10 results on '"DIVAKAR, Pradeep K."'
Search Results
2. Lichens of Parmelioid Clade as Promising Multitarget Neuroprotective Agents
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Sieteiglesias, Víctor, González-Burgos, Elena, Bermejo-Bescós, Paloma, Divakar, Pradeep K., and Gómez-Serranillos, María Pilar
- Abstract
Neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease are multifactorial disorders which are increasing in incidence and prevalence over the world without existing effective therapies. The search for new multitarget compounds is the latter therapeutic strategy to address these pathological conditions. Lichens have an important and unknown therapeutic value attributed to their unique secondary metabolites. The aim of this study is to evaluate for the first time the in vitroneuroprotective activities and molecular mechanisms underlying methanol extracts of lichens of the parmelioid clade and to characterize major bioactive secondary metabolites responsible for their pharmacological actions. Of the 15 parmelioid lichen species, our results showed that Parmotrema perlatumand Hypotrachyna formosanamethanol extracts exhibited high antioxidant activity as evidenced in ORAC, DPPH, and FRAP assays. Then, SH-SY5Y cells were pretreated with methanol extracts (24 h) followed by Fenton reagent exposure (2 h). Pretreatments with these two more antioxidant methanol lichen extracts increased cell viability, reduced intracellular ROS, prevented oxidative stress biomarkers accumulation, and upregulated antioxidant enzyme (CAT, SOD, GR, and GPx) activity compared to Fenton reagent cells. The neuroprotective activity was much higher for H. formosanathan for P. perlatum, even equal to or higher than Trolox (reference compound). Moreover, H. formosanaextracts inhibited both AChE and BuChE activities in a concentration dependent manner, and P. perlatumonly showed concentration dependent activity against AChE. Finally, chemical composition analysis using TLC and HPLC methods revealed that physodic acid, lividic acid, and lichexanthone are major secondary metabolites in H. formosanaand stictic acid and constictic acid are in P. perlatum. These results demonstrated that P. perlatumand, specially, H. formosanaare promising multitargeted neuroprotective agents due to their antioxidant and AChE and BuChE inhibition activities.
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- 2019
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3. Parallel Miocene-dominated diversification of the lichen-forming fungal genus Oropogon(Ascomycota: Parmeliaceae) in different continents
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Wei, Xin-Li, Leavitt, Steven D., Huang, Jen-Pan, Esslinger, Theodore L., Wang, Li-Song, Moncada, Bibiana, Lücking, Robert, Divakar, Pradeep K., and Lumbsch, H. Thorsten
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Lineages with broad, intercontinental distributions can provide insight into factors that influence diversity across both temporal and geographic scales. Lichens are well known for distinct biogeographic distribution patterns, including a high number of lineages with intercontinental distributions. The lichen-forming fungal genus Oropogon, from one of the largest families of lichen-forming ascomycetes, Parmeliaceae, occurs in both Asia and the Neotropics. How this genus obtained this disjunct distribution is not currently known. To better understand factors shaping diversity in Oropogon, we (i) estimated the timing of diversification of major clades within this genus; (ii) inferred the historical biogeography of Oropogon; and (iii) identified factors that potentially affected the distribution and evolution of this genus. Our results suggest that the genus originally radiated during the early Miocene, with subsequent diversification events occurring during the middle Miocene. Ancestral area reconstructions for Oropogonsuggest that the genus was either widespread with subsequent separate diversification in Asia and America or originated in the New World (America), with subsequent migration to Asia. We hypothesize that the Mi-1 glaciation impacted diversification of Oropogonspecies in Asia, and that the rise of major mountain ranges, such as the Himalayas, helped promote diversification in Oropogonin the Old World.
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- 2017
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4. Molecular phylogeny and historical biogeography of the lichen-forming fungal genus Flavoparmelia(Ascomycota: Parmeliaceae)
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Del-Prado, Ruth, Blanco, Oscar, Lumbsch, H. Thorsten, Divakar, Pradeep K., Elix, John. A., Molina, M. Carmen, and Crespo, Ana
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The lichen-forming fungal genus Flavoparmeliaincludes species with distinct distribution patterns, including subcosmopolitan, restricted, and disjunct species. We used a dataset of nuclear ITS and LSU ribosomal DNA including 51 specimens to understand the influence of historical events on the current distribution patterns in the genus. We employed Bayesian, maximum likelihood and maximum parsimony approaches for phylogenetic analyses, a likelihood-based approach to ancestral area reconstruction, and a Bayesian approach to estimate divergence times of major lineages within the genus. We identified two major clades in the genus, one of them separating into two subclades and one of those into four groups. Several of the groups and clades have restricted geographical ranges in the Southern Hemisphere, but two groups include species with wider distribution areas. Our analyses suggest that the genus originated in southern South America during the Eocene–Oligocene transition and that the diversification of the Australasian groups occurred recently. The subcosmopolitan distribution of species is explained by long-distance dispersal, while vicariance probably played a major role in the origin of the genus. Several currently accepted species were found to be non-monophyletic, indicating that the species delimitation in the genus requires further studies.
