Nguyen Duc Tung - Academia.edu (original) (raw)
Papers by Nguyen Duc Tung
Journal of Non Equilibrium Thermodynamics, 1989
PloS one, 2015
The impact of daily temperature variations on arthropod life history remains woefully understudie... more The impact of daily temperature variations on arthropod life history remains woefully understudied compared to the large body of research that has been carried out on the effects of constant temperatures. However, diurnal varying temperature regimes more commonly represent the environment in which most organisms thrive. Such varying temperature regimes have been demonstrated to substantially affect development and reproduction of ectothermic organisms, generally in accordance with Jensen's inequality. In the present study we evaluated the impact of temperature alternations at 4 amplitudes (DTR0, +5, +10 and +15°C) on the developmental rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) and their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). We have modelled their developmental rates as a function of temperature using both linear and nonlinear models. Diurnally a...
Contemporary Southeast Asia, 2002
This article seeks to analyse the strength and weaknesses of the three main international relatio... more This article seeks to analyse the strength and weaknesses of the three main international relations (IR) approaches, namely, neo-realist, liberal institutionalist, and constructivist frameworks, applied to the VietnamASEAN relationship since the mid-1980s. While the ...
CHEMICAL & PHARMACEUTICAL BULLETIN, 2009
Ginseng (the root of Panax ginseng C. A. MEYER, Araliaceae) is one of the most commonly used trad... more Ginseng (the root of Panax ginseng C. A. MEYER, Araliaceae) is one of the most commonly used traditional medicines in Korea, China, Japan, and other Asian countries for the treatment of various conditions. Biologically active constituents of ginseng have been pursued extensively, and many dammarane-type triterpene oligoglycosides have been characterized as the principal ingredients. 1,2) Recently, the chemical components of the leaves and flower buds of P. ginseng have been reported including also various dammarane-type saponins. 3-5) In our studies of the chemical constituents of P. ginseng, two new dammarane-type saponins, ginsenoside Ki (1a) and ginsenoside Km (1b), along with 15 known ones (2-16), were isolated from the leaves of P. ginseng. This paper deals with the isolation and structural elucidation of the new ginsenosides 1a and 1b. Results and Discussion The methanolic extract from the leaves of P. ginseng was suspended in water and partitioned successively with nhexane and CH 2 Cl 2. The H 2 O layer was subjected to Diaion HP-20 column chromatography, followed by various silica gel and YMC reversed-phase columns to afford ginsenoside Ki (1a), ginsenoside Km (1b), ginsenoside Re (2), 6) ginsenoside Rg 1 (3), 6) notoginsenoside R 1 (4), 7) floralginsenoside M (5), 4) floralginsenoside N (6), 4) ginsenoside F 1 (7), 8) ginsenoside F 5 (8), 9) ginsenoside F 3 (9), 9) vinaginsenoside R 4 (10), 10) ginsenoside Ia (11), 11) ginsenoside Rd (12), 12) ginsenoside Rc (13), 4) ginsenoside Rb 2 (14), 10) ginsenoside Rb 1 (15), 10) and ginsenoside Rh 6 (16) 10) (Fig. 1). To the best of our knowledge, floralginsenoside M (5) and floralginsenoside N (6) were isolated for the first time from the leaves of P. ginseng. Ginsenoside Ki (1a), an amorphous powder, has the molecular formula C 36 H 62 O 10 as deduced by a high-resolusion 1412 Vol. 57, No. 12 Notes
Bioorganic & Medicinal Chemistry Letters, 2013
On the search for anti-cancer compounds from Thai traditional herb medicines, a bioassay-guided f... more On the search for anti-cancer compounds from Thai traditional herb medicines, a bioassay-guided fractionation and chemical investigation of the methanol extract of Mammea siamensis flower resulted in the isolation and identification of eight compounds (1-8) including a novel geranylated coumarin, namely mammeanoyl (2), and seven known compounds (1 and 3-8). The structure of new compound 2 was elucidated based on the extensive spectroscopic and chemical methods. Among the isolated compounds, three structurally related coumarins 3, 4, and 5 showed significant antiproliferative activities against human leukemia and stomach cancer cell lines. However, these compounds did not affect the cell viabilities of colon cancer, hepatoma, and normal skin fibroblast cell lines. Further analysis demonstrated that the morphological features of apoptosis including DNA fragmentation and chromatin condensation were observed in human leukemia HL-60 cells treated with compounds 3, 4, and 5. In addition, compound 3 led to caspase-3 activation and cleavage of poly (ADP-ribose) polymerase (PARP), and compound 3-induced DNA fragmentation was inhibited by caspase-specific inhibitors. These results suggest that compound 3, 4, and 5 exert antiproliferative actions through apoptotic cell death in leukemia cells and these compounds may have the potential to be developed into new anti-cancer drug candidates.
