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Article ; Online: A Versatile Axle for the Construction of Disassemblage Rotaxanes.

Powers, Lucas A / Smithrud, David B

2016 Volume 21, Issue 8

Abstract: Rotaxanes are unique mechanical devices that hold great promise as sensors. We report on two new rotaxanes that contain an acid or base sensitive trigger and readily disassemble in a wide range of environments. Disassemblage was observed under TLC and ¹H- ...

Abstract	Rotaxanes are unique mechanical devices that hold great promise as sensors. We report on two new rotaxanes that contain an acid or base sensitive trigger and readily disassemble in a wide range of environments. Disassemblage was observed under TLC and ¹H-NMR analysis. The axle is highly charged, which enhances solubility in aqueous environments, and can be readily derivatized with sensor components. The trigger was swapped in a one-pot method, which is promising for the rapid production of a series of sensors.
MeSH term(s)	Hydrogen-Ion Concentration ; Magnetic Resonance Spectroscopy ; Rotaxanes/chemical synthesis ; Rotaxanes/chemistry ; Solubility
Chemical Substances	Rotaxanes
Language	English
Publishing date	2016-08-10
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	1413402-0
ISSN	1420-3049 ; 1431-5165 ; 1420-3049
ISSN (online)	1420-3049
ISSN	1431-5165 ; 1420-3049
DOI	10.3390/molecules21081043
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Article ; Online: Pt-rotaxanes as cytotoxic agents.

Wang, Xiaoyang / Smithrud, David B

Bioorganic & medicinal chemistry letters

2011 Volume 21, Issue 22, Page(s) 6880–6883

Abstract: Cytotoxic agents that specifically target cancer cells are in high demand. Modifying drugs with targeting groups however, can produce deleterious effects on drug pharmokinetics. In this study, platinum (Pt) was linked with host-rotaxanes to discover the ... ...

Abstract	Cytotoxic agents that specifically target cancer cells are in high demand. Modifying drugs with targeting groups however, can produce deleterious effects on drug pharmokinetics. In this study, platinum (Pt) was linked with host-rotaxanes to discover the effect on the cytotoxicity of Pt when carried by a highly modified rotaxane as a ligand. One host-rotaxane (Pt-BocRot) contains the basic components of a rotaxane: wheel (with a Boc protecting group), axle, and blocking group. A second rotaxane (Pt-ArgRot) contains arginine moieties on its wheel instead to potentially improve association with the phosphate groups on cell membranes or DNA backbone. The cytotoxicities of the rotaxanes and various model compounds were determined using ovarian cancer SKOV-3 cell line, which is resistant to cisplatin. We found Pt-ArgRot was slightly more cytotoxic than Pt-BocRot. Both were clearly more cytotoxic than rotaxanes without Pt and the model compounds. As importantly, they killed cells through an apoptotic mechanism. These results suggest that targeting agents for a particular cell type can be incorporated with Pt-complexes using the rotaxane architecture to improve drug specificity.
MeSH term(s)	Antineoplastic Agents/chemistry ; Antineoplastic Agents/pharmacology ; Apoptosis/drug effects ; Cell Line, Tumor ; Cytotoxins/chemistry ; Cytotoxins/pharmacology ; Female ; Humans ; Organoplatinum Compounds/chemistry ; Organoplatinum Compounds/pharmacology ; Ovarian Neoplasms/drug therapy ; Rotaxanes/chemistry ; Rotaxanes/pharmacology
Chemical Substances	Antineoplastic Agents ; Cytotoxins ; Organoplatinum Compounds ; Rotaxanes
Language	English
Publishing date	2011-11-15
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	1063195-1
ISSN	1464-3405 ; 0960-894X
ISSN (online)	1464-3405
ISSN	0960-894X
DOI	10.1016/j.bmcl.2011.09.007
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Article ; Online: A Versatile Axle for the Construction of Disassemblage Rotaxanes

Lucas A. Powers / David B. Smithrud

Molecules, Vol 21, Iss 8, p

2016 Volume 1043

Abstract	Rotaxanes are unique mechanical devices that hold great promise as sensors. We report on two new rotaxanes that contain an acid or base sensitive trigger and readily disassemble in a wide range of environments. Disassemblage was observed under TLC and 1H-NMR analysis. The axle is highly charged, which enhances solubility in aqueous environments, and can be readily derivatized with sensor components. The trigger was swapped in a one-pot method, which is promising for the rapid production of a series of sensors.
Keywords	rotaxanes ; disassemble ; switch ; pH ; Organic chemistry ; QD241-441
Language	English
Publishing date	2016-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Host-rotaxanes model proteins that promote ligand association through a favorable change in configurational entropy.

