Nguyen van Hung - Academia.edu (original) (raw)
Papers by Nguyen van Hung
Journal of Natural Products, 2001
Cheminform, 2003
For Abstract see ChemInform Abstract in Full Text.
Tetrahedron, 2003
Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from ... more Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as 'litseane'. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes 1 -8 as racemates. Isolates 1 -8 inhibited HIV-1 replication in HOG.R5 cells with IC 50 values ranging from 2 to 15 mg/ml (8 -58 mM) while affecting the growth of HOG.R5 at concentrations 2-3-fold higher. Based on this data, structure -activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production. q
Journal of Medicinal Chemistry, 2006
Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and G... more Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and Gagnep. (Annonaceae) led to the isolation of a new class of potential anticancer lead molecules. They are a cluster of compounds composed of a C(18) carbon skeleton, a known but heretofore unnamed type, which we have designated as miliusane. Two known (1 and 2) as well as 20 new miliusanes (3-22) have been isolated and identified. They belong to two substructural classes of miliusanes. One subclass (1-19) was determined to be composed of a gamma-lactone spiro-ring system, the opening of which led to the second group of compounds (21 and 22) containing a tetrahydrofuran ring system. Compounds 1-3, 5, 8, 9, 18, 20, and 21 demonstrated significant cytotoxic activity in our cancer cell line panel comprising KB, Col-2, LNCaP, Lu-1, MCF-7, and HUVEC. The structures were determined by spectroscopic and chemical methods. The structure of miliusate was further confirmed by X-ray crystallographic analysis. The absolute stereochemistry of miliusanes was established by the Mosher ester method. Forty-two modified miliusane derivatives were also prepared and evaluated for their cytotoxic activities.
Journal of Natural Products, 2004
Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbet... more Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbetulinic acid (2), and 3 -O-cis-coumaroylbetulinic acid (4), along with two known triterpenes, 3 -O-trans-coumaroylbetulinic acid (3) and ursolic acid (6) were isolated from the leaves and twigs of Strychnos vanprukii Craib. All isolates showed moderate anti-HIV activity with IC 50 values ranging from 3 to 7 µg/mL (5 to 15 µM) in an indicator cell line for HIV infectivity. The structures of the new isolates were elucidated by spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition, the structure of 1 was confirmed by X-ray crystallography. a CC50 ) concentration mediating 50% cytotoxicity. b IC50 ) concentration mediating 50% antiviral response. c SI ) selectivity index. d Betulinic acid was isolated previously from Vatica cinerea King. 7 e ED50, 50% cytoprotective activity against HIV-1IIIB cytopathicity in vitro in µM (SI). f Nt40 ) nontoxic @ 40 µg/mL.
Planta Medica, 2005
Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well ... more Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well as the γ-lactone derivative of oleic acid, from the CH 2 Cl 2 extract of the stem bark of Micromelum hirsutum. The carbazoles include the new micromeline (2) and five known alkaloids: lansine (3), 3methylcarbazole (4), methyl carbazole-3-carboxylate (5), 3-formylcarbazole (6), and 3-formyl-6methoxycarbazole (7). Compound 1 was identified as the lactone derivative of oleic acid, (−)-Z-9octadecene-4-olide, for which the trivial name micromolide (1) is suggested. It showed potent in vitro anti-TB activity against H37Rv (MIC: 1.5 μg/mL), a selectivity index (SI) of 63, and exhibited activity against the Erdman strain of M. tuberculosis in a J774 mouse macrophage model (EC 90 : 5.6 μg/mL). Thus, 1 appears worthy of further evaluation as a potential new anti-TB agent. Isolates 2, 3, 6 and 7 had anti-TB MIC values between 14.3 and 42.3 μg/mL, while compounds 4 and 5 were considered inactive (MIC > 128 μg/mL). Structure elucidation and identification were based on spectroscopic analysis, including MS, 1D/2D NMR, and a full 1 H spin system analysis of 1.