Agricultural Engineering International: CIGR Journal, 2009
Process heat and electrical power for the rural area in Vietnam is in the state of serious defici... more Process heat and electrical power for the rural area in Vietnam is in the state of serious deficiency. In fact, for Vietnamese rural area, electric energy has not been being well-supplied, but it profits by a high potential of renewable energy from biomass, such as ...
Chemical & Pharmaceutical Bulletin, 2010
Panax ginseng (C.A. MEYER, Araliaceae), an ancient and famous herbal drug in oriental traditional... more Panax ginseng (C.A. MEYER, Araliaceae), an ancient and famous herbal drug in oriental traditional medicine, has been used as a tonic and for the treatment of various diseases. 1,2) Biologically active constituents of whole parts of P. ginseng have been pursued extensively and many dammarane-type triterpene oligoglycosides have been characterized as the principal components. 1-4) Traditionally, the root of P. ginseng (ginseng), the most used and valuable part, has been processed to make white ginseng (WG, roots air-dried after peeling) and red ginseng (RG, roots steamed at 98-100°C without peeling) to enhance its preservation and efficacy. In which, RG is more common as an herbal medicine than WG, because steaming induces changes in the chemical constituents and enhances the biological activities of ginseng. Extracts from roots and leaves have similar multifaceted pharmacological activities (e.g. central nervous and cardiovascular systems). Moreover, in terms of costs and source availability, ginseng leaf has advantages over its root. 5) Nevertheless, there has been no study concerning processed leaves of this plant. In our ongoing research on P. ginseng, 6,7) it was found that a saponin extract of steamed leaves showed potent cytotoxic effect on HL-60 cells. Subsequently, the current study on chemical components of the steamed leaves led to the isolation of three new damarane-type saponins, ginsenosides SL 1-SL 3 (1-3), and eleven known ones (4-14). Here, this paper deals with the structure elucidation of the new ginsenosides SL 1-SL 3 (1-3) and evaluation of cytotoxic activity against HL-60 cells of all compounds. Results and Discussion The methanolic extract of the steamed leaves of P. ginseng was suspended in H 2 O and partitioned with CH 2 Cl 2. Then, the H 2 O layer was subjected to a Diaion HP-20 column, followed by various silica gel and YMC reversed-phase columns to yield three new dammarane-type saponins, ginsenoside SL 1-SL 3 (1-3) (Fig. 1), and eleven known ones (4-14), including (20S)-ginsenoside Rh 1 (4), 8) ginsenoside F 1 (5), 9) ginsenoside Rh 4 (6), 8) (20S)-ginsenoside Rg 2 (7), 10) (20R)-ginsenoside Rg 2 (8), 10) ginsenoside Rg 6 (9), 11) ginsenoside F 4 (10), 11) ginsenoside Rh 3 (11), 8) ginsenoside Rk 2 (12), 8) (20S)-ginsenoside Rh 2 (13), 12) and (20R)-ginsenoside Rh 2 (14), 12) respectively (Fig. 2). Ginsenoside SL 1 (1), an amorphous powder, has the molecular formula C 36 H 62 O 11 as deduced by a high-resolution Fourier-transform ion-cyclotron-resonance mass spectrometry (HR-FT-ICR-MS) experiment (Found at m/z [MϩNa] ϩ 693.4141, Calcd for C 36 H 62 O 11 Na 693.4190). Acid hydrolysis of 1 liberated D-glucose, confirmed by gas chromatography (GC) analysis. It was proposed to possess a hydroperoxyl group due to positive response to N,N-dimethyl-p-phenylenediammonium dichloride reagent. The 1 H-NMR spectrum of 1 showed signals due to the aglycone part [d 0.
