Mechanistic studies on the photodynamic effect induced by a dicationic fullerene C60 derivative on Escherichia coli and Candida albicans cells (original) (raw)
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Oxidative damage induced by the fullerene C 60 on photosensitization in rat liver microsomes
Chemico-biological Interactions, 1998
We have examined the ability of a commonly used fullerene, C60, to induce oxidative damage on photosensitization using rat liver microsomes as model membranes. When C60 was incorporated into rat liver microsomes in the form of its cyclodextrin complex and exposed to UV or visible light, it induced significant oxidative damage in terms of (1) lipid peroxidation as assayed by thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides and conjugated dienes, and (2) damage to proteins as assessed by protein carbonyls and loss of the membrane-bound enzymes. The oxidative damage induced was both time- and concentration-dependent. C60 plus light-induced lipid peroxidation was significantly inhibited by the quenchers of singlet oxygen (1O2), β-carotene and sodium azide, and deuteration of the buffer-enhanced peroxidation. These observations indicate that C60 is an efficient inducer of peroxidation and is predominantly due to 1O2. Biological antioxidants such as glutathione, ascorbic acid and α-tocopherol significantly differ in their ability to inhibit peroxidation induced by C60. Our studies, hence, indicate that C60, on photosensitization, can induce significant lipid peroxidation and other forms of oxidative damage in biological membranes and that this phenomenon can be greatly modulated by endogenous antioxidants and scavengers of reactive oxygen species.
Nanomedicine (London, England), 2015
Antimicrobial photodynamic inactivation with fullerenes bearing cationic charges may overcome resistant microbes. We synthesized C60-fullerene (LC16) bearing decaquaternary chain and deca-tertiary-amino groups that facilitates electron-transfer reactions via the photoexcited fullerene. Addition of the harmless salt, potassium iodide (10 mM) potentiated the ultraviolet A (UVA) or white light-mediated killing of Gram-negative bacteria Acinetobacter baumannii, Gram-positive methicillin-resistant Staphylococcus aureus and fungal yeast Candida albicans by 1-2+ logs. Mouse model infected with bioluminescent Acinetobacter baumannii gave increased loss of bioluminescence when iodide (10 mM) was combined with LC16 and UVA/white light. The mechanism may involve photoinduced electron reduction of (1)(C60>)* or (3)(C60>)* by iodide producing I· or I2 followed by subsequent intermolecular electron-transfer events of (C60>)(-)· to produce reactive radicals.
European Journal of Medicinal Chemistry, 2008
A novel N,N-dimethyl-2-(4 0 -N,N,N-trimethylaminophenyl)fulleropyrrolidinium iodide (DTC 60 2þ ) has been synthesized by 1,3-dipolar cycloaddition using 4-(N,N-dimethylamino) benzaldehyde, N-methylglycine and fullerene C 60 . This approach produced an N-methyl-2-(4 0 -N,N-dimethylaminophenyl)fulleropyrrolidine with 38% yield. Exhaustive methylation of this fullerene derivative with methyl iodide yielded 95% of dicationic DTC 60 2þ . The spectroscopic and photodynamic properties of the DTC 60 2þ were compared with a non-charged N-methyl-2-(4 0 -acetamidophenyl)fulleropyrrolidine (MAC 60 ) and a monocationic N,N-dimethyl-2-(4 0 -acetamidophenyl)fulleropyrrolidinium iodide (DAC 60 þ ). The dicationic DTC 60 2þ is essentially aggregated in solution of different solvents and it is partially dissolved as monomer in benzene/benzyl-n-hexadecyldimethyl ammonium chloride (BHDC) 0.1 M/water (W 0 ¼ 10) reverse micelles. The singlet molecular oxygen, O 2 ( 1 D g ), production was evaluated using 1,3diphenylisobenzofuran. The photodynamic effect was strongly dependent on the medium, diminishes when the sensitizer is aggregated and increases in an appropriately surrounded microenvironment. The photodynamic inactivation produced by these fullerene derivatives was investigated in vitro on a typical Gram-negative bacterium, Escherichia coli. Photosensitized inactivation of E. coli cellular suspensions by DTC 60 2þ exhibits a w3.5 log decrease of cell survival (99.97% of cellular inactivation), when the cultures are treated with 1 mM of sensitizer and irradiated for 30 min. This photosensitized inactivation remains high even after one washing step. Also, the photodynamic activity was confirmed by growth delay of E. coli cultures. The growth was arrested when E. coli was exposed to 2 mM of cationic fullerene and irradiated, whereas a negligible effect was found for the non-charged MAC 60 . These studies indicate that dicationic DTC 60 2þ is an interesting agent with potential applications in photodynamic inactivation of bacteria.
