Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Bongkrekic acid (BKA), isolated from the bacterium Burkholderia cocovenenans, is an inhibitor of adenine nucleotide translocator, which inhibits apoptosis, and is thus an important tool for the mechanistic investigation of apoptosis. An efficient total synthesis of BKA has been achieved by employing a three-component convergent strategy based on Kocienski-Julia olefination and Suzuki-Miyaura coupling. It is noteworthy that segmentB has been prepared as a new doubly functionalized coupling partner, which contributes to shortening of the number of steps. Torquoselective olefination with an ynolate has also been applied for the efficient construction of an unsaturated ester. Furthermore, it is revealed that 1-methyl-2-azaadamantane N-oxyl is an excellent reagent for final oxidation to afford BKA in high yield. Based on the total synthesis, several BKA analogues were prepared for structure-activity relationship studies, which indicated that the carboxylic acid moieties were essential for the apoptosis inhibitory activity of BKA. More easily available BKA analogues with potent apoptosis inhibitory activity were also developed.

DOI： 10.1002/chem.201501304

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The photoaffinity labeling technique using photoreactive cardiolipin (CL) is a powerful means for investigating the molecular mechanism of the formation of a specific cytochrome c-cardiolipin complex. Using phosphoramidite chemistry, we synthesized three photoreactive CLs, that possess an unstable diazirine ring at different positions; that is, the acyl chain in the sn-1 or sn-2 position and the central glycerol moiety. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2015.03.056

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1-O-cis-Cinnamoyl-beta-D-glucopyranose is known to be one of the most potent allelochemical candidates and was isolated from Spiraea thunbergii Sieb by Hiradate et al. (2004), who suggested that it derived its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. In this study, key structural features and substituent effects of cis-cinnamic acid (cis-CA) on lettuce root growth inhibition was investigated. These structure-activity relationship studies indicated the importance of the spatial relationship of the aromatic ring and carboxylic acid moieties. In this context, conformationally constrained cis-CA analogues, in which the aromatic ring and cis-olefin were connected by a carbon bridge, were designed, synthesized, and evaluated as plant growth inhibitors. The results of the present study demonstrated that the inhibitory activities of the five-membered and six-membered bridged compounds were enhanced, up to 0.27 mu M, and were ten times higher than cis-CA, while the potency of the other compounds was reduced. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.phytochem.2013.10.001

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C34-epi and C34-epi-C35-trifluoro analogues of solamin, a mono-THF annonaceous acetogenin, were synthesized. Their inhibitory activity, along with previously synthesized analogues (C35-fluoro, C35-difluoro, and C35-trifluorosolamins), against bovine mitochondrial NADH-ubiquinone oxidoreductase (complex I) was determined. The present study revealed that the methyl group on the gamma-lactone moiety is critical to the potent inhibition of complex I by natural acetogenins. (c) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2013.01.018

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Antimycin A(3) (AA) is used as an inhibitor of cyclic electron transport around photosystem I. However, the high concentrations of AA that are needed for inhibition have secondary effects, even in chloroplasts. Here, we screened for chemicals that inhibited ferredoxin-dependent plastoquinone reduction in ruptured chloroplasts at lower concentrations than those required for AA. We identified two AA-like compounds: AAL1 and AAL2. AAL1 likely shares an inhibitory site with AA, most probably in the PGR5-PGRL1 protein complex, and enhances O-2 evolution in photosystem II, most likely via an uncoupler-like effect. AAL1 and AAL2 are unlikely to penetrate intact leaves. In ruptured chloroplasts, AALs are superior to AA as inhibitors of cyclic electron transport. (C) 2013 The Authors. Published by Elsevier BM, on behalf of Federation of European Biochemical Societies. All rights reserved.

