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Eight analogues of 2,5-bis(carboethoxyamino)-3,6-diaziridinyl-1,4-benzoquinone have been synthesized and tested for cytotoxicity against four different leukemic and lymphomic cell lines. For K562 and BSM cells, the toxicity could be correlated with the ease of reduction of the compounds as determined by the one-electron reduction potentials and the electron(More)
L1210 and K562 leukaemic cells have been used to study the relationship between cytotoxicity and free radical production by two aziridinyl benzoquinones, 2,5-bis(carboethoxyamino)3,6-diaziridinyl-1,4-benzoquinone (AZQ) and 2,5-bis(2-hydroxyethylamino)-3,6-diaziridinyl-1,4-benzoquinone (BZQ). BZQ showed a high level of toxicity in both cell lines, but no ESR(More)
Irradiation of dry or fully hydrated frozen DNA systems (conditions of direct damage) has been shown by electron-spin resonance spectroscopy to give rise to electron-gain centres localized on thymine (T.-) and electron loss centres ('holes') localized on guanine (G.+) with approximately equal yields. Our parallel studies on the development of both single-(More)
The properties of the semiquinone radicals produced for 2,5-bis(carboethoxyamino)-3,6-diaziridinyl-1,4-benzoquinone (AZQ) and 2,5-bis(2-hydroxyethylamino)-3,6-diaziridinyl-1,4-benzoquinone (BZQ), have been investigated. AZQ semiquinone radicals can be produced from the reduction of AZQ by superoxide radicals, whereas BZQ semiquinone radicals are unstable in(More)
The mechanisms of cytotoxicity of the antitumour diaziridinylbenzoquinones, AZQ and BZQ, have been investigated. HPLC analysis has been used to study the products as well as the rate of decomposition of acid-assisted ring-opening in aqueous medium as a function of pH. Microconcentrators with a molecular weight cutoff of 30 kDa were utilised to study the(More)
NADPH consumption and esr spectroscopy have been used to study the rate of formation and signal intensity of free radicals produced by various anthracycline anti-tumour drugs in rat liver microsomal extract. The drugs investigated were Adriamycin, 4'Deoxyadriamycin, Daunorubicin, 4 Demethoxydaunorubicin and Carminomycin. Pulse radiolysis was also used to(More)
The free radical (II) produced by one-electron reduction of adriamycin (I) exists in aqueous solution at pH 7.0 in equilibrium with the parent and the two-electron reduced form (III). Over some hundreds of milliseconds deglycosylation takes place yielding an aglycone (IV) which subsequently rearranges to form a more stable aglycone, 7-deoxyadriamycinone(More)
Seven important variables having profound impact on the ability of a mixing tank to suspend particles have been investigated using computational fluid dynamics (CFD) technology. The results obtained from this study can be applied across a broad range of industries such as the chemical, biochemical, petrochemical and mineral processing industries. Finally, a(More)
Eight analogues of 2,5-bis(carboethoxyamino)-3,6-diaziridinyl-l,4benzoquinone have been synthesized and tested for cytotoxicity against four different leukemic and lymphomic cell lines. For K562 and BSM cells, the toxicity could be correlated with the ease of reduction of the compounds as determined by the one-electron reduction potentials and the electron(More)