Tetrahedron Letters, 2001
We report herein the first isolation of a novel structural type sesquiterpene designated as 'lits... more We report herein the first isolation of a novel structural type sesquiterpene designated as 'litseane' from the twigs and leaves of Litsea verticillata Hance (Lauraceae). The isolate (litseaverticillol A, 1) was obtained as a racemate through bioassay-guided fractionation and found to inhibit the replication of human immunodeficiency virus (HIV) type 1 with an IC 50 value of 5.0 mg/mL (21.4 mM) and a selectivity index of 2.6. Spectroscopic data and a potential biosynthetic pathway are given.
Pharmaceutical Biology, 2002
Antimalarial bioassay-directed fractionation led to the isolation of a new active indole alkaloid... more Antimalarial bioassay-directed fractionation led to the isolation of a new active indole alkaloid, decursivine (1), from the leaves and stems of Rhaphidophora decursiva Schott (Araceae). In addition, a leaf sample yielded the structurally-related compound serotobenine (2), previously reported from a taxonomically unrelated family, which was not active against Plasmodium falciparum. The structure of 1 was elucidated by spectroscopic means, and its antimalarial activity was observed with IC 50 values of 3.93 and 4.41 mg/ml against the D6 and W2 clones of Plasmodium falciparum, respectively.
Journal of Natural Products, 2001
Phytochemistry, 2002
The eudesmane sesquiterpenoid, verticillatol (1), as well as the lignan, (+)-5 0 -demethoxyepiexc... more The eudesmane sesquiterpenoid, verticillatol (1), as well as the lignan, (+)-5 0 -demethoxyepiexcelsin (2), and a known lignan, (+)epiexcelsin (3), were isolated from Litsea verticillata Hance. Lignan 2 showed moderate anti-HIV activity with an IC 50 value of 16.4 mg/ml (42.7 mM), while the known lignan 3 was inactive up to a concentration of 20 mg/ml (48.3 mM). Compound 1 demonstrated weak activity with an IC 50 value of 34.5 mg/ml (144.7 mM) while being devoid of cytotoxicity at 20 mg/ml. The structures were elucidated by 1D and 2D NMR spectroscopy, and the absolute configuration of the new sesquiterpenoid was determined by the generation of Mosher esters. #
Cheminform, 2003
For Abstract see ChemInform Abstract in Full Text.
Tetrahedron, 2003
Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from ... more Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as 'litseane'. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes 1 -8 as racemates. Isolates 1 -8 inhibited HIV-1 replication in HOG.R5 cells with IC 50 values ranging from 2 to 15 mg/ml (8 -58 mM) while affecting the growth of HOG.R5 at concentrations 2-3-fold higher. Based on this data, structure -activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production. q
Journal of Natural Products, 2003
Journal of Medicinal Chemistry, 2006
Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and G... more Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and Gagnep. (Annonaceae) led to the isolation of a new class of potential anticancer lead molecules. They are a cluster of compounds composed of a C(18) carbon skeleton, a known but heretofore unnamed type, which we have designated as miliusane. Two known (1 and 2) as well as 20 new miliusanes (3-22) have been isolated and identified. They belong to two substructural classes of miliusanes. One subclass (1-19) was determined to be composed of a gamma-lactone spiro-ring system, the opening of which led to the second group of compounds (21 and 22) containing a tetrahydrofuran ring system. Compounds 1-3, 5, 8, 9, 18, 20, and 21 demonstrated significant cytotoxic activity in our cancer cell line panel comprising KB, Col-2, LNCaP, Lu-1, MCF-7, and HUVEC. The structures were determined by spectroscopic and chemical methods. The structure of miliusate was further confirmed by X-ray crystallographic analysis. The absolute stereochemistry of miliusanes was established by the Mosher ester method. Forty-two modified miliusane derivatives were also prepared and evaluated for their cytotoxic activities.
