The Experts below are selected from a list of 1683 Experts worldwide ranked by ideXlab platform
Vaclav Suchý - One of the best experts on this subject based on the ideXlab platform.
-
dracophane a metacyclophane derivative from the resin of Dracaena cinnabari balf
Phytochemistry, 2002Co-Authors: Dagmar Vesela, Radek Marek, Karel Ubik, Kamila Lunerova, Vladimir Sklenař, Vaclav SuchýAbstract:Dracophane, a novel structural derivative of metacyclophane, was isolated from the resin of Dracaena cinnabari Balf. The structure of this compound was determined by spectroscopic methods to be 3,12,21-trihydroxy-1,10,19-tris(4-hydroxyphenyl)-5,14,23-trimethoxy[3.3.3]metacyclophane.
-
chemoprotective potentials of homoisoflavonoids and chalcones of Dracaena cinnabari modulations of drug metabolizing enzymes and antioxidant activity
Phytotherapy Research, 2001Co-Authors: Miroslav Machala, Renata Kubinova, Pavla Hořavova, Vaclav SuchýAbstract:A series of homoisoflavonoids and chalcones, isolated from the endemic tropical plant Dracaena cinnabari Balf. (Agavaceae), were tested for their potential to inhibit cytochrome P4501A (CYP1A) enzymes and Fe-enhanced in vitro peroxidation of microsomal lipids in C57B1/6 mouse liver. The effects of the polyphenolic compounds were compared with those of prototypal flavonoid modulators of CYP1A and the well-known antioxidant, butylated hydroxytoluene. 2-Hydroxychalcone and partly 4,6-dihydroxychalcone were found to be strong inhibitors of CYP1A-dependent 7-ethoxyresorufin O-deethylase (EROD) activity in vitro comparable to the effects of quercetin and chrysin. The first screening of flavonoids and chalcones of Dracaena cinnabari for antioxidant activity was done in an in vitro microsomal peroxidation assay. While chalcones were shown to be poor antioxidants, 7,8-methylenedioxy-3(4-hydroxybenzyl) chromane, as one of the tested homoisoflavonoids, exhibited a strong antioxidant activity comparable to that of the strongest flavonol antioxidant, quercetin.
Petr Madera - One of the best experts on this subject based on the ideXlab platform.
-
sap flow measurements in a socotra dragon s blood tree Dracaena cinnabari in its area of origin
Tropical Plant Biology, 2018Co-Authors: Nadezhda Nadezhdina, Abdulraqeeb Alokaishi, Petr MaderaAbstract:For the first time, in situ field measurements of sap flow were conducted in adult Dracaena cinnabari plant native to the arid tropical climate of Socotra Island. The heat field deformation (HFD) method was applied using both single and multi-point sensors to study azimuthal and radial sap flow variability in stem, roots and first-order branches over two weeks during a winter monsoon. The main aim of this work was to monitor sap flow in adult D. cinnabari in-situ to better understand its physiological adaptation to extreme arid environments. The second aim was to compare our results with earlier sap flow measurements in adult D. draco uing the same HFD method. The last question we wanted to answer was comparison of sap flow measurements in both, young and adult Dracaena species. We found that sap flow magnitude is low and of a similar range in all observed D. species. High sap flow variability was recorded in different parts of adult D. cinnabari plant which changed throughout the day responding to interplay between intrinsic and extrinsic water potential gradients induced by sunlight. Maximum sap flow levels had variable pattern around stem in response to sun exposure, similarly as it was observed in adult D. draco plant. Sensors installed tangentially in stem xylem showed that water transport in adult D. cinnabari may move in lateral direction. This work also presents several methodological aspects detected from earlier observations of dicots which proved to be more pronounced in adult D. species. These methodologies relate to interpreting negative sap flow rates in conjunction with established axial flow reversal during hydraulic redistribution usually occurring under low evaporative demands and dry soil. Conversely, flow reversal during the day under high evaporative demands and wet soil may designate lateral water movement induced by internal water redistribution.