DOI： 10.1016/j.fob.2013.09.007

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1-O-cis-Cinnamoyl-β-d-glucopyranose is one of the most potent allelochemicals that has been isolated from Spiraea thunbergii Sieb by Hiradate et al. It derives its strong inhibitory activity from cis-cinnamic acid (cis-CA), which is crucial for phytotoxicity. By preparing and assaying a series of cis-CA analogues, it was previously found that the key features of cis-CA for lettuce root growth inhibition are a phenyl ring, cis-configuration of the alkene moiety, and carboxylic acid. On the basis of a structure-activity relationship study, the substituent effects on the aromatic ring of cis-CA were examined by systematic synthesis and the lettuce root growth inhibition assay of a series of cis-CA analogues having substituents on the aromatic ring. While ortho- and para-substituted analogues exhibited low potency in most cases, meta-substitution was not critical for potency, and analogues having a hydrophobic and sterically small substituent were more likely to be potent. Finally, several cis-CA analogues were found to be more potent root growth inhibitors than cis-CA. © 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.phytochem.2013.08.013

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1-O-cis-cinnamoyl-beta-D-glucopyranose is one of the most potent allelochemicals isolated from Spiraea thunbergii Sieb. It is suggested that it derives its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. It was synthesized to confirm its structure and bioactivity, and also a series of cis-cinnamic acid analogues were prepared to elucidate the key features of cis-cinnamic acid for lettuce root growth inhibition. The cis-cyclopropyl analogue showed potent inhibitory activity while the saturated and alkyne analogues proved to be inactive, demonstrating the importance of the as-double bond. Moreover, the aromatic ring could not be replaced with a saturated ring. However, the 1,3-dienylcyclo-hexene analogue showed strong activity. These results suggest that the geometry of the C-C double bond between the carboxyl group and the aromatic ring is essential for potent inhibitory activity. In addition, using several light sources, the photostability of the cinnamic acid derivatives and the role of the C-C double bond were also investigated. (c) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.phytochem.2012.08.001

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Bongkrekic acid (BKA) is an inhibitor of adenine nucleotide translocase (ANT). Since inhibition of ANT is connected to the inhibition of cytochrome c release from mitochondria, which then results in the suppression of apoptosis, it has been used as a tool for the mechanistic investigation of apoptosis. BKA consists of a long carbon chain with two asymmetric centers, a nonconjugated olefin, two conjugated dienes, three methyl groups, a methoxyl group, and three carboxylic acids. This complicated chemical structure has caused difficulties in synthesis, supply, and biochemical mechanistic investigations. In this study, we designed and synthesized more simple tricarboxylic acids that were inspired by the molecular structure of BKA. Their cytotoxicity and apoptosis-preventing activity in HeLa cells and the effect on the mitochondrial inner membrane potential (Delta Psi m) in HL-60 cells were then evaluated. All tested tricarboxylic acid derivatives including BKA showed little toxicity against HeLa cells. BKA and two of the synthesized derivatives significantly suppressed staurosporine (STS)-induced reductions in cell viability. Furthermore, STS-induced Delta Psi m collapse was significantly restored by pretreatment with BKA and a tricarboxylic acid derivative. Other derivatives, in which one of three carboxylic acids was esterified, exhibited potent toxicity, especially a derivative bearing a carbon chain of the same length as that of BKA. In conclusion, we have developed a new lead compound as an apoptosis inhibitor bearing three carboxylic acids connected with the proper length of a long carbon chain.

