·綜述·
線粒體靶向抗氧化劑研究進(jìn)展
樊鵬程1,2,葛越3,蔣煒1,2,景臨林1,2,馬慧萍1,2,賈正平1,2(1.蘭州軍區(qū)蘭州總醫(yī)院藥劑科,甘肅 蘭州 730050;2.全軍高原環(huán)境損傷防治研究重點(diǎn)實(shí)驗(yàn)室,甘肅 蘭州 730050;3.延安市寶塔區(qū)婦幼保健院,陜西 延安 716000)
[摘要]線粒體是細(xì)胞呼吸的主要場(chǎng)所,在細(xì)胞的生命周期中扮演重要角色,三羧酸循環(huán)和氧化磷酸化都是在線粒體中進(jìn)行。線粒體功能障礙可導(dǎo)致一系列疾病,如缺血-再灌注損傷、敗血癥和糖尿病等。線粒體是神經(jīng)退行性病變的治療靶點(diǎn),也是藥物轉(zhuǎn)運(yùn)策略研究的引人注目的靶位。雖然線粒體所介導(dǎo)的疾病進(jìn)程的分子機(jī)制尚未完全闡明,但氧化應(yīng)激是關(guān)鍵的環(huán)節(jié)。開(kāi)發(fā)線粒體靶向的抗氧化應(yīng)激保護(hù)藥物具有誘人的前景。線粒體靶向抗氧化劑是指以線粒體為作用靶位的具有抗氧化作用的藥物。該文介紹了現(xiàn)有的線粒體靶向抗氧化劑的概念、分類及其疾病治療研究進(jìn)展。
[關(guān)鍵詞]線粒體靶向;抗氧化劑;活性氧;氧化應(yīng)激
[基金項(xiàng)目]國(guó)家自然科學(xué)基金資助項(xiàng)目(81202458);全軍醫(yī)藥衛(wèi)生科研項(xiàng)目(CLZ12JB06)
[作者簡(jiǎn)介]樊鵬程,博士.Tel:(0931)8994671;E-mail:fpch2001@yeah.net
[通訊作者]賈正平.E-mail:pharmapaper@hotmail.com
[中圖分類號(hào)]R329.28[文獻(xiàn)標(biāo)志碼]A
DOI[]10.3969/j.issn.1006-0111.2015.01.001
[收稿日期]2013-11-28[修回日期]2014-03-26
Research progress in mitochondria-targeted antioxidants
FAN Pengcheng1,2,GE Yue3,Jiang Wei1,2,JING Linlin1,2,MA Huiping1,2,JIA Zhengping1,2(1.Department of Pharmacy,Lanzhou General Hospital of Lanzhou Region,Lanzhou 730050,China;2.Key Laboratory of Entire Army Plateau Environment Injury Prevention Research,Lanzhou 730050,China;3.Meternal and Child Health Care of Baota District,Yan′an 716000,China)
Abstract[]Mitochondria are the main places of cellular respiration as well as the citric acid cycle and oxidative phosphorylation.It plays an important role in controlling the life and death of cells.Mitochondrial dysfunction leads to a series of human diseases such as ischemia-reperfusion injury,sepsis and diabetes.Mitochondrial become an attractive target for drug transporters strategy and therapeutic targets for neurodegeneration.Although the molecular mechanisms responsible for mitochondria mediated disease processes are not fully elucidated yet,the oxidative stress appears to be critical.Accordingly,strategies are being developed for the targeted delivery of antioxidants to mitochondria.The prospect of development of mitochondrial targeted drugs with anti-oxidative stress protection is tempting.Mitochondrial targeting antioxidants were the antioxidant drugs which took mitochondria as the target site.In this review,weintroduced the conception and classification of mitochondrial targeted antioxidants and the research progress of disease treatment by mitochondrial targeted antioxidants.
