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Yvan Vander Heyden - One of the best experts on this subject based on the ideXlab platform.
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Multivariate data analysis to evaluate the fingerprint peaks responsible for the cytotoxic activity of Mallotus species
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2012Co-Authors: C. Tistaert, Bieke Dejaegher, Gabrielle Chataigné, Céline Rivière, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Yvan Vander HeydenAbstract:The Mallotus genus comprises numerous species used as traditional medicines in oriental countries and provides scientists a broad basis in the search for pharmacologically active constituents. In this paper, the cytotoxicity of 39 Mallotus extracts, different in species, part of the plant used, origin, and harvest season, is evaluated combining cytotoxicity assays with fingerprint technology and data handling tools. At first, the antiproliferative activity of the plant extracts is analyzed both on a non-cancerous cell line (WI-38--human lung fibroblast) and on a cancerous cell line (HeLa human cervix carcinoma). The results are linked to a data set of high-performance liquid chromatographic fingerprint profiles of the samples using multivariate calibration techniques. The regression coefficients of the multivariate model are then evaluated to indicate those peaks potentially responsible for the cytotoxic activity of the Mallotus extracts. In a final step, the cytotoxic extracts are analyzed by HPLC-MS and the indicated peaks identified.
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Potentially antioxidant compounds indicated from Mallotus and Phyllanthus species fingerprints
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2012Co-Authors: Sumate Thiangthum, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Mohammad Goodarzi, A.y. Gordien, Leena Suntornsuk, Yvan Vander HeydenAbstract:The genera of Mallotus and Phyllanthus contain several species that are commonly used as traditional medicines in oriental countries. Some species show interesting pharmaceutical activities, such as an antioxidant activity. To produce clinically useful medicines or food supplements (nutraceuticals) from these herbs, the species should be identified and a thorough quality control should be implemented. Nowadays, the integration of chromatographic and chemometric approaches allows a high-throughput identification and activity prediction of medicinal plants. In this study, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied and compared to distinguish Mallotus and Phyllanthus species. Moreover, peaks from their chromatographic fingerprints, which were responsible for their antioxidant activity were assigned. For the latter purpose, the relevant information was extracted from the chromatographic fingerprints using linear multivariate calibration techniques, i.e., Partial Least Squares (PLS) and Orthogonal Projections to Latent Structures (O-PLS). Results reveal that exploratory analysis using PCA shows somewhat diverging clustering tendencies between Mallotus and Phyllanthus samples than HCA. However, both approaches mainly confirm each other. Concerning the multivariate calibration techniques, both PLS and O-PLS models demonstrate good predictive abilities. By comparing the regression coefficients of the models with the chromatographic fingerprints, the peaks that are potentially responsible for the antioxidant activity of the extracts could be confirmed.
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Potential antioxidant compounds in Mallotus species fingerprints. Part II: fingerprint alignment, data analysis and peak identification
Analytica chimica acta, 2012Co-Authors: C. Tistaert, Bieke Dejaegher, Gabrielle Chataigné, Céline Rivière, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Yvan Vander HeydenAbstract:Some Mallotus species are commonly used as traditional medicine (TM) ingredients in Vietnam and China, but only a few are studied for their activities. In Part I, high-performance liquid chromatography (HPLC) fingerprints of 39 Mallotus samples (17 species) were developed and, because of the complexity of and the large differences between the samples, it was chosen to analyse the unaligned fingerprints. The peaks, potentially responsible for the antioxidant activity in given Mallotus species, were indicated by the regression coefficients from an orthogonal projections to latent structures (O-PLS) model. In the present study, an in depth discussion on the need for alignment of the Mallotus fingerprints for the indication of the potentially active compounds is made, as well as an experimental analysis and identification of the previously indicated peaks by HPLC-mass spectrometry (HPLC-MS). Additionally, to thoroughly study and discuss the alignment problem, the modelling and prediction of the antioxidant activity of green tea samples based on HPLC fingerprints were also considered.