DOI： 10.1021/tx300315h

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Induction of the peroxidase activity of cytochrome c (cyt c) by cardiolipin (CL) and H(2)O(2) in mitochondria is suggested to be a key event in early apoptosis. Although electrostatic interaction between the positively charged cyt c and negatively charged CL is a predominant force behind the formation of a specific cyt c-CL complex and sequential induction of the peroxidase activity, molecular mechanisms of hydrophobic interactions involving the fatty acyl chains of CL remain to be investigated. To elucidate the function of the acyl chains, particularly the role of the double bond, we synthesized a variety of CL analogues and examined their peroxidase inducing activity. Irrespective of the number of double bonds in I the acyl chains, the peroxidase activity of cyt c induced by liposomes composed of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and a different CL (9:1 molar ratio) was similar, except for that of 1,1',2,2'-tetrastearoylcardiolipin (TSCL, C18:0)-containing liposomes. The peroxidase inducing activity of TSCL-containing liposomes was 3-4-fold greater than that of other CL-containing liposomes. The, peroxidase activity induced by all CL-containing liposomes was much lower at high ionic strengths than that at low ionic strengths because of diminution of the electrostatic interaction. The peroxidase inducing effects of various CL-containing liposomes were related well to their ability to associate with cyt c. Thus, our results revealed that at low CL levels, the saturated acyl chain of CL is favorable for the activation of peroxidase activity of CL-bound cyt c and the proposed critical role of the, double bond is not a general feature of the cyt c-CL interaction. The polarity of the membrane surface of TSCL-containing liposomes was slightly, but significantly, lower than that of other CL-containing liposomes, suggesting that the higher activating ability of TSCL-containing liposomes may be due to a reduced level of hydration of the polar head region reflecting tighter packing of the fully saturated acyl chains. Moreover, using CL analogues in which a central glycerol head moiety was modified, we revealed that the natural structure of the head moiety is not critical for the formation of the active cyt c-CL complex. The effects of the CL content of the liposomal membrane on the cyt c-CL interaction are discussed.

DOI： 10.1021/bi2010202

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Natural acetogenins are among the most potent inhibitors of bovine heart mitochondrial NADH-ubiquinone oxidoreductase (complex I). Our photoaffinity labeling study suggested that the hydroxylated bis-THF ring moiety of acetogenins binds at "site A" in the third matrix-side loop connecting the fifth and sixth transmembrane helices in the ND1 subunit [Kakutani et al. (2010) Biochemistry 49, 4794-4803]. Nevertheless, since this proposition was led using a photoreactive Delta lac-acetogenin derivative, it needs to be directly verified using a natural acetogenin-type probe. We therefore conducted photoaffinity labeling using a photoreactive natural acetogenin mimic ([(125)I]diazinylated natural acetogenin, [1251]DANA), which has a small photolabile diazirine group, in place of a hydroxy group, attached to the bis-THF ring moiety. Analysis of the photocross-linked protein in bovine heart submitochondrial particles unambiguously revealed that [(125)I]DANA binds to the membrane subunit ND1 with high specificity. The photocross-linking was completely blocked in the presence of just a 5-fold excess of bullatacin, indicating that [(125)I]DANA is an excellent mimic of natural acetogenins and hence binds to the site that accommodates natural products. Careful examination of the fragmentation patterns of the crosslinked ND1 generated by different proteases and their combinations indicated that the cross-linked residue is predominantly located at the supposed site A in the third matrix-side loop. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.bbabio.2011.05.012

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DOI： 10.1016/j.bbabio.2011.05.012

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l -0-cis-Cinnamoyl-β-D-glucopyranose, an allelochemical isolated from Spiraea thunbergii, exhibits potent plant growth inhibitory activity. cis-Cinnamic acid is the essential portion structure of 1-0-cis-cinnamoyl-β-D-glucopyranose responsible for the growth inhibitory activity. cis-Cinnamic acid exhibited potent inhibitory activity against the elongation of lettuce roots, and the half maximal effective concentration (EC_<50>) of cis-cinnamic acid was 2.2 μM. In this project we adopted cis-cinnamic acid as a novel lead compound, and examined the structure-activity relationship of cis-cinnamic acid to develop the environmentally friendly agrochemical. Moreover, we synthesized the fluorescent probes of cis-cinnamic acid aiming at the clarification of the mechanism of the activity expression. At first, we synthesized 1-0-cis-cinnamoyl-β-D-glucopyranose by the Hanessian protocol, and the synthetic compound showed similar inhibitory activity (EC_<50> 6.4 μg/mL) with that of the natural product (EC_<50> 4.0 μg/rnL). Next, we synthesized the cis-cinnamic acid analogues, and evaluated the inhibitory activities on the elongation of lettuce roots. Some analogues were found to be more p