[Key words]mitochondria-targeted;antioxidant;reactive oxygen species;oxidative stress
線粒體在細(xì)胞的生命周期中扮演重要角色,是連接細(xì)胞應(yīng)激信號(hào)通路和神經(jīng)細(xì)胞凋亡的重要橋梁[1],它參與了缺氧致神經(jīng)細(xì)胞凋亡的過(guò)程[2,3]。線粒體是細(xì)胞呼吸的主要場(chǎng)所,三羧酸循環(huán)和氧化磷酸化都是在線粒體中進(jìn)行。線粒體除了通過(guò)位于其內(nèi)膜的呼吸鏈發(fā)揮細(xì)胞呼吸的功能外,在維持細(xì)胞正常物質(zhì)代謝及離子轉(zhuǎn)運(yùn)中都具有重要作用。研究表明,線粒體損傷可能是神經(jīng)細(xì)胞缺氧損傷的中心環(huán)節(jié),缺氧會(huì)導(dǎo)致神經(jīng)元細(xì)胞線粒體膜去極化,線粒體膜電位降低[4,5],呼吸鏈電子傳遞受阻,能量代謝障礙,以及各種生理學(xué)指標(biāo)改變,從而導(dǎo)致線粒體功能異常。缺氧對(duì)線粒體的影響還表現(xiàn)為細(xì)胞色素C釋放[6],活性氧(reactive oxygen species,ROS)生成增加[6],線粒體通透轉(zhuǎn)運(yùn)孔開(kāi)放等。在一些神經(jīng)退行性病變中亦發(fā)現(xiàn)線粒體功能異常,如阿爾茨海默癥、帕金森癥、亨廷頓舞蹈癥及肌萎縮側(cè)索硬化癥[7]。
1線粒體靶向抗氧化劑概念
近年來(lái)新型體內(nèi)抗氧化藥物的開(kāi)發(fā)越來(lái)越為研究者所關(guān)注[8-10]。線粒體因其在細(xì)胞能量代謝、細(xì)胞凋亡、鈣離子內(nèi)穩(wěn)態(tài)、細(xì)胞信號(hào)通路中的重要地位而成為藥物轉(zhuǎn)運(yùn)策略的誘人靶點(diǎn)[7-11]。同時(shí)線粒體也是神經(jīng)退行性病變的治療靶點(diǎn),開(kāi)發(fā)線粒體靶向的神經(jīng)保護(hù)藥物的研發(fā)具有誘人的前景[7-12]。線粒體靶向抗氧化劑是指以線粒體為作用靶位的具有抗氧化作用的藥物。線粒體靶向抗氧化劑包括:以三苯基膦為載體的線粒體靶向抗氧化劑;基于氨基酸和多肽的線粒體靶向抗氧化劑;谷胱甘肽膽堿酯和N-乙?;?L-半胱氨酸。其中MitoQ和SkQR1對(duì)缺血再灌注及缺氧致氧化應(yīng)激引起的大鼠神經(jīng)損傷具有保護(hù)作用[13]。
2線粒體靶向抗氧化劑分類
有關(guān)藥物選擇性靶向線粒體研究有許多途徑,包括基于線粒體生物物理學(xué)的靶向方法:基于線粒體內(nèi)膜高負(fù)電位的線粒體靶向藥物;基于線粒體內(nèi)特定酶催化前藥釋放藥物;基于轉(zhuǎn)運(yùn)載體傳遞的前藥。目前已有的線粒體靶向抗氧化劑大致分為三類:①基于三苯基膦作為線粒體載體的化合物;②基于氨基酸和多肽的線粒體靶向化合物;③體內(nèi)抗氧化分子為母核的線粒體靶向化合物。
三苯基膦類線粒體靶向抗氧化劑主要是利用線粒體外膜與間隙、內(nèi)膜與基質(zhì)之間膜電位負(fù)電勢(shì)的差異,以脂溶性和正電性均較高的三苯基膦分子作為載體,將具有抗氧化作用的母核分子在線粒體中跨膜轉(zhuǎn)運(yùn)至線粒體基質(zhì)以起到清除過(guò)多ROS的作用[7,11,14-17]。MitoVit E是最早出現(xiàn)的該類線粒體靶向抗氧化劑,由新西蘭達(dá)尼丁Otago大學(xué)化學(xué)與生化部的Smith等最早合成[18]。