The Experts below are selected from a list of 564 Experts worldwide ranked by ideXlab platform
Caroline M Preston - One of the best experts on this subject based on the ideXlab platform.
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a first step towards identification of tannin derived black carbon conventional pyrolysis py gc ms and thermally assisted hydrolysis and methylation thm gc ms of charred condensed tannins
Organic Geochemistry, 2012Co-Authors: Joeri Kaal, Klaas G J Nierop, Peter Kraal, Caroline M PrestonAbstract:Tannins account for a significant proportion of plant biomass and are likely to contribute to the residues formed by incomplete biomass combustion (black carbon, BC). Nonetheless, the molecular properties of thermally modified tannins have not been investigated in laboratory charring experiments. We applied conventional analytical pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) to investigate the effects of heat treatment with a muffle furnace on the properties of condensed tannins (CT) from Corsican pine (Pinus nigra) needles. Py–GC–MS showed a decrease in the relative abundance of the 1,2,3-trihydroxybenzenes (pyrogallols) at ⩾300 °C and of the dihydroxybenzenes (mainly catechols) at ⩾350 °C due to dehydroxylation of the CT B ring. Further dehydroxylation led to formation of monohydroxybenzenes (phenols), which showed a strong enrichment between 350 and 400 °C and, at higher temperatures, to a series of monocyclic and polycyclic aromatics [benzene, alkyl benzenes and polycondensed aromatic hydrocarbons (PAHs)]. Degradation of the A ring could not be recognized via Py–GC–MS, probably because of the poor chromatographic behavior of 1,3,5-trihydroxybenzenes (Phloroglucinols). The progressive dehydroxylation and eventual polycondensation of the CT B ring was corroborated using THM–GC–MS. In addition, with THM–GC–MS the thermal rearrangement of CT A rings at 300 °C and higher was inferred from the relative abundance of 1,3,5-trimethoxybenzenes (methylated phloroglucinol derivatives). These compounds were observed at moderate/high temperature (up to 450 °C) and can not be produced from THM of lignin, suggesting that they may be markers of CT in natural BC samples.
Joeri Kaal - One of the best experts on this subject based on the ideXlab platform.
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a first step towards identification of tannin derived black carbon conventional pyrolysis py gc ms and thermally assisted hydrolysis and methylation thm gc ms of charred condensed tannins
Organic Geochemistry, 2012Co-Authors: Joeri Kaal, Klaas G J Nierop, Peter Kraal, Caroline M PrestonAbstract:Tannins account for a significant proportion of plant biomass and are likely to contribute to the residues formed by incomplete biomass combustion (black carbon, BC). Nonetheless, the molecular properties of thermally modified tannins have not been investigated in laboratory charring experiments. We applied conventional analytical pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) to investigate the effects of heat treatment with a muffle furnace on the properties of condensed tannins (CT) from Corsican pine (Pinus nigra) needles. Py–GC–MS showed a decrease in the relative abundance of the 1,2,3-trihydroxybenzenes (pyrogallols) at ⩾300 °C and of the dihydroxybenzenes (mainly catechols) at ⩾350 °C due to dehydroxylation of the CT B ring. Further dehydroxylation led to formation of monohydroxybenzenes (phenols), which showed a strong enrichment between 350 and 400 °C and, at higher temperatures, to a series of monocyclic and polycyclic aromatics [benzene, alkyl benzenes and polycondensed aromatic hydrocarbons (PAHs)]. Degradation of the A ring could not be recognized via Py–GC–MS, probably because of the poor chromatographic behavior of 1,3,5-trihydroxybenzenes (Phloroglucinols). The progressive dehydroxylation and eventual polycondensation of the CT B ring was corroborated using THM–GC–MS. In addition, with THM–GC–MS the thermal rearrangement of CT A rings at 300 °C and higher was inferred from the relative abundance of 1,3,5-trimethoxybenzenes (methylated phloroglucinol derivatives). These compounds were observed at moderate/high temperature (up to 450 °C) and can not be produced from THM of lignin, suggesting that they may be markers of CT in natural BC samples.