Journal of Non Equilibrium Thermodynamics, 1989
PloS one, 2015
The impact of daily temperature variations on arthropod life history remains woefully understudie... more The impact of daily temperature variations on arthropod life history remains woefully understudied compared to the large body of research that has been carried out on the effects of constant temperatures. However, diurnal varying temperature regimes more commonly represent the environment in which most organisms thrive. Such varying temperature regimes have been demonstrated to substantially affect development and reproduction of ectothermic organisms, generally in accordance with Jensen's inequality. In the present study we evaluated the impact of temperature alternations at 4 amplitudes (DTR0, +5, +10 and +15°C) on the developmental rate of the predatory mites Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus McGregor (Acari: Phytoseiidae) and their natural prey, the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae). We have modelled their developmental rates as a function of temperature using both linear and nonlinear models. Diurnally a...
Contemporary Southeast Asia, 2002
This article seeks to analyse the strength and weaknesses of the three main international relatio... more This article seeks to analyse the strength and weaknesses of the three main international relations (IR) approaches, namely, neo-realist, liberal institutionalist, and constructivist frameworks, applied to the VietnamASEAN relationship since the mid-1980s. While the ...
CHEMICAL & PHARMACEUTICAL BULLETIN, 2009
Ginseng (the root of Panax ginseng C. A. MEYER, Araliaceae) is one of the most commonly used trad... more Ginseng (the root of Panax ginseng C. A. MEYER, Araliaceae) is one of the most commonly used traditional medicines in Korea, China, Japan, and other Asian countries for the treatment of various conditions. Biologically active constituents of ginseng have been pursued extensively, and many dammarane-type triterpene oligoglycosides have been characterized as the principal ingredients. 1,2) Recently, the chemical components of the leaves and flower buds of P. ginseng have been reported including also various dammarane-type saponins. 3-5) In our studies of the chemical constituents of P. ginseng, two new dammarane-type saponins, ginsenoside Ki (1a) and ginsenoside Km (1b), along with 15 known ones (2-16), were isolated from the leaves of P. ginseng. This paper deals with the isolation and structural elucidation of the new ginsenosides 1a and 1b. Results and Discussion The methanolic extract from the leaves of P. ginseng was suspended in water and partitioned successively with nhexane and CH 2 Cl 2. The H 2 O layer was subjected to Diaion HP-20 column chromatography, followed by various silica gel and YMC reversed-phase columns to afford ginsenoside Ki (1a), ginsenoside Km (1b), ginsenoside Re (2), 6) ginsenoside Rg 1 (3), 6) notoginsenoside R 1 (4), 7) floralginsenoside M (5), 4) floralginsenoside N (6), 4) ginsenoside F 1 (7), 8) ginsenoside F 5 (8), 9) ginsenoside F 3 (9), 9) vinaginsenoside R 4 (10), 10) ginsenoside Ia (11), 11) ginsenoside Rd (12), 12) ginsenoside Rc (13), 4) ginsenoside Rb 2 (14), 10) ginsenoside Rb 1 (15), 10) and ginsenoside Rh 6 (16) 10) (Fig. 1). To the best of our knowledge, floralginsenoside M (5) and floralginsenoside N (6) were isolated for the first time from the leaves of P. ginseng. Ginsenoside Ki (1a), an amorphous powder, has the molecular formula C 36 H 62 O 10 as deduced by a high-resolusion 1412 Vol. 57, No. 12 Notes
Bioorganic & Medicinal Chemistry Letters, 2013
On the search for anti-cancer compounds from Thai traditional herb medicines, a bioassay-guided f... more On the search for anti-cancer compounds from Thai traditional herb medicines, a bioassay-guided fractionation and chemical investigation of the methanol extract of Mammea siamensis flower resulted in the isolation and identification of eight compounds (1-8) including a novel geranylated coumarin, namely mammeanoyl (2), and seven known compounds (1 and 3-8). The structure of new compound 2 was elucidated based on the extensive spectroscopic and chemical methods. Among the isolated compounds, three structurally related coumarins 3, 4, and 5 showed significant antiproliferative activities against human leukemia and stomach cancer cell lines. However, these compounds did not affect the cell viabilities of colon cancer, hepatoma, and normal skin fibroblast cell lines. Further analysis demonstrated that the morphological features of apoptosis including DNA fragmentation and chromatin condensation were observed in human leukemia HL-60 cells treated with compounds 3, 4, and 5. In addition, compound 3 led to caspase-3 activation and cleavage of poly (ADP-ribose) polymerase (PARP), and compound 3-induced DNA fragmentation was inhibited by caspase-specific inhibitors. These results suggest that compound 3, 4, and 5 exert antiproliferative actions through apoptotic cell death in leukemia cells and these compounds may have the potential to be developed into new anti-cancer drug candidates.
