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Shoji Y, Terashima Y, Ohkubo K, Ito H, Maruyama K, Fukuzumi S, Nakanishi I. Scandium Ion-Promoted Electron-Transfer Disproportionation of 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-Oxide (PTIO •) in Acetonitrile and Its Regeneration Induced by Water. Int J Mol Sci 2024; 25:4417. [PMID: 38674002 PMCID: PMC11050215 DOI: 10.3390/ijms25084417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/09/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO•), a persistent nitronyl nitroxide radical, has been used for the detection and trapping of nitric oxide, as a redox mediator for batteries, for the activity estimation of antioxidants, and so on. However, there is no report on the reactivity of PTIO• in the presence of redox-inactive metal ions. In this study, it is demonstrated that the addition of scandium triflate, Sc(OTf)3 (OTf = OSO2CF3), to an acetonitrile (MeCN) solution of PTIO• resulted in an electron-transfer disproportionation to generate the corresponding cation (PTIO+) and anion (PTIO-), the latter of which is suggested to be stabilized by Sc3+ to form [(PTIO)Sc]2+. The decay of the absorption band at 361 nm due to PTIO•, monitored using a stopped-flow technique, obeyed second-order kinetics. The second-order rate constant for the disproportionation, thus determined, increased with increasing the Sc(OTf)3 concentration to reach a constant value. A drastic change in the cyclic voltammogram recorded for PTIO• in deaerated MeCN containing 0.10 M Bu4NClO4 was also observed upon addition of Sc(OTf)3, suggesting that the large positive shift of the one-electron reduction potential of PTIO• (equivalent to the one-electron oxidation potential of PTIO-) in the presence of Sc(OTf)3 may result in the disproportionation. When H2O was added to the PTIO•-Sc(OTf)3 system in deaerated MeCN, PTIO• was completely regenerated. It is suggested that the complex formation of Sc3+ with H2O may weaken the interaction between PTIO- and Sc3+, leading to electron-transfer comproportionation to regenerate PTIO•. The reversible disproportionation of PTIO• was also confirmed by electron paramagnetic resonance (EPR) spectroscopy.
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Grants
- JP18K06620 Ministry of Education, Culture, Sports, Science and Technology
- JP20H02779 Ministry of Education, Culture, Sports, Science and Technology
- JP20H04819 Ministry of Education, Culture, Sports, Science and Technology
- JP18H04650 Ministry of Education, Culture, Sports, Science and Technology
- JP17H03010 Ministry of Education, Culture, Sports, Science and Technology
- JP16H02268 Ministry of Education, Culture, Sports, Science and Technology
- JP23K04686 Ministry of Education, Culture, Sports, Science and Technology
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Affiliation(s)
- Yoshimi Shoji
- Quantum RedOx Chemistry Team, Institute for Quantum Life Science (iQLS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.S.); (H.I.)
| | - Yuri Terashima
- Environmental Radiation Effects Research Group, Department of Radiation Measurement and Dose Assessment, Institute for Radiological Science (NIRS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.T.); (K.M.)
| | - Kei Ohkubo
- Institute for Advanced Co-Creation Studies, Open and Transdisciplinary Research Initiatives, Osaka University, Suita 565-0871, Osaka, Japan;
| | - Hiromu Ito
- Quantum RedOx Chemistry Team, Institute for Quantum Life Science (iQLS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.S.); (H.I.)
| | - Kouichi Maruyama
- Environmental Radiation Effects Research Group, Department of Radiation Measurement and Dose Assessment, Institute for Radiological Science (NIRS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.T.); (K.M.)
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea;
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Ibaraki, Japan
| | - Ikuo Nakanishi
- Quantum RedOx Chemistry Team, Institute for Quantum Life Science (iQLS), Quantum Life and Medical Science Directorate (QLMS), National Institutes for Quantum Science and Technology (QST), Chiba-shi 263-8555, Chiba, Japan; (Y.S.); (H.I.)