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N-methyl-5-carboxamide-2-pyridone from Mallotus barbatus: A chemosystematic marker of the Euphorbiaceae genus Mallotus
Biochemical Systematics and Ecology, 2012Co-Authors: Céline Rivière, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Minhchau Van, Yvan Vander Heyden, Van Nguyen Thi Hong, Kiem Phan Van, Joëlle Quetin-leclercqAbstract:A derivative of nicotinamide, N 1 -methyl-2-pyridone-5-carboxamide, was isolated from Mallotus barbatus with two flavonoids, quercitrin and 3- O -α-L-rhamnosyl kaempferol and one pentacyclic triterpene, friedelin. Figure options Download full-size image Download as PowerPoint slide
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Identification by LC-ESI-MS of flavonoids responsible for the antioxidant properties of Mallotus species from Vietnam.
Natural product communications, 2011Co-Authors: N T Van Hong, Bieke Dejaegher, C. Tistaert, Gabrielle Chataigné, Céline Rivière, Quang Qt Hong, Nam Nn Hoai, Thanh Nguyen Thi Kim, P Van Kiem, Yvan Vander HeydenAbstract:Several Mallotus species (Euphorbiaceae) are used in Vietnam as edible plants or as traditional medicines for different indications, some related to the treatment of inflammatory diseases. This study investigated the antioxidant activities of 33 samples from 17 Vietnamese Mallotus species. We also evaluated potential cytotoxic activity against human cervix carcinoma HeLa and human lung fibroblast WI-38 cells. Our aim is to develop safe dietary supplements with a protective effect against various diseases caused by tissue damage and the acceleration of the aging process linked to reactive oxygen species. These tests allowed the identification of non-cytotoxic plant species exhibiting significant antiradical properties. These antioxidant properties may be explained by their polyphenol composition. The antioxidant activity of the most active Mallotus species was further analyzed with and without tannins removal. We also identified by LC-ESI-MS some flavonoids responsible for a part of this activity.
C. Tistaert - One of the best experts on this subject based on the ideXlab platform.
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discrimination and classification techniques applied on Mallotus and phyllanthus high performance liquid chromatography fingerprints
Analytica Chimica Acta, 2015Co-Authors: Johan Viaene, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Mohammad Goodarzi, Hoang Le A Tuan, Joelle Quetinleclercq, Vander Y HeydenAbstract:Mallotus and Phyllanthus genera, both containing several species commonly used as traditional medicines around the world, are the subjects of this discrimination and classification study. The objective of this study was to compare different discrimination and classification techniques to distinguish the two genera (Mallotus and Phyllanthus) on the one hand, and the six species (Mallotus apelta, Mallotus paniculatus, Phyllanthus emblica, Phyllanthus reticulatus, Phyllanthus urinaria L. and Phyllanthus amarus), on the other. Fingerprints of 36 samples from the 6 species were developed using reversed-phase high-performance liquid chromatography with ultraviolet detection (RP-HPLC-UV). After fingerprint data pretreatment, first an exploratory data analysis was performed using Principal Component Analysis (PCA), revealing two outlying samples, which were excluded from the calibration set used to develop the discrimination and classification models. Models were built by means of Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA), Classification and Regression Trees (CART) and Soft Independent Modeling of Class Analogy (SIMCA). Application of the models on the total data set (outliers included) confirmed a possible labeling issue for the outliers. LDA, QDA and CART, independently of the pretreatment, or SIMCA after "normalization and column centering (N_CC)" or after "Standard Normal Variate transformation and column centering (SNV_CC)" were found best to discriminate the two genera, while LDA after column centering (CC), N_CC or SNV_CC; QDA after SNV_CC; and SIMCA after N_CC or after SNV_CC best distinguished between the 6 species. As classification technique, SIMCA after N_CC or after SNV_CC results in the best overall sensitivity and specificity.
