Two phenolic antioxidants in Suoyang enhance viability of •OH-damaged mesenchymal stem cells: comparison and mechanistic chemistry

Chemistry Central Journal, Aug 2017

Background Suoyang originates from a psammophyte named Cynomorium songaricum Rupr and has been known as a phenolic-antioxidant-enriched traditional Chinese herbal medicine. The present study attempted to investigate the protective effect of phenolic antioxidants in Suoyang towards •OH-mediated MSCs and then further discusses the chemical mechanisms. Methods The lyophilized aqueous extract of Suoyang (LAS) was prepared and characterized using HPLC. Then, two phenolic antioxidant references, epicatechin and luteolin-7-O-β-D-glucoside, along with LAS, were investigated for their effects on the viability of •OH-treated MSCs using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay. The comparison and mechanistic chemistry of epicatechin and luteolin-7-O-β-D-glucoside were further explored using various antioxidant assays, including PTIO•-scavenging, FRAP (ferric ion reducing antioxidant power), ABTS+•-scavenging, and DPPH•-scavenging. Their Fe2+-binding capacities were also compared using ultraviolet (UV) spectra. Results The HPLC analysis indicated that there are 8 phenolic antioxidants in LAS, including epicatechin, luteolin-7-O-β-D-glucoside, gallic acid, protocatechuic acid, catechin, isoquercitrin, phlorizin, and naringenin. The MTT assay revealed that epicatechin could more effectively increase the survival of •OH-treated MSCs than luteolin-7-O-β-D-glucoside. Similarly, epicatechin exhibited higher antioxidant abilities than luteolin-7-O-β-D-glucoside in the DPPH•-scavenging, ABTS+•-scavenging, FRAP, and PTIO•-scavenging assays. In the Fe2+-binding assay, luteolin-7-O-β-D-glucoside gave a stronger UV peak at 600 nm, with ε = 2.62 × 106 M−1 cm−1, while epicatechin produced two peaks at 450 nm (ε = 8.47 × 105 M−1 cm−1) and 750 nm (ε = 9.68 × 105 M−1 cm−1). Conclusion As two reference antioxidants in Suoyang, epicatechin and luteolin-7-O-β-D-glucoside can enhance the viability of •OH-damaged MSCs. Such a beneficial effect may be from their antioxidant effects, including direct-antioxidant and indirect-antioxidant (i.e., Fe2+-binding) processes. In the direct-antioxidant process, proton (H+), one electron (e), or even hydrogen-atom (•H) transfer may occur to fulfill radical-scavenging (especially •OH-scavenging); in this aspect, epicatechin is superior to luteolin-7-O-β-D-glucoside due to the presence of more phenolic –OHs. The additional –OHs can also be responsible for the better cytoprotective effect. In terms of indirect-antioxidant potential, however, epicatechin is inferior to luteolin-7-O-β-D-glucoside due to the absence of a hydroxyl-keto moiety. These findings will provide new information about medicinal psammophytes for MSC transplantation.

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Two phenolic antioxidants in Suoyang enhance viability of •OH-damaged mesenchymal stem cells: comparison and mechanistic chemistry