Zhu, Jing / Smithrud, David B

Organic & biomolecular chemistry

2007 Volume 5, Issue 18, Page(s) 2992–2999

Abstract: Proteins can reduce the entropic penalty for ligand association through a favorable change in configurational entropy. To investigate this process, the Delta G(o), Delta H(o), and DeltaS(o) of complexes formed between host-rotaxanes and guests were ... ...

Abstract	Proteins can reduce the entropic penalty for ligand association through a favorable change in configurational entropy. To investigate this process, the Delta G(o), Delta H(o), and DeltaS(o) of complexes formed between host-rotaxanes and guests were determined and compared to discover the relationship between rotaxane-structure and the energies involved in guest-association in water and DMSO. Fluorescence quenching assays provided the association constants. Van't Hoff analysis of variable temperature assays gave the enthalpies of binding. The driving force for the association of a guest and a host-rotaxane can switch from being enthalpically to entropically driven with a change in the solvent or guest. This study shows that a dramatic increase in the entropy of binding can be obtained through the addition of a rotaxane-wheel to a synthetic host. An increased motion of the wheel appears to be the source of the positive binding entropy, which would be an example of favorable configurational entropy promoting complex formation.
MeSH term(s)	Entropy ; Ligands ; Models, Chemical ; Proteins/chemistry ; Rotaxanes/chemistry
Chemical Substances	Ligands ; Proteins ; Rotaxanes
Language	English
Publishing date	2007-09-21
Publishing country	England
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2097583-1
ISSN	1477-0539 ; 1477-0520
ISSN (online)	1477-0539
ISSN	1477-0520
DOI	10.1039/b707955a
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Ca

Smithrud, David B / Powers, Lucas / Lunn, Jennifer / Abernathy, Scott / Peschka, Michael / Ho, Shuk-Mei / Tarapore, Pheruza

ACS medicinal chemistry letters

2017 Volume 8, Issue 2, Page(s) 163–167

Abstract: New therapies are needed to eradicate androgen resistant, prostate cancer. Prostate cancer usually metastasizes to bone where the concentration of calcium is high, making ... ...

Abstract	New therapies are needed to eradicate androgen resistant, prostate cancer. Prostate cancer usually metastasizes to bone where the concentration of calcium is high, making Ca
Language	English
Publishing date	2017-01-04
Publishing country	United States
Document type	Journal Article
ISSN	1948-5875
ISSN	1948-5875
DOI	10.1021/acsmedchemlett.6b00347
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Article: Crown Ether Host-Rotaxanes as Cytotoxic Agents.

Smithrud, David B / Wang, Xiaoyang / Tarapore, Pheruza / Ho, Shuk-Mei

ACS medicinal chemistry letters

2012 Volume 4, Issue 1, Page(s) 27–31

Abstract: Highly toxic bacterial ionophores are commonly used in veterinary medicine, but their therapeutic index is too narrow for human usage. With the goal of developing ionophores with a broader therapeutic index, we constructed highly derivatized synthetic ... ...

Abstract	Highly toxic bacterial ionophores are commonly used in veterinary medicine, but their therapeutic index is too narrow for human usage. With the goal of developing ionophores with a broader therapeutic index, we constructed highly derivatized synthetic ionophores. The toxicities of crown ether host-rotaxanes (CEHR's) against the SKOV-3 cell line were measured. The effect of Mg
Language	English
Publishing date	2012-11-08
Publishing country	United States
Document type	Journal Article
ISSN	1948-5875
ISSN	1948-5875
DOI	10.1021/ml3003204
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Article ; Online: Synthesis and investigation of host-[2]rotaxanes that bind metal cations.

