The Experts below are selected from a list of 1794 Experts worldwide ranked by ideXlab platform
Toh-seok Kam - One of the best experts on this subject based on the ideXlab platform.
-
Macroline-Sarpagine Bisindole Alkaloids with Antiproliferative Activity from Alstonia penangiana.
Journal of natural products, 2019Co-Authors: Joanne Soonyee Yeap, Siew-huah Lim, Yun-yee Low, Kae-shin Sim, Hazwani Mat Saad, Chun-hoe Tan, Toh-seok KamAbstract:A methanol extract of the stem bark of the Malayan Alstonia penangiana provided seven new Bisindole alkaloids, comprising six macroline–sarpagine alkaloids (angustilongines E–K, 1–6) and one macrol...
-
Conolodinines A–D, Aspidosperma–Aspidosperma Bisindole Alkaloids with Antiproliferative Activity from Tabernaemontana corymbosa
2019Co-Authors: Dawn Su-yin Sim, Siew-huah Lim, Yun-yee Low, Suerialoasan Navanesan, Subramaniam Gurusamy, Kae-shin Sim, Toh-seok KamAbstract:Examination of the EtOH extract of the leaves of the Malayan Tabernaemontana corymbosa resulted in the isolation of four new (1–4) and two known Bisindole alkaloids (5, 6) of the Aspidosperma–Aspidosperma type. The structures of these alkaloids were determined based on analysis of the spectroscopic data (NMR and HRESIMS). X-ray diffraction analyses of the related Bisindole alkaloids conophylline (5) and conophyllinine (6) established the absolute configurations. Treatment of the Bisindole alkaloid conophylline (5) with benzeneselenic anhydride gave, in addition to the known Bisindole polyervinine (7) previously isolated from another Malayan Tabernaemontana, another Bisindole product, 8, an isolable tautomer of 7. X-ray diffraction analyses yielded the absolute configurations of both Bisindoles and in addition showed that polyervinine (7) exists primarily as the neutral dione structure. The Bisindoles (1–8) and the related conophylline-type Bisindoles (9–13) showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, A549, HT-29, and HCT 116 cells, with IC50 values for the active compounds in the 0.01–5 μM range
-
Ajmaline, Oxindole, and Cytotoxic Macroline–Akuammiline Bisindole Alkaloids from Alstonia penangiana
2018Co-Authors: Joanne Soon-yee Yeap, Siew-huah Lim, Yun-yee Low, Kienthai Yong, Suerialoasan Navanesan, Subramaniam Gurusamy, Kae-shin Sim, Toh-seok KamAbstract:Examination of the EtOH extract of the Malayan Alstonia penangiana resulted in the isolation of 10 new alkaloids, comprising two ajmaline (1, 2), four macroline oxindole (3–6), and four macroline–akuammiline Bisindole alkaloids (7–10). The structures of these alkaloids were determined based on analysis of the spectroscopic data and, in the case of the oxindole 6 and the Bisindole alkaloid 7, also confirmed by X-ray diffraction analysis. The Bisindole alkaloids 7 and 8 showed pronounced in vitro growth inhibitory activity against an array of human cancer cell lines, including KB, vincristine-resistant KB, PC-3, LNCaP, MCF7, MDA-MB-231, HT-29, HCT 116, and A549 cells with IC50 values in the 0.3–8.3 μM range
-
Ibogan, Aspidosperman, Vincamine, and Bisindole Alkaloids from a Malayan Tabernaemontana corymbosa: Iboga Alkaloids with C-20α Substitution
Journal of natural products, 2016Co-Authors: Choy-eng Nge, Kam-weng Chong, Noel F. Thomas, Siew-huah Lim, Yun-yee Low, Toh-seok KamAbstract:Ten new indole alkaloids (1-10) comprising five ibogan, two aspidosperman, one vincamine, and two Bisindole alkaloids, in addition to 32 known alkaloids, were isolated from the stem-bark extract of a Malayan Tabernaemontana corymbosa. The structures of these alkaloids were determined based on analysis of the NMR and MS data and, in five instances (1, 3, 5, 6, 8), confirmed by X-ray diffraction analysis. Two of the iboga alkaloids, conodusines B (2) and C (3), and the iboga-containing Bisindole tabernamidine B (10) are notable for the presence of an α-substituted acetyl group at C-20 of the iboga carbon skeleton. The iboga alkaloid (+)-conodusine E (5) had MS and NMR data that were identical to those of (-)-ervatamine I, recently isolated from Ervatamia hainanensis. Establishment of the absolute configuration of (+)-conodusine E (5) was based on analysis of the ECD data, correlation with (-)-heyneanine, and X-ray analysis, which showed that (+)-5 belongs to the same enantiomeric series as exemplified by (-)-coronaridine. The configuration at C-20' of the previously reported Tabernaemontana Bisindole alkaloid 19'-oxotabernamine (renamed tabernamidine B) required revision based on the present results. Several of the Bisindoles showed pronounced in vitro growth inhibitory activity against drug-sensitive and vincristine-resistant KB cells.