Jin Won Hyun - One of the best experts on this subject based on the ideXlab platform.
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phloroglucinol attenuates the cognitive deficits of the 5xfad mouse model of alzheimer s disease
PLOS ONE, 2015Co-Authors: Eun-jeong Yang, Jin Won Hyun, Junghwa Ryu, Moonseok Choi, Sangzin Ahn, Shinkyu Choi, Young Hae Chong, Moon-jeong Chang, Hye-sun KimAbstract:Alzheimer’s disease (AD) is the most common form of dementia among the elderly. Neuritic plaques whose primary component is amyloid beta peptide (Aβ) and neurofibrillary tangles which are composed of hyperphosphorylated tau, are known to be the neuropathological hallmarks of AD. In addition, impaired synaptic plasticity in neuronal networks is thought to be important mechanism underlying for the cognitive deficits observed in AD. Although various causative factors, including excitotoxicity, mitochondrial dysregulation and oxidative damage caused by Aβ, are involved in early onset of AD, fundamental therapeutics that can modify the progression of this disease are not currently available. In the present study, we investigated whether phloroglucinol (1, 3, 5—trihydroxybenzene), a component of phlorotannins, which are plentiful in Ecklonia cava, a marine brown alga species, displays therapeutic activities in AD. We found that phloroglucinol attenuates the increase in reactive oxygen species (ROS) accumulation induced by oligomeric Aβ1–42 (Aβ1–42) treatment in HT-22, hippocampal cell line. In addition, phloroglucinol was shown to ameliorate the reduction in dendritic spine density induced by Aβ1–42 treatment in rat primary hippocampal neuron cultures. We also found that the administration of phloroglucinol to the hippocampal region attenuated the impairments in cognitive dysfunction observed in 22-week-old 5XFAD (Tg6799) mice, which are used as an AD animal model. These results indicate that phloroglucinol displays therapeutic potential for AD by reducing the cellular ROS levels.
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Phloroglucinol Attenuates the Cognitive Deficits of the 5XFAD Mouse Model of Alzheimer’s Disease
2015Co-Authors: Eun-jeong Yang, Jin Won Hyun, Junghwa Ryu, Moonseok Choi, Sangzin Ahn, Shinkyu Choi, Young Hae Chong, Moon-jeong Chang, Hye-sun KimAbstract:Alzheimer’s disease (AD) is the most common form of dementia among the elderly. Neuritic plaques whose primary component is amyloid beta peptide (Aβ) and neurofibrillary tangles which are composed of hyperphosphorylated tau, are known to be the neuropathological hallmarks of AD. In addition, impaired synaptic plasticity in neuronal networks is thought to be important mechanism underlying for the cognitive deficits observed in AD. Although various causative factors, including excitotoxicity, mitochondrial dysregulation and oxidative damage caused by Aβ, are involved in early onset of AD, fundamental therapeutics that can modify the progression of this disease are not currently available. In the present study, we investigated whether phloroglucinol (1, 3, 5—trihydroxybenzene), a component of phlorotannins, which are plentiful in Ecklonia cava, a marine brown alga species, displays therapeutic activities in AD. We found that phloroglucinol attenuates the increase in reactive oxygen species (ROS) accumulation induced by oligomeric Aβ1–42 (Aβ1–42) treatment in HT-22, hippocampal cell line. In addition, phloroglucinol was shown to ameliorate the reduction in dendritic spine density induced by Aβ1–42 treatment in rat primary hippocampal neuron cultures. We also found that the administration of phloroglucinol to the hippocampal region attenuated the impairments in cognitive dysfunction observed in 22-week-old 5XFAD (Tg6799) mice, which are used as an AD animal model. These results indicate that phloroglucinol displays therapeutic potential for AD by reducing the cellular ROS levels.
