Synthesis and characterization of positively charged pentacationic fullerene monoadducts for antimicrobial photodynamic inactivation.
ABSTRACT: We designed and synthesized two analogous pentacationic fullerenyl monoadducts, C??(>ME?N??C?) (1) and C??(>ME?N??C?) (2), with variation of the methoxyethyleneglycol length. Each of these derivatives bears a well-defined number of cationic charges aimed to enhance and control their ability to target pathogenic Gram-positive and Gram-negative bacterial cells for allowing photodynamic inactivation. The synthesis was achieved by the use of a common synthon of pentacationic N,N?,N,N,N,N-hexapropylhexa(aminoethyl)amine arm (C?N??) having six attached propyl groups, instead of methyl or ethyl groups, to provide a well-balanced hydrophobicity-hydrophilicity character to pentacationic precursor intermediates and better compatibility with the highly hydrophobic C?? cage moiety. We demonstrated two plausible synthetic routes for the preparation of 1 and 2 with the product characterization via various spectroscopic methods.
Project description:Novel water-soluble decacationically armed C(60) and C(70) decaiodide monoadducts, C(60)- and C(70)[>M(C(3)N(6)(+)C(3))(2)], were synthesized, characterized, and applied as photosensitizers and potential nano-PDT agents against pathogenic bacteria and cancer cells. A high number of cationic charges per fullerene cage and H-bonding moieties were designed for rapid binding to the anionic residues displayed on the outer parts of bacterial cell walls. In the presence of a high number of electron-donating iodide anions as parts of quaternary ammonium salts in the arm region, we found that C(70)[>M(C(3)N(6)(+)C(3))(2)] produced more HO(•) than C(60)[>M(C(3)N(6)(+)C(3))(2)], in addition to (1)O(2). This finding offers an explanation of the preferential killing of Gram-positive and Gram-negative bacteria by C(60)[>M(C(3)N(6)(+)C(3))(2)] and C(70)[>M(C(3)N(6)(+)C(3))(2)], respectively. The hypothesis is that (1)O(2) can diffuse more easily into porous cell walls of Gram-positive bacteria to reach sensitive sites, while the less permeable Gram-negative bacterial cell wall needs the more reactive HO(•) to cause real damage.
Project description:Antimicrobial photodynamic therapy uses photosensitizers designed to bind to microorganisms and generate reactive oxygen species when illuminated with visible light.We synthesized a highly water-soluble fullerene monoadduct, C70[>M(C3N6(+)C3)2]-(I(-))10 (LC17), and bisadduct, C70[>M(C3N6(+)C3)2][>M(C3N6C3)2] (LC18), both with a well-defined decacationic quaternary ammonium iodide moiety with ten positive charges per C70 to give water solubility and bacterial binding. We determined the antimicrobial effects against human pathogens, Gram-positive (Staphylococcus aureus) and Gram-negative species (Escherichia coli and Acinetobacter baumannii) when activated by UVA or white light.White light was more effective with LC17, while UVA light was more effective with LC18. Both compounds were effective in a mouse model of Gram-negative third-degree burn infections determined by bioluminescence imaging.We propose that the attachment of an additional deca(tertiary-ethylenylamino)malonate arm to C70 allowed the moiety to act as a potent electron donor and increased the generation yield of hydroxyl radicals under UVA illumination.
Project description:We report the synthesis and anticancer photodynamic properties of two new decacationic fullerene (LC14) and red light-harvesting antenna-fullerene conjugated monoadduct (LC15) derivatives. The antenna of LC15 was attached covalently to C60>with distance of only <3.0 ? to facilitate ultrafast intramolecular photoinduced-electron-transfer (for type-I photochemistry) and photon absorption at longer wavelengths. Because LC15 was hydrophobic we compared formulation in Cremophor EL micelles with direct dilution from dimethylacetamide. LC14 produced more (1)O2 than LC15, while LC15 produced much more HO·than LC14 as measured by specific fluorescent probes. When delivered by DMA, LC14 killed more HeLa cells than LC15 when excited by UVA light, while LC15 killed more cells when excited by white light consistent with the antenna effect. However LC15 was more effective than LC14 when delivered by micelles regardless of the excitation light. Micellar delivery produced earlier apoptosis and damage to the endoplasmic reticulum as well as to lysosomes and mitochondria.This team of authors report the synthesis and the photodynamic properties of two new derivatives for cancer treatment; one is a decacationic fullerene (LC14) and the other is a red light-harvesting antenna-fullerene conjugated monoadduct (LC15) utilizing a HeLa cell model.
Project description:DNA oligonucleotides containing site-specific N7-guanine monoadducts of cisplatin, diepoxybutane, and epichlorohydrin were used as templates for DNA synthesis by two bacterial DNA polymerases and human polymerase ?. These polymerases were able to bypass the lesions effectively, although the efficiency was decreased, with inhibition increasing with the size of the lesion. Fidelity of incorporation was essentially unaltered, suggesting that N7-guanine monoadducts do not significantly contribute to the mutational spectra of these agents.
