析。結果：加入不同官能基的L-色胺酸所合成的產物都是紫色，且在紫外光/可見光的光譜中的最大吸收波長皆相同，質譜儀分析結果則顯示，L-tryptophan 、與5-OH-L-tryptophan的產物圖譜不同、而1-CH₃-L-tryptophan的產物則無法分析。斑馬魚胚胎毒性測試結果顯示，Violaecein和1-CH₃-Violacein 不會對胚胎發育造成影響，但是5-OH-Violacein則會造成胚胎發育異常。DNA 剪切能力測試也顯示，只有5-OH-Violacein具有剪切DNA的能力，其他則否。重要性：本實驗成功地利用紫色桿菌合成Violacein及其衍生物，並發現了5-OH-Violacein比Violacein 具有更高的生物活性。;Aims: Chromobacterium sp. is a Gram negative bacterium which inhabit in soil and water environments. Chromobacterium produce a purple color compound named Violacein. This colorful compound makes Chromobacterium and its culture mediumin purple color. Violacein is a five rings compound synthesized from two L-tryptophan molecules. Studies have shown that Violacein has anti-bacteria and anti-tumor activities. The purpose of this study is to investigate whether Violacein can be synthesized from different tryptophan analogues, and whether these Violacein derivatives have different bioactivities. Materials and Methods: Chromobacterium sp. was cultured in liquid medium containing different concentrations of L-tryptophan, 1-CH₃-L-tryptophan, and 5-OH-L-tryptophan. After 48 hours incubation at room temperature, Violacein and its derivatives were extracted by EA, analyzed by UV/visible spectrophotometer and MS. Violacein and its derivatives were also tested for their embryo toxicity and DNA cleavage activity in vitro. Results: The compounds synthesized from different tryptophan analogues were all purple and have the same maxima absorption wave length in the UV/visible spectra. However, MS spectra of compounds synthesized from L-tryptophan and 5-OH-L-tryptophan were different. The results of zebrafish embryo toxicity tests indicated that violaecin and 1-CH₃-Violacein had no effect on embryo development, but 5-OH-Violacein caused development defects. DNA cleavage tests also showed that only 5-OH-Violacein could digest DNA in vitro. Violaecin and 1-CH₃-Violacein could not digest DNA. Significances: Results from this study indicate that Chromobacterium sp. can be used to synthesize Violacein derivatives from different tryptophan analogues, and revealed that 5-OH-Violacein is a higher bioactivity compound than violaecein.