研究發(fā)現(xiàn)以線粒體膜電位作為藥物分子向線粒體遷移的動(dòng)力,MitoVit E在線粒體和胞漿中的濃度差異達(dá)5 000~6 000倍,并由此證明了一個(gè)新的概念,即將抗氧化劑定向轉(zhuǎn)運(yùn)進(jìn)入線粒體能夠選擇性地阻止線粒體氧化損傷[18]。研究者發(fā)現(xiàn)MitoVit E能夠減少由H2O2誘導(dǎo)的Jurkat細(xì)胞中半胱氨酸蛋白酶-3(caspase-3)的活化[19],從而減少因氧化應(yīng)激引起的細(xì)胞凋亡。MitoQ幾乎是和MitoVit E同時(shí)出現(xiàn)[20],是最早研究的三苯基膦類線粒體靶向藥物之一,也是目前研究最為熱門的線粒體靶向抗氧化劑[21]。MitoQ的設(shè)計(jì)思想來(lái)源于癸基泛醇的抗氧化及對(duì)線粒體的保護(hù)作用[13],并通過(guò)三苯基膦載體將癸基泛定向運(yùn)輸入線粒體基質(zhì),其在線粒體中的含量和胞質(zhì)中相差500~600倍[20,22]。Rodriguez等對(duì)MitoQ安全性進(jìn)行了評(píng)價(jià),認(rèn)為其治療劑量下長(zhǎng)期口服對(duì)小鼠是安全的[23]。目前國(guó)外已經(jīng)進(jìn)入Ⅲ期臨床研究,有可能成為第一個(gè)上市的線粒體靶向藥物[7-11]。MitoQ具有多種活性,包括:對(duì)缺血再灌注肝臟的保護(hù)作用[12,20],對(duì)脂肪性肝炎和CCl4引起的中毒性肝炎具有保護(hù)作用[24];對(duì)脂多糖肽聚糖誘發(fā)敗血癥模型大鼠的保護(hù)作用[25];對(duì)Parkinson模型小鼠的治療作用[26];對(duì)可卡因?qū)е滦募【€粒體損傷的保護(hù)作用[27];對(duì)有機(jī)磷所致大鼠氧化應(yīng)激和腦損傷的保護(hù)作用[28];對(duì)化療藥物順鉑引起的腎功能損傷具有保護(hù)作用[12]??梢钥闯鯩itoQ的保護(hù)作用主要集中在因氧化應(yīng)激所導(dǎo)致的自由基釋放增加而引起的組織損傷。
三苯基膦類線粒體靶向抗氧化劑除MitoVit E和MitoQ外,還有MitoPBN、MitoPeroxidase,其結(jié)構(gòu)見(jiàn)圖1。
圖1 三苯基膦類線粒體靶向抗氧化劑結(jié)構(gòu)圖
SS四肽(SS tetrapeptides)類線粒體靶向抗氧化劑為一類芳香族陽(yáng)離子多肽,其結(jié)構(gòu)基序?yàn)榻惶娴姆枷悱h(huán)、氨基酸殘基以及2′,6′-二甲基酪氨酸殘基(Dmt)[29],見(jiàn)圖2。這類四肽化合物的抗氧化活性來(lái)源于其結(jié)構(gòu)中的Dmt,因其相關(guān)化合物3,5-二甲基苯酚為一類已知的酚類抗氧化劑[30]。其最初的研究目的是為了開(kāi)發(fā)一類具有中樞活性的阿片類鎮(zhèn)痛藥[31,32]。該類化合物包括Dmt-D-Arg-Phe-Lys-NH2(SS-02),Phe-D-Arg-Phe-Lys-NH2(SS-20) (不含Dmt),以及D-Arg-Dmt-Lys-Phe-NH2(SS-31),Dmt-D-Arg-Phe-Atn-Dap-NH2(SS-19)。SS-02可以清除H2O2并抑制亞油酸和低密度脂蛋白引起的脂質(zhì)過(guò)氧化,由此證明了該類四肽的抗氧化劑特性[29]。同SS-02含有相同氨基酸殘基但是序列不同的SS-31有著相似的抗氧化作用,不含有Dmt的SS-20則無(wú)抗氧化劑活性。由此提示該類四肽的抗氧化活性來(lái)源于Dmt。SS-02 和SS-31可以防止缺氧30 min的離體缺血再灌注豚鼠心肌收縮力下降,SS-20則無(wú)此效果。這些研究結(jié)果提示,這類細(xì)胞滲透性四肽是有效的抗氧化劑。同時(shí)該類化合物不需要增加陽(yáng)離子分子作為線粒體轉(zhuǎn)運(yùn)分子,故可能對(duì)去極化的線粒體也有效果。
