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Siegfried E Drewes - One of the best experts on this subject based on the ideXlab platform.
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Cryptocarya liebertiana and ocotea bullata their phytochemical relationship
Phytochemistry, 1997Co-Authors: Siegfried E Drewes, Marion H Horn, Stephen MaviAbstract:Abstract Isolation of the major components from the bark of mature Cryptocarya liebertiana shows that ocobullenone and its precursor (both previously isolated from Ocotea bullata) are present in detectable concentrations in this source. These particular compounds are absent in other South African Cryptocarya species. The result is significant since Cryptocarya bark is currently being utilized by traditional healers as an alternative to O. bullata bark.
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α pyrones and their derivatives from two Cryptocarya species
Phytochemistry, 1995Co-Authors: Siegfried E Drewes, Marion M Horn, Robert Scott ShawAbstract:From Cryptocarya myrtifolia, Cryptocaryalactone and its deacetyl derivative have been isolated for only the second time, together with the novel 7-styryl-2,6-dioxabicyclo [3,3,1]nonan-3-one. This cyclic compound could also be obtained by simple transformation of deacetylCryptocaryalactone. Cryptocarya myrtifolia also yielded the known cryptofolione and an oxidation product in trace quantities.
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5 6 dihydro α pyrones and two bicyclic tetrahydro α pyrone derivatives from Cryptocarya latifolia
Phytochemistry, 1995Co-Authors: Siegfried E Drewes, Marion M Horn, Bethuel M Sehlapelo, Robert Scottshaw, Peter SandorAbstract:Abstract Two new 6-substituted-5,6-dihydro-α-pyrones have been isolated from the bark Cryptocarya latifolia. In addition two new, closely related dioxabicyclo [3,3,1]nonan-2-one derivatives, have been obtained in lower concentration from the same plant source.
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a 6 substituted 5 6 dihydro α pyrone from two species of Cryptocarya
Phytochemistry, 1994Co-Authors: Bethuel M Sehlapelo, Siegfried E Drewes, Robert ScottshawAbstract:Abstract A new 6-substituted-5,6-dihydro-α-pyrone (cryptofolione) has been isolated from the bark of two species of Cryptocarya . Its structure was elucidated by NMR techniques and chemical conversions. The relative stereochemistry at the two carbons bearing the hydroxyl groups was deduced after transformation into the corresponding acetonide derivative.
Khalijah Awang - One of the best experts on this subject based on the ideXlab platform.
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A New Coumarin from the Bark of Cryptocarya bracteolata
Chemistry of Natural Compounds, 2020Co-Authors: Nurdin Saidi, Khalijah Awang, Mustanir YahyaAbstract:Isolation of compounds from the bark of Cryptocarya bracteolata yielded a new coumarin, 6,7,8-trimethoxy-3,4-dihydrocoumarin. The structure of the compound was elucidated from spectral data, including IR, UV, 1D NMR (^13C, ^1H, and DEPT), 2D NMR (HMQC, HMBC, and COSY), EI-MS, and ESI-MS techniques.
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corrosion inhibition on mild steel in 1 m hcl solution by Cryptocarya nigra extracts and three of its constituents alkaloids
RSC Advances, 2020Co-Authors: Mas Faiz, Khalijah Awang, Azeana Zahari, Hazwan HussinAbstract:Corrosion inhibition effect of the crude extracts (hexane, dichloromethane, methanol) from the bark of Cryptocarya nigra and three alkaloids named N-methylisococlaurine 1, N-methyllaurotetanine 2 and atherosperminine 3 isolated from the Cryptocarya nigra dichloromethane extract (CNDE) were investigated for mild steel corrosion in 1 M HCl solution. An electrochemical impedance study showed that CNDE and 2 reduced the corrosion significantly through a charge transfer mechanism with inhibition efficiency of 91.05% and 88.05%, respectively. Potentiodynamic polarization data indicated that CNDE acted through anodic type inhibition while 2 was a mixed type inhibitor with predominant anodic effectiveness. ΔGads values calculated from the Langmuir adsorption isotherm plots for CNDE (−28.2 kJ mol−1) and 2 (−13.2 kJ mol−1) suggested that they adsorbed on the mild steel surface via a physisorption mechanism. Scanning electron microscopy micrographs and elemental composition studies confirmed the formation of a protective film over the metal surface. Wastewater quality parameters of all the inhibitors demonstrated good biodegradability as their values were within the permissible limits to discharge for irrigation and horticultural uses.