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Multivariate data analysis to evaluate the fingerprint peaks responsible for the cytotoxic activity of Mallotus species
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2012Co-Authors: C. Tistaert, Bieke Dejaegher, Gabrielle Chataigné, Céline Rivière, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Yvan Vander HeydenAbstract:The Mallotus genus comprises numerous species used as traditional medicines in oriental countries and provides scientists a broad basis in the search for pharmacologically active constituents. In this paper, the cytotoxicity of 39 Mallotus extracts, different in species, part of the plant used, origin, and harvest season, is evaluated combining cytotoxicity assays with fingerprint technology and data handling tools. At first, the antiproliferative activity of the plant extracts is analyzed both on a non-cancerous cell line (WI-38--human lung fibroblast) and on a cancerous cell line (HeLa human cervix carcinoma). The results are linked to a data set of high-performance liquid chromatographic fingerprint profiles of the samples using multivariate calibration techniques. The regression coefficients of the multivariate model are then evaluated to indicate those peaks potentially responsible for the cytotoxic activity of the Mallotus extracts. In a final step, the cytotoxic extracts are analyzed by HPLC-MS and the indicated peaks identified.
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Potentially antioxidant compounds indicated from Mallotus and Phyllanthus species fingerprints
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2012Co-Authors: Sumate Thiangthum, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Mohammad Goodarzi, A.y. Gordien, Leena Suntornsuk, Yvan Vander HeydenAbstract:The genera of Mallotus and Phyllanthus contain several species that are commonly used as traditional medicines in oriental countries. Some species show interesting pharmaceutical activities, such as an antioxidant activity. To produce clinically useful medicines or food supplements (nutraceuticals) from these herbs, the species should be identified and a thorough quality control should be implemented. Nowadays, the integration of chromatographic and chemometric approaches allows a high-throughput identification and activity prediction of medicinal plants. In this study, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied and compared to distinguish Mallotus and Phyllanthus species. Moreover, peaks from their chromatographic fingerprints, which were responsible for their antioxidant activity were assigned. For the latter purpose, the relevant information was extracted from the chromatographic fingerprints using linear multivariate calibration techniques, i.e., Partial Least Squares (PLS) and Orthogonal Projections to Latent Structures (O-PLS). Results reveal that exploratory analysis using PCA shows somewhat diverging clustering tendencies between Mallotus and Phyllanthus samples than HCA. However, both approaches mainly confirm each other. Concerning the multivariate calibration techniques, both PLS and O-PLS models demonstrate good predictive abilities. By comparing the regression coefficients of the models with the chromatographic fingerprints, the peaks that are potentially responsible for the antioxidant activity of the extracts could be confirmed.
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Potential antioxidant compounds in Mallotus species fingerprints. Part II: fingerprint alignment, data analysis and peak identification
Analytica chimica acta, 2012Co-Authors: C. Tistaert, Bieke Dejaegher, Gabrielle Chataigné, Céline Rivière, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Yvan Vander HeydenAbstract:Some Mallotus species are commonly used as traditional medicine (TM) ingredients in Vietnam and China, but only a few are studied for their activities. In Part I, high-performance liquid chromatography (HPLC) fingerprints of 39 Mallotus samples (17 species) were developed and, because of the complexity of and the large differences between the samples, it was chosen to analyse the unaligned fingerprints. The peaks, potentially responsible for the antioxidant activity in given Mallotus species, were indicated by the regression coefficients from an orthogonal projections to latent structures (O-PLS) model. In the present study, an in depth discussion on the need for alignment of the Mallotus fingerprints for the indication of the potentially active compounds is made, as well as an experimental analysis and identification of the previously indicated peaks by HPLC-mass spectrometry (HPLC-MS). Additionally, to thoroughly study and discuss the alignment problem, the modelling and prediction of the antioxidant activity of green tea samples based on HPLC fingerprints were also considered.