-
a comparative structural and functional study of leaf traits and sap flow in Dracaena cinnabari and Dracaena draco seedlings
Functional Plant Biology, 2015Co-Authors: Nadezhda Nadezhdina, Roman Plichta, Valeriy Nadezhdin, Roman Gebauer, Radek Jupa, Hana Habrova, Petr MaderaAbstract:Water relations for two remote populations of Dracaena tree species from the dragon tree group, Dracaena cinnabari Balfour f. and Dracaena draco (L.) L., were studied to test our hypothesis that morphological and anatomical differences in leaf structure may lead to varied functional responses to changing environmental conditions. Sap flow measurements were performed using the heat field deformation method for four Dracaena seedlings grown in one glasshouse and two greenhouses, and leaf traits related to plant–water relationships were characterised. All traits studied confirmed that D. cinnabari leaves are more xeric in their morpho-anatomical structure compared with D. draco leaves. No radial sap flow variability was detected in D. draco plant stems, whereas sap flow was found to be higher in the inner part of D. cinnabari stems. The regular occurrence of reverse sap flow at night in both Dracaena species was consistent with a staining experiment. Vapour pressure deficit (VPD) was found to be the main driver for transpiration for both Dracaena species. However, the relationship between VPD and sap flow appeared to be different for each species, with a clockwise or no hysteresis loop for D. draco and a counter-clockwise hysteresis loop for D. cinnabari. This resulted in a shorter transpiration cycle in D. cinnabari. The observed superior water-saving strategy of D. cinnabari corresponds to its more xeric morpho-anatomical leaf structure compared with D. draco.
-
crown age estimation of a monocotyledonous tree species Dracaena cinnabari using logistic regression
Trees-structure and Function, 2012Co-Authors: Radim Adolt, Hana Habrova, Petr MaderaAbstract:Unique woodlands of Dracaena cinnabari (DC) are at risk throughout most of their range (Socotra Island, Yemen) as a result of missing regeneration and overmaturity. Effective conservation measures depend on reliable predictions of future population dynamics, which depend on accurate data on current age structure. However, age determination of Dracaena sp. has long been a scien- tific challenge, because the common method of tree ring counts cannot be applied to this or to most other mono- cotyledonous trees. In the present study, the indirect method for crown age estimation proposed by Adolt and Pavlis (Trees 18:43-53, 2004) was further developed using a more appropriate statistical technique and an intuitive model formulation. This new technique is based on the relationship between the number of branching orders and the number of flowering events that result from a specific growth pattern. We used logistic regression to directly model annual flowering probability, the reciprocal value of which corresponds to the length of the interval between flowering events. Our methodology was applied to data sets collected at two ecologically distinct sites. In Firmihin, the time between flowering events decreases from 28 years between the first and second event to 10 years between the 25th and 26th event. The length of time between flower events in Skant, however, was estimated to be a constant value of 6.5 years. We propose the application of gener- alised mixed-effects models and methods of survey sam- pling to improve the accuracy of crown age estimation in DC. Our methodology may also be useful for age estima- tions of other tree species with similar growth patterns, such as Dracaena draco and Aloe dichotoma.
Wenli Mei - One of the best experts on this subject based on the ideXlab platform.
-
de novo transcriptome characterization of Dracaena cambodiana and analysis of genes involved in flavonoid accumulation during formation of dragon s blood
Scientific Reports, 2016Co-Authors: Jiahong Zhu, Tianjun Cao, Haofu Dai, Dong Guo, Wenli Mei, Shiqing PengAbstract:Dragon’s blood is a red resin mainly extracted from Dracaena plants, and has been widely used as a traditional medicine in East and Southeast Asia. The major components of dragon’s blood are flavonoids. Owing to a lack of Dracaena plants genomic information, the flavonoids biosynthesis and regulation in Dracaena plants remain unknown. In this study, three cDNA libraries were constructed from the stems of D. cambodiana after injecting the inducer. Approximately 266.57 million raw sequencing reads were de novo assembled into 198,204 unigenes, of which 34,873 unique sequences were annotated in public protein databases. Many candidate genes involved in flavonoid accumulation were identified. Differential expression analysis identified 20 genes involved in flavonoid biosynthesis, 27 unigenes involved in flavonoid modification and 68 genes involved in flavonoid transport that were up-regulated in the stems of D. cambodiana after injecting the inducer, consistent with the accumulation of flavonoids. Furthermore, we have revealed the differential expression of transcripts encoding for transcription factors (MYB, bHLH and WD40) involved in flavonoid metabolism. These de novo transcriptome data sets provide insights on pathways and molecular regulation of flavonoid biosynthesis and transport, and improve our understanding of molecular mechanisms of dragon’s blood formation in D. cambodiana.