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- 2013
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5. The Lichen Genus Parmotremain South Korea
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Jayalal, Udeni, Divakar, Pradeep K., Joshi, Santosh, Oh, Soon-Ok, Koh, Young Jin, and Hur, Jae-Seoun
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AbstractParmotremaA. Massal. is a common lichen genus scattered throughout the Korean Peninsula; however, no detailed taxonomic or revisionary study of this genus has been conducted for nearly two decades. Therefore, this study revised the taxonomy of this genus based on specimens deposited in the lichen herbarium at the Korean Lichen Research Institute and samples were identified using recent literature. In this revisionary study, a total of eighteen species of Parmotremaincluding eight new records [Parmotrema cetratum(Ach.) Hale, Parmotrema cristiferum(Taylor) Hale, Parmotrema grayanum(Hue) Hale, Parmotrema defectum(Hale) Hale, Parmotrema dilatatum(Vain.) Hale, Parmotrema margaritatum(Hue) Hale, Parmotrema pseudocrinitum(Abbayes) Hale, and Parmotrema subsumptum(Nyl.) Hale] are documented. Detailed descriptions of each species with their morphological, anatomical and chemical characteristics are also given and a key to the known Parmotremaspecies of the Korean Peninsula is presented.
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- 2013
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6. Phylogenetic generic classification of parmelioid lichens (Parmeliaceae, Ascomycota) based on molecular, morphological and chemical evidence
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Crespo, Ana, Kauff, Frank, Divakar, Pradeep K., del Prado, Ruth, Pérez-Ortega, Sergio, de Paz, Guillermo Amo, Ferencova, Zuzana, Blanco, Oscar, Roca-Valiente, Beatriz, Núñez-Zapata, Jano, Cubas, Paloma, Argüello, Arturo, Elix, John A., Esslinger, Theodore L., Hawksworth, David L., Millanes, Ana, Molina, M. Carmen, Wedin, Mats, Ahti, Teuvo, Aptroot, Andre, Barreno, Eva, Bungartz, Frank, Calvelo, Susana, Candan, Mehmet, Cole, Mariette, Ertz, Damien, Goffinet, Bernard, Lindblom, Louise, Lücking, Robert, Lutzoni, Francois, Mattsson, Jan-Eric, Messuti, María Inés, Miadlikowska, Jolanta, Piercey-Normore, Michele, Rico, Víctor J., Sipman, Harrie J.M., Schmitt, Imke, Spribille, Toby, Thell, Arne, Thor, Göran, Upreti, Dalip K., and Lumbsch, H. Thorsten
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Parmelioid lichens are a diverse and ubiquitous group of foliose lichens. Generic delimitation in parmelioid lichens has been in a state of flux since the late 1960s with the segregation of the large, heterogeneous genus Parmelia into numerous smaller genera. Recent molecular phylogenetic studies have demonstrated that some of these new genera were monophyletic, some were not, and others, previously believed to be unrelated, fell within single monophyletic groups, indicating the need for a revision of the generic delimitations. This study aims to give an overview of current knowledge of the major clades of all parmelioid lichens. For this, we assembled a dataset of 762 specimens, including 31 of 33 currently accepted parmelioid genera (and 63 of 84 accepted genera of Parmeliaceae). We performed maximum likelihood and Bayesian analyses of combined datasets including two, three and four loci. Based on these phylogenies and the correlation of morphological and chemical characters that characterize monophyletic groups, we accept 27 genera within nine main clades. We re-circumscribe several genera and reduce Parmelaria to synonymy with Parmotrema. Emodomelanelia Divakar & A. Crespo is described as a new genus (type: E. masonii). Nipponoparmelia (Kurok.) K.H. Moon, Y. Ohmura & Kashiw. ex A. Crespo & al. is elevated to generic rank and 15 new combinations are proposed (in the genera Flavoparmelia, Parmotrema, Myelochroa, Melanelixia and Nipponoparmelia). A short discussion of the accepted genera is provided and remaining challenges and areas requiring additional taxon sampling are identified.
