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De Simone BC, Mazzone G, Toscano M, Russo N. On the origin of photodynamic activity of hypericin and its iodine-containing derivatives. J Comput Chem 2022; 43:2037-2042. [PMID: 36129210 PMCID: PMC9826312 DOI: 10.1002/jcc.27002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/30/2022] [Accepted: 09/05/2022] [Indexed: 01/11/2023]
Abstract
The main photophysical properties, useful for establishing whether hypericin in anionic form and some of its derivatives containing heavy atoms such as iodine, can be proposed for their use in photodynamic therapy, were determined using density functional based computations. The results showed that in the anionic form and in the iodinated derivatives, the absorption wavelength undergoes a bathochromic shift, the singlet-triplet energy gap assumes values that allow to excite the oxygen molecule from its ground to the excited singlet state, and that the spin-orbit couplings between singlet and triplet states significantly increase.
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Affiliation(s)
| | - Gloria Mazzone
- Department of Chemistry and Chemical TechnologiesUniversity of CalabriaRendeItaly
| | - Marirosa Toscano
- Department of Chemistry and Chemical TechnologiesUniversity of CalabriaRendeItaly
| | - Nino Russo
- Department of Chemistry and Chemical TechnologiesUniversity of CalabriaRendeItaly
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de Morais FAP, Gonçalves RS, Vilsinski BH, de Oliveira ÉL, Rocha NL, Hioka N, Caetano W. Hypericin photodynamic activity in DPPC liposome. PART I: biomimetism of loading, location, interactions and thermodynamic properties. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 190:118-127. [PMID: 30513414 DOI: 10.1016/j.jphotobiol.2018.11.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 07/02/2018] [Accepted: 11/27/2018] [Indexed: 10/27/2022]
Abstract
Hypericin (Hyp) is a potential photosensitizer drug for Photodynamic Therapy (PDT). However, the high lipophilicity of Hyp prevents its preparation in water. To overcome the Hyp solubility problem, this study uses the liposomal vesicle of DPPC. Otherwise liposome is also one of the most employed artificial systems that mimetizes cell membranes. Our present focus is the interaction of Hyp into DPPC liposome as biomimetic system. We studied the loading, interaction, and localization of Hyp (2.8 μmol L-1) in DPPC (5.4 mmol L-1) liposomes, as well as the thermodynamic aspects of Hyp-liposomes. The Hyp addition to the DPPC liposome dispersion showed a Encapsulation Efficiency for [Hyp] = 2.8 μmol L-1 in [DPPC] = 5.3 mmol L-1 of 74.3% and 89.3% at 30.0 and 50.0 °C, respectively. The encapsulation profile obeys a pseudo first-order kinetic law, with a rate constant of 1.26 × 10-3 s-1 at 30.0 °C. Also the data suggests this reaction is preceded by an extremely rapid step. A study on the binding of Hyp/DPPC liposomes (Kb), performed at several temperatures, showed results of 4.8 and 18.5 × 103 L mol-1 at 293 and 323 K, respectively. Additionally, a decrease was observed in the ΔG of the Hyp/DPPC interaction (-20.6 and - 26.4 kL mol-1 at 293 and 323 K, respectively). The resulting ΔH > 0 with ΔS < 0 shows that the entropy is driven the process. Studies of Hyp location in the liposome at 298 K revealed the existence of two different Hyp populations with a Stern-Volmer constant (Ksv) of 4.65 and 1.87 L mol-1 using iodide as an aquo-suppressor at concentration ranged from 0 to 0.025 mol L-1 and from 0.025 to 0.150 mol L-1, respectively. Furthermore, studies of Fluorescence Resonance Energy Transfer, using DPH as a donor and Hyp as an acceptor, revealed that Hyp is allocated in different binding sites of the liposome. This is dependent on temperature. Thermal studies revealed that the Hyp/DPPC formulation presented reasonable stability. Size and morphological investigations showed that Hyp incorporation increases the average size of DPPC liposomes from 116 to 154 nm. The study demonstrated the ability of the Hyp-DPPC liposome as an interesting system for drug delivery system that can be applied to PDT.
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Affiliation(s)
- Flávia A P de Morais
- Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5.790, 87020-900, Maringá, PR, Brazil.
| | - Renato S Gonçalves
- Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5.790, 87020-900, Maringá, PR, Brazil.
| | - Bruno H Vilsinski
- Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5.790, 87020-900, Maringá, PR, Brazil
| | - Évelin L de Oliveira
- Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5.790, 87020-900, Maringá, PR, Brazil
| | - Nicola L Rocha
- Instituto de Química, Universidade Estadual de Campinas, Rua Carlos Gomes 241- Campinas - SP, Brazil
| | - Noboru Hioka
- Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5.790, 87020-900, Maringá, PR, Brazil.
| | - Wilker Caetano
- Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5.790, 87020-900, Maringá, PR, Brazil.
