Three hitherto undescribed Stemona alkaloids,named stemajapines A-C(1-3),along with six known alkaloids(4-9),were isolated and identified from the roots of Stemona japonica(Blume)Miq.(Stemonaceae).Their structures wer...Three hitherto undescribed Stemona alkaloids,named stemajapines A-C(1-3),along with six known alkaloids(4-9),were isolated and identified from the roots of Stemona japonica(Blume)Miq.(Stemonaceae).Their structures were established by the analysis of the mass data,NMR spectra,and computational chemistry.Stemjapines A and B were degraded maistemonines without spiro-lactone ring and skeletal methyl from maistemonine.Concurrence of alkaloids 1 and 2 revealed an undescribed way to form diverse Stemona alkaloids.Bioassay results disclosed the anti-inflammatory natural constituents stemjapines A and C with IC_(50) values of 19.7 and 13.8μM,respectively,compared to positive control dexamethasone with 11.7μM.The findings may point out a new direction of Stemona alkaloids inaddition to its traditional antitussive and insecticide activities.展开更多
A new alkaloid, named sessilistemonamine D, was isolated from the roots of Stemona sessilifolia and the structure and relative configuration were determined on the basis of NMR and MS spectrometric data analysis.
As a part of the ongoing search for new constituents of Stemona species in China, chemical investigation of Stemona sessilifolia, a plant used in the traditional Chinese medicine to treat respiratory disorders, was ca...As a part of the ongoing search for new constituents of Stemona species in China, chemical investigation of Stemona sessilifolia, a plant used in the traditional Chinese medicine to treat respiratory disorders, was carried out. To identify the chemical components rapidly, a selected sample of S. sessilifolia containing bibenzyls was tested using LC-ESIMS and analyzed further using stop-flow LC-UV-NMR, which was sensitive for the detection of the main constituents. LC microfractions were collected using the LC-UV-NMR technique and HR-EIMS off-line analysis was cartied out on the collected fractions. This chemical screening strategy allowed for the on-line identification of the main constituents of S. sessilifolia and provided information that was useful for a further peak-guided isolation procedure. Using these methods, four bibenzyls were isolated： two known compounds, 3,5-dihydroxy-4-methyl bibenzyl（1） and 3, 5-dihydroxy-2＇-methoxy-4-methyl bibenzyl （ 2 ）, and two novel compounds, 3,3＇-dihydroxy-5, 6＇-dimethoxy bibenzyl（3） and 3,5-dihydroxy-2＇, 5＇-dimethoxy bibenzyl （4）.展开更多
Two new alkaloids, maistemonine and oxymaistemonine were isolated from the roots of $temona mairei collected from Yunnan Province, southwest of China. Their structures were elucidated by 2D-NMR techniques including ~1...Two new alkaloids, maistemonine and oxymaistemonine were isolated from the roots of $temona mairei collected from Yunnan Province, southwest of China. Their structures were elucidated by 2D-NMR techniques including ~1H-~1H COSY, ^(13)C-~1H-COSY, NOESY and other spectral analyses.展开更多
Four new alkaloids, didehydroprotostemonine, isoprotostemonine, neostemonine and stemodiol, were isolated from the roots of a Chinese medicinal plant, Stemona japonica, collected form Zhejiang Province, southern China...Four new alkaloids, didehydroprotostemonine, isoprotostemonine, neostemonine and stemodiol, were isolated from the roots of a Chinese medicinal plant, Stemona japonica, collected form Zhejiang Province, southern China. Their structures were elucidated by extensive spectral analyses.展开更多
A novel alkaloid was isolated from the stems and leaves of Stemona parviflora Wright. Based on the spectral methods, its structure was elucidated as parvineostemonine.
Two new alkaloids namely tuberostemoninal and tuberostemoamide as minor components were isolated from the roots of Stemona tubeross.Their structures were determined by various 2D NMR and other spectra and finally conf...Two new alkaloids namely tuberostemoninal and tuberostemoamide as minor components were isolated from the roots of Stemona tubeross.Their structures were determined by various 2D NMR and other spectra and finally confirmed by X-ray analysis.展开更多
Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromi...Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.展开更多
Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.De...Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.Deciphering the interactions between floral cues and pollinators is crucial for analyzing the reproductive success of flowering plants. In this study, we examined the composition of the fetid floral scents produced by several Stemona species, including nine S. tuberosa populations from across China, using dynamic headspace adsorption, gas chromatography, and mass spectrometry techniques. We compared variations in floral phenotype,including floral longevity, nectar rewards, pollinator behavior, and flower length and color among the Stemona species. Of the 54 scent compounds identified,the major compounds include fetid dimethyl disulfide,dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol,isoamyl alcohol, and indole. We detected striking differentiation in floral scent at both the species and population level, and even within a population of plants with different colored flowers. Floral characteristics related to sapromyophily and deceptive pollination,including flower color mimicking livor mortis and a lack of nectar, were found in five Stemona species, indicating that Stemona is a typical sapromyophilous taxon. Species of this monocot genus might employ evolutionary tactics to exploit saprophilous flies for pollination.展开更多
文摘Three hitherto undescribed Stemona alkaloids,named stemajapines A-C(1-3),along with six known alkaloids(4-9),were isolated and identified from the roots of Stemona japonica(Blume)Miq.(Stemonaceae).Their structures were established by the analysis of the mass data,NMR spectra,and computational chemistry.Stemjapines A and B were degraded maistemonines without spiro-lactone ring and skeletal methyl from maistemonine.Concurrence of alkaloids 1 and 2 revealed an undescribed way to form diverse Stemona alkaloids.Bioassay results disclosed the anti-inflammatory natural constituents stemjapines A and C with IC_(50) values of 19.7 and 13.8μM,respectively,compared to positive control dexamethasone with 11.7μM.The findings may point out a new direction of Stemona alkaloids inaddition to its traditional antitussive and insecticide activities.