Journal of Natural Products, 2003
In a continuing search for anti-HIV compounds from plants of Vietnam, 19 compounds, including a n... more In a continuing search for anti-HIV compounds from plants of Vietnam, 19 compounds, including a new triterpene, were isolated from an extract of the leaves and stem of Vatica cinerea. The new triterpene was determined to be a cycloartane triterpenoid with 29 skeletal carbons and was assigned the name vaticinone (1). The known triterpenes included three cycloartanes, a lanostane, two dammaranes, three lupanes, an ursane, and an oleanane. A chlorophyll isolate was identified as pheophorbide a (13). The majority of the triterpenes, the sesquiterpene, 1-hydroxycyclocolorenone, and pheophorbide a showed anti-HIV activity, with the chlorophyll being the most active, demonstrating an IC 50 value of 1.5 µg/mL (2.5 µM), while being completely devoid of toxicity up to a concentration of 20 µg/mL (33.8 µM). Vaticinone (1) was found to inhibit the replication of HIV-1, with an IC 50 value of 6.5 µg/mL (15.3 µM; selective index ) 1.4). The structures of these isolates were determined by spectral data including 1D and 2D NMR spectra.
Journal of Natural Products, 2004
Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbet... more Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbetulinic acid (2), and 3 -O-cis-coumaroylbetulinic acid (4), along with two known triterpenes, 3 -O-trans-coumaroylbetulinic acid (3) and ursolic acid (6) were isolated from the leaves and twigs of Strychnos vanprukii Craib. All isolates showed moderate anti-HIV activity with IC 50 values ranging from 3 to 7 µg/mL (5 to 15 µM) in an indicator cell line for HIV infectivity. The structures of the new isolates were elucidated by spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition, the structure of 1 was confirmed by X-ray crystallography. a CC50 ) concentration mediating 50% cytotoxicity. b IC50 ) concentration mediating 50% antiviral response. c SI ) selectivity index. d Betulinic acid was isolated previously from Vatica cinerea King. 7 e ED50, 50% cytoprotective activity against HIV-1IIIB cytopathicity in vitro in µM (SI). f Nt40 ) nontoxic @ 40 µg/mL.
Phytochemistry, 2001
The pregnane steroid, (E)-aglawone, along with four known triterpenes, and a known sterol mixture... more The pregnane steroid, (E)-aglawone, along with four known triterpenes, and a known sterol mixture were isolated from the bark of Aglaia lawii (Wight) Saldanha ex Ramamoorty (Meliaceae). The structural determination/identification was accomplished by a combination of 1D- and 2D-NMR spectroscopic techniques. The relative stereochemistry of the known triterpene, 20S,24S-epoxydammarane-3alpha,25-diol acetate, was also unequivocally determined for the first time by X-ray crystallography. The isolates were not active against various human cancer cell lines.
Planta Medica, 2005
Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well ... more Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well as the γ-lactone derivative of oleic acid, from the CH 2 Cl 2 extract of the stem bark of Micromelum hirsutum. The carbazoles include the new micromeline (2) and five known alkaloids: lansine (3), 3methylcarbazole (4), methyl carbazole-3-carboxylate (5), 3-formylcarbazole (6), and 3-formyl-6methoxycarbazole (7). Compound 1 was identified as the lactone derivative of oleic acid, (−)-Z-9octadecene-4-olide, for which the trivial name micromolide (1) is suggested. It showed potent in vitro anti-TB activity against H37Rv (MIC: 1.5 μg/mL), a selectivity index (SI) of 63, and exhibited activity against the Erdman strain of M. tuberculosis in a J774 mouse macrophage model (EC 90 : 5.6 μg/mL). Thus, 1 appears worthy of further evaluation as a potential new anti-TB agent. Isolates 2, 3, 6 and 7 had anti-TB MIC values between 14.3 and 42.3 μg/mL, while compounds 4 and 5 were considered inactive (MIC > 128 μg/mL). Structure elucidation and identification were based on spectroscopic analysis, including MS, 1D/2D NMR, and a full 1 H spin system analysis of 1.