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alkaloids from Cryptocarya densiflora blume lauraceae and their cholinesterase inhibitory activity
Phytochemistry Letters, 2017Co-Authors: Wan Nurul Nazneem Wan Othman, Sook Yee Liew, Marc Litaudon, Mohd Azlan Nafiah, Yasodha Sivasothy, Jamaludin Mohamad, Kartini Ahmad, Khalijah AwangAbstract:Abstract (−)-Desmethylsecoantofine N-oxide (1), a new seco-phenanthroindolizidine alkaloid along with prodensiflorins A and B (2-3), two new proaporphine alkaloids, were isolated from the leaves of Cryptocarya densiflora Blume. Their structures were established on the basis of 1D and 2D NMR techniques and LCMS-IT-TOF analysis. (+)-N-methyllaurotetanine (4), (+)-laurotetanine (5), (+)-nornantenine (6), crychine (7), (−)-isocaryachine (8), (+)-reticuline (9), (−)-desmethylsecoantofine (10), (+)-oridine (11), dicentrinone (12) and (−)-antofine (13) were also isolated with compounds 4, 7–9 and 12–13 being characterized for the first time in this plant. Compounds 1-3 were moderate to weak AChE and BChE inhibitors while compound 10 was a DPPH free radical scavenger.
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cholinesterase inhibitory activity of isoquinoline alkaloids from three Cryptocarya species lauraceae
Bioorganic & Medicinal Chemistry, 2016Co-Authors: Wan Nurul Nazneem Wan Othman, Sook Yee Liew, Kooi Yeong Khaw, Vikneswaran Murugaiyah, Marc Litaudon, Khalijah AwangAbstract:Alzheimer's disease is the most common form of dementia among older adults. Acetylcholinesterase and butyrylcholinesterase are two enzymes involved in the breaking down of the neurotransmitter acetylcholine. Inhibitors for these enzymes have potential to prolong the availability of acetylcholine. Hence, the search for such inhibitors especially from natural products is needed in developing potential drugs for Alzheimer's disease. The present study investigates the cholinesterase inhibitory activity of compounds isolated from three Cryptocarya species towards acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Nine alkaloids were isolated; (+)-nornantenine 1, (-)-desmethylsecoantofine 2, (+)-oridine 3, (+)-laurotetanine 4 from the leaves of Cryptocarya densiflora BI., atherosperminine 5, (+)-N-methylisococlaurine 6, (+)-N-methyllaurotetanine 7 from the bark of Cryptocarya infectoria Miq., 2-methoxyatherosperminine 8 and (+)-reticuline 9 from the bark of Cryptocarya griffithiana Wight. In general, most of the alkaloids showed higher inhibition towards BChE as compared to AChE. The phenanthrene type alkaloid; 2-methoxyatherosperminine 8, exhibited the most potent inhibition against BChE with IC50 value of 3.95μM. Analysis of the Lineweaver-Burk (LB) plot of BChE activity over a range of substrate concentration suggested that 2-methoxyatherosperminine 8 exhibited mixed-mode inhibition with an inhibition constant (Ki) of 6.72μM. Molecular docking studies revealed that 2-methoxyatherosperminine 8 docked well at the choline binding site and catalytic triad of hBChE (butyrylcholinesterase from Homo sapiens); hydrogen bonding with Tyr 128 and His 438 residues respectively.
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new phenyl propanoids from Cryptocarya bracteolata
Natural Product Communications, 2016Co-Authors: Nurdin Saidi, Marc Litaudon, Hiroshi Morita, Mohd Azlan Nafiah, Khalijah AwangAbstract:Two new phenyl propanoids were extracted from the bark of Cryptocarya bracteolate Gamb., ethyl 3-(2'-hydroxy-3',4',5'-trimethoxyphenyl) propanoate (1) and ethyl 3-(2'-glucosyl-3',4',5'-trimethoxyphenyl)propanoate (2), together with seven known alkaloids, (+)-lirioferine (3), (+)-bracteoline (4), (+)-reticuline (5), (+)-reticulineN-oxide (6), (-)-norargemonine (7), (+)-bisnorargemonine (8) and atherolin (9). The structures of compounds were established through several spectroscopic methods; 1D and 2D-NMR, UV, IR and MS.
Robert Scottshaw - One of the best experts on this subject based on the ideXlab platform.