Free Radical Biology and Medicine, 2007
Photodynamic therapy (PDT) employs the combination of non-toxic photosensitizers (PS) and harmless visible light to generate reactive oxygen species (ROS) and kill cells. Most clinically studied PS are based on the tetrapyrrole structure of porphyrins, chlorins and related molecules, but new nontetrapyrrole PS are being sought. Fullerenes are soccer-ball shaped molecules composed of sixty or seventy carbon atoms and have attracted interest in connection with the search for biomedical applications of nanotechnology. Fullerenes are biologically inert unless derivatized with functional groups, whereupon they become soluble and can act as PS. We have compared the photodynamic activity of six functionalized fullerenes with 1, 2, or 3 hydrophilic or 1, 2, or 3 cationic groups. The octanol-water partition coefficients were determined and the relative contributions of Type I photochemistry (photogeneration of superoxide in the presence of NADH) and Type II photochemistry (photogeneration of singlet oxygen) were studied by measurement of oxygen consumption, 1270-nm luminescence and EPR spin-trapping of the superoxide product. We studied three mouse cancer cell lines: (J774, LLC and CT26) incubated for 24 h with fullerenes and illuminated with white light. The order of effectiveness as PS was inversely proportional to the degree of substitution of the fullerene nucleus for both the neutral and cationic series. The monopyrrolidinium fullerene was the most active PS against all cell lines and induced apoptosis 4-6 hours after illumination. It produced diffuse intracellular fluorescence when dichlorodihydrofluorescein was added as an ROS probe suggesting a Type I mechanism for phototoxicity. We conclude that certain functionalized fullerenes have potential as novel PDT agents and phototoxicity may be mediated both by superoxide and by singlet oxygen.
Toxicology, 2000
Fullerenes have attracted considerable attention in recent years due to their unique chemical structure and potential applications. Hence it is of interest to study their biological effects. Using rat liver microsomes as model systems we have examined the ability of the most commonly used fullerene, C60 and its water-soluble derivative, C60(OH)18 to induce membrane damage on photosensitization. For photoexcitation, UV or tungsten lamps were used. Damage was assessed as lipid peroxidation products like conjugated dienes, lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS), protein oxidation in the form of protein carbonyls, besides loss of membrane bound enzymes. Both fullerene derivatives induced significant oxidative damage. The alterations induced were both time- and concentration-dependent. Role of different reactive oxygen species (ROS) in the damage induced was examined by various scavengers of ROS and by deuteration of the buffer. The changes induced by C60 were predominantly due to 1O2 while that by C60(OH)18 was mainly due to radical species. Biological antioxidants such as glutathione, ascorbic acid and α-tocopherol were capable of inhibiting membrane damage induced by both the fullerenes. However, the damage induced by C60(OH)18 was more for both lipids and proteins than that showed by C60. C60 also showed enhancement in the formation of lipid peroxidation in sarcoma 180 ascites microsomes. In conclusion, our studies indicate that fullerene/its derivative can generate ROS on photoexcitation and can induce significant lipid peroxidation/protein oxidation in membranes and these phenomena can be prevented by endogenous/natural antioxidants.
ECS transactions, 2013
Photodynamic inactivation of pathogenic bacteria and cancer cells by novel water-soluble decacationic fullerene monoadducts, C60[>M(C3N6 (+)C3)2] and C70[>M(C3N6 (+)C3)2], were investigated. 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 C70[>M(C3N6 (+)C3)2] produced more highly reactive HO(•) radical than C60[>M(C3N6 (+)C3)2], in addition to singlet oxygen ((1)O2). This finding offers an explanation of the preferential killing of Gram-positive and Gram-negative bacteria by C60[>M(C3N6 (+)C3)2] and C70[>M(C3N6 (+)C3)2], respectively. The hypothesis is that (1)O2 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.