DOI： 10.24496/tennenyuki.53.0_607

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Acetogenins are valuable inhibitor probes to get an insight into the structural and functional properties of mitochondrial NADH-ubiquinone oxidoreductase (complex I). We synthesized a photoreactive acetogenin mimic ([(125)I]DANA) which retained a strong inhibitory activity. The preliminary photoaffinity labeling with bovine heart submitochondrial particles revealed that [(125)I]DANA binds to the ND1 subunit among 45 different subunits with high specificity. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2011.03.149

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Production of a wide variety of cardiolipin (CL) analogues is critical for studying molecular mechanism of diverse biological functions of CL in mitochondria. We describe a concise procedure for the synthesis of CL using a phosphoramidite approach, which allows for the production of diverse CL analogues bearing linoleic acid(s) at any position on the glycerol backbone. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2010.02.071

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Total synthesis of pyranicin and its deoxygenated analogues was achieved using Cl(2)Pd(CH(3)CN)(2) catalyzed diastereoselective cyclization of the allylic ester as the key step. The inhibitory activity of these compounds for mitochondrial NADH-ubiquinone oxicloreductase (complex I) was poorer than those of ordinary mono-THF acetogenins such as annonacin. (C) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2008.06.028

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Studies of the action mechanism of acetogenins, the most potent and structurally unique inhibitors of bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase), are valuable in characterizing the inhibitor binding site in this enzyme. Our previous study deepened our understanding of the dynamic function of the spacer region of bis-THF acetogenins [Abe, M., et al. (2005) Biochemistry 44, 14898-14906] but, at the same time, posed new important questions. First, while the two toxophores (i.e., the hydroxylated THF and the gamma-lactone rings) span a distance shorter than that of the extended 13 carbon atoms [-(CH(2))(13)-], what is the apparent optimal length of the spacer for the inhibition of 13 carbon atoms? In other words, what is the functional role of the additional methylene groups? Second, why was the inhibitory potency of the mono-THF derivative, but not the bis-THF derivative, drastically reduced by hardening the spacer covering 10 carbon atoms into a rodlike shape [-CH(2)-(C C)(4)-CH(2)-]? This study was designed not only to answer these questions but also to further disclose the dynamic functions of the spacer. We here synthesized systematically designed acetogenins, including mono- and bis-THF derivatives, and evaluated their inhibitory effects on bovine complex I. With regard to the first question, we demonstrated that the additional methylenes enhance the hydrophobicity of the spacer region, which may be thermodynamically advantageous for bringing the polar gamma-lactone ring into the membrane-embedded segment of complex I. With regard to the second question, we observed that a decrease in the flexibility of the spacer region is more adverse to the action of the mono-THF series than that of the bis-THF series. As a cause of this difference, we suggest that for bis-THF derivatives, one of the two THF rings, being adjacent to the spacer, is capable of working as a pseudospacer to overcome the remarkable decrease in the conformational freedom and/or the length of the spacer. Moreover, using photoresponsive acetogenins that undergo drastic and reversible conformational changes with alternating UV-vis irradiation, we provided further evidence that the spacer region is free from steric congestion arising from the putative binding site probably because there is no receptor wall for the spacer region.

DOI： 10.1021/bi800506s

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Total synthesis of pyranicin was achieved using Cl(2)Pd(CH(3)CN)(2)-catalyzed diastereoselective cyclization of the allylic ester as the key step. The inhibitory activity of this compound for mitochondrial NADH-ubiquinone oxidoreductase (complex I) was slightly poorer than that of ordinary mono-THF acetogenins such as cis-solamin.