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protective effect of phlorotannin components phloroglucinol and eckol on radiation induced intestinal injury in mice
Phytotherapy Research, 2008Co-Authors: Changjong Moon, Jae Woo Park, Jin Won Hyun, Nam Ho Lee, Sungho Kim, Jongchoon Kim, Taekyun ShinAbstract:Components of phlorotannin, which were extracted from Ecklonia species, have been reported to have in vitro radioprotective and antioxidative effects. The radioprotective effects of two of the components of phlorotannin, phloroglucinol and eckol, in intestinal stem cells were examined by evaluating their effects on jejunal crypt survival and apoptosis in gamma-irradiated mice. Pretreating the mice (i.p. 20 mg/kg of body weight at 12 and 36 h before irradiation) prior to irradiation with either phloroglucinol or eckol significantly improved the survival of the jejunal crypt (p < 0.001 and p < 0.01 vs irradiation controls at 3.5 days after 8 Gy irradiation, respectively). The administration of phloroglucinol and eckol prior to irradiation protected the intestinal crypts from radiation-induced apoptosis (p < 0.05 vs irradiation controls at 12 h after 1 Gy irradiation). Although the mechanism for this inhibitory effect remains unknown, these results showed that phloroglucinol and eckol might be useful radioprotectors that can defend intestinal stem cells against the oxidative damage caused by gamma-irradiation.
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cytoprotective effect of phloroglucinol on oxidative stress induced cell damage via catalase activation
Journal of Cellular Biochemistry, 2006Co-Authors: Kyoung Ah Kang, Sungwook Chae, Rui Zhang, Myung Sun Jung, Jong Seok Baik, Jin Won HyunAbstract:We investigated the cytoprotective effect of phloroglucinol, which was isolated from Ecklonia cava (brownalga),againstoxidativestressinducedcelldamageinChinesehamsterlungfibroblast(V79-4)cells.Phloroglucinol was found to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydrogen peroxide (H2O2), hydroxy radical, intracellular reactive oxygen species (ROS), and thus prevented lipid peroxidation. As a result, phloroglucinol reduced H2O2 induced apoptotic cells formation in V79-4 cells. In addition, phloroglucinol inhibited cell damage induced by serum starvation and radiation through scavenging ROS. Phloroglucinol increased the catalase activity and its protein expression. In addition, catalase inhibitor abolished the protective effect of phloroglucinol from H2O2 induced cell damage. Furthermore, phloroglucinol increased phosphorylation of extracellular signal regulated kinase (ERK). Taken together, the results suggest that phloroglucinol protects V79-4 cells against oxidative damage by enhancing the cellular catalase activity and modulating ERK signal pathway. J. Cell. Biochem. 97: 609-620, 2006. 2005 Wiley-Liss, Inc.
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induction of antioxidant enzymes in phloroglucinol treated cells
한국환경성돌연변이·발암원학회지, 2005Co-Authors: Kyoung Ah Kang, Sungwook Chae, Rui Zhang, Myung Sun Jung, Jong Seok Baik, Kyoung Hwa Lee, Young Min Ham, Nam Ho Lee, Jin Won HyunAbstract:We investigated the cytoprotective effect of phloroglucinol, which was isolated from Ecklonia cava (brown seaweed), against oxidative stress induced cell damage in Chinese hamster lung fibroblast (V79-4) cells. Phloroglucinol was found to scavenge intracellular reactive oxygen species (ROS) generated by γ-ray radiation. In addition, phloroglucinol inhibited cell damage induced by radiation through scavenging ROS. Phloroglucinol increased the superoxide dismutase and glutathione peroxidase activity. Taken together, the results suggest that phloroglucinol protects V79-4 cells against oxidative damage by enhancing the cellular antioxidant enzymes activity.
Klaas G J Nierop - One of the best experts on this subject based on the ideXlab platform.