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5 6 dihydro α pyrones and two bicyclic tetrahydro α pyrone derivatives from Cryptocarya latifolia
Phytochemistry, 1995Co-Authors: Siegfried E Drewes, Marion M Horn, Bethuel M Sehlapelo, Robert Scottshaw, Peter SandorAbstract:Abstract Two new 6-substituted-5,6-dihydro-α-pyrones have been isolated from the bark Cryptocarya latifolia. In addition two new, closely related dioxabicyclo [3,3,1]nonan-2-one derivatives, have been obtained in lower concentration from the same plant source.
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a 6 substituted 5 6 dihydro α pyrone from two species of Cryptocarya
Phytochemistry, 1994Co-Authors: Bethuel M Sehlapelo, Siegfried E Drewes, Robert ScottshawAbstract:Abstract A new 6-substituted-5,6-dihydro-α-pyrone (cryptofolione) has been isolated from the bark of two species of Cryptocarya . Its structure was elucidated by NMR techniques and chemical conversions. The relative stereochemistry at the two carbons bearing the hydroxyl groups was deduced after transformation into the corresponding acetonide derivative.
Marc Litaudon - One of the best experts on this subject based on the ideXlab platform.
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alkaloids from Cryptocarya densiflora blume lauraceae and their cholinesterase inhibitory activity
Phytochemistry Letters, 2017Co-Authors: Wan Nurul Nazneem Wan Othman, Sook Yee Liew, Marc Litaudon, Mohd Azlan Nafiah, Yasodha Sivasothy, Jamaludin Mohamad, Kartini Ahmad, Khalijah AwangAbstract:Abstract (−)-Desmethylsecoantofine N-oxide (1), a new seco-phenanthroindolizidine alkaloid along with prodensiflorins A and B (2-3), two new proaporphine alkaloids, were isolated from the leaves of Cryptocarya densiflora Blume. Their structures were established on the basis of 1D and 2D NMR techniques and LCMS-IT-TOF analysis. (+)-N-methyllaurotetanine (4), (+)-laurotetanine (5), (+)-nornantenine (6), crychine (7), (−)-isocaryachine (8), (+)-reticuline (9), (−)-desmethylsecoantofine (10), (+)-oridine (11), dicentrinone (12) and (−)-antofine (13) were also isolated with compounds 4, 7–9 and 12–13 being characterized for the first time in this plant. Compounds 1-3 were moderate to weak AChE and BChE inhibitors while compound 10 was a DPPH free radical scavenger.
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cholinesterase inhibitory activity of isoquinoline alkaloids from three Cryptocarya species lauraceae
Bioorganic & Medicinal Chemistry, 2016Co-Authors: Wan Nurul Nazneem Wan Othman, Sook Yee Liew, Kooi Yeong Khaw, Vikneswaran Murugaiyah, Marc Litaudon, Khalijah AwangAbstract:Alzheimer's disease is the most common form of dementia among older adults. Acetylcholinesterase and butyrylcholinesterase are two enzymes involved in the breaking down of the neurotransmitter acetylcholine. Inhibitors for these enzymes have potential to prolong the availability of acetylcholine. Hence, the search for such inhibitors especially from natural products is needed in developing potential drugs for Alzheimer's disease. The present study investigates the cholinesterase inhibitory activity of compounds isolated from three Cryptocarya species towards acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Nine alkaloids were isolated; (+)-nornantenine 1, (-)-desmethylsecoantofine 2, (+)-oridine 3, (+)-laurotetanine 4 from the leaves of Cryptocarya densiflora BI., atherosperminine 5, (+)-N-methylisococlaurine 6, (+)-N-methyllaurotetanine 7 from the bark of Cryptocarya infectoria Miq., 2-methoxyatherosperminine 8 and (+)-reticuline 9 from the bark of Cryptocarya griffithiana Wight. In general, most of the alkaloids showed higher inhibition towards BChE as compared to AChE. The phenanthrene type alkaloid; 2-methoxyatherosperminine 8, exhibited the most potent inhibition against BChE with IC50 value of 3.95μM. Analysis of the Lineweaver-Burk (LB) plot of BChE activity over a range of substrate concentration suggested that 2-methoxyatherosperminine 8 exhibited mixed-mode inhibition with an inhibition constant (Ki) of 6.72μM. Molecular docking studies revealed that 2-methoxyatherosperminine 8 docked well at the choline binding site and catalytic triad of hBChE (butyrylcholinesterase from Homo sapiens); hydrogen bonding with Tyr 128 and His 438 residues respectively.