DOI： 10.1021/ol70902w

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Natural antibiotic polyene amides such as myxalamides are potent inhibitors of mitochondrial complex I. Because of the significant instability of this series of compounds due to an extended pi-conjugation skeleton, a detailed characterization of their inhibitory action has not been performed. To elucidate the action mechanism as well as binding manner of polyene an-tides with complex 1, identification of the roles of each functional group in the inhibitory action is needed. We here synthesized a series of amide analogues and carried out structure-activity studies with bovine heart mitochondrial complex I. With respect to the left-hand portion, the natural pi-conjugation skeleton common to many natural products is not required for the inhibition and can be substituted with a simpler substructure such as a conjugated diene. The geometry and shape of the left-hand portion were shown to be important for the inhibition, suggesting that this portion may bind to a narrow hydrophobic pocket in the enzyme rather than merely partitioning into the lipid membrane phase. Concerning the right-hand portion of the inhibitor, the presence of the 2-methyl, amide NH, and (S)-1'-methyl groups was crucial for the activity, suggesting that both methyl groups neighboring the amide group finely adjust the hydrogen-bonding ability of the amide group. in contrast, modifications of the 2'-OH group did not significantly influence the activity, suggesting that the role of this functional group is not to serve as a hydrogen bond donor to the enzyme but to act as a hydrophilic anchor directing the right-hand portion at or near the membrane surface. Detailed characterization of the action mechanism indicated that the polyene amides share a common binding domain with other complex I inhibitors, though their binding position (or manner) within the domain may differ considerably from that of other inhibitors.

DOI： 10.1021/bi7010306

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The first synthesis of two possible diastereomers of tonkinelin was achieved. By comparison of the optical rotation of two candidates of tonkinelin and the natural compound, it is suggested that the absolute configuration of natural tonkinelin is likely to be (17S,18S). The inhibitory activity of these compounds was examined with bovine heart mitochondrial NADH-ubiquinone oxidoreductase. These compounds showed remarkably weak inhibitory activity compared to ordinary acetogenins such as bullatacin. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmc.2007.02.002

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The asymmetric total synthesis of murisolin, (15R, 16R, 19R, 20S)-murisolin A, and (15R, 16R, 19S, 20S)-16,19-cis-murisolin was performed by using an epoxy alcohol as a versatile chiral building block for synthesizing the stereoisomers of mono-THF annonaceous acetogenins. The inhibitory activity of these murisolin compounds was examined with bovine heart mitochondrial complex I, and they showed almost the same activity.

DOI： 10.1002/asia.200600261

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We have revealed that Delta lac-acetogenins, a new class of inhibitors of bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase), act differently from ordinary inhibitors such as rotenone and piericidin A [Ichimaru et al. (2005) Biochemistry 44, 816-825]. Since a detailed study of these unique inhibitors might provide new insight into the terminal electron transfer step of the enzyme, we further characterized their inhibitory action using the most potent Delta lac-acetogenin derivative (compound 1). Unlike ordinary complex I inhibitors, 1 had a dose-response curve for inhibition of the reduction of exogenous short-chain ubiquinones that was difficult to explain with a simple bimolecular association model. The inhibitory effect of 1 on ubiquinol-NAD(+) oxidoreductase activity (reverse electron transfer) was much weaker than that on NADH oxidase activity (forward electron transfer), indicating a direction-specific effect. These results suggest that the binding site of 1 is not identical to that of ubiquinone and the binding of 1 to the enzyme secondarily (or indirectly) disturbs the redox reaction of ubiquinone. Using endogenous and exogenous ubiquinone as an electron acceptor of complex I, we investigated the effect of 1 in combination with different ordinary inhibitors on the superoxide production from the enzyme. The results indicated that the level of superoxide production induced by 1 is significantly lower than that induced by ordinary inhibitors probably because of fewer electron leaks from the ubisemiquinone radical to molecular oxygen and that the site of inhibition by 1 is downstream of that by ordinary inhibitors. The unique inhibitory action of hydrophobic Delta lac-acetogenins may be closely associated with the dynamic function of the membrane domain of complex I.