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- 2010
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7. A new species in the lichen genus Sticta(Schreb.) Ach. (Lobariaceae) from the Indian subcontinent
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Upreti, Dalip K. and Divakar, Pradeep K.
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Sticta indicaD.Awasthi & Upreti, is newly described. The new taxon has a restricted distribution in temperate Himalayas growing on rocks in association with mosses in moist shady more or less thinned out Quercus semecarpifoliaforests.
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- 2010
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8. Molecular phylogeny of parmotremoid lichens (Ascomycota, Parmeliaceae)
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Blanco, Oscar, Crespo, Ana, Divakar, Pradeep K., Elix, John A., and Lumbsch, H. Thorsten
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Parmotremais one of the larger genera segregated from Parmelia s. lat.Additional genera recently have been segregated from this large genus based mainly on morphological and chemical features. We have employed molecular data from three genes to continue a revision of the generic concept within the parmelioid lichens. A Bayesian analysis of nuclear ITS, LSU rDNA and mitochondrial SSU rDNA sequences was performed. The genera Canomaculina, Concamerella, Parmelariaand Rimeliaappear nested within Parmotrema.Alternative hypotheses to maintain the independence of Canomaculina, Concamerellaand Rimeliaare shown to be highly unlikely and are rejected. As a consequence these three genera are reduced to synonymy with Parmotrema.An alternative topology segregating Parmelariafrom Parmotrema s. lat.cannot be rejected with the dataset at hand. However we have established that this genus is closely related to Parmotremarather than to cetrarioid species as was considered previously. The revised genus Parmotremaincludes species that have an upper cortex consisting of a palisade plectenchyma or rarely paraplectenchyma with vaults, have a pored or fenestrated epicortex, lack pseudocyphellae, have or lack cilia, have laminal, perforate or eperforate apothecia, usually have simple rhizines and filiform, cylindrical, bacilliform or sublageniform conidia. It is closely related to Flavoparmeliabut the status of these genera requires further investigation. Nineteen new combinations are made.
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- 2005
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9. A note on the occurrence of Xanthoparmelia saxeti(Stizenb.) Amo, A. Crespo, Elix & Lumbsch in India
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Joshi, Yogesh, Tripathi, Manish, Divakar, Pradeep K., and Upreti, Dalip K.
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The paper describes for the first time the occurrence of Xanthoparmelia saxeti(Stizenb.) Amo, A. Crespo, Elix and Lumbsch in Himalaya, where it was found growing over siliceous rocks in and around Sun Temple, Kosi Katarmal, Almora district, Uttarakhand. Previously, the species was reported for the first time under the name Karoowia saxetifrom Karnantaka and recently Divakar and colleagues collected specimens from the same state, but the species had not been previously mentioned by any Indian worker from India. A brief description of the species along with the status of Karoowiaand Xanthoparmeliais given in the text.
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- 2014
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10. Draft genome sequences of five Calonectriaspecies from Eucalyptusplantations in China, Celoporthe dispersa, Sporothrix phasmaand Alectoria sarmentosa
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Liu, Feifei, Chen, Shuaifei, Ferreira, Maria A., Chang, Runlei, Sayari, Mohammad, Kanzi, Aquillah M., Wingfield, Brenda D., Wingfield, Michael J., Pizarro, David, Crespo, Ana, Divakar, Pradeep K., de Beer, Z. Wilhelm, and Duong, Tuan A.
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Draft genome sequences of five Calonectriaspecies [including Calonectria aciculata, C. crousiana, C. fujianensis, C. honghensisand C. pseudoturangicola], Celoporthe dispersa, Sporothrix phasmaand Alectoria sarmentosaare presented. Species of Calonectriaare the causal agents of Eucalyptus leaf blight disease, threatening the growth and sustainability of Eucalyptusplantations in China. Celoporthe dispersais the causal agent of stem canker in native Syzygium cordatumand exotic Tibouchina granulosain South Africa. Sporothrix phasmawas first discovered in the infructescences of Protea laurifoliaand Protea neriifoliain South Africa. Alectoria sarmentosais fruticose lichen belongs to the alectorioid clade of the family Parmeliaceae. The availability of these genome sequences will facilitate future studies on the systematics, population genetics, and genomics of these fungi.
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- 2019
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