-
steroidal saponins from dragon s blood of Dracaena cambodiana
Fitoterapia, 2014Co-Authors: Haiyan Shen, Haofu Dai, Wenjian Zuo, Hui Wang, Ying Luo, Youxing Zhao, Zhikai Guo, Wenli MeiAbstract:Six new steroidal saponins, cambodianosides A-F (1-6), together with seven known ones, were isolated from the dragon's blood of Dracaena cambodiana. The structures of 1-6 were elucidated on the basis of detailed spectroscopic analysis, including 1D and 2D NMR techniques and chemical methods. The cytotoxicities of all the isolated compounds were evaluated in vitro against three human cancer cell lines, and compounds 7, 8, and 11 showed significant inhibitory activities.
-
two new antimicrobial flavanes from dragon s blood of Dracaena cambodiana
Journal of Asian Natural Products Research, 2012Co-Authors: Huiqin Chen, Haofu Dai, Wenjian Zuo, Hui Wang, Haiyan Shen, Ying Luo, Wenli MeiAbstract:Two new flavonoids, named cambodianins D (1) and E (2), together with two known flavanes (2S)-7,4′-dihydroxy-6,8-dimethylflavane (3) and (2S)-7,3′-dihydroxy-4′-methoxy-8-methylflavane (4), were isolated from dragon's blood of Dracaena cambodiana. The new compounds were determined by HR-ESI-MS and spectroscopic techniques (UV, IR, 1D, and 2D NMR). Compounds 1–3 exhibited antimicrobial activities.
-
chemical constituents from dragon s blood of Dracaena cambodiana
Chinese Journal of Natural Medicines, 2011Co-Authors: Haofu Dai, Hui Wang, Ying Luo, Wenli MeiAbstract:Abstract Aim To investigate the chemical constituents from dragon's blood of Dracaena cambodiana in Hainan. Methods Compounds were purified by silica gel and Sephadex LH-20 column chromatography, and their structures were identified on the basis of physicochemical properties and spectroscopic data. Results Eight compounds were isolated and identified as syringaresinol ( 1 ), pinoresinol ( 2 ), balanophonin ( 3 ), 2-(4-hydroxyphenyl)-6-(3-methoxy-4-hydroxyphenyl)-3, 7-dioxabicyclo[3.3.0]octane ( 4 ), 5, 7- dihydroxy-4′-methoxy-8-methylflavane ( 5 ), 7, 4′-dihydroxy-8-methoxyhomoisoflavane ( 6 ), (2 R )-7, 4′-dihydroxy-8-methylflavane ( 7 ) and (2 S )-7, 3′-dihydroxy-4′-methoxyflavane ( 8 ). Conclusion Compounds 1–8 were reported from the dragon′s blood of D. cambodiana for the first time.
-
antioxidant phenolic compounds of Dracaena cambodiana
Molecules, 2010Co-Authors: Ying Luo, Hui Wang, Wenli Mei, Haofu DaiAbstract:The antioxidant activities of the petroleum ether, ethyl acetate, n-BuOH and water extract fractions from Dracaena cambodiana Pierre ex Gagnep were evaluated in this study. The ethyl acetate fraction contained the highest amount of total phenolics and total flavonoids, and showed the greatest DPPH˙, ABTS+ and Superoxide anion radical-scavenging capacities. The DPPH˙, ABTS+ and Superoxide anion radical-scavenging capacities of nine compounds isolated from the ethyl acetate fraction were also evaluated. The results indicated that these compounds contributed to the antioxidant activity of D. cambodiana. Therefore, D. cambodiana and these compounds might be used as natural antioxidants.
Haofu Dai - One of the best experts on this subject based on the ideXlab platform.
-
de novo transcriptome characterization of Dracaena cambodiana and analysis of genes involved in flavonoid accumulation during formation of dragon s blood
Scientific Reports, 2016Co-Authors: Jiahong Zhu, Tianjun Cao, Haofu Dai, Dong Guo, Wenli Mei, Shiqing PengAbstract:Dragon’s blood is a red resin mainly extracted from Dracaena plants, and has been widely used as a traditional medicine in East and Southeast Asia. The major components of dragon’s blood are flavonoids. Owing to a lack of Dracaena plants genomic information, the flavonoids biosynthesis and regulation in Dracaena plants remain unknown. In this study, three cDNA libraries were constructed from the stems of D. cambodiana after injecting the inducer. Approximately 266.57 million raw sequencing reads were de novo assembled into 198,204 unigenes, of which 34,873 unique sequences were annotated in public protein databases. Many candidate genes involved in flavonoid accumulation were identified. Differential expression analysis identified 20 genes involved in flavonoid biosynthesis, 27 unigenes involved in flavonoid modification and 68 genes involved in flavonoid transport that were up-regulated in the stems of D. cambodiana after injecting the inducer, consistent with the accumulation of flavonoids. Furthermore, we have revealed the differential expression of transcripts encoding for transcription factors (MYB, bHLH and WD40) involved in flavonoid metabolism. These de novo transcriptome data sets provide insights on pathways and molecular regulation of flavonoid biosynthesis and transport, and improve our understanding of molecular mechanisms of dragon’s blood formation in D. cambodiana.