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Keša P, Antalík M. Determination of p K a constants of hypericin in aqueous solution of the anti-allergic hydrotropic drug Cromolyn disodium salt. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.03.059] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Shen L. Photophysical and photosensitizing characters of 2-phenylbenzimidazole-5-sulfonic acid. A theoretical study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 150:187-189. [PMID: 26046497 DOI: 10.1016/j.saa.2015.05.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 04/29/2015] [Accepted: 05/10/2015] [Indexed: 06/04/2023]
Abstract
The sunscreen agent 2-phenylbenzimidazole-5-sulfonic acid (PBSA) has been reported to exhibit photosensitizing activity. In the present study, the photophysical and photosensitizing properties of PBSA were investigated by means of quantum chemical calculations with the aim to gain deeper insights into the underlying photosensitizing mechanisms. The results indicate that singlet oxygen may be generated spontaneously through direct energy transfer from triplet excited state PBSA to (3)O2, and superoxide anion radical is formed through electron transfer between the anion of PBSA and (3)O2. This offers some deeper insights into the photosensitizing mechanisms of PBSA.
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Affiliation(s)
- Liang Shen
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255049, PR China.
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Coitiño EL, Mella A, Cárdenas-Jirón GI. Theoretical assessment of the photosensitization mechanisms of porphyrin–ruthenium(II) complexes for the formation of reactive oxygen species. J Photochem Photobiol A Chem 2014. [DOI: 10.1016/j.jphotochem.2014.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Shen L. Photosensitization Mechanisms of Triplet Excited State β-Lapachone. A Density Functional Theory Study. Nat Prod Commun 2011. [DOI: 10.1177/1934578x1100601128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
β-Lapachone is a natural product with multiple pharmacological activities and mechanistic studies indicated that reactive oxygen species (ROS) generated by β-lapachone play significant roles in its pharmacological actions. As photosensitization is an important ROS-generating pathway, in the present work, the photosensitization mechanisms of β-lapachone are explored on the basis of density functional theory estimated triplet excited state characters. Starting from triplet excited state β-lapachone, the possible generating pathways of 1O2 and O2·– are elucidated and the solvent effects on the photosensitizing reactions are also discussed.
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Affiliation(s)
- Liang Shen
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255049, P. R. China
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Youssef T, Fadel M, Fahmy R, Kassab K. Evaluation of hypericin-loaded solid lipid nanoparticles: Physicochemical properties, photostability and phototoxicity. Pharm Dev Technol 2010; 17:177-86. [DOI: 10.3109/10837450.2010.529148] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Shen L, Ji HF. The mechanisms of ROS-photogeneration by berberine, a natural isoquinoline alkaloid. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2010; 99:154-6. [DOI: 10.1016/j.jphotobiol.2010.03.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Revised: 03/04/2010] [Accepted: 03/29/2010] [Indexed: 10/19/2022]
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Qian X, Lee PW, Cao S. China: forward to the green pesticides via a basic research program. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:2613-23. [PMID: 20128592 DOI: 10.1021/jf904098w] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The 973 Program is China's keystone national research program established to support basic research in natural and physical sciences. In addition to promoting the development of core technology and scientific infrastructure needed to enable China to meet the social and economic challenges of the 21st century, the training and mentoring of the new generation of China's young scientists are also important objectives of this national program. The green chemical pesticide research program is a part of the 973 Program. The main objectives of stage 1 of the green chemical pesticide research program (2003-2008) are to establish China's capability to conduct basic research in the discovery of "green" crop protection chemicals that are not only novel in mode of action and highly selective to pest species that are unique to China's agricultural situation but also possess favorable environmental and human hazard and risk potentials. The target-based discovery strategy was selected as the main discovery platform. This strategy not only provided this research program the best chance to discover new products but also provided members of this research team opportunities to establish core technologies in chemoinformatics/computation-aided pesticide design using QSAR, QAAR, sensitive and selective bioassay methodology, combinatorial synthesis, hit to lead optimization, and biological targets that were derived from resistance-AChE, IGR, nAChR, etc. On the basis of the learning from stage 1, stage 2 (2010-2014) of this program will focus on the molecular target-oriented innovation of green chemical pesticides. This commentary presents key learnings and accomplishments from the stage 1 of China's green chemical pesticide research program. It is hoped that this information will stimulate further constructive collaborations between pesticide scientists from China and abroad.