Agricultural Engineering International: CIGR Journal, 2009
Process heat and electrical power for the rural area in Vietnam is in the state of serious defici... more Process heat and electrical power for the rural area in Vietnam is in the state of serious deficiency. In fact, for Vietnamese rural area, electric energy has not been being well-supplied, but it profits by a high potential of renewable energy from biomass, such as ...
Chemical & Pharmaceutical Bulletin, 2010
Panax ginseng (C.A. MEYER, Araliaceae), an ancient and famous herbal drug in oriental traditional... more Panax ginseng (C.A. MEYER, Araliaceae), an ancient and famous herbal drug in oriental traditional medicine, has been used as a tonic and for the treatment of various diseases. 1,2) Biologically active constituents of whole parts of P. ginseng have been pursued extensively and many dammarane-type triterpene oligoglycosides have been characterized as the principal components. 1-4) Traditionally, the root of P. ginseng (ginseng), the most used and valuable part, has been processed to make white ginseng (WG, roots air-dried after peeling) and red ginseng (RG, roots steamed at 98-100°C without peeling) to enhance its preservation and efficacy. In which, RG is more common as an herbal medicine than WG, because steaming induces changes in the chemical constituents and enhances the biological activities of ginseng. Extracts from roots and leaves have similar multifaceted pharmacological activities (e.g. central nervous and cardiovascular systems). Moreover, in terms of costs and source availability, ginseng leaf has advantages over its root. 5) Nevertheless, there has been no study concerning processed leaves of this plant. In our ongoing research on P. ginseng, 6,7) it was found that a saponin extract of steamed leaves showed potent cytotoxic effect on HL-60 cells. Subsequently, the current study on chemical components of the steamed leaves led to the isolation of three new damarane-type saponins, ginsenosides SL 1-SL 3 (1-3), and eleven known ones (4-14). Here, this paper deals with the structure elucidation of the new ginsenosides SL 1-SL 3 (1-3) and evaluation of cytotoxic activity against HL-60 cells of all compounds. Results and Discussion The methanolic extract of the steamed leaves of P. ginseng was suspended in H 2 O and partitioned with CH 2 Cl 2. Then, the H 2 O layer was subjected to a Diaion HP-20 column, followed by various silica gel and YMC reversed-phase columns to yield three new dammarane-type saponins, ginsenoside SL 1-SL 3 (1-3) (Fig. 1), and eleven known ones (4-14), including (20S)-ginsenoside Rh 1 (4), 8) ginsenoside F 1 (5), 9) ginsenoside Rh 4 (6), 8) (20S)-ginsenoside Rg 2 (7), 10) (20R)-ginsenoside Rg 2 (8), 10) ginsenoside Rg 6 (9), 11) ginsenoside F 4 (10), 11) ginsenoside Rh 3 (11), 8) ginsenoside Rk 2 (12), 8) (20S)-ginsenoside Rh 2 (13), 12) and (20R)-ginsenoside Rh 2 (14), 12) respectively (Fig. 2). Ginsenoside SL 1 (1), an amorphous powder, has the molecular formula C 36 H 62 O 11 as deduced by a high-resolution Fourier-transform ion-cyclotron-resonance mass spectrometry (HR-FT-ICR-MS) experiment (Found at m/z [MϩNa] ϩ 693.4141, Calcd for C 36 H 62 O 11 Na 693.4190). Acid hydrolysis of 1 liberated D-glucose, confirmed by gas chromatography (GC) analysis. It was proposed to possess a hydroperoxyl group due to positive response to N,N-dimethyl-p-phenylenediammonium dichloride reagent. The 1 H-NMR spectrum of 1 showed signals due to the aglycone part [d 0.