Journal of Natural Products, 2001
Cheminform, 2003
For Abstract see ChemInform Abstract in Full Text.
Tetrahedron, 2003
Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from ... more Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as 'litseane'. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes 1 -8 as racemates. Isolates 1 -8 inhibited HIV-1 replication in HOG.R5 cells with IC 50 values ranging from 2 to 15 mg/ml (8 -58 mM) while affecting the growth of HOG.R5 at concentrations 2-3-fold higher. Based on this data, structure -activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production. q
Journal of Medicinal Chemistry, 2006
Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and G... more Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and Gagnep. (Annonaceae) led to the isolation of a new class of potential anticancer lead molecules. They are a cluster of compounds composed of a C(18) carbon skeleton, a known but heretofore unnamed type, which we have designated as miliusane. Two known (1 and 2) as well as 20 new miliusanes (3-22) have been isolated and identified. They belong to two substructural classes of miliusanes. One subclass (1-19) was determined to be composed of a gamma-lactone spiro-ring system, the opening of which led to the second group of compounds (21 and 22) containing a tetrahydrofuran ring system. Compounds 1-3, 5, 8, 9, 18, 20, and 21 demonstrated significant cytotoxic activity in our cancer cell line panel comprising KB, Col-2, LNCaP, Lu-1, MCF-7, and HUVEC. The structures were determined by spectroscopic and chemical methods. The structure of miliusate was further confirmed by X-ray crystallographic analysis. The absolute stereochemistry of miliusanes was established by the Mosher ester method. Forty-two modified miliusane derivatives were also prepared and evaluated for their cytotoxic activities.
Journal of Natural Products, 2004
Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbet... more Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbetulinic acid (2), and 3 -O-cis-coumaroylbetulinic acid (4), along with two known triterpenes, 3 -O-trans-coumaroylbetulinic acid (3) and ursolic acid (6) were isolated from the leaves and twigs of Strychnos vanprukii Craib. All isolates showed moderate anti-HIV activity with IC 50 values ranging from 3 to 7 µg/mL (5 to 15 µM) in an indicator cell line for HIV infectivity. The structures of the new isolates were elucidated by spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition, the structure of 1 was confirmed by X-ray crystallography. a CC50 ) concentration mediating 50% cytotoxicity. b IC50 ) concentration mediating 50% antiviral response. c SI ) selectivity index. d Betulinic acid was isolated previously from Vatica cinerea King. 7 e ED50, 50% cytoprotective activity against HIV-1IIIB cytopathicity in vitro in µM (SI). f Nt40 ) nontoxic @ 40 µg/mL.
Planta Medica, 2005
Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well ... more Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well as the γ-lactone derivative of oleic acid, from the CH 2 Cl 2 extract of the stem bark of Micromelum hirsutum. The carbazoles include the new micromeline (2) and five known alkaloids: lansine (3), 3methylcarbazole (4), methyl carbazole-3-carboxylate (5), 3-formylcarbazole (6), and 3-formyl-6methoxycarbazole (7). Compound 1 was identified as the lactone derivative of oleic acid, (−)-Z-9octadecene-4-olide, for which the trivial name micromolide (1) is suggested. It showed potent in vitro anti-TB activity against H37Rv (MIC: 1.5 μg/mL), a selectivity index (SI) of 63, and exhibited activity against the Erdman strain of M. tuberculosis in a J774 mouse macrophage model (EC 90 : 5.6 μg/mL). Thus, 1 appears worthy of further evaluation as a potential new anti-TB agent. Isolates 2, 3, 6 and 7 had anti-TB MIC values between 14.3 and 42.3 μg/mL, while compounds 4 and 5 were considered inactive (MIC > 128 μg/mL). Structure elucidation and identification were based on spectroscopic analysis, including MS, 1D/2D NMR, and a full 1 H spin system analysis of 1.