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Affiliation(s)
- Xuhong Qian
- Shanghai Key Laboratory of Chemical Biology, Institute of Pharmaceuticals and Pesticides, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
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Hypericins as potential leads for new therapeutics. Int J Mol Sci 2010; 11:562-94. [PMID: 20386655 PMCID: PMC2852855 DOI: 10.3390/ijms11020562] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/27/2010] [Accepted: 01/28/2010] [Indexed: 12/22/2022] Open
Abstract
70 years have passed since the first isolation of the naphthodianthrones hypericin and pseudohypericin from Hypericum perforatum L. Today, they continue to be one of the most promising group of polyphenols, as they fascinate with their physical, chemical and important biological properties which derive from their unique chemical structure. Hypericins and their derivatives have been extensively studied mainly for their antitumor, antiviral and antidepressant properties. Notably, hypericin is one of the most potent naturally occurring photodynamic agents. It is able to generate the superoxide anion and a high quantum yield of singlet oxygen that are considered to be primarily responsible for its biological effects. The prooxidant photodynamic properties of hypericin have been exploited for the photodynamic therapy of cancer (PDT), as hypericin, in combination with light, very effectively induces apoptosis and/or necrosis of cancer cells. The mechanism by which these activities are expressed continues to be a main topic of discussion, but according to scientific data, different modes of action (generation of ROS & singlet oxygen species, antiangiogenesis, immune responces) and multiple molecular pathways (intrinsic/extrinsic apoptotic pathway, ERK inhibition) possibly interrelating are implicated. The aim of this review is to analyse the most recent advances (from 2005 and thereof) in the chemistry and biological activities (in vitro and in vivo) of the pure naphthodianthrones, hypericin and pseudohypericin from H. perforatum. Extracts from H. perforatum were not considered, nor pharmakokinetic or clinical data. Computerised literature searches were performed using the Medline (PubMed), ChemSciFinder and Scirus Library databases. No language restrictions were imposed.
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Density functional theory study of the photosensitization mechanisms of indigo. OPEN CHEM 2009. [DOI: 10.2478/s11532-009-0044-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe triplet excited state properties and photosensitization mechanisms of indigo were investigated based on density functional theory calculations. The solvent effects on the photosensitization mechanisms of indigo have also been considered. The thermodynamic feasibility of the possible 1O2 and O2·−-photogeneration pathways by triplet excited state indigo in different solvents was explored, in order to gain some deeper insights into the photosensitization characters of the dye.
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Shen L. Deactivation mechanisms of triplet excited state hypericin by β-carotene. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020802454851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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13
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Ji HF, Shen L. Mechanisms of reactive oxygen species photogeneration by benzo[a]pyrene: A DFT study. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.theochem.2008.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ji HF, Shen L. Triplet excited state characters and photosensitization mechanisms of α-terthienyl: A theoretical study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2009; 94:51-3. [DOI: 10.1016/j.jphotobiol.2008.09.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 09/12/2008] [Accepted: 09/30/2008] [Indexed: 10/21/2022]
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15
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Ji HF, Shen L. A DFT study on deactivation of triplet excited state riboflavin by polyphenols. Int J Mol Sci 2008; 9:1908-1914. [PMID: 19325725 PMCID: PMC2635615 DOI: 10.3390/ijms9101908] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 09/07/2008] [Accepted: 09/27/2008] [Indexed: 11/16/2022] Open
Abstract
The deactivation of triplet excited state riboflavin by polyphenols, e.g. rutin and catechin, was studied on the basis of density functional theory calculations. The results show that the H-atom transfer pathway is more feasible on thermodynamic grounds in comparison with the direct energy transfer or direct electron transfer pathways involved in the triplet excited state riboflavin deactivation by rutin/catechin. The findings are helpful to understand the protective effect of polyphenols against the riboflavin induced photosensitizing damage.
