設計與合成帕拉米弗衍生物作為有效抗流感試劑

Design and Synthesis of Peramivir Derivatives as Effective Anti-influenza Agents

王鵬程(Peng-Cheng Wang)

指導教授 ： 方俊民

國立臺灣大學/理學院/化學研究所/博士(2016年)

https://doi.org/10.6342/NTU201601344

摘要

流行性感冒是由流感病毒所引起的急性呼吸道疾病，長期以來不斷危害全球人類的健康，由於流感病毒不斷突變，且隨時有造成大流行的可能性，因此，開發嶄新的流感藥物變得相當重要。目前抗流感藥物主要分為離子通道蛋白抑制劑與神經胺酸酶(NA)抑制劑，由於流感病毒NA subtypes的作用位置相當守恆，很多藥物開發者根據此NA保守作用區來開發流感藥物。美國食品暨藥物管理局目前已通過的流感藥物包含zanamivir (ZA), oseltamivir (OS)與peramivir (PE)。
本實驗過去分別開發出tamiphosphor (TP, 20)與zanaphosphor (ZP, 27)，這兩個化合物主要是運用生物等配體的概念將oseltamivir carboxylate (OC, 14)與ZA (3)的羧酸官能基以磷酸取代，利用磷酸上有較多的氫氧基與NA中S1區域的Arg118, Arg292與Arg371產生更多的靜電吸引力，藉此提升其抑制NA的能力與保護細胞免於受到病毒感染的能力。
有鑑於克流感的抗藥性問題已發生多年，因此，開發可對抗突變株病毒的流感藥物變得相當急迫。本研究的第一部分是合成peramivir之生物等配物，期望研發出抗突變株病毒的流感藥物。不如我們預期的，磷酸生物等配物peraphosphor (28)抑制NA的效果比peramivir差，但此化合物對於H3N2、H5N1與H7N9的病毒仍保有很強的NA抑制能力。另外，磷酸脫水化合物46對於H1N1與H5N1病毒的NA抑制能力最好，其活性與GS4071相當。除此之外，單磷酯化合物保護細胞免於受到病毒感染的能力較其相對應的磷酸化合物好。
感染H5N1的流感病患之死亡率相當高，主要原因是病毒感染宿主細胞後會引發cytokine storm，迅速的發炎反應導致宿主細胞的防禦能力降低，因此，如何同時抑制流感病毒與過多的發炎反應變得相當重要。以往本實驗室開發的雙標靶抗流感藥物，在瑞樂沙的C7位置以酯鍵連接咖啡酸的共軛化合物72除了保留NA的抑制效果並且能夠抑制發反應，具有良好的抗流感與抗發炎效果。
本論文之第二部分主要是根據此研究成果，設計與合成peramivir與咖啡酸的共軛化合物，期望開發出同時具有抗流感與抗發炎的口服流感藥物。實驗結果顯示這些共軛化合物的抗發炎能力相當弱，但在NA抑制與抗流感病毒的活性測試都展現相當優異的效果，其中以醯胺共軛化合物87的NA抑制能力、抗流感病毒能力與保護小鼠免於受到病毒感染的效果最好，預期此化合物有機會以口服餵藥成為嶄新的抗突變株H275Y流感藥物。

關鍵字

流感藥物 ； 生物等配物

並列摘要

Influenza is an acute respiratory diseases caused by influenza virus. Influenza has affected human health worldwide for a long time. The development of novel anti-influenza agents is important because influenza virus frequently mutate and may result in pandemic infection. There are two classes of anti-influenza drugs by targeting the M2 ion channel or neuraminidase (NA) of influenza viruses. Because the structures of NA active sites are rather conserved, many drug companies develop anti-influenza drugs based on this conserved active sites. Three NA inhibitors zanamivir (ZA), oseltamivir (OS) and peramivir (PE) have been approved by FDA for use as anti-influenza drugs.
Our lab have previously developed tamiphosphor (TP, 20) and zanaphosphor (ZP, 27) as the phosphonate congeners of ZA and oseltamivir carboxylate (OC). By replacing the carboxylate group in ZA and OC with a phosphonate group, TP and ZP show more potent NA inhibition and better protection of host cells from influenza viral infection since phosphonate ion in ZP and TP exhibits more extensive electrostatic interactions with the three arginine residues (R118, R292 and R371) in the active site of NA.
Since oseltamivir-resistant viruses have occurred over the years, it is urgent to develop new anti-influenza drugs that can inhibit oseltamivir-resistant strains. We have synthesized a series of PE bioisosteres aiming to combat oseltamivir-resistant viruses. Peraphosphor (PP, 28) unexpectedly has inferior NA inhibitory activity to PE. However, this compound is a potent NA inhibitor against H3N2, H5N1 and H7N9 viruses. The NA inhibitory activity of PP dehydration compound (46) is comparable to that of OC for H1N1 and H5N1 viruses. All the phosphonate monoalkyl esters exhibit superior anti-influenza activities to their parent phosphonic acids.
The high mortality of human infected by H5N1 virus has been attributed to the excessive induction of a severe cytokine storm which reduced the defense ability of host cell. It is important to develop anti-influenza agents for simultaneous inhibition of influenza virus NA and suppression of pro-inflammatory cytokines. Our lab Kung-Cheng Liu has explored the novel dual-targeted bifunctional anti-influenza drugs formed by conjugation with anti-inflammatory agents. In particular, the caffeic acid bearing ZA conjugates by ester linkage (72) showed simultaneous inhibition of influenza virus neuraminidase and suppression of pro-inflammatory cytokines.
Based on these results, we designed and synthesized a series of caffeic acid bearing PE conjugates aiming to develop oral anti-influenza drugs with anti-inflammatory activity. The cytokines suppression experiments showed that the inhibitory activities of cytokines of these PE conjugates are poor. However, the NA inhibition and anti-influenza activities of these PE conjugates are excellent, especially for amide conjugates (87). This compound provided remarkable protection of mice against influenza infections. It has potential to become a novel oral anti-influenza drug for treatment of H275Y resistant strain virus.

並列關鍵字

anti-influenza drugs ； bioisosteres

參考文獻

第五章：參考文獻

1. Taubenberger, J. K.; Morens, D. M. 1918 Influenza: the mother of all pandemics. Emerg. Inf. Dis. 2006, 12, 15–22.

2. Glezen, W. P. Emerging infections : pandemic influenza. Epidemiologic Reviews 1996, 18, 64–76.

3. Holmes, E. C.; Ghedin, E.; Miller, N.; Taylor, J.; Bao, Y.; George, K. St.; Grenfell, B. T.; Salzberg, S. L.; Fraser, C. M.; Lipman, D. J.; Taubenberger, J. K. Whole–genome analysis of human influenza A virus reveals multiple persistent lineages and reassortment among recent H3N2 viruses. PLoS Biol. 2005, 3, 1579–1589.

4. Lowen, A. C.; Palese, P. Influenza virus transmission: basic science and implication for the use of antiviral drugs during a pandemic. Infect. Disord. Drug Targets 2007, 7, 318–328.