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new phenyl propanoids from Cryptocarya bracteolata
Natural Product Communications, 2016Co-Authors: Nurdin Saidi, Marc Litaudon, Hiroshi Morita, Mohd Azlan Nafiah, Khalijah AwangAbstract:Two new phenyl propanoids were extracted from the bark of Cryptocarya bracteolate Gamb., ethyl 3-(2'-hydroxy-3',4',5'-trimethoxyphenyl) propanoate (1) and ethyl 3-(2'-glucosyl-3',4',5'-trimethoxyphenyl)propanoate (2), together with seven known alkaloids, (+)-lirioferine (3), (+)-bracteoline (4), (+)-reticuline (5), (+)-reticulineN-oxide (6), (-)-norargemonine (7), (+)-bisnorargemonine (8) and atherolin (9). The structures of compounds were established through several spectroscopic methods; 1D and 2D-NMR, UV, IR and MS.
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BENZYLISOQUINOLINE ALKALOIDS FROM BARK OF Cryptocarya rugulosa
Indonesian Journal of Chemistry, 2011Co-Authors: Nurdin Saidi, Marc Litaudon, Khalijah Awang, Mat Ropi Mukhtar, Hiroshi Morita, A. Hamid A. HadiAbstract:Seven known Benzylisoquinoline alkaloids, Papraline 1 , (+)-norcinnamolaurine 2 , (+)-codamine 3 , (+)-6-methoxy-1-(3'-methoxybenzyl)-N-methyl-7-isoquinolinol 4 , (+)-reticuline N-oxide 5 , (+)-reticuline 6 and (-)-N-methylisococlaurine 7 were isolated from bark of Cryptocarya rugulosa. A combination of 1D-NMR ( 1 H, 13 C, DEPT, NOE), 2D-NMR (COSY, NOESY, HMQC, HMBC), MS (HRESI + , FAB + and EI) spectroscopy used to elucidate the structure.
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new phenantrene alkaloids from Cryptocarya crassinervia
Fitoterapia, 2008Co-Authors: Khalijah Awang, Nurdin Saidi, Mat Ropi Mukhtar, Hamid A A Hadi, Hiroshi Morita, Marc LitaudonAbstract:The bark of Cryptocarya crassinervia provided two new phenantrene alkaloids, 2-hydroxyatherosperminine (1) and N-demethyl-2-methoxyatherosperminine (2).
Norio Aimi - One of the best experts on this subject based on the ideXlab platform.
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First total synthesis and determination of the absolute configuration of strictifolione, a new 6-(ω-phenylalkenyl)-5,6-dihydro-α-pyrone, isolated from Cryptocarya strictifolia
Tetrahedron Letters, 2002Co-Authors: Lia D Juliawaty, Sjamsul Arifin Achmad, Hiromitsu Takayama, Yoshimi Watanabe, Mariko Kitajima, Norio AimiAbstract:Starting from (S)-malic acid and (S)-glycidol, the first total synthesis of strictifolione, a new 6-(ω-phenylalkenyl)-5,6-dihydro-α-pyrone isolated from Cryptocarya strictifolia, was accomplished, which confirmed its structure including the absolute configuration of the asymmetric centers.
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a new type of stilbene related secondary metabolite idenburgene from Cryptocarya idenburgensis
ChemInform, 2001Co-Authors: Lia D Juliawaty, Sjamsul Arifin Achmad, Hiromitsu Takayama, Mariko Kitajima, Norio AimiAbstract:A new type of natural product, idenburgene (1), was isolated from Crytocarya idenburgensis, and its unique structure was elucidated. Four known compounds, 3-hydroxy-5-methoxystilbene (2), 2',6'-dihydroxy-4'-methoxydihydrochalcone (3), stigmast-4-ene-3-one, and beta-sitosterol were also isolated and identified.
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a 6 substituted 5 6 dihydro 2 pyrone from Cryptocarya strictifolia
Phytochemistry, 2000Co-Authors: Lia D Juliawaty, Sjamsul Arifin Achmad, Hiromitsu Takayama, Mariko Kitajima, Norio AimiAbstract:The structure and absolute configuration of an alpha-pyrone isolated from Cryptocarya strictifolia was elucidated as 6R-(4'R,6'R-dihydroxy-8'-phenyloct-1'-enyl)-5,6-dihydro-2H-pyran-2 -one. Pinocembrin and lysicamine were also isolated.