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Affiliation(s)
| | - Liang Shen
- Author to whom correspondence should be addressed; E-mail:
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Shen L, Ji HF. How α-tocopherol quenches triplet state riboflavin? Insights from theory. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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17
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Quenching Reactions of Triplet State Riboflavin by Vitamin C: A Theoretical Investigation. J AM OIL CHEM SOC 2008. [DOI: 10.1007/s11746-008-1270-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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Ji HF, Shen L. Theoretical analysis of the deactivation reactions of triplet state riboflavin by hydroxycinnamic acid derivatives. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802301938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Hong-Fang Ji
- a Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study , Shandong University of Technology , Zibo, P.R. China
| | - Liang Shen
- a Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study , Shandong University of Technology , Zibo, P.R. China
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Theoretical investigation on the triplet excited state properties of the porphyrin-related photosensitizers and the implications in illustrating their photosensitization mechanisms. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2008.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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20
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Shen L, Ji HF. Theoretical exploration of the ROS-photogenerating mechanisms of α-tocopherolquinone. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020802294323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Shen L, Ji HF. A theoretical study on the quenching mechanisms of triplet state riboflavin by tryptophan and tyrosine. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2008; 92:10-12. [DOI: 10.1016/j.jphotobiol.2008.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 03/26/2008] [Accepted: 03/28/2008] [Indexed: 11/27/2022]
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Theoretical investigation of the photosensitization mechanisms of urocanic acid. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2008; 91:96-8. [PMID: 18359241 DOI: 10.1016/j.jphotobiol.2008.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 02/13/2008] [Accepted: 02/15/2008] [Indexed: 11/20/2022]
Abstract
The photosensitization mechanisms of urocanic acid (UA), the main skin chromophores of ultraviolet (UV) light, are investigated by means of theoretical calculations. The results indicate that the direct photooxidative damage to DNA bases by triplet state UA through electron transfer reaction is not favorable on thermodynamic grounds. However, UA can photogenerate various reactive oxygen species (ROS, e.g., (1)O(2), O(2)(-)) theoretically and the ROS-generating mechanisms are illustrated as follows. Firstly, the (1)O(2)-generating pathway involves direct energy transfer between triplet state UA and (3)O(2). Secondly, UA gives birth to O(2)(-) through two pathways: (i) direct electron transfer between triplet state UA and (3)O(2); (ii) electron transfer between anion radical of UA (generated through autoionization reactions) and (3)O(2).
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Shen L, Ji HF, Zhang HY. Photophysical and photochemical properties of anthraquinones: A DFT study. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2007.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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24
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Shen L. Theoretical Study on the Photophysical and Photochemical Properties of Elsinochrome A. J Biomol Struct Dyn 2007; 25:321-6. [DOI: 10.1080/07391102.2007.10507180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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25
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Shen L, Ji HF. Theoretical study on physicochemical properties of curcumin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:619-23. [PMID: 16979936 DOI: 10.1016/j.saa.2006.08.018] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 08/15/2006] [Accepted: 08/15/2006] [Indexed: 05/11/2023]
Abstract
Curcumin is a yellow-orange pigment, which has attracted considerable attention due to its wide spectrum of biological and pharmacological activities. In spite of much effort devoted on curcumin, there still exist some open questions concerning its fundamental physicochemical properties. The present study suggests that the DFT and TD-DFT calculations are useful to answer these questions. Firstly, the thermodynamic as well as spectral parameters support that curcumin exists predominantly in enol form in solution. Secondly, the calculated absorption spectra of curcumin anions provides direct evidence that the lowest pK(a) of curcumin corresponds to the dissociation of enolic proton, which not only reconciles the controversy on this topic, but also has important implications on the proton-transfer/dissociation-associated radical-scavenging mechanisms of curcumin.
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Affiliation(s)
- Liang Shen
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study, Shandong University of Technology, Zibo 255049, PR China
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Ji HF, Zhang HY, Shen L. Proton dissociation is important to understanding structure–activity relationships of gallic acid antioxidants. Bioorg Med Chem Lett 2006; 16:4095-8. [PMID: 16713262 DOI: 10.1016/j.bmcl.2006.04.096] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 04/20/2006] [Accepted: 04/28/2006] [Indexed: 01/18/2023]
Abstract
Gallic acid derivatives (GADs) can efficiently scavenge free radicals, which is partially responsible for their neuroprotective effects. As GADs tend to deprotonate to give birth to GAD anions, which has big influence on the radical-scavenging behaviors of GADs, to understand the structure-activity relationships (SARs) of GAD antioxidants, the anions should be taken into consideration. In this paper, a combined density functional theory method, labeled as (RO)B3LYP/6-311+G(2d,2p)//AM1/AM1, was employed to calculate homolytic O-H bond dissociation enthalpies and adiabatic ionization potentials for GADs and derived anions in solvent (ethanol), by which the experimentally observed SARs of GADs were better elucidated.
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Affiliation(s)
- Hong-Fang Ji
- Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Center for Advanced Study, Shandong University of Technology, Zibo 255049, PR China
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