Wang, Xiaoyang / Zhu, Jing / Smithrud, David B

The Journal of organic chemistry

2010 Volume 75, Issue 10, Page(s) 3358–3370

Abstract: Materials that bind metal cations are highly sought after for new devices. In this report, we show that rotaxanes can transfer metal cations with picrate, perchlorate, or chloride counterions from an aqueous solution into chloroform. The rotaxanes ... ...

Abstract	Materials that bind metal cations are highly sought after for new devices. In this report, we show that rotaxanes can transfer metal cations with picrate, perchlorate, or chloride counterions from an aqueous solution into chloroform. The rotaxanes contain a dibenzyl-24-crown-8 ether as the wheel with either a benzyl-18-crown-6 ether (CEBG-R1-3) or a 3,5-dimethylbenzyl moiety (ArBG-R) as one blocking group. Alkali and alkaline picrate salts were efficiently extracted from an aqueous solution, presented in the millimolar range, into chloroform. Large association constants were derived for the complexes in chloroform, especially for the divalent cation Mg(2+). Switching the counterion to chloride greatly diminished the amount of salt extracted. To explore the transfer mechanism of the rotaxanes, a comparison was made in the amount of NaClO(4), KClO(4), NaCl, and KCl extracted by CEBG-R1, ArBG-R, benzyl-18-crown-6 ether (B18C6), and two model compounds, which were used to represent the crown-ether blocking group and the axle of a rotaxane. Two-dimensional NMR analysis was performed on the rotaxane-cation complexes in CDCl(3). We found that the host rotaxanes transfer the perchlorate salts poorly when compared to B18C6, but they transfer chloride salts from 1 M salt solutions, whereas B18C6 does not. The transfer of chloride salts appears to rely on an allosteric type relationship between the binding of the chloride ion and metal cation to a rotaxane. Accordingly, when chloride binds to the dialkylammonium ion of the axle, the wheel moves along the axle and forms a binding site for a metal cation. In this report we demonstrate that host rotaxanes can bind metal cations, change their geometries upon cation and anion association, and operate through allosteric mechanisms, making them promising candidates for molecular devices.
MeSH term(s)	Binding Sites ; Cations/chemistry ; Molecular Structure ; Potassium/chemistry ; Rotaxanes/chemical synthesis ; Rotaxanes/chemistry ; Sodium/chemistry ; Stereoisomerism
Chemical Substances	Cations ; Rotaxanes ; Sodium (9NEZ333N27) ; Potassium (RWP5GA015D)
Language	English
Publishing date	2010-05-21
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/jo100330e
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Article: Creation and investigation of protein-core mimetics with parallel and antiparallel aligned amino acids.

Fotins, Juris / Smithrud, David B

The Journal of organic chemistry

2005 Volume 70, Issue 11, Page(s) 4452–4459

Abstract: Mimetic protein cores were created that align a set of l-Phe, d-Phe, or l-Leu residues in a parallel or an antiparallel arrangement in chloroform. Not all cores show a single conformation at room temperature. Stable structures require a synergistic ... ...

Abstract	Mimetic protein cores were created that align a set of l-Phe, d-Phe, or l-Leu residues in a parallel or an antiparallel arrangement in chloroform. Not all cores show a single conformation at room temperature. Stable structures require a synergistic relationship between the H-bonding groups and the residues within the core. The spatial arrangement of the side chains dictates whether a zippered or a crossed pattern of H-bonds is observed for these cores. Variable-temperature (1)H NMR experiments were used to determine the strengths of the H-bonds. The existence of H-bonds was verified through FTIR spectroscopic analysis. Large temperature coefficients exist for some protons of aromatic rings that are held in a T-shaped arrangement. A comparison of these temperature coefficients shows that a more stable core is obtained by combining benzenoid and nitrobenzenoid rings as compared to benzenoid rings. Structures were determined using a combination of 2D NMR analysis and molecular modeling.
MeSH term(s)	Amino Acids/chemistry ; Hydrogen Bonding ; Leucine/chemistry ; Magnetic Resonance Spectroscopy ; Models, Molecular ; Molecular Mimicry ; Molecular Structure ; Phenylalanine/chemistry ; Protein Conformation ; Proteins/chemical synthesis ; Proteins/chemistry ; Thermodynamics
Chemical Substances	Amino Acids ; Proteins ; Phenylalanine (47E5O17Y3R) ; Leucine (GMW67QNF9C)
Language	English
Publishing date	2005-05-27
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/jo0479563
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Article: Pt-rotaxanes as cytotoxic agents

