- Microwave-assisted modified synthesis of C8-analogues of naturally occurring methylxanthines: Synthesis, biological evaluation and their practical applications
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An efficient, microwave-assisted, oxidant-interceded, transition-metal-free, cross-dehydrogenative Csp 2-Csp 3 coupling of C8-Caffeine 2/Theobromine 3/theophylline 4 with substituted aliphatic alcohol
- Chaudhary, Sandeep,Mathur, Manas,Shyamlal, Bharti Rajesh Kumar,Yadav, Dharmendra K.
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- Reduction-Triggered Doxorubicin Delivery by Self-Assembled Nanospheres of Lipoylated Caffeine
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This study reports a new amphiphilic bioconjugate (CAFF-LA) derived from the lipoylation of a hydroxyethyl derivative of caffeine. In water, CAFF-LA self-assembles into nanospheres with an average size of 155 nm, as evidenced from dynamic light scattering and electron microscopy studies. The nanospheres are stable in serum and could be disintegrated upon exposure to the reducing environment of dithiothreitol (DTT; 10 mM) and glutathione (GSH; 10 mM). These nanospheres easily encapsulate the chemotherapy medication, doxorubicin (DOX), and demonstrate an efficacious transport into doxorubicin-resistant cervical cancer (HeLa) cells, wherein a marked induction in apoptosis and significantly lower IC50 have been observed when compared to that of free drug. The in vitro assessment of cell viability and hemocompatibility present these nanospheres as potentially safe and efficient intracellular reduction stimulus-responsive drug-delivery vehicles.
- Chaudhary, Sandeep,Kondaiah, Paturu,Kumar Shyamlal, Bharti Rajesh,Kumar, Krishan,Verma, Rajbala
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- Benzophenone-Photosensitized Reactions of Xanthinic Compounds. A Mechanistic Study
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Photosensitized reaction of xanthinic compounds (XH) as caffeine (CF), theobromine (TB) and theophylline (TF) by benzophenone (BZ) in ethanol solution was investigated. In the three cases four main reaction products (benzopinacol; diphenylcarbinol; 1,1-diphenyl-1,2-propanediol and 8-[1-(1-hydroxyethyl)] xanthine) were identified and then characterized by melting point, 1H NMR, 13C NMR and mass spectrometry. The quenching of triplet BZ by the three XH was detected and a thorough kinetic analysis was performed. Caffeine produces mainly physical quenching, while TF reacts by N-H hydrogen abstraction. For TB both mechanisms are operative. Heats of reactions were calculated for chosen reactive steps of the mechanism by the PM3 method. They provide additional support to the proposed reaction scheme. We demonstrate that the mechanism leading to XP formation does not proceed through the X? radical directly obtained by H abstraction. An alternative reaction path through an intermediate radical originated on the addition of ethanol radical to XH is proposed. Redox potentials for the oxidation of XH were estimated by cyclic voltametry and by using the Rehm-Weller equation the redox quenching of triplet BZ by XH was discarded.
- Murgida, Daniel H.,Aramendia, Pedro F.,Erra-Balsells, Rosa
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p. 487 - 494
(2007/10/03)
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- Photochemical Reactions of Caffeine with Aliphatic Aldehydes
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Photochemical reactions of caffeine with several aliphatic aldehydes are performed.In the reactions with ethanal, propanal and butanal stable 8-acyl-8,9-dihydrocaffeines 2 and 3 together with unreduced 8-acylcaffeines 4 and 8-(α-hydroxy-alkyl)caffeines 6 are produced.Under similar conditions, the reactions of 2-methylpropanal, 2-methylbutanal and 2,2-dimethylbutanal resulted in the formation of the corresponding 8-alkylcaffeines 7. - Key Words: Caffeine / Aldehydes / Photochemistry / Purines
- Erndt, Aleksander,Fiedorowicz, Maciej,Kostuch, Andrzej,Para, Andrzej
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p. 1043 - 1046
(2007/10/02)
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