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N-methyl-5-carboxamide-2-pyridone from Mallotus barbatus: A chemosystematic marker of the Euphorbiaceae genus Mallotus
Biochemical Systematics and Ecology, 2012Co-Authors: Céline Rivière, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Minhchau Van, Yvan Vander Heyden, Van Nguyen Thi Hong, Kiem Phan Van, Joëlle Quetin-leclercqAbstract:A derivative of nicotinamide, N 1 -methyl-2-pyridone-5-carboxamide, was isolated from Mallotus barbatus with two flavonoids, quercitrin and 3- O -α-L-rhamnosyl kaempferol and one pentacyclic triterpene, friedelin. Figure options Download full-size image Download as PowerPoint slide
Bieke Dejaegher - One of the best experts on this subject based on the ideXlab platform.
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discrimination and classification techniques applied on Mallotus and phyllanthus high performance liquid chromatography fingerprints
Analytica Chimica Acta, 2015Co-Authors: Johan Viaene, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Mohammad Goodarzi, Hoang Le A Tuan, Joelle Quetinleclercq, Vander Y HeydenAbstract:Mallotus and Phyllanthus genera, both containing several species commonly used as traditional medicines around the world, are the subjects of this discrimination and classification study. The objective of this study was to compare different discrimination and classification techniques to distinguish the two genera (Mallotus and Phyllanthus) on the one hand, and the six species (Mallotus apelta, Mallotus paniculatus, Phyllanthus emblica, Phyllanthus reticulatus, Phyllanthus urinaria L. and Phyllanthus amarus), on the other. Fingerprints of 36 samples from the 6 species were developed using reversed-phase high-performance liquid chromatography with ultraviolet detection (RP-HPLC-UV). After fingerprint data pretreatment, first an exploratory data analysis was performed using Principal Component Analysis (PCA), revealing two outlying samples, which were excluded from the calibration set used to develop the discrimination and classification models. Models were built by means of Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA), Classification and Regression Trees (CART) and Soft Independent Modeling of Class Analogy (SIMCA). Application of the models on the total data set (outliers included) confirmed a possible labeling issue for the outliers. LDA, QDA and CART, independently of the pretreatment, or SIMCA after "normalization and column centering (N_CC)" or after "Standard Normal Variate transformation and column centering (SNV_CC)" were found best to discriminate the two genera, while LDA after column centering (CC), N_CC or SNV_CC; QDA after SNV_CC; and SIMCA after N_CC or after SNV_CC best distinguished between the 6 species. As classification technique, SIMCA after N_CC or after SNV_CC results in the best overall sensitivity and specificity.
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Multivariate data analysis to evaluate the fingerprint peaks responsible for the cytotoxic activity of Mallotus species
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2012Co-Authors: C. Tistaert, Bieke Dejaegher, Gabrielle Chataigné, Céline Rivière, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Yvan Vander HeydenAbstract:The Mallotus genus comprises numerous species used as traditional medicines in oriental countries and provides scientists a broad basis in the search for pharmacologically active constituents. In this paper, the cytotoxicity of 39 Mallotus extracts, different in species, part of the plant used, origin, and harvest season, is evaluated combining cytotoxicity assays with fingerprint technology and data handling tools. At first, the antiproliferative activity of the plant extracts is analyzed both on a non-cancerous cell line (WI-38--human lung fibroblast) and on a cancerous cell line (HeLa human cervix carcinoma). The results are linked to a data set of high-performance liquid chromatographic fingerprint profiles of the samples using multivariate calibration techniques. The regression coefficients of the multivariate model are then evaluated to indicate those peaks potentially responsible for the cytotoxic activity of the Mallotus extracts. In a final step, the cytotoxic extracts are analyzed by HPLC-MS and the indicated peaks identified.
