SYNTHESIS OF SOME NEW<i>S</i>-DABO AND HEPT ANALOGUES WITH EXPECTED BIOLOGICAL ACTIVITY AGAINST HBV

Aal, Mohammed Taha Abdel

doi:10.1081/scc-120003633

Cited by 12 publications

(3 citation statements)

References 9 publications

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“…[1][2][3][4][5][6][7] Uracil, which forms part of these compounds, has been the subject of many studies because of its biological and pharmaceutical activities. [2,[8][9][10][11][12][13] Also, its thio derivatives have attracted similar interest, because 2-thiouracil and 4-thiouracil have been identified as minor components of t-RNA and can be used as anticancer and antithyroid drugs. [14] Moreover, their existence in many tautomeric forms seems to be crucial for explaining mutation occurring during DNA duplication.…”

Section: Introductionmentioning

confidence: 99%

Association of Cu²⁺with Uracil and Its Thio Derivatives: A Theoretical Study

et al. 2004

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The structures and relative stabilities of the complexes between Cu2+ and uracil, 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil were investigated by B3LYP/6-311+G(2df,2p)//B3LYP/6-31G* DFT calculations. In those systems in which both types of basic centers, that is, a carbonyl and a thiocarbonyl group, are present, association of Cu2+ with the oxygen atom is systematically favored, in contrast to what was found for the corresponding Cu+ complexes. This can be understood by considering that association of Cu2+ is immediately followed by oxidation of the base, which accumulates the negative charge at the oxygen atoms. Similarly, for 2,4-dithiouracil the most basic site for Cu+ attachment is the sulfur atom at the 4-position, while for association of Cu2+ it is sulfur at the 2-position. In contrast, differences between uracil-Cu+ and uracil-Cu2+ complexes are very small, and in both cases the oxygen atom at the 4-position is the most basic. Cu2+ binding energies are about 4 and 1.2 times larger than Cu+ binding energies and proton affinities, respectively. Uracil- and thiouracil-Cu2+ complexes are thermodynamically unstable but kinetically stable with respect to their dissociation into uracil*+ + Cu+ or thiouracil*+ + Cu+. The Cu2+ binding energies vary with the difference between the second ionization potential of the metal and the first ionization potential of the base. regardless of the reference acid (H+, Cu+, Cu2+) the basicity trend is 2,4-dithiouracil > 4-thiouracil > 2-thiouracil > uracil.

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Section: Introductionmentioning

confidence: 99%

Association of Cu²⁺with Uracil and Its Thio Derivatives: A Theoretical Study

et al. 2004

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“…Uracil (U) is one of the most important constituents of RNA and plays an irreplaceable role in the transmission of genetic information . In particular, nucleobases have been used as supramolecular synthons owing to their efficiency in coding for noncovalent interaction motifs.…”

Section: Introductionmentioning

confidence: 99%

“…Uracil (U) is one of the most important constituents of RNA and plays an irreplaceabler ole in the transmission of genetic information. [14,15] In particular,n ucleobases have been used as supramolecular synthons owing to their efficiency in coding for noncovalent interaction motifs. Amongn ucleobases, Ui s versatile because of its continuous H-bond donor and acceptor sites, whichd isplay self-complementary patterns of interactions.…”

Section: Introductionmentioning

confidence: 99%

Remarkable Differences in Spin Couplings for Various Self‐Paired Dimers of Ring‐Expansion‐Radicalized Uracil: A Basis for the Design of Magnetically Anisotropic Assemblies

Zhao

2018

ChemPhysChem

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The spin-coupling properties of a series of radicalized uracil (rU) dimer diradicals with different H-bonding modes is examined. Each rU has four double H-bonding sites [the amide units: two at the Watson-Crick face (upper site WC and lower site WC ), a Hoogsteen site (HO), and a minor-groove site (MI)], and ten homogeneous dimers (rU-rU) can self-pair with well-defined diradical characters and comparable stability to the native U dimers. More interestingly, all these dimers exhibit distinctly different spin-coupling characters (ferromagnetic (FM) versus antiferromagnetic (AFM) and large- versus small-magnitude spin couplings), indicative of remarkable magnetic-coupling anisotropy of rU. This observation originates from the fusion of a cyclopentadienyl radical to U, which leads to uneven spin-density distribution. In rU, the fused five-membered radical ring can spin-polarize to the edge in the minor groove, and thus dimerization of rU leads to different H-bonded structures with remarkably different magnetic couplings. The calculated larger magnetic coupling constants J are 1003.7 and 540.2 cm for the WC -HO and MI-HO H-bonding modes between rU, which exhibit considerably large FM couplings, the MI-MI, WC -WC and WC -WC modes show moderate FM couplings (J=0.4-77 cm ), and the other modes exhibit moderate or weak AFM couplings. These observations indicate that the HO and MI sites are favorable spin-coupling sites. In addition, the H-bond lengths and electronic structures of the H-bonding sites, proton transfer, and extra H-bonding interaction with the surroundings can also affect the magnetic couplings of the base pairs. Clearly, the unique magnetic coupling anisotropy of rU provides a promising application basis for the design and assembly of bio-inspired anisotropically magnetic membranes and even magnetism-tunable building blocks for novel magnetic nanoscale devices.

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Synthesis of Some New S‐DABO and HEPT Analogues with Expected Biological Activity Against HBV.

Aal

2002

ChemInform

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SYNTHESIS OF SOME NEWS-DABO AND HEPT ANALOGUES WITH EXPECTED BIOLOGICAL ACTIVITY AGAINST HBV

Cited by 12 publications

References 9 publications

Association of Cu²⁺with Uracil and Its Thio Derivatives: A Theoretical Study

Association of Cu²⁺with Uracil and Its Thio Derivatives: A Theoretical Study

Remarkable Differences in Spin Couplings for Various Self‐Paired Dimers of Ring‐Expansion‐Radicalized Uracil: A Basis for the Design of Magnetically Anisotropic Assemblies

Synthesis of Some New S‐DABO and HEPT Analogues with Expected Biological Activity Against HBV.

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SYNTHESIS OF SOME NEWS-DABO AND HEPT ANALOGUES WITH EXPECTED BIOLOGICAL ACTIVITY AGAINST HBV

Cited by 12 publications

References 9 publications

Association of Cu2+with Uracil and Its Thio Derivatives: A Theoretical Study

Association of Cu2+with Uracil and Its Thio Derivatives: A Theoretical Study

Remarkable Differences in Spin Couplings for Various Self‐Paired Dimers of Ring‐Expansion‐Radicalized Uracil: A Basis for the Design of Magnetically Anisotropic Assemblies

Synthesis of Some New S‐DABO and HEPT Analogues with Expected Biological Activity Against HBV.

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Association of Cu²⁺with Uracil and Its Thio Derivatives: A Theoretical Study

Association of Cu²⁺with Uracil and Its Thio Derivatives: A Theoretical Study