文摘A new alkaloid, named sessilistemonamine D, was isolated from the roots of Stemona sessilifolia and the structure and relative configuration were determined on the basis of NMR and MS spectrometric data analysis.
基金Supported by Science and Technology Committee of Shanghai, P R China(No 036505003)
文摘As a part of the ongoing search for new constituents of Stemona species in China, chemical investigation of Stemona sessilifolia, a plant used in the traditional Chinese medicine to treat respiratory disorders, was carried out. To identify the chemical components rapidly, a selected sample of S. sessilifolia containing bibenzyls was tested using LC-ESIMS and analyzed further using stop-flow LC-UV-NMR, which was sensitive for the detection of the main constituents. LC microfractions were collected using the LC-UV-NMR technique and HR-EIMS off-line analysis was cartied out on the collected fractions. This chemical screening strategy allowed for the on-line identification of the main constituents of S. sessilifolia and provided information that was useful for a further peak-guided isolation procedure. Using these methods, four bibenzyls were isolated： two known compounds, 3,5-dihydroxy-4-methyl bibenzyl（1） and 3, 5-dihydroxy-2＇-methoxy-4-methyl bibenzyl （ 2 ）, and two novel compounds, 3,3＇-dihydroxy-5, 6＇-dimethoxy bibenzyl（3） and 3,5-dihydroxy-2＇, 5＇-dimethoxy bibenzyl （4）.
文摘Two new alkaloids, maistemonine and oxymaistemonine were isolated from the roots of $temona mairei collected from Yunnan Province, southwest of China. Their structures were elucidated by 2D-NMR techniques including ~1H-~1H COSY, ^(13)C-~1H-COSY, NOESY and other spectral analyses.
文摘Four new alkaloids, didehydroprotostemonine, isoprotostemonine, neostemonine and stemodiol, were isolated from the roots of a Chinese medicinal plant, Stemona japonica, collected form Zhejiang Province, southern China. Their structures were elucidated by extensive spectral analyses.
基金supported by the National Natural Science Foundation of China (No. 30123005) and Bicoll Biotechnology Shanghai Co Ltd. Authors thank Professor Qiong Xin ZHONG (Department of Biological Science Hainan Normal University) for collecting Stemona parviflora
文摘A novel alkaloid was isolated from the stems and leaves of Stemona parviflora Wright. Based on the spectral methods, its structure was elucidated as parvineostemonine.
文摘Two new alkaloids namely tuberostemoninal and tuberostemoamide as minor components were isolated from the roots of Stemona tubeross.Their structures were determined by various 2D NMR and other spectra and finally confirmed by X-ray analysis.
文摘Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.
基金Support for this study was provided by grants from the NSFC-Yunnan joint fund to support key projects to G.Chen(U1602264)the National Natural Science Foundation of China(31670322)the Young Academic and Technical Leader Raising Foundation of Yunnan Province(2015HB091)to G.Chen
文摘Flowers or inflorescences often deploy various signals, including visual, olfactory, and gustatory cues,that can be detected by their pollinators. In many plants,these cues and their functions are poorly understood.Deciphering the interactions between floral cues and pollinators is crucial for analyzing the reproductive success of flowering plants. In this study, we examined the composition of the fetid floral scents produced by several Stemona species, including nine S. tuberosa populations from across China, using dynamic headspace adsorption, gas chromatography, and mass spectrometry techniques. We compared variations in floral phenotype,including floral longevity, nectar rewards, pollinator behavior, and flower length and color among the Stemona species. Of the 54 scent compounds identified,the major compounds include fetid dimethyl disulfide,dimethyl trisulfide, 1-pyrroline, butyric acid, p-cresol,isoamyl alcohol, and indole. We detected striking differentiation in floral scent at both the species and population level, and even within a population of plants with different colored flowers. Floral characteristics related to sapromyophily and deceptive pollination,including flower color mimicking livor mortis and a lack of nectar, were found in five Stemona species, indicating that Stemona is a typical sapromyophilous taxon. Species of this monocot genus might employ evolutionary tactics to exploit saprophilous flies for pollination.
