Free radical addition of trichloromethyl to caffeine access to C-8 polyhalogenoalkane derivatives and to unexpected 5-trichloromethyl-1,3,7 trimethyl-5,7-dihydrouric acid

Zylber, J.; Zylber, N.; Chiaroni, A.; Riche, C.

doi:10.1016/s0040-4039(01)91186-4

Cited by 8 publications

(2 citation statements)

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“…Mes-Acr and Ru, Ir-based catalysts were examined: the reaction resulted in a lower yield of 3a (ESI, Table 2†). Due to the electrophilic nature of the trichloromethyl radical, 18 polarity matching between the trichloromethyl radical and the olefin derivative was considered. Thereafter, the impact of the electronic effects in the leaving groups on the radical addition reactivity of the substrate was considered.…”

Section: Resultsmentioning

confidence: 99%

Visible light promoted polyhalomethylation of alkenes: alkylation and cyclization

et al. 2022

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Section: Resultsmentioning

confidence: 99%

Visible light promoted polyhalomethylation of alkenes: alkylation and cyclization

et al. 2022

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“…Conceivably, the C6 position of the thiol‐activated C2,6‐radical species was much less sterically hindered and more accessible to caffeine attacks than C2. On the other hand, the C8 position of the caffeine purine ring has been shown to be the most active site, forming numerous radical adducts with different types of free radicals [28–30, 51]. Thus, a C8‐substituent of caffeine at the C6 of NCS‐C was expected to form the mono‐caffeine adduct NCS‐C–GSH–caffeine.…”

Section: Resultsmentioning

confidence: 99%

Neocarzinostatin as a probe for DNA protection activity—molecular interaction with caffeine

Chin

Kuo

et al. 2011

Molecular Carcinogenesis

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Neocarzinostatin (NCS), a potent mutagen and carcinogen, consists of an enediyne prodrug and a protein carrier. It has a unique double role in that it intercalates into DNA and imposes radical-mediated damage after thiol activation. Here we employed NCS as a probe to examine the DNA-protection capability of caffeine, one of common dietary phytochemicals with potential cancer-chemopreventive activity. NCS at the nanomolar concentration range could induce significant single- and double-strand lesions in DNA, but up to 75 ± 5% of such lesions were found to be efficiently inhibited by caffeine. The percentage of inhibition was caffeine-concentration dependent, but was not sensitive to the DNA-lesion types. The well-characterized activation reactions of NCS allowed us to explore the effect of caffeine on the enediyne-generated radicals. Postactivation analyses by chromatographic and mass spectroscopic methods identified a caffeine-quenched enediyne-radical adduct, but the yield was too small to fully account for the large inhibition effect on DNA lesions. The affinity between NCS chromophore and DNA was characterized by a fluorescence-based kinetic method. The drug-DNA intercalation was hampered by caffeine, and the caffeine-induced increases in DNA-drug dissociation constant was caffeine-concentration dependent, suggesting importance of binding affinity in the protection mechanism. Caffeine has been shown to be both an effective free radical scavenger and an intercalation inhibitor. Our results demonstrated that caffeine ingeniously protected DNA against the enediyne-induced damages mainly by inhibiting DNA intercalation beforehand. The direct scavenging of the DNA-bound NCS free radicals by caffeine played only a minor role.

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1996

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Free radical addition of trichloromethyl to caffeine access to C-8 polyhalogenoalkane derivatives and to unexpected 5-trichloromethyl-1,3,7 trimethyl-5,7-dihydrouric acid

Cited by 8 publications

References 13 publications

Visible light promoted polyhalomethylation of alkenes: alkylation and cyclization

Visible light promoted polyhalomethylation of alkenes: alkylation and cyclization

Neocarzinostatin as a probe for DNA protection activity—molecular interaction with caffeine

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