Tetrahedron Letters, 2001
We report herein the first isolation of a novel structural type sesquiterpene designated as 'lits... more We report herein the first isolation of a novel structural type sesquiterpene designated as 'litseane' from the twigs and leaves of Litsea verticillata Hance (Lauraceae). The isolate (litseaverticillol A, 1) was obtained as a racemate through bioassay-guided fractionation and found to inhibit the replication of human immunodeficiency virus (HIV) type 1 with an IC 50 value of 5.0 mg/mL (21.4 mM) and a selectivity index of 2.6. Spectroscopic data and a potential biosynthetic pathway are given.
Pharmaceutical Biology, 2002
Antimalarial bioassay-directed fractionation led to the isolation of a new active indole alkaloid... more Antimalarial bioassay-directed fractionation led to the isolation of a new active indole alkaloid, decursivine (1), from the leaves and stems of Rhaphidophora decursiva Schott (Araceae). In addition, a leaf sample yielded the structurally-related compound serotobenine (2), previously reported from a taxonomically unrelated family, which was not active against Plasmodium falciparum. The structure of 1 was elucidated by spectroscopic means, and its antimalarial activity was observed with IC 50 values of 3.93 and 4.41 mg/ml against the D6 and W2 clones of Plasmodium falciparum, respectively.
Journal of Natural Products, 2001
Phytochemistry, 2002
The eudesmane sesquiterpenoid, verticillatol (1), as well as the lignan, (+)-5 0 -demethoxyepiexc... more The eudesmane sesquiterpenoid, verticillatol (1), as well as the lignan, (+)-5 0 -demethoxyepiexcelsin (2), and a known lignan, (+)epiexcelsin (3), were isolated from Litsea verticillata Hance. Lignan 2 showed moderate anti-HIV activity with an IC 50 value of 16.4 mg/ml (42.7 mM), while the known lignan 3 was inactive up to a concentration of 20 mg/ml (48.3 mM). Compound 1 demonstrated weak activity with an IC 50 value of 34.5 mg/ml (144.7 mM) while being devoid of cytotoxicity at 20 mg/ml. The structures were elucidated by 1D and 2D NMR spectroscopy, and the absolute configuration of the new sesquiterpenoid was determined by the generation of Mosher esters. #
Cheminform, 2003
For Abstract see ChemInform Abstract in Full Text.
Tetrahedron, 2003
Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from ... more Bioassay directed-fractionation led to the identification of litseaverticillols A -H (1 -8) from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as 'litseane'. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes 1 -8 as racemates. Isolates 1 -8 inhibited HIV-1 replication in HOG.R5 cells with IC 50 values ranging from 2 to 15 mg/ml (8 -58 mM) while affecting the growth of HOG.R5 at concentrations 2-3-fold higher. Based on this data, structure -activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production. q
Journal of Natural Products, 2003
Journal of Medicinal Chemistry, 2006
Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and G... more Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and Gagnep. (Annonaceae) led to the isolation of a new class of potential anticancer lead molecules. They are a cluster of compounds composed of a C(18) carbon skeleton, a known but heretofore unnamed type, which we have designated as miliusane. Two known (1 and 2) as well as 20 new miliusanes (3-22) have been isolated and identified. They belong to two substructural classes of miliusanes. One subclass (1-19) was determined to be composed of a gamma-lactone spiro-ring system, the opening of which led to the second group of compounds (21 and 22) containing a tetrahydrofuran ring system. Compounds 1-3, 5, 8, 9, 18, 20, and 21 demonstrated significant cytotoxic activity in our cancer cell line panel comprising KB, Col-2, LNCaP, Lu-1, MCF-7, and HUVEC. The structures were determined by spectroscopic and chemical methods. The structure of miliusate was further confirmed by X-ray crystallographic analysis. The absolute stereochemistry of miliusanes was established by the Mosher ester method. Forty-two modified miliusane derivatives were also prepared and evaluated for their cytotoxic activities.