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a first step towards identification of tannin derived black carbon conventional pyrolysis py gc ms and thermally assisted hydrolysis and methylation thm gc ms of charred condensed tannins
Organic Geochemistry, 2012Co-Authors: Joeri Kaal, Klaas G J Nierop, Peter Kraal, Caroline M PrestonAbstract:Tannins account for a significant proportion of plant biomass and are likely to contribute to the residues formed by incomplete biomass combustion (black carbon, BC). Nonetheless, the molecular properties of thermally modified tannins have not been investigated in laboratory charring experiments. We applied conventional analytical pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) to investigate the effects of heat treatment with a muffle furnace on the properties of condensed tannins (CT) from Corsican pine (Pinus nigra) needles. Py–GC–MS showed a decrease in the relative abundance of the 1,2,3-trihydroxybenzenes (pyrogallols) at ⩾300 °C and of the dihydroxybenzenes (mainly catechols) at ⩾350 °C due to dehydroxylation of the CT B ring. Further dehydroxylation led to formation of monohydroxybenzenes (phenols), which showed a strong enrichment between 350 and 400 °C and, at higher temperatures, to a series of monocyclic and polycyclic aromatics [benzene, alkyl benzenes and polycondensed aromatic hydrocarbons (PAHs)]. Degradation of the A ring could not be recognized via Py–GC–MS, probably because of the poor chromatographic behavior of 1,3,5-trihydroxybenzenes (Phloroglucinols). The progressive dehydroxylation and eventual polycondensation of the CT B ring was corroborated using THM–GC–MS. In addition, with THM–GC–MS the thermal rearrangement of CT A rings at 300 °C and higher was inferred from the relative abundance of 1,3,5-trimethoxybenzenes (methylated phloroglucinol derivatives). These compounds were observed at moderate/high temperature (up to 450 °C) and can not be produced from THM of lignin, suggesting that they may be markers of CT in natural BC samples.
Peter Kraal - One of the best experts on this subject based on the ideXlab platform.
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a first step towards identification of tannin derived black carbon conventional pyrolysis py gc ms and thermally assisted hydrolysis and methylation thm gc ms of charred condensed tannins
Organic Geochemistry, 2012Co-Authors: Joeri Kaal, Klaas G J Nierop, Peter Kraal, Caroline M PrestonAbstract:Tannins account for a significant proportion of plant biomass and are likely to contribute to the residues formed by incomplete biomass combustion (black carbon, BC). Nonetheless, the molecular properties of thermally modified tannins have not been investigated in laboratory charring experiments. We applied conventional analytical pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and thermally assisted hydrolysis and methylation (THM–GC–MS) to investigate the effects of heat treatment with a muffle furnace on the properties of condensed tannins (CT) from Corsican pine (Pinus nigra) needles. Py–GC–MS showed a decrease in the relative abundance of the 1,2,3-trihydroxybenzenes (pyrogallols) at ⩾300 °C and of the dihydroxybenzenes (mainly catechols) at ⩾350 °C due to dehydroxylation of the CT B ring. Further dehydroxylation led to formation of monohydroxybenzenes (phenols), which showed a strong enrichment between 350 and 400 °C and, at higher temperatures, to a series of monocyclic and polycyclic aromatics [benzene, alkyl benzenes and polycondensed aromatic hydrocarbons (PAHs)]. Degradation of the A ring could not be recognized via Py–GC–MS, probably because of the poor chromatographic behavior of 1,3,5-trihydroxybenzenes (Phloroglucinols). The progressive dehydroxylation and eventual polycondensation of the CT B ring was corroborated using THM–GC–MS. In addition, with THM–GC–MS the thermal rearrangement of CT A rings at 300 °C and higher was inferred from the relative abundance of 1,3,5-trimethoxybenzenes (methylated phloroglucinol derivatives). These compounds were observed at moderate/high temperature (up to 450 °C) and can not be produced from THM of lignin, suggesting that they may be markers of CT in natural BC samples.