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Li X, Ouyang X, Chen B, Liu S, Zeng J. Linkage and Stereochemistry Characters of Phenolic Antioxidant Product Formation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:5382-5390. [PMID: 36693163 DOI: 10.1021/acs.jafc.2c06563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The present study developed a smart and novel strategy to elucidate the linkage and stereochemistry characters during phenolic antioxidant product formation. A series of phenolic isomers or analogues were treated with 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide radical, to create 16 antioxidant dimerization reactions in aqueous solution. The products were rapidly identified by ultraperformance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass-spectrometry. Through a systematic function-structure relationship analysis of these reactions and theoretical calculations, it is concluded that the phenolic antioxidant product is formed via linear linkage or furanocyclic linkage. The linear linkage is fulfilled via a radical coupling and controlled by the O-O linkage exclusion, meta-linkage exclusion, and catechol-activated principles. However, when an exocyclic π-bond conjugates with the phenolic core and is affixed at the -OH para-position, the furanocyclic linkage may occur via a subsequent intramolecular Michael addition. The intramolecular addition always lacks Re-attack to show "α,β diastereoselectivity." The α,β diastereoselectivity is the stereochemistry character of furanocyclic linkage during phenolic antioxidant product formation. All these novel findings can benefit not only the field food science but also other fields as well.
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Affiliation(s)
- Xican Li
- School of Chinese Herbal Medicine, Guangzhou University of Chinese Medicine, Guangzhou Higher Education Mega Center, Waihuang East Road No. 232, Guangzhou510006, People's Republic of China
| | - Xiaojian Ouyang
- School of Chinese Herbal Medicine, Guangzhou University of Chinese Medicine, Guangzhou Higher Education Mega Center, Waihuang East Road No. 232, Guangzhou510006, People's Republic of China
| | - Ban Chen
- School of Biological Engineering and Food, Hubei University of Technology, Wuhan430068, People's Republic of China
| | - Shuqin Liu
- School of Chinese Herbal Medicine, Guangzhou University of Chinese Medicine, Guangzhou Higher Education Mega Center, Waihuang East Road No. 232, Guangzhou510006, People's Republic of China
| | - Jingyuan Zeng
- School of Chinese Herbal Medicine, Guangzhou University of Chinese Medicine, Guangzhou Higher Education Mega Center, Waihuang East Road No. 232, Guangzhou510006, People's Republic of China
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V MN, Mahmood S, Shah AM, Al-Suede FSR. Suppression of Melanoma Growth in a Murine Tumour Model Using Orthosiphon stamineus Benth. Extract Loaded in Ethanolic Phospholipid Vesicles (Spherosome. Curr Drug Metab 2022; 23:317-328. [PMID: 35430963 DOI: 10.2174/1389200223666220416215129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/17/2022] [Accepted: 03/01/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND Orthosiphon stamineus Benth (O.S) is a traditional south-east Asian herb. The extract of O.S is used in the formulation of ethanolic nanolipid vesicle system to have considerable potential for tumour therapeutics. METHOD The research objective is to develop and characterise the anticancer and antiangiogenic effect of O.S extract in the form of nano-ethanolic spherosomes (ESP) using phospholipids in melanoma. Spherosomes formulation of O.S was developed using the thin-film re-hydration method and converted to gel using Acrypol 1%. The formulations were subjected to optimisation and physical-chemical characterisations like particle size, surface charge, DSC, FTIR, TEM. Cytotoxicity of O.S and ESP were studied using an endothelial cell line (EA. hy926). Furthermore, anti-melanoma effect of O.S spherosome gel was studied in albino mice after topical administration. RESULTS ESP-6 with the ratio of extract (O.S): cholesterol: phospholipid (1: 6: 0.5) showed the highest entrapment efficiency (80.56 ± 0.84%) using ultraviolet spectroscopy. In-vivo permeation/penetration studies revealed deeper absorption of ESP-6 compared with a hydroethanolic gel of O.S. In-vitro and in vivo anti-melanoma studies demonstrated the significant tumour-suppressing effect of ESP-6 on murine melanoma. Percentage inhibition of tumour growth by O.S and ESP-6 at 3000 mg/kg showed 63.98 ± 7.86% and 87.76 ± 7.90%, respectively. CONCLUSION Spherosome vesicles were developed with a smooth surface. The results demonstrated that O.S extract showed no toxicity when tested on the endothelial cell line. O.S loaded in spherosomes has the potential to lower the growth of melanoma in mice. The spherosomes loaded with O.S do not promote tumour growth or act as antiangiogenetic in melanoma.
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Affiliation(s)
- Mansoureh Nazari V
- Universitas Augustus 17, 1945,14350 Jakarta.,School of pharmaceutical sciences, Universiti Sains Malaysia, Minden
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