DOI： 10.1021/bi060713f

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We synthesized a series of Alac-acetogenins in which the two alkyl side chains were systematically modified, and examined their inhibitory effect on bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase). The results revealed that the physicochemical properties of the side chains, such as the balance of hydrophobicity and the width (or bulkiness) of the chains, are important structural factors for a potent inhibitory effect of amphiphilic Alac-acetogenins. This is probably because such properties decide the precise location of the hydrophilic bis-THF ring moiety in the enzyme embedded in the inner mitochondrial membrane. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2006.03.082

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PESTICIDE SCI SOC JAPAN  

Delta lac-Acetogenins are a novel type of inhibitor acting at the terminal electron transfer step of mitochondrial NADH-ubiquinone oxidoreductase (complex 1). To identify the binding site of Delta lac-acetogenins by photoaffinity labeling, we synthesized a photolabile Delta lac-acetogenin that possesses a biotin probe to enable the detection and the isolation of the labeled peptide without the use of a radioisotope. The photolabile Delta lac-acetogenin synthesized in this study elicited potent inhibition of bovine heart mitochondrial complex 1 at the nanomolar level. (c) Pesticide Science Society of Japan.

DOI： 10.1584/jpestics.31.156

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Studies on the inhibitory mechanism of acetogenins, the most potent inhibitors of mitochondrial functional complex I (NADH-ubiquinone oxidoreductase), are useful for elucidating the structural and features of the terminal electron transfer step of this enzyme. Previous studies of the structure-activity relationship revealed that except for the alkyl spacer linking the two toxophores (i.e., the hydroxylated THF and the gamma-lactone rings), none of the multiple functional groups of these inhibitors is essential for potent inhibition. To elucidate the function of the alkyl spacer, two sets of systematically selected analogues were synthesized. First, the length of the spacer was varied widely. Second, the local flexibility of the spacer was specifically reduced by introducing multiple bond(s) into different regions of the spacer. The optimal length of the spacer for inhibition was approximately 13 carbon atoms. The decrease in the strength of the inhibitory effect caused by elongating the spacer from 13 carbons was much more drastic than that caused by shortening. Local flexibility in a specific region of the spacer was not important for the inhibition. These observations indicate that the active conformation,of the spacer is not an extended form, and is not necessarily restricted to a certain rigid shape. Moreover, an analogue in which a spacer covering 10 carbon atoms was hardened into a rodlike shape still maintained a potent inhibitory effect. Our results strongly suggest that the spacer portion is free from steric congestion arising from the putative binding site probably because there is no cavity-like binding site for the spacer portion. The manner of acetogenin binding to the enzyme may not be explained by a simple "key and keyhole" analogy.

DOI： 10.1021/bi051568t

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Acetogenin analogs in which the bis-adjacent THF ring was replaced with an enantioselectively synthesized 1,2-cyclo-pentanediol bis-ether skeleton were synthesized to obtain simplified mimics, and their inhibitory effect on mitochondrial NADH-ubiquinone oxidoreductase (complex I) was examined. The results clearly demonstrate that the 1,2-cyclopentanediol bis-ether motif can substitute for the bis-THF ring while maintaining very potent inhibitory activity at the nanomolar level. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2005.05.150

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We have synthesized Delta1ac-acetogenins that are new acetogenin mimics possessing two n-alkyl tails without an alpha,beta-unsaturated gamma-lactone ring and suggested that their inhibition mechanism may be different from that of common acetogenins [Hamada et al. (2004) Biochemistry 43, 3651-3658]. To elucidate the inhibition mechanism of Delta1ac-acetogenins in more detail, we carried out wide structural modifications of original Delta1ac-acetogenins and characterized the inhibitory action with bovine heart mitochondrial complex I. In contrast to common acetogenins, both the presence of adjacent bis-THF rings and the stereochemistry around the hydroxylated bis-THF rings are important structural factors required for potent inhibition. The inhibitory potency of a derivative possessing an n-butylphenyl ether structure (compound 7) appeared to be superior to that of the original Delta1ac-acetogenins and equivalent to that of bullatacin, one of the most potent natural acetogenins. Double-inhibitor titration of steady-state complex I activity showed that the extent of inhibition of compound 7 and bullatacin is not additive, suggesting that the binding sites of the two inhibitors are not identical. Competition tests using a fluorescent ligand indicated that the binding site of compound 7 does not overlap with that of other complex I inhibitors. The effects of compound 7 on superoxide production from complex I are also different from those of other complex I inhibitors. Our results clearly demonstrate that Delta1ac-acetogenins are a novel type of inhibitor acting at the terminal electron-transfer step of bovine complex I.