-
steroidal saponins from dragon s blood of Dracaena cambodiana
Fitoterapia, 2014Co-Authors: Haiyan Shen, Haofu Dai, Wenjian Zuo, Hui Wang, Ying Luo, Youxing Zhao, Zhikai Guo, Wenli MeiAbstract:Six new steroidal saponins, cambodianosides A-F (1-6), together with seven known ones, were isolated from the dragon's blood of Dracaena cambodiana. The structures of 1-6 were elucidated on the basis of detailed spectroscopic analysis, including 1D and 2D NMR techniques and chemical methods. The cytotoxicities of all the isolated compounds were evaluated in vitro against three human cancer cell lines, and compounds 7, 8, and 11 showed significant inhibitory activities.
-
two new antimicrobial flavanes from dragon s blood of Dracaena cambodiana
Journal of Asian Natural Products Research, 2012Co-Authors: Huiqin Chen, Haofu Dai, Wenjian Zuo, Hui Wang, Haiyan Shen, Ying Luo, Wenli MeiAbstract:Two new flavonoids, named cambodianins D (1) and E (2), together with two known flavanes (2S)-7,4′-dihydroxy-6,8-dimethylflavane (3) and (2S)-7,3′-dihydroxy-4′-methoxy-8-methylflavane (4), were isolated from dragon's blood of Dracaena cambodiana. The new compounds were determined by HR-ESI-MS and spectroscopic techniques (UV, IR, 1D, and 2D NMR). Compounds 1–3 exhibited antimicrobial activities.
-
chemical constituents from dragon s blood of Dracaena cambodiana
Chinese Journal of Natural Medicines, 2011Co-Authors: Haofu Dai, Hui Wang, Ying Luo, Wenli MeiAbstract:Abstract Aim To investigate the chemical constituents from dragon's blood of Dracaena cambodiana in Hainan. Methods Compounds were purified by silica gel and Sephadex LH-20 column chromatography, and their structures were identified on the basis of physicochemical properties and spectroscopic data. Results Eight compounds were isolated and identified as syringaresinol ( 1 ), pinoresinol ( 2 ), balanophonin ( 3 ), 2-(4-hydroxyphenyl)-6-(3-methoxy-4-hydroxyphenyl)-3, 7-dioxabicyclo[3.3.0]octane ( 4 ), 5, 7- dihydroxy-4′-methoxy-8-methylflavane ( 5 ), 7, 4′-dihydroxy-8-methoxyhomoisoflavane ( 6 ), (2 R )-7, 4′-dihydroxy-8-methylflavane ( 7 ) and (2 S )-7, 3′-dihydroxy-4′-methoxyflavane ( 8 ). Conclusion Compounds 1–8 were reported from the dragon′s blood of D. cambodiana for the first time.
-
antioxidant phenolic compounds of Dracaena cambodiana
Molecules, 2010Co-Authors: Ying Luo, Hui Wang, Wenli Mei, Haofu DaiAbstract:The antioxidant activities of the petroleum ether, ethyl acetate, n-BuOH and water extract fractions from Dracaena cambodiana Pierre ex Gagnep were evaluated in this study. The ethyl acetate fraction contained the highest amount of total phenolics and total flavonoids, and showed the greatest DPPH˙, ABTS+ and Superoxide anion radical-scavenging capacities. The DPPH˙, ABTS+ and Superoxide anion radical-scavenging capacities of nine compounds isolated from the ethyl acetate fraction were also evaluated. The results indicated that these compounds contributed to the antioxidant activity of D. cambodiana. Therefore, D. cambodiana and these compounds might be used as natural antioxidants.
Nadezhda Nadezhdina - One of the best experts on this subject based on the ideXlab platform.