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Potentially antioxidant compounds indicated from Mallotus and Phyllanthus species fingerprints
Journal of chromatography. B Analytical technologies in the biomedical and life sciences, 2012Co-Authors: Sumate Thiangthum, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Mohammad Goodarzi, A.y. Gordien, Leena Suntornsuk, Yvan Vander HeydenAbstract:The genera of Mallotus and Phyllanthus contain several species that are commonly used as traditional medicines in oriental countries. Some species show interesting pharmaceutical activities, such as an antioxidant activity. To produce clinically useful medicines or food supplements (nutraceuticals) from these herbs, the species should be identified and a thorough quality control should be implemented. Nowadays, the integration of chromatographic and chemometric approaches allows a high-throughput identification and activity prediction of medicinal plants. In this study, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied and compared to distinguish Mallotus and Phyllanthus species. Moreover, peaks from their chromatographic fingerprints, which were responsible for their antioxidant activity were assigned. For the latter purpose, the relevant information was extracted from the chromatographic fingerprints using linear multivariate calibration techniques, i.e., Partial Least Squares (PLS) and Orthogonal Projections to Latent Structures (O-PLS). Results reveal that exploratory analysis using PCA shows somewhat diverging clustering tendencies between Mallotus and Phyllanthus samples than HCA. However, both approaches mainly confirm each other. Concerning the multivariate calibration techniques, both PLS and O-PLS models demonstrate good predictive abilities. By comparing the regression coefficients of the models with the chromatographic fingerprints, the peaks that are potentially responsible for the antioxidant activity of the extracts could be confirmed.
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Potential antioxidant compounds in Mallotus species fingerprints. Part II: fingerprint alignment, data analysis and peak identification
Analytica chimica acta, 2012Co-Authors: C. Tistaert, Bieke Dejaegher, Gabrielle Chataigné, Céline Rivière, Nam Nguyen Hoai, Minhchau Van, Joëlle Quetin-leclercq, Yvan Vander HeydenAbstract:Some Mallotus species are commonly used as traditional medicine (TM) ingredients in Vietnam and China, but only a few are studied for their activities. In Part I, high-performance liquid chromatography (HPLC) fingerprints of 39 Mallotus samples (17 species) were developed and, because of the complexity of and the large differences between the samples, it was chosen to analyse the unaligned fingerprints. The peaks, potentially responsible for the antioxidant activity in given Mallotus species, were indicated by the regression coefficients from an orthogonal projections to latent structures (O-PLS) model. In the present study, an in depth discussion on the need for alignment of the Mallotus fingerprints for the indication of the potentially active compounds is made, as well as an experimental analysis and identification of the previously indicated peaks by HPLC-mass spectrometry (HPLC-MS). Additionally, to thoroughly study and discuss the alignment problem, the modelling and prediction of the antioxidant activity of green tea samples based on HPLC fingerprints were also considered.
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N-methyl-5-carboxamide-2-pyridone from Mallotus barbatus: A chemosystematic marker of the Euphorbiaceae genus Mallotus
Biochemical Systematics and Ecology, 2012Co-Authors: Céline Rivière, Bieke Dejaegher, C. Tistaert, Nam Nguyen Hoai, Minhchau Van, Yvan Vander Heyden, Van Nguyen Thi Hong, Kiem Phan Van, Joëlle Quetin-leclercqAbstract:A derivative of nicotinamide, N 1 -methyl-2-pyridone-5-carboxamide, was isolated from Mallotus barbatus with two flavonoids, quercitrin and 3- O -α-L-rhamnosyl kaempferol and one pentacyclic triterpene, friedelin. Figure options Download full-size image Download as PowerPoint slide
S.e.c. Sierra - One of the best experts on this subject based on the ideXlab platform.
