Synthesis and DNA cleaving properties of hybrid molecules containing propargylic sulfones and minor groove binding lexitropsins

Effects of structural modification on the DNA binding properties and photo-induced cleavage reactivity of propargylic sulfones conjugated with an anthraquinone structure

Propargylic sulfones are known as pH-dependent DNA cleaving agents. We have designed a novel propargylic sulfone conjugated with an anthraquinone structure and evaluated its DNA binding and cleavage characteristics. The propargylic sulfone 3 showed high intercalating ability attributable to anthraquinone chromophore, leading to the efficient alkylation of DNA. The anthraquinone chromophore in 3 also acted as a photosensitizer, and photoirradiation of 3 with DNA induced one-electron oxidation, resulting in the further DNA cleavage. Evaluation of the effect of 3 against EMT6/KU cells revealed that 3 exhibited potent cytotoxicity, even without photoirradiation.

Bifunctional 2-naphthyl propargylic sulfones exhibiting high DNA intercalating and alkylating activity

A number of novel 2-naphthyl propargylic sulfones were synthesized as nucleic base alkylating agents. Extremely high DNA cleavage activity was observed for the sulfones with a free omega-hydroxyl group in the carbon chain in contrast to the ester conjugates possessing an additional intercalating unit.

Remarkable tethering effect on DNA cleavage of propargylic sulfone conjugates with intercalating moieties

A number of novel propargylic sulfone conjugates 3 and 4 with intercalating moieties were synthesized and evaluated for DNA cleavage activity through nucleic base alkylation. A remarkable enhancement in DNA cleaving potency was observed with those conjugates 3 possessing a suitable spacer, a right attachment point at the aromatic ring, and a good intercalator.

Preclinical assessment of hypocrellin B and hypocrellin B derivatives as sensitizers for photodynamic therapy of cancer: progress update

Hypocrellins are perylenequinone pigments with substantial absorption in the red spectral region and high singlet oxygen yield. They are available in pure monomeric form and may be derivatized to optimize properties of red light absorption, tissue biodistribution and toxicity. In vitro screening of synthetic derivatives of the naturally occurring compound, hypocrellin B (HB), for optimal properties of cyto-(dark) toxicity and phototoxicity resulted in selection of three compounds for preclinical evaluation: HBEA-R1 (ethanolaminated HB), HBBA-R2 (butylaminated HB) and HBDP-R1 [2-(N,N-dimethylamino)-propylamine-HB]. Extinction coefficients at 630 nm (epsilon 630) are 6230, 6190 and 4800, respectively; and 1O2 quantum yields, phi, 0.60, 0.32 and 0.42. Intracellular uptake is essentially complete within 2 h (HBEA-R1, HBBA-R2) and 20 h (HBDP-R1). Greatest uptake is associated with lysosomes and Golgi. The HBEA-R1 and HBBA-R2 elicit phototoxicity in vitro primarily via the type II mechanism, with some type I activity under stringently hypoxic conditions. Transcutaneous phototherapy with HBEA-R1 permanently ablates EMT6/Ed tumors growing in the flanks of Balb/c mice, with minimal cutaneous effects. The HBBA-R2 does not elicit mutagenic activity in strains TA98 and TA100 of Salmonella typhimurium. Further development of selected hypocrellin derivatives as photosensitizers for photodynamic therapy is warranted.

Design, synthesis and sequence selective DNA cleavage of functional models of bleomycin--II. 1,2-trans-disubstituted cyclopropane units as novel linkers

The design and syntheses of functional models for bleomycin in which AMPHIS, a simplified model of the metal-chelating subunit of bleomycin is connected to distamycin analogs with a series of linkers, are described. Kinetic studies and DNA cleavage assay show that 1,2-trans-disubstituted cyclopropane units are the best linkers within this series. Study of selective DNA cleavage on high resolution polyacrylamide sequencing gels indicates that the linker modified hybrids generally cleave selectively at the 5' end of poly T sites and at the 3' end of poly A sites. Cleavage activity is enhanced for most of the compounds related to those with shorter linkers, previously reported, (Huang, L.; Quada, Jr J. C.; Lown, J. W. Bioconjugate Chem. 1995, 6, 21, Ref. 1) probably as a result of the linker allowing the active complex to approach the target deoxyribose more closely and efficiently. Certain of the compounds, ones containing a (S)-methyl in the linker and the (S,S)-cyclopropyl linker, exhibit unique cleavage sites, indicating that these linkers allow the hybrids to locate novel, individual DNA binding sites.

Hybrid molecules containing propargylic sulfones and DNA minor groove-binding lexitropsins: synthesis, sequence specificity of reaction with DNA and biological evaluation

A series of hybrids, 4-13, incorporating propargylic sulfones and minor groove-binding oligopeptide carriers, was synthesized. The anticipated preferential binding at adenine sites within the minor groove was confirmed by sequencing determination of these agents on high-resolution gels, indicating preferential alkylation at guanine, and significantly, high selectivity for 5'-GACG and 5'-GGTG. The ability of these hybrids to cleave DNA, as determined by agarose-gel assay, is consistent with the ethidium bromide fluorescence assay. The cytotoxicities of these compounds were also determined against human KB cells in vitro. Higher cytotoxic activities were observed for the compounds containing fewer N-methylpyrrole units, an imidazole group and a 2,3-disubstituted naphthyl moiety.