Journal of Natural Products, 2003
In a continuing search for anti-HIV compounds from plants of Vietnam, 19 compounds, including a n... more In a continuing search for anti-HIV compounds from plants of Vietnam, 19 compounds, including a new triterpene, were isolated from an extract of the leaves and stem of Vatica cinerea. The new triterpene was determined to be a cycloartane triterpenoid with 29 skeletal carbons and was assigned the name vaticinone (1). The known triterpenes included three cycloartanes, a lanostane, two dammaranes, three lupanes, an ursane, and an oleanane. A chlorophyll isolate was identified as pheophorbide a (13). The majority of the triterpenes, the sesquiterpene, 1-hydroxycyclocolorenone, and pheophorbide a showed anti-HIV activity, with the chlorophyll being the most active, demonstrating an IC 50 value of 1.5 µg/mL (2.5 µM), while being completely devoid of toxicity up to a concentration of 20 µg/mL (33.8 µM). Vaticinone (1) was found to inhibit the replication of HIV-1, with an IC 50 value of 6.5 µg/mL (15.3 µM; selective index ) 1.4). The structures of these isolates were determined by spectral data including 1D and 2D NMR spectra.
Journal of Natural Products, 2004
Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbet... more Three new betulinic acid derivatives, 3 -O-trans-feruloylbetulinic acid (1), 3 -O-cis-feruloylbetulinic acid (2), and 3 -O-cis-coumaroylbetulinic acid (4), along with two known triterpenes, 3 -O-trans-coumaroylbetulinic acid (3) and ursolic acid (6) were isolated from the leaves and twigs of Strychnos vanprukii Craib. All isolates showed moderate anti-HIV activity with IC 50 values ranging from 3 to 7 µg/mL (5 to 15 µM) in an indicator cell line for HIV infectivity. The structures of the new isolates were elucidated by spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition, the structure of 1 was confirmed by X-ray crystallography. a CC50 ) concentration mediating 50% cytotoxicity. b IC50 ) concentration mediating 50% antiviral response. c SI ) selectivity index. d Betulinic acid was isolated previously from Vatica cinerea King. 7 e ED50, 50% cytoprotective activity against HIV-1IIIB cytopathicity in vitro in µM (SI). f Nt40 ) nontoxic @ 40 µg/mL.
Phytochemistry, 2001
The pregnane steroid, (E)-aglawone, along with four known triterpenes, and a known sterol mixture... more The pregnane steroid, (E)-aglawone, along with four known triterpenes, and a known sterol mixture were isolated from the bark of Aglaia lawii (Wight) Saldanha ex Ramamoorty (Meliaceae). The structural determination/identification was accomplished by a combination of 1D- and 2D-NMR spectroscopic techniques. The relative stereochemistry of the known triterpene, 20S,24S-epoxydammarane-3alpha,25-diol acetate, was also unequivocally determined for the first time by X-ray crystallography. The isolates were not active against various human cancer cell lines.
Planta Medica, 2005
Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well ... more Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well as the γ-lactone derivative of oleic acid, from the CH 2 Cl 2 extract of the stem bark of Micromelum hirsutum. The carbazoles include the new micromeline (2) and five known alkaloids: lansine (3), 3methylcarbazole (4), methyl carbazole-3-carboxylate (5), 3-formylcarbazole (6), and 3-formyl-6methoxycarbazole (7). Compound 1 was identified as the lactone derivative of oleic acid, (−)-Z-9octadecene-4-olide, for which the trivial name micromolide (1) is suggested. It showed potent in vitro anti-TB activity against H37Rv (MIC: 1.5 μg/mL), a selectivity index (SI) of 63, and exhibited activity against the Erdman strain of M. tuberculosis in a J774 mouse macrophage model (EC 90 : 5.6 μg/mL). Thus, 1 appears worthy of further evaluation as a potential new anti-TB agent. Isolates 2, 3, 6 and 7 had anti-TB MIC values between 14.3 and 42.3 μg/mL, while compounds 4 and 5 were considered inactive (MIC > 128 μg/mL). Structure elucidation and identification were based on spectroscopic analysis, including MS, 1D/2D NMR, and a full 1 H spin system analysis of 1.