Wang, Xiaoyang / Smithrud, David B

Bioorganic & medicinal chemistry letters. 2011 Nov. 15, v. 21, no. 22

2011

Abstract	Cytotoxic agents that specifically target cancer cells are in high demand. Modifying drugs with targeting groups however, can produce deleterious effects on drug pharmokinetics. In this study, platinum (Pt) was linked with host-rotaxanes to discover the effect on the cytotoxicity of Pt when carried by a highly modified rotaxane as a ligand. One host-rotaxane (Pt-BocRot) contains the basic components of a rotaxane: wheel (with a Boc protecting group), axle, and blocking group. A second rotaxane (Pt-ArgRot) contains arginine moieties on its wheel instead to potentially improve association with the phosphate groups on cell membranes or DNA backbone. The cytotoxicities of the rotaxanes and various model compounds were determined using ovarian cancer SKOV-3 cell line, which is resistant to cisplatin. We found Pt-ArgRot was slightly more cytotoxic than Pt-BocRot. Both were clearly more cytotoxic than rotaxanes without Pt and the model compounds. As importantly, they killed cells through an apoptotic mechanism. These results suggest that targeting agents for a particular cell type can be incorporated with Pt-complexes using the rotaxane architecture to improve drug specificity.
Keywords	DNA ; apoptosis ; arginine ; cell membranes ; cisplatin ; cytotoxicity ; ovarian neoplasms ; platinum
Language	English
Dates of publication	2011-1115
Size	p. 6880-6883.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	1063195-1
ISSN	1464-3405 ; 0960-894X
ISSN (online)	1464-3405
ISSN	0960-894X
DOI	10.1016/j.bmcl.2011.09.007
Database	NAL-Catalogue (AGRICOLA)

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Article: Structure-function relationship of amino acid-[2]rotaxanes.

Smukste, Inese / Smithrud, David B

The Journal of organic chemistry

2003 Volume 68, Issue 7, Page(s) 2547–2558

Abstract: Synthetic methodology was developed to construct amino acid-[2]rotaxanes that have phenylalanine and 3,5-di-tert-butylbenzene as blocking groups and dibenzo-24-crown-8, derivatized with either N-acetylargininyl or a carboxylic group, as the ring. A ... ...

Abstract	Synthetic methodology was developed to construct amino acid-[2]rotaxanes that have phenylalanine and 3,5-di-tert-butylbenzene as blocking groups and dibenzo-24-crown-8, derivatized with either N-acetylargininyl or a carboxylic group, as the ring. A relative measure of the intramolecular interaction energies between the functional groups in DMSO/water mixtures is obtained by comparing their pK(a) values. Rotaxane structures were investigated through 2D NMR analysis and molecular dynamics simulations. Association constants for complexes of amino acids and rotaxanes in various protonation states were determined in a variety of solvent systems by (1)H NMR analysis. The unique intracomponent interactions that exist in the rotaxanes and their ability to act as artificial receptors are discussed.
MeSH term(s)	Amino Acids/chemistry ; Catalysis ; Chemistry, Organic/methods ; Computer Simulation ; Ethers, Cyclic/chemistry ; Indicators and Reagents ; Magnetic Resonance Spectroscopy ; Models, Molecular ; Molecular Structure ; Phenylalanine/chemistry ; Rotaxanes ; Structure-Activity Relationship
Chemical Substances	Amino Acids ; Ethers, Cyclic ; Indicators and Reagents ; Rotaxanes ; Phenylalanine (47E5O17Y3R)
Language	English
Publishing date	2003-04-04
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	123490-0
ISSN	1520-6904 ; 0022-3263
ISSN (online)	1520-6904
ISSN	0022-3263
DOI	10.1021/jo026530q
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