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Leaf anatomy of Mallotus and the related genera Blumeodendron and Hancea (Euphorbiaceae sensu stricto)
Botanical Journal of the Linnean Society, 2012Co-Authors: Živa Fišer Pečnikar, S.e.c. Sierra, Kristo K. J. Kulju, Pieter Baas, Peter C. Van WelzenAbstract:The leaf anatomy of Mallotus and Hancea (both subtribe Rottlerinae, tribe Acalypheae) and Blumeodendron (tribe Pycnocomeae) from Euphorbiaceae sensu stricto (subfamily Acalyphoideae) was studied in detail on the basis of 84 specimens belonging to 71 species. Some leaf anatomical features do not show much variation; almost all species have a relatively constant dorsiventral mesophyll, paracytic stomata and collateral bundles in the mesophyll. However, the diversity of other characters is great, especially the hair types, and useful in characterizing infrageneric groups. Capitate glandular hairs are characteristic for Hancea, whereas globular to disc-shaped glandular hairs occur in most Mallotus spp. Glandular hairs are absent in the two other genera. Morphological diversity in globular to disc-shaped hairs in Mallotus also provides taxonomically important information. Hancea is characterized by the presence of brachysclereids and cristarque cells and by an abundance of columnar and fibriform mesophyll sclereids. Blumeodendron shares with Hancea the presence of brachysclereids and fibriform sclereids, but is further characterized by the presence of giant stomata. In this study, leaf anatomy is used to discuss the infrageneric delimitation of Mallotus and Hancea and to compare these genera with the more distantly related Blumeodendron. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ••, ••–••.
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Key to the Malesian species of Mallotus (Euphorbiaceae)
Blumea - Biodiversity Evolution and Biogeography of Plants, 2010Co-Authors: P.c. Van Welzen, K.k.m. Kulju, S.e.c. Sierra, J. W. F. SlikAbstract:An identification key to all Malesian species of Mallotus was still lacking. So far, only keys per section of Mallotus or keys per island were generated. This is the first attempt to create a key for all species of Mallotus in Malesia.
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The phylogeny of Mallotus s.str. (Euphorbiaceae) inferred from DNA sequence and morphological data
TAXON, 2010Co-Authors: S.e.c. Sierra, K.k.m. Kulju, Ziva Fiser, Marcela Aparicio, Peter C. Van WelzenAbstract:Mallotus s.str. is a monophyletic, large, palaeotropical genus in the family Euphorbiaceae. We investigated the phylogeny of the genus in order to (1) determine the evolutionary relationships within the Mallotus s.str. clade; (2) assess whether the six sections as circumscribed in the traditional classification reflect clades and evaluate the characters used in the classification; and (3) determine what are additional new clades and their supporting morphological characters. For this purpose we assembled different datasets: plastid (matK) and nuclear (gpd) DNA sequences, macromorphological features and leaf anatomical data. We found that Mallotus sect. Mallotus, sect. Polyadenii and sect. Stylanthus are monophyletic, M. sect. Axenfeldia and sect. Rottleropsis are polyphyletic, and M sect. Philippinenses is paraphyletic. Six additional clades with morphological synapomorphies were also identified. An analysis of quantitative morphological data, in combination with qualitative morphological and molecular datasets resulted in almost completely resolved phylogenies and increased support values. However, the higher-level relationships between the clades are not supported in our analyses and the position of many taxa is still ambiguous.
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molecular phylogeny of macaranga Mallotus and related genera euphorbiaceae s s insights from plastid and nuclear dna sequence data
American Journal of Botany, 2007Co-Authors: K.k.m. Kulju, S.e.c. Sierra, Stefano G A Draisma, Rosabelle Samuel, Peter C Van WelzenAbstract:: Macaranga and Mallotus (Euphorbiaceae s.s.) are two closely related, large paleo(sub)tropical genera. To investigate the phylogenetic relationships between and within them and to determine the position of related genera belonging to the subtribe Rottlerinae, we sequenced one plastid (trnL-F) and three nuclear (ITS, ncpGS, phyC) markers for species representative of these genera. The analyses demonstrated the monophyly of Macaranga and the paraphyly of Mallotus and revealed three highly supported main clades. The genera Cordemoya and DeuteroMallotus and the Mallotus sections Hancea and Oliganthae form a basal Cordemoya s.l. clade. The two other clades, the Macaranga clade and the Mallotus s.s. clade (the latter with Coccoceras, Neotrewia, Octospermum, and Trewia), are sister groups. In the Macaranga clade, two basal lineages (comprising mostly sect. Pseudorottlera) and a crown group with three geographically homogenous main clades were identified. The phylogeny of the Mallotus s.s. clade is less clear because of internal conflict in all four data sets. Many of the sections and informal infrageneric groups of Macaranga and Mallotus do not appear to be monophyletic. In both the Macaranga and Mallotus s.s. clades, the African and/or Madagascan taxa are nested in Asian clades, suggesting migrations or dispersals from Asia to Africa and Madagascar.