-
Vobatensines A-F, Cytotoxic Iboga-Vobasine Bisindoles from Tabernaemontana corymbosa.
Journal of natural products, 2016Co-Authors: Dawn Su-yin Sim, Noel F. Thomas, Siew-huah Lim, Yun-yee Low, Kae-shin Sim, Wuen-yew Teoh, Toh-seok KamAbstract:Six new Bisindole alkaloids of the iboga-vobasine type, vobatensines A–F (1–6), in addition to four known Bisindoles (8–11), were isolated from a stem bark extract of a Malayan Tabernaemontana corymbosa. The structures of these alkaloids were determined based on analysis of the spectroscopic data and in the case of vobatensines A (1), B (2), and 16′-decarbomethoxyvoacamine (8) also confirmed by partial syntheses. Nine of these alkaloids (1–5, 8–11) showed pronounced in vitro growth inhibitory activity against human KB, PC-3, LNCaP, HCT 116, HT-29, MCF7, MDA-MB-231, and A549 cancer cells.
Yu Xi Yuan - One of the best experts on this subject based on the ideXlab platform.
-
tabercorymines a and b two vobasinyl ibogan type Bisindole alkaloids from tabernaemontana corymbosa
Organic Letters, 2017Co-Authors: Yu Zhang, Yu Xi Yuan, Yuehu Wang, Masuo Goto, Susan L MorrisnatschkeAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
Organic letters, 2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB
Xiao-jiang Hao - One of the best experts on this subject based on the ideXlab platform.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
Organic letters, 2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB
-
Angustifonines A and B, Cytotoxic Bisindole Alkaloids from Bousigonia angustifolia
Journal of natural products, 2014Co-Authors: Yu Zhang, Xiao-jiang HaoAbstract:Two new Bisindole alkaloids, angustifonines A (1) and B (2), comprising the union of a rearranged monoterpenoid quinoline and an aspidospermine alkaloid, as well as 27 known indole alkaloids were isolated from the twigs and leaves of Bousigonia angustifolia. Their structures and absolute configurations were elucidated by a combination of MS, NMR, and computational methods. Angustifonines A and B exhibited cytotoxicity against various human cancer cell lines with IC50 values of 2.71-16.22 mu M. A possible biosynthesis pathway toward the new Bisindole alkaloids 1 and 2 is presented.
-
Angustifonines A and B, Cytotoxic Bisindole Alkaloids from Bousigonia angustifolia
2014Co-Authors: Yu Zhang, Xiao-jiang HaoAbstract:Two new Bisindole alkaloids, angustifonines A (1) and B (2), comprising the union of a rearranged monoterpenoid quinoline and an aspidospermine alkaloid, as well as 27 known indole alkaloids were isolated from the twigs and leaves of Bousigonia angustifolia. Their structures and absolute configurations were elucidated by a combination of MS, NMR, and computational methods. Angustifonines A and B exhibited cytotoxicity against various human cancer cell lines with IC50 values of 2.71–16.22 μM. A possible biosynthesis pathway toward the new Bisindole alkaloids 1 and 2 is presented
-
indole alkaloids from ervatamia chinensis
Phytochemistry, 2012Co-Authors: Ling-li Guo, Yu Zhang, Wei Yang, Yuanyuan Cheng, Xiao-jiang HaoAbstract:Four vobasinyl-ibogan type Bisindole alkaloids, ervachinines A-D (1-4), along with 12 known terpenoid indole alkaloids, were isolated from the whole plant of Ervatamia chinensis. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR, and the absolute configurations of 1-4 were determined by CD exciton chirality method. All of the compounds were evaluated for in vitro cytotoxicity against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480. Bisindole alkaloids 1-6 exhibited inhibitory effects, with IC50 values comparable to those of cisplatin. (C) 2011 Elsevier Ltd. All rights reserved.