圖2 基于氨基酸和多肽的線粒體靶向抗氧化劑結(jié)構(gòu)圖
谷胱甘肽在抗氧化防御及生物體親電子物質(zhì)解毒機(jī)制中扮演關(guān)鍵角色。有研究表明,二羧酸和2-酮戊二酸載體負(fù)責(zé)將谷胱甘肽轉(zhuǎn)運(yùn)至線粒體中[33]。雖然線粒體谷胱甘肽池中谷胱甘肽的數(shù)量約僅占15%,但是線粒體谷胱甘肽池在細(xì)胞防護(hù)中起著關(guān)鍵作用。開(kāi)發(fā)增加線粒體中谷胱甘肽濃度的藥物及其他硫醇抗氧化劑可防止細(xì)胞免受氧化損傷,起到線粒體保護(hù)作用[16]。MitoGSH和相關(guān)化合物MitoNAC(圖3)可減輕叔丁基氫過(guò)氧化物誘導(dǎo)的大鼠心肌線粒體去極化,延遲H2O2誘導(dǎo)的新生大鼠心室肌細(xì)胞和紋狀體神經(jīng)元線粒體去極化過(guò)程,減少N-methyl-d-aspartate誘導(dǎo)的紋狀體神經(jīng)元ROS生成。因此,開(kāi)發(fā)谷胱甘肽及其相關(guān)的硫醇線粒體靶向抗氧化劑是一種預(yù)防氧化應(yīng)激相關(guān)線粒體功能異常的有效途徑。其在氧化應(yīng)激相關(guān)急慢性疾病的治療領(lǐng)域存在廣泛的應(yīng)用前景。
圖3 MtioGSH和MitoNAC線粒體靶向抗氧化劑結(jié)構(gòu)圖
3小結(jié)
線粒體在細(xì)胞的生命周期中發(fā)揮重要作用,線粒體內(nèi)ROS爆發(fā)導(dǎo)致線粒體損傷,進(jìn)而引起細(xì)胞凋亡是致缺氧、缺血再灌注損傷、神經(jīng)退行性病變、衰老等病理過(guò)程的關(guān)鍵環(huán)節(jié)。上述病理過(guò)程早期,細(xì)胞線粒體中產(chǎn)生大量自由基,使細(xì)胞處于ROS等氧化物過(guò)量聚集的氧化狀態(tài),氧化應(yīng)激失衡導(dǎo)致線粒體膜和細(xì)胞膜脂質(zhì)過(guò)氧化,線粒體能量代謝障礙及凋亡信號(hào)通路激活等損傷出現(xiàn)。線粒體損傷和機(jī)體自由基釋放增加密切相關(guān),保護(hù)或維持線粒體功能可達(dá)到預(yù)防或治療氧化應(yīng)激所致機(jī)體損傷的作用。開(kāi)發(fā)以線粒體為特定作用部位的靶向制劑能夠?qū)€粒體提供特異性保護(hù)作用,使得線粒體免受氧化應(yīng)激損傷。親脂性陽(yáng)離子基團(tuán)在線粒體靶向抗氧化劑運(yùn)載方面顯示了巨大的潛力。但其仍存在如下不足:①傳遞能力(只有電中性及小分子量的分子可以被轉(zhuǎn)運(yùn));②其亞定位(這類化合物傾向定位于線粒體基質(zhì)及連接基質(zhì)的內(nèi)膜內(nèi)表面,而無(wú)法定位于發(fā)生許多重要代謝過(guò)程的線粒體內(nèi)膜外表面、外膜、膜間隙);③其毒性(在高濃度時(shí)他們可以使線粒體膜電位去極化而危及細(xì)胞生存)。
研究新的具有抗氧化作用且毒性小的線粒體靶向藥物,是治療缺血再灌注損傷、神經(jīng)退行性病變、缺氧等疾病的靶向藥物研究領(lǐng)域的一條新途徑。
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[本文編輯]陳靜