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Re-shaping Mallotus [Part 2]: inclusion of Neotrewia, Octospermum and Trewia in Mallotus s.s. (Euphorbiaceae s.s.)
Blumea - Biodiversity Evolution and Biogeography of Plants, 2007Co-Authors: K.k.m. Kulju, S.e.c. Sierra, P.c. Van WelzenAbstract:A recent molecular phylogenetic study of Mallotus and related genera showed that three small Asiatic genera are clearly part of a strongly supported main Mallotus clade (Mallotus s.s. clade), rendering the genus paraphyletic. In this paper these genera, Neotrewia, Octospermum and Trewia, are merged with Mallotus. The monotypic Neotrewia and Octospermum were originally described within Mallotus and are now transferred back to it. Trewia was never included in Mallotus; it has two distinct species, for which new combinations within Mallotus are made. A full taxonomic treatment with descriptions, distribution maps and drawings is given for the species transferred, and a new generic description for Mallotus is provided. The morphology of the newly transferred species in comparison to Mallotus in general and to related species in particular is discussed.
Peter C. Van Welzen - One of the best experts on this subject based on the ideXlab platform.
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Macaranga and Mallotus species (Euphorbiaceae) as indicators for disturbance in the mixed lowland dipterocarp forest
2016Co-Authors: Of East Kalimantan, J. Ferry W. Slik, Paul J. A. Keßler, Peter C. Van WelzenAbstract:The indicator value (IV) of Macaranga and Mallotus species (Euphorbiaceae) for different types of disturbance in lowland dipterocarp forest was assessed by counting and identifying all individuals of species of these genera taller than 30 cm in 45 (10 m×300 m) plots at nine locations. Twelve Macaranga and nine Mallotus species were found. The main forest disturbance types (primary forest, secondary forest, selectively logged forest, forest burned once, and repeatedly burned forest used for shifting-cultivation) each had their own set of indicator species. The level of disturbance in the forest types was assessed by measuring nine forest structural parameters. The occurrence of Macaranga and Mallotus species was closely related to the level of disturbance in a forest. Most Macaranga species were characteristic of high disturbance levels, while most Mallotus species preferred intermediate to low levels of disturbance. However, both genera had species at both disturbance extremes. Using multiple regression analysis, combinations of Macaranga and Mallotus species were formed and used to predict the separate forest structural parameters and the general level of disturbance of a forest. The Macaranga and Mallotus species could be grouped into (1) primary forest ‘remnant ’ species; (2) generalist pioneer species; and (3) high disturbance pioneer species
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Mallotus actinoneurus and Mallotus tokiae (Euphorbiaceae), a new record and a new species for Thailand
2013Co-Authors: Peter C. Van WelzenAbstract:A new species of Mallotus (Euphorbiaceae) is described for Peninsular Thailand. Typical are the densely spined fruits, lack of infl orescences (axillary fl owers), lack of indumentum and opposite leaves. Mallotus actinoneurus, up to now only known from NE Peninsular Malaysia, is also found at the Thai side of the border. The staminate infl orescences and fl owers of this species were previously unknown, the infl orescences and buds are newly described here.