-
sap flow measurements in a socotra dragon s blood tree Dracaena cinnabari in its area of origin
Tropical Plant Biology, 2018Co-Authors: Nadezhda Nadezhdina, Abdulraqeeb Alokaishi, Petr MaderaAbstract:For the first time, in situ field measurements of sap flow were conducted in adult Dracaena cinnabari plant native to the arid tropical climate of Socotra Island. The heat field deformation (HFD) method was applied using both single and multi-point sensors to study azimuthal and radial sap flow variability in stem, roots and first-order branches over two weeks during a winter monsoon. The main aim of this work was to monitor sap flow in adult D. cinnabari in-situ to better understand its physiological adaptation to extreme arid environments. The second aim was to compare our results with earlier sap flow measurements in adult D. draco uing the same HFD method. The last question we wanted to answer was comparison of sap flow measurements in both, young and adult Dracaena species. We found that sap flow magnitude is low and of a similar range in all observed D. species. High sap flow variability was recorded in different parts of adult D. cinnabari plant which changed throughout the day responding to interplay between intrinsic and extrinsic water potential gradients induced by sunlight. Maximum sap flow levels had variable pattern around stem in response to sun exposure, similarly as it was observed in adult D. draco plant. Sensors installed tangentially in stem xylem showed that water transport in adult D. cinnabari may move in lateral direction. This work also presents several methodological aspects detected from earlier observations of dicots which proved to be more pronounced in adult D. species. These methodologies relate to interpreting negative sap flow rates in conjunction with established axial flow reversal during hydraulic redistribution usually occurring under low evaporative demands and dry soil. Conversely, flow reversal during the day under high evaporative demands and wet soil may designate lateral water movement induced by internal water redistribution.
-
are Dracaena nebulophytes able to drink atmospheric water
Environmental and Experimental Botany, 2017Co-Authors: Nadezhda Nadezhdina, Valerij NadezhdinAbstract:Abstract In arid and semi-arid environments, fog interception as a water acquisition mechanism has been long recognized as an important factor for plant survival. The “narrow-leaf syndrome” increases water absorption from horizontal precipitation and is typical of nebulophytes characterized by dense rosette type crowns, to which also Dracaena species belong. In this paper, we demonstrate that Dracaena nebulophytes are able to direct water intercepted from fog through the leaf axils into their succulent woody organs to be stored for later use. We conducted leaf axil watering (LAW) experiments in four young Dracaena plants (two Dracaena cinnabari and two Dracaena draco) while simultaneously measuring sap flow in plant stems using the heat field deformation method. It was assumed that inducing water potential within stems closed to zero would initiate simultaneous bidirectional water transport from the stem to the crown and roots, and that this moment would be reflected in corresponding sap flow. Three hypothetical scenarios of induced water transport imbalance were confirmed by analyzing measured temperature gradients around heated probes and calculating sap flow. Sap flow responses to LAW clearly appeared to be dependent on flow direction prior to water treatments, on the strength of forces driving upward and downward water movement and the quantity of water applied. Intrinsic sap flow changes depicted in the results confirm the hypothesis that the Dracaena species are able to direct atmospheric water through the axils of their leaves to stem tissues. This mechanism of bypassing soil water represents an alternative means of water uptake in plants and is especially important in foggy areas of arid and semi-arid climates.
-
a comparative structural and functional study of leaf traits and sap flow in Dracaena cinnabari and Dracaena draco seedlings
Functional Plant Biology, 2015Co-Authors: Nadezhda Nadezhdina, Roman Plichta, Valeriy Nadezhdin, Roman Gebauer, Radek Jupa, Hana Habrova, Petr MaderaAbstract:Water relations for two remote populations of Dracaena tree species from the dragon tree group, Dracaena cinnabari Balfour f. and Dracaena draco (L.) L., were studied to test our hypothesis that morphological and anatomical differences in leaf structure may lead to varied functional responses to changing environmental conditions. Sap flow measurements were performed using the heat field deformation method for four Dracaena seedlings grown in one glasshouse and two greenhouses, and leaf traits related to plant–water relationships were characterised. All traits studied confirmed that D. cinnabari leaves are more xeric in their morpho-anatomical structure compared with D. draco leaves. No radial sap flow variability was detected in D. draco plant stems, whereas sap flow was found to be higher in the inner part of D. cinnabari stems. The regular occurrence of reverse sap flow at night in both Dracaena species was consistent with a staining experiment. Vapour pressure deficit (VPD) was found to be the main driver for transpiration for both Dracaena species. However, the relationship between VPD and sap flow appeared to be different for each species, with a clockwise or no hysteresis loop for D. draco and a counter-clockwise hysteresis loop for D. cinnabari. This resulted in a shorter transpiration cycle in D. cinnabari. The observed superior water-saving strategy of D. cinnabari corresponds to its more xeric morpho-anatomical leaf structure compared with D. draco.