合成含有較高生物利用度之雙效型瑞樂沙衍生抗流感藥物

Design and Synthesis of Zanamivir Derivatives as Dual Functional Anti-influenza Drugs with Improved Bioavailability

李年加(Nien-Chia Lee)

指導教授 ： 方俊民

國立臺灣大學/理學院/化學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.11276

摘要

流行性感冒是一種嚴重的急性呼吸道感染,對於人類健康會有很嚴重的威脅,其病毒可以經由飛沫或是生物之間的接觸作為傳染途徑,而曾經在世界各地爆發的流感H5N1以及 H1N1,都可能再次造成大規模的流行,為了避免流感再次發生,開發和改良藥物是有其必要性。而瑞樂沙及克流感是現今治療流行性感冒感染的藥物之一,它們可以阻斷病毒表面一種由糖蛋白組成的神經胺酸酶,藉著來抑制病毒離去宿主細胞,避免再去感染周圍的細胞。然而,瑞樂沙進入人體中,能被生物吸收的效率太差, 導致它只能透過鼻腔吸入的方式進入人體;而克流感雖然抑制效果優於瑞樂沙,但在結構上的特異性因素,病毒經過多次突變後,對克流感的抗藥性會隨之增加,使得克流感抑制效果有逐漸轉弱的趨勢。
此外,流行性感冒通常會伴隨發炎的反應,因此,我們發展一種新型的雙效藥物,以瑞樂沙當做藥物基礎,試著開發瑞樂沙和抗發炎藥物的共軛型式,選擇三種含有較高脂溶性的抗發炎藥物(萘普生、布洛芬、咖啡酸),去與原來的瑞樂沙C9上做連接,並且藉由瑞樂沙對流感病毒的NA辨識能力,能將藥物集中在受病毒感染的組織周圍,藉此提高抗發炎的選擇性,預期能提高藥物在生物體中作用的時間。
利用本實驗室所開發出瑞樂沙的合成方法,先合成中間體22,再進一步成功合成出前軀藥物37系列,並針對結構上的修飾,進一步得到甲基酯衍生物41,將這些衍生物進行抗流感的活性測試,結果顯示衍生物37a和37b皆有不錯的抗NA抑制效果;比較令人訝異的是,咖啡酸衍生藥物37c和41c在初期NA抑制活性上, 顯示幾乎沒抑制活性;而甲基酯衍生物41c,在透過酵素水解甲基酯後,能回復抑 制病毒的效果(EC50 = 128 nM)。
期望這種雙功能性的前軀藥物能在進入人體細胞經由酵素水解來釋放瑞樂沙和抗發炎藥物進一步來抑制病毒的活性,未來仍須透過小鼠生物實驗來做進一步的驗證。

關鍵字

瑞樂沙 ； 流行性感冒 ； 神經胺酸酶 ； 前軀藥物 ； 抗發炎藥物

並列摘要

Influenza is a severe health problem by causing serious acute respiratory infection. Influenza viruses can be spread by infectious droplet or creature’s interaction. The worldwide spread of the H5N1 flu and H1N1 flu may break out once more. To avoid the potential menace, designing and synthesizing new drugs have come to be recent trends. Zanamivir is one of the effective drugs for the treatment of influenza infections. They can block influenza virus neuraminidase, a glycoprotein on virus surface, to prevent virus from leaving host cell to infect surrounding cells. However, zanamivir must be administered by inhalation due to its poor bioavailability after transmitted into body.
Influenza infection is usually accompanied by inflammation. Hence, we design a new type of dual-target conjugates of zanamivir with anti-inflammatory drug. We choose three anti-inflammatory drugs with good lipophilicity, including naproxen, ibuprofen and caffeic acid, to link with zanamivir at the C9 position. The moiety of zanamivir acted as a recognition unit that brought the anti-inflammatory moiety to the damaged tissue to suppress the cytokines caused by influenza virus. The prodrug is also expected to work as a long-acting neuraminidase inhibitor.
In this study, we developed the zanamivir derivatives 37 through an intermediate compound 22, and further modified the C1 carboxylic acid to afford the methyl ester derivatives 41 as potential prodrugs. The results showed that the derivatives 37a and 37b had good NA inhibition. Unexpectedly, the preliminary test showed that the caffeic acid derivatives 37c and 41c had nearly no inhibition. Our cell-based assay indicated that methyl ester 41c resumed anti-influenza activity with EC50 = 128 nM.
The dual functional prodrugs are expected to undergo endogenous enzymatic hydrolysis in body to give the parental zanamivir and anti-inflammatory drugs, which may show synergistic effect in inhibition of influenza virus. Mice experiments are necessary in the future.

並列關鍵字

zanamivir ； influenza ； neuraminidase ； prodrug ； anti-inflammatory drug

參考文獻

1. De Clerq, E. Nat. Rev. Drug discov. 2006, 5, 1015–1025. Antiviral agents active against influenza A viruses.

2. Suzuki, Y. Biol. Pharm. Bull. 2005, 28, 399–408 Sialobiology of influenza molecular mechanism of host range variation of influenza viruses.

3. Horimoto, T.; Kawaoka, Y. Nat. Rev. Microbiol. 2005, 3, 591–600. Influenza: lessons from past pandemics, warnings from current incidents.

4. von Itzstein, M. Nat. Rev. Drug Discov. 2007, 6, 967–974. The war against influenza: discovery and development of sialidase inhibitors.

5. Das, K.; Aramini, J. M.; Ma, L.-C.; Krug, R. M.; Arnold, E. Nat. Struct. Mol. Biol. 2010, 17, 530–538. Structures of influenza A proteins and insights into antiviral drug targets.