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Leaf anatomy of Mallotus and the related genera Blumeodendron and Hancea (Euphorbiaceae sensu stricto)
Botanical Journal of the Linnean Society, 2012Co-Authors: Živa Fišer Pečnikar, S.e.c. Sierra, Kristo K. J. Kulju, Pieter Baas, Peter C. Van WelzenAbstract:The leaf anatomy of Mallotus and Hancea (both subtribe Rottlerinae, tribe Acalypheae) and Blumeodendron (tribe Pycnocomeae) from Euphorbiaceae sensu stricto (subfamily Acalyphoideae) was studied in detail on the basis of 84 specimens belonging to 71 species. Some leaf anatomical features do not show much variation; almost all species have a relatively constant dorsiventral mesophyll, paracytic stomata and collateral bundles in the mesophyll. However, the diversity of other characters is great, especially the hair types, and useful in characterizing infrageneric groups. Capitate glandular hairs are characteristic for Hancea, whereas globular to disc-shaped glandular hairs occur in most Mallotus spp. Glandular hairs are absent in the two other genera. Morphological diversity in globular to disc-shaped hairs in Mallotus also provides taxonomically important information. Hancea is characterized by the presence of brachysclereids and cristarque cells and by an abundance of columnar and fibriform mesophyll sclereids. Blumeodendron shares with Hancea the presence of brachysclereids and fibriform sclereids, but is further characterized by the presence of giant stomata. In this study, leaf anatomy is used to discuss the infrageneric delimitation of Mallotus and Hancea and to compare these genera with the more distantly related Blumeodendron. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ••, ••–••.
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The phylogeny of Mallotus s.str. (Euphorbiaceae) inferred from DNA sequence and morphological data
TAXON, 2010Co-Authors: S.e.c. Sierra, K.k.m. Kulju, Ziva Fiser, Marcela Aparicio, Peter C. Van WelzenAbstract:Mallotus s.str. is a monophyletic, large, palaeotropical genus in the family Euphorbiaceae. We investigated the phylogeny of the genus in order to (1) determine the evolutionary relationships within the Mallotus s.str. clade; (2) assess whether the six sections as circumscribed in the traditional classification reflect clades and evaluate the characters used in the classification; and (3) determine what are additional new clades and their supporting morphological characters. For this purpose we assembled different datasets: plastid (matK) and nuclear (gpd) DNA sequences, macromorphological features and leaf anatomical data. We found that Mallotus sect. Mallotus, sect. Polyadenii and sect. Stylanthus are monophyletic, M. sect. Axenfeldia and sect. Rottleropsis are polyphyletic, and M sect. Philippinenses is paraphyletic. Six additional clades with morphological synapomorphies were also identified. An analysis of quantitative morphological data, in combination with qualitative morphological and molecular datasets resulted in almost completely resolved phylogenies and increased support values. However, the higher-level relationships between the clades are not supported in our analyses and the position of many taxa is still ambiguous.
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Macaranga and Mallotus species (Euphorbiaceae) as indicators for disturbance in the mixed lowland dipterocarp forest of East Kalimantan (Indonesia)
Ecological Indicators, 2003Co-Authors: J. W. Ferry Slik, Paul J. A. Keßler, Peter C. Van WelzenAbstract:The indicator value (IV) of Macarangaand Mallotus species (Euphorbiaceae) for different types of disturbance in lowland dipterocarp forest was assessed by counting and identifying all individuals of species of these genera taller than 30 cm in 45 (10 m × 300 m) plots at nine locations. Twelve Macarangaand nine Mallotus species were found. The main forest disturbance types (primary forest, secondary forest, selectively logged forest, forest burned once, and repeatedly burned forest used for shifting-cultivation) each had their own set of indicator species. The level of disturbance in the forest types was assessed by measuring nine forest structural parameters. The occurrence of Macarangaand Mallotusspecies was closely related to the level of disturbance in a forest. Most Macarangaspecies were characteristic of high disturbance levels, while most Mallotusspecies preferred intermediate to low levels of disturbance. However, both genera had species at both disturbance extremes. Using multiple regression analysis, combinations of Macarangaand Mallotus species were formed and used to predict the separate forest structural parameters and the general level of disturbance of a forest. The Macaranga and Mallotus species could be grouped into (1) primary forest ‘remnant’ species; (2) generalist pioneer species; and (3) high disturbance pioneer species. © 2002 Elsevier Science Ltd. All rights reserved.