Project description:Functionalized fullerenes are gaining wide interest for mediating photodynamic therapy (PDT) of diseases such as cancers and infections. We recently reported the synthesis of two new decacationic fullerene monoadducts: C60[>M(C3N6(+)C3)2]-(I(-))10(LC14) and its derivative with a light-harvesting antenna conjugated as a C60[>CPAF-(MN6(+)C3)2]-(I(-))10 nanostructure (LC15). We studied the ability of these compounds to mediate PDT of human cancer cells in vitro when excited by UVA light or by white light. Here we report the synthesis of a new fullerene derivative C60[>M(C3N6(+)C3)2][>M(C3N6C3)2]-(I(-))10 (LC16 derived from LC14), as a malonate bisadduct containing a covalently bound decatertiary amine arm. We investigated the relative abilities of the three compounds to generate singlet oxygen ((1)O2), hydroxyl radicals (HO·), and hydrogen peroxide (H2O2) after excitation by UVA or by white light. We used three different classes of pathogenic microbial cells (Gram-positive bacterium, methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative bacterium Escherichia coli, and fungal yeast Candida albicans). LC15 was the most powerful broad spectrum antimicrobial fullerenyl photosensitizer (FPS) followed by LC16, and LC14 was least powerful. Killing depended on both fullerene monoadduct concentration and light fluence. UVA was five times more effective than white light for killing, but not for generation of ROS and relative absorption was greater in white spectral region. Bacterial killing was not much inhibited by addition of azide anions and in some cases was potentiated. In the absence of oxygen, microbial photokilling was highly potentiated (up to 5 logs) by the addition of azide anions. We conclude that molecular functional addends that encourage a type I electron-transfer mechanism increase the ability of photoactivated fullerene monoadducts to kill microbial cells. Oxygen-independent photokilling is possible with fullerene monoadducts in the presence of azide anions, probably mediated by azidyl radicals. UVA excitation may kill bacteria partly by an electron-transfer mechanism directly into bacteria as well as by ROS.
Project description:Fullerenes are promising candidates for photodynamic therapy (PDT). Thus, C?? and novel C??O? fullerenes were functionalized with and without an additional deca-tertiary ethyleneamino-chain as an electron source, giving rise to two distinct pairs of photosensitizers, the monoadducts LC-17, LC-19 and the bisadducts LC18 and LC-20 to perform PDT in HeLa cells with UVA, blue, green, white and red light. Shorter wavelengths gave more phototoxicity with LC-20 while LC-19 was better at longer wavelengths; the ratio between killing obtained with LC-19 and LC-20 showed an almost perfect linear correlation (R = 0.975) with wavelength. The incorporation of a deca-tertiary amine chain in the C??O? fullerene gave more PDT killing when excited with shorter wavelengths or in the presence of low ascorbate concentration through higher generation of hydroxyl radicals. Photoactivated C??O? fullerenes induced apoptosis of HeLa cancer cells, together with mitochondrial and lysosomal damage demonstrated by acridine orange and rhodamine 123 fluorescent probes.Photoactivated C?? and C??O? fullerenes were demonstrated to induce apoptosis of HeLa cancer cells, together with mitochondrial and lysosomal damage, as a function of wavelength. The study is paving the way to future clinical uses of these agents in photodynamic therapy.
Project description:A palladium mediated synthesis of a common synthon for the syntheses of antioxidant analogues of naturally occurring salvianolic acids is presented. The synthetic route may be used to obtain analogues with a balanced lipophilicity/hydrophilicity which may result in potentially interesting LDL antioxidants for the prevention of cardiovascular diseases.
Project description:Photodynamic therapy (PDT) is an emerging approach for the treatment of tumor diseases that has received growing interest in the past few years. In this study, we constructed liposomal photosensitizers (PS) for PDT by shoehorning as light-harvesting "antenna" molecules and dense fullerene (C60) into lipid membrane bilayers. The liposomal PS showed improved photodynamic activity toward human cancer cells via the photoenergy transfer from photoactivated antenna molecules to C60.
Project description:Upon exposure to UVA light, psoralens can induce DNA interstrand cross-links (ICLs), which can block DNA replication and transcription. Among the psoralen derivatives, 8-methoxypsoralen (8-MOP) is conventionally applied for psoriasis therapy, and amotosalen S59 is used to inactivate bacterial and viral pathogens in blood components. In addition to the ICL formation, psoralens also readily form various monoadducts (MAs) with thymidine residues in DNA when exposed to UVA light, and the biological implications for these monoadducts remain unclear. Here, we reported a method that encompassed digestion with a single enzyme (nuclease P1) and LC-MS/MS, for the simultaneous quantification of ICL and MAs induced in human cells exposed with 8-MOP or S59 and UVA light. Our results showed that the yield of ICL induced by S59, which increased from 3.9 to 12.8 lesions/10(3) nucleotides as the dose of UVA light increased from 0.5 to 10.0 J/cm(2), was approximately 100 fold more than that induced by 8-MOP. In addition, three and five products were identified as 8-MOP- and S59-MAs, respectively, and the yields of MAs were significantly lower than that for ICL. The yields of the three 8-MOP-MAs were 7.6-2.2, 1.9-9.9, and 7.2-51 per 10(6) nucleotides and those of the five S59-MAs were 215-19, 106-39, 25-21, 32-146, and 22-26 per 10(6) nucleotides as the dose of UVA light increased from 0.5 to 10.0 J/cm(2). Although the yields of MAs induced by 8-MOP and S59 were lower than those of the respective ICLs under the same exposure conditions, the formation of appreciable amounts of MAs might account for some of the mutations induced by psoralens.
Project description:We have evaluated the photodynamic activities of C60 derivative·?-cyclodextrin (?-CDx) complexes and demonstrated that they were significantly higher than those of the pristine C60 and C70·?-CDx complexes under photoirradiation at long wavelengths (610-720 nm), which represent the optimal wavelengths for photodynamic therapy (PDT). In particular, the cationic C60 derivative·?-CDx complex had the highest photodynamic ability because the complex possessed the ability to generate high levels of (1)O2 and provided a higher level of intracellular uptake. The photodynamic activity of this complex was greater than that of photofrin, which is the most widely used of the known clinical photosensitizers. These findings therefore provide a significant level of information toward the optimization of molecular design strategies for the synthesis of fullerene derivatives for PDT.