DOI： 10.1021/bi0479003

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A convergent total synthesis of cis-solamin (1a) and its diastereomer (1b) was accomplished. A key reaction of this approach was the use of VO(acac)(2)-catalyzed diastereoselective epoxidation of (Z)-bis-homoallylic alcohol 3 followed by spontaneous cyclization for the cis-THF ring formation. By comparison of the optical rotation of the two possible diastereomers, it is suggested that the absolute configuration of natural cis-solamin is 1a. Inhibitory action of synthetic 1a and 1b with bovine heart mitochondrial complex I are reported. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2004.09.011

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In this study a combined electrochemical and FTIR spectroscopic approach was applied to monitor the binding of stigmatellin, a Q(o) site inhibitor of the cytochrome bc(1) complex from Saccharomyces cerevisiae. Natural stigmatellin A induced clear shifts in the redox-induced FTIR difference spectra. For data interpretation a stigmatellin derivative (UST) with the conjugated trienes replaced by an aliphatic tail was synthesized, and the carbonyl group shown in crystal structures to interact with His181, the [2Fe-2S] ligand of the Rieske, was specifically C-13 labeled. Electrochemically induced FTIR difference spectra of the inhibitors in CH3OD were obtained and revealed signals characteristic for the oxidized and reduced forms of the labeled and unlabeled compounds. On the basis of signals from the inhibitors alone, the binding of the inhibitor to the bc(1) complex was monitored. Direct evidence for the interaction of the carbonyl group with the protein was provided by the observed shift of the v(C=O) vibrational mode of about 10 cm(-1). In addition, redox-dependent reorganizations of the protein were identified, including protonation changes of acidic residues at 1746 and 1734 cm(-1). The conformational changes observed upon inhibitor binding are discussed with respect to the crystal structures and proposed mechanistic models [Hunte, C., Koepke, J., Lange, C., Rossmanith, T., and Michel, H. (2000) Structure 8, 669-684; Palsdottir, H., Lojero, C. G., Trumpower, B. L., and Hunte, C. (2003) J. Biol. Chem. 278, 31303-31311].

DOI： 10.1021/bi049649x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Studies on the inhibition mechanism of acetogenins, the most potent inhibitors of complex I, are useful to elucidate the structural and functional features of the terminal electron-transfer step of this enzyme. We synthesized acetogenin mimics that possess two alkyl tails without a gamma-lactone ring, named Deltalac-acetogenin, and examined their inhibitory action on bovine heart mitochondrial complex I. Unexpectedly, the Deltalac-acetogenin carrying two n-undecanyl groups (compound 3) elicited very potent inhibition comparable to that of bullatacin. The inhibitory potency of compound 3 markedly decreased with shortening the length of either or both alkyl tails, indicating that symmetric as well as hydrophobic properties of the inhibitor are important for the inhibition. Both acetylation and deoxygenation of either or both of two OH groups adjacent to the tetrahydrofuran (THF) rings resulted in a significant decrease in inhibitory potency. These structural dependencies of the inhibitory action of Deltalac-acetogenins are in marked contrast to those of ordinary acetogenins. Double-inhibitor titration of steady-state complex I activity showed that inhibition of compound 3 and bullatacin are not additive, though the inhibition site of both inhibitors is downstream of iron-sulfur cluster N2. Our results indicate that the mode of inhibitory action of Deltalac-acetogenins differs from that of ordinary acetogenins. Therefore, Deltalac-acetogenins can be regarded as a novel type of inhibitor acting on the terminal electron-transfer step of complex I.