Xie et al. Chemistry Central Journal Two phenolic antioxidants in Suoyang enhance viability of •OH-damaged mesenchymal stem cells: comparison and mechanistic chemistry Yulu Xie 0 2 Xican Li 0 2 Jieying Xu 0 Qian Jiang 0 2 Hong Xie 0 2 Jianfeng He 0 2 Dongfeng Chen 0 1 3 0 School of Chinese Herbal Medicine, Guangzhou University of Chinese Medicine , Waihuan East Road No. 232 , Guangzhou Higher Education Mega Center , Guangzhou 510006 , China 1 School of Basic Medical Science, Guangzhou University of Chinese Medicine , Guangzhou 510006 , China 2 Innovative Research & Development Laboratory of TCM, Guangzhou University of Chinese Medicine , Guangzhou 510006 , China 3 The Research Center of Basic Integrative Medicine, Guangzhou University of Chinese Medicine , Guangzhou 510006 , China Background: Suoyang originates from a psammophyte named Cynomorium songaricum Rupr and has been known as a phenolic-antioxidant-enriched traditional Chinese herbal medicine. The present study attempted to investigate the protective effect of phenolic antioxidants in Suoyang towards •OH-mediated MSCs and then further discusses the chemical mechanisms. Methods: The lyophilized aqueous extract of Suoyang (LAS) was prepared and characterized using HPLC. Then, two phenolic antioxidant references, epicatechin and luteolin-7-O-β-D-glucoside, along with LAS, were investigated for their effects on the viability of •OH-treated MSCs using the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay. The comparison and mechanistic chemistry of epicatechin and luteolin-7-O-β-D-glucoside were further explored using various antioxidant assays, including PTIO•-scavenging, FRAP (ferric ion reducing antioxidant power), ABTS+•-scavenging, and DPPH•-scavenging. Their Fe2+-binding capacities were also compared using ultraviolet (UV) spectra. Results: The HPLC analysis indicated that there are 8 phenolic antioxidants in LAS, including epicatechin, luteolin7-O-β-D-glucoside, gallic acid, protocatechuic acid, catechin, isoquercitrin, phlorizin, and naringenin. The MTT assay revealed that epicatechin could more effectively increase the survival of •OH-treated MSCs than luteolin-7-O-β-Dglucoside. Similarly, epicatechin exhibited higher antioxidant abilities than luteolin-7-O-β-D-glucoside in the DPPH•scavenging, ABTS+•-scavenging, FRAP, and PTIO•-scavenging assays. In the Fe2+-binding assay, luteolin-7-O-β-Dglucoside gave a stronger UV peak at 600 nm, with ε = 2.62 × 106 M−1 cm−1, while epicatechin produced two peaks at 450 nm (ε = 8.47 × 105 M−1 cm−1) and 750 nm (ε = 9.68 × 105 M−1 cm−1). Conclusion: As two reference antioxidants in Suoyang, epicatechin and luteolin-7-O-β-D-glucoside can enhance the viability of •OH-damaged MSCs. Such a beneficial effect may be from their antioxidant effects, including directantioxidant and indirect-antioxidant (i.e., Fe2+-binding) processes. In the direct-antioxidant process, proton (H+), one electron (e), or even hydrogen-atom (•H) transfer may occur to fulfill radical-scavenging (especially •OH-scavenging); in this aspect, epicatechin is superior to luteolin-7-O-β-D-glucoside due to the presence of more phenolic -OHs. The additional -OHs can also be responsible for the better cytoprotective effect. In terms of indirect-antioxidant potential, however, epicatechin is inferior to luteolin-7-O-β-D-glucoside due to the absence of a hydroxyl-keto moiety. These findings will provide new information about medicinal psammophytes for MSC transplantation. Background A plant that grows in the desert or desert steppe is called a desert plant (or psammophyte). From the perspectives of free radical biology, desert plants may encounter a series of serious reactive oxygen species (ROS) damages from strong UV light, atmospheric ROS, great differences in temperature, and oxygen consumption for photosynthesis, since the ecological environment of the desert differs from that of land. Indeed, in such a hydropenia environment, the levels of ROS in plants will exceed the threshold value, and excessive ROS can oxidatively damage the proteins, nucleic acids, and enzymes, then lead to the death of plants [ 1 ]. Thus, some surviving desert plants have been suggested to have strong vital force and an effective antioxidant defense system against ROS-induced oxidative damage. The antioxidant defense systems can be classified into enzyme (including polypeptide) and non-enzyme systems. The non-enzyme defense system usually refers to phenolic antioxidants [ 2 ]. Hence, these surviving psammophytes are expected to be a library of bioactive components (especially efficient phenolic antioxidants). Cynomorium songaricum Rupr. (C. songaricum, Fig.  1a), a typical psammophyte, is widely distributed in the desert or desert steppe in the north–west provinces of China, Central Asian, Iran, and Fig. 1 Photos of Cynomorium songaricum Rupr (a) and Suoyang (b) Mongolia. Phytochemical studies have indicated that there are various chemical components in C. son (...truncated)


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Yulu Xie, Xican Li, Jieying Xu, Qian Jiang, Hong Xie, Jianfeng He, Dongfeng Chen. Two phenolic antioxidants in Suoyang enhance viability of •OH-damaged mesenchymal stem cells: comparison and mechanistic chemistry, Chemistry Central Journal, 2017, pp. 84, Volume 11, Issue 1, DOI: 10.1186/s13065-017-0313-1