Yu Zhang - One of the best experts on this subject based on the ideXlab platform.
-
tabercorymines a and b two vobasinyl ibogan type Bisindole alkaloids from tabernaemontana corymbosa
Organic Letters, 2017Co-Authors: Yu Zhang, Yu Xi Yuan, Yuehu Wang, Masuo Goto, Susan L MorrisnatschkeAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
Organic letters, 2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB
-
Angustifonines A and B, Cytotoxic Bisindole Alkaloids from Bousigonia angustifolia
Journal of natural products, 2014Co-Authors: Yu Zhang, Xiao-jiang HaoAbstract:Two new Bisindole alkaloids, angustifonines A (1) and B (2), comprising the union of a rearranged monoterpenoid quinoline and an aspidospermine alkaloid, as well as 27 known indole alkaloids were isolated from the twigs and leaves of Bousigonia angustifolia. Their structures and absolute configurations were elucidated by a combination of MS, NMR, and computational methods. Angustifonines A and B exhibited cytotoxicity against various human cancer cell lines with IC50 values of 2.71-16.22 mu M. A possible biosynthesis pathway toward the new Bisindole alkaloids 1 and 2 is presented.
-
Angustifonines A and B, Cytotoxic Bisindole Alkaloids from Bousigonia angustifolia
2014Co-Authors: Yu Zhang, Xiao-jiang HaoAbstract:Two new Bisindole alkaloids, angustifonines A (1) and B (2), comprising the union of a rearranged monoterpenoid quinoline and an aspidospermine alkaloid, as well as 27 known indole alkaloids were isolated from the twigs and leaves of Bousigonia angustifolia. Their structures and absolute configurations were elucidated by a combination of MS, NMR, and computational methods. Angustifonines A and B exhibited cytotoxicity against various human cancer cell lines with IC50 values of 2.71–16.22 μM. A possible biosynthesis pathway toward the new Bisindole alkaloids 1 and 2 is presented
Ling-li Guo - One of the best experts on this subject based on the ideXlab platform.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
Organic letters, 2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB.
-
Tabercorymines A and B, Two Vobasinyl–Ibogan-Type Bisindole Alkaloids from Tabernaemontana corymbosa
2017Co-Authors: Yu Xi Yuan, Ling-li Guo, Yu Zhang, Yuehu Wang, Masuo Goto, Susan L. Morris-natschke, Kuo Hsiung Lee, Xiao-jiang HaoAbstract:Tabercorymines A (1) and B (2), two new vobasinyl–ibogan-type Bisindole alkaloids with an unprecedented skeleton, were isolated from Tabernaemontana corymbosa. Their structures were established by a combination of spectroscopic data, chemical transformation, single-crystal X-ray diffraction, and ECD calculation. Compound 1 represents a novel Bisindole alkaloid, characterized by a caged heteropentacyclic ring system incorporating an unprecedented C-7/C-20 bond in the vobasinyl unit. Alkaloids 1 and 2 showed potent antiproliferative activity against several human cancer cell lines, including vincristine-resistant KB
-
indole alkaloids from ervatamia chinensis
Phytochemistry, 2012Co-Authors: Ling-li Guo, Yu Zhang, Wei Yang, Yuanyuan Cheng, Xiao-jiang HaoAbstract:Four vobasinyl-ibogan type Bisindole alkaloids, ervachinines A-D (1-4), along with 12 known terpenoid indole alkaloids, were isolated from the whole plant of Ervatamia chinensis. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR, and the absolute configurations of 1-4 were determined by CD exciton chirality method. All of the compounds were evaluated for in vitro cytotoxicity against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480. Bisindole alkaloids 1-6 exhibited inhibitory effects, with IC50 values comparable to those of cisplatin. (C) 2011 Elsevier Ltd. All rights reserved.