DOI： 10.1021/bi030242m

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The presence of two hydroxy groups adjacent to the THF ring(s) is a common structural feature of natural acetogenins. To elucidate the role of each hydroxy group in the inhibitory action of acetogenins, we synthesized three acetogenin analogues which lack either or both of the hydroxy groups, and investigated their inhibitory activities with bovine heart mitochondrial complex I. Our results indicate that the presence of either of the two hydroxy groups sufficiently sustains a potent inhibitory effect. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2003.11.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

To elucidate the inhibitory action of acetogenins, we synthesized an acetogenin derivative which possesses tetraol in place of the tetrahydrofuran ring and examined its inhibitory activity against bovine heart mitochondrial complex I. Our results indicate that these hydroxy groups are an essential structural factor though it is not effective as bis-THF hydroxy groups combination. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.bmcl.2003.11.057

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A convergent synthesis of two possible diastereomers of reticulatain-1 (1a and 1b) was accomplished. Comparison of the specific optical rotations of 1a and 1b did not allow for the strict determination of the absolute configuration. However, bis-(R)MTPA esters of la and lb showed a clear difference in chemical shifts in the (1) H NMR spectra. If the bis-(R)-MTPA ester of natural reticulatain-1 (1) is available, the absolute configuration of 1 will be determined. Inhibitory action of these compounds was examined with bovine heart mitochondrial complex I. Both compounds showed almost the same activity. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tetlet.2003.11.109

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PESTICIDE SCI SOC JAPAN  

Natural acetogenins are the most potent inhibitors of mitochondrial complex I. By synthesizing a ubiquinone-acetogenin hybrid inhibitor (named Q-acetogenin), we previously showed that a gamma-lactone ring of acetogenins is completely substitutable with a ubiquinone ring. In this study, to open a new experimental approach to the study of acetogenin-complex I interaction, we report procedures for synthesizing (13)G-labeled Q-acetogenins, wherein the carbonyl carbon at the 1- or 4-position of the ubiquinone ring is specifically C-13-labeled.

DOI： 10.1584/jpestics.29.127

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

To elucidate the inhibitory action of acetogenins, the most potent inhibitors of mitochondrial complex I, we synthesized an acetogenin analogue which possesses a ubiquinone ring (i.e., the physiological substrate of complex I) in place of the alpha,beta-unsaturated gamma-lactone ring of natural acetogenins, and named it Q-acetogenin. Our results indicate that the gamma-lactone ring of acetogenins is completely substitutable with the ubiquinone ring. This fact is discussed in light of the inhibitory action of acetogenins. (C) 2003 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0960-894X(03)00439-6

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Language：Japanese   Publisher：(公社)日本生化学会  

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Language：Japanese   Publisher：Pesticide Science Society of Japan  

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DOI： 10.14841/jspp.2011.0.0302.0

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Language：Japanese   Publisher：日本農薬学会  

DOI： 10.1584/jpestics.35.591

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Language：Japanese   Publisher：Symposium on the chemistry of natural products  

1. Synthesis of mono-THF acetogenin The asymmetric synthesis of murisolin (1), (15R,16R,19R,20S)-murisolin A (2), (15R,16R,19S,20S)-16,19-cis-murisolin (3), solamin (4), cis-solamin (5), annonacin (6) was performed using an epoxy alcohol 11 as a versatile chiral building block for synthesizing the stereoisomers of mono-THF annonaceous acetogenins. 2. Synthetic studies of THP containing acetogenins Synthesis of pyranicin (7), 10-deoxypyranicin (8), 4,10-dideoxypyranicin (9) was achieved using Pd(II)-catalyzed diastereoselective cyclization of the allylic ester as the key step. Synthesis of THP moiety of mucocin (10) is currently underway. 3. The inhibitory activity of mitochondrial complex I The inhibitory activity of mitochondrial comlex I of mono-THF acetogenins showed almost same activities. This observation suggested that the stereochemistry around the THF ring(s) is of minor importance for the activity. As to the inhibitory activity of pyranicin (7) and its dehydrogenated analogues, the activity was poorer than that of ordinary mono-THF acetogenins.

DOI： 10.24496/tennenyuki.52.0_421

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER SCIENCE BV  

DOI： 10.1016/j.bbabio.2010.04.076

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DOI： 10.14895/hannou.30.0.238.0

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：ELSEVIER SCIENCE BV  

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