Biomedical potential of the reactive oxygen species generation and quenching by fullerenes (C 60
Biomaterials, 2008
Fullerene (C 60 ), a third carbon allotrope, is a classical engineered material with the potential application in biomedicine. One of the biologically most relevant features of C 60 is the ability to quench various free radicals, behaving as a ''free radical sponge''. Conversely, photosensitization of C 60 leads to its transition to a long-lived triplet excited state and the subsequent energy or electron transfer to molecular oxygen, yielding highly reactive singlet oxygen ( 1 O 2 ) or superoxide anion (O 2 À ), respectively. These reactive oxygen species (ROS) react with a wide range of biological targets and are known to be involved in both cellular signaling and cell damage. Therefore, the dual property of fullerenes to either quench or generate cell-damaging ROS could be potentially exploited for their development as cytoprotective or cytotoxic anticancer/antimicrobial agents. However, the attempts to that effect have been hampered by the extremely low water solubility of C 60 , and by the fact that solubilization procedures profoundly influence the ROS-generating/quenching properties of C 60 , either through chemical modification or through formation of complex nanoscale particles with different photophysical properties. We here analyze the mechanisms and biological consequences of ROS generation/quenching by C 60 , focusing on the influence that different physico-chemical alterations exert on its ROS-related biological behavior.
Cationic Fullerenes Are Effective and Selective Antimicrobial Photosensitizers
Chemistry & Biology, 2005
Fullerenes are soccer ball-shaped molecules composed of carbon atoms, and, when derivatized with functional groups, they become soluble and can act as photosensitizers. Antimicrobial photodynamic therapy combines a nontoxic photosensitizer with harmless visible light to generate reactive oxygen species that kill microbial cells. We have compared the antimicrobial activity of six functionalized C 60 compounds with one, two, or three hydrophilic or cationic groups in combination with white light against gram-positive bacteria, gram-negative bacteria, and fungi. After a 10 min incubation, the bis-and tris-cationic fullerenes were highly active in killing all tested microbes (4-6 logs) under conditions in which mammalian cells were comparatively unharmed. These compounds performed significantly better than a widely used antimicrobial photosensitizer, toluidine blue O. The high selectivity and efficacy exhibited by these photosensitizers encourage further testing for antimicrobial applications.
Photochemical & Photobiological Sciences, 2021
A novel amphiphilic photosensitizing agent based on a tricationic fullerene C 60 (DMC 60 3+) was efficiently synthesized from its non-charged analogue MMC 60. These fullerenes presented strong UV absorptions, with a broad range of less intense absorption up to 710 nm. Both compounds showed low fluorescence emission and were able to photosensitize the production of reactive oxygen species. Furthermore, photodecomposition of l-tryptophan sensitized by both fullerenes indicated an involvement of type II pathway. DMC 60 3+ was an effective agent to produce the photodynamic inactivation (PDI) of Staphylococcus aureus, Escherichia coli and Candida albicans. Mechanistic insight indicated that the photodynamic action sensitized by DMC 60 3+ was mainly mediated by both photoprocesses in bacteria, while a greater preponderance of the type II pathway was found in C. albicans. In presence of potassium iodide, a potentiation of PDI was observed due to the formation of reactive iodine species. Therefore, the amphiphilic DMC 60 3+ can be used as an effective potential broad-spectrum antimicrobial photosensitizer.
Nanomedicine: Nanotechnology, Biology and Medicine, 2013
Fullerenes are promising candidates for photodynamic therapy (PDT). Thus, C 70 and novel C 84 O 2 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 84 O 2 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 84 O 2 fullerenes induced apoptosis of HeLa cancer cells, together with mitochondrial and lysosomal damage demonstrated by acridine orange and rhodamine 123 fluorescent probes.