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The genus Nuphar (Nymphaeaceae) comprises aquatic plant species inhabiting freshwater bodies of the Northern hemisphere temperate regions known as yellow water-lilies. Nuphar lutea and N. pumila are the only representatives in the European continent and present different ecologies: the former is a widespread generalist, while the latter is restricted to northern latitudes or high-altitudes due to its requirements for colder and oligotrophic waters. The Central Europe mountainous areas, the Massif Central (France) and the Cantabrian Mountains (north Iberian Peninsula) harbor relict isolated N. pumila populations endangered by eutrophication and hybridization with N. lutea. We aim to detect hybridization processes in the Massif Central and Cantabrian Mountains populations and compare the genetic diversity of N. pumila in the relict populations of Central Europe by using microsatellite (SSR) markers. No evidence of hybridization was found in the Iberian population, whereas the admixture between N. pumila and N. lutea in the Massif Central populations could be due to hybridization or ancient introgression. Our current knowledge would benefit from genetic diversity studies focusing on both species throughout their distributional range. The Iberian and Massif Central N. pumila populations were genetically distinct, representing two different clusters from other relict populations, with low genetic diversity and a genetic boundary within Central Europe. [ABSTRACT FROM AUTHOR]

The 1986 Chornobyl Nuclear Power Plant accident caused radioactive contamination of water bodies within the Pripyat River floodplain, resulting in the accumulation of radionuclides by macrophytes, which are fundamental species in water ecosystems. Yellow water lily Nuphar lutea (L.) Smith., a macrophyte playing a significant role in the formation of vegetation cover in aquatic ecosystems, is commonly considered as a bioindicator of water pollution. In this study, we investigate the potential of N. lutea as an indicator of radionuclide contamination in water bodies, particularly through changes in its reproductive structures, such as pollen viability, morphology of pollen grains, seeds, and fruits. Our findings reveal that pollen viability remains stable at total absorbed dose rates below 14.4 μGy/h, with only 1-4% of sterile grains. However, beyond this threshold the percentage of sterile grains increases nearly fivefold, pointing to high internal plant exposure to 90 Sr. A similar trend was observed in the allometry and size of pollen grains, where small and flattened grains are formed in the reservoir with the highest external radiation dose rate (≥14.4 μGy/h). On the other hand, while morphometric parameters of fruits are influenced by radiation, their variation appears to be the result of a combination of physicochemical factors and the trophic status of a water body. Our research highlights the adverse impact of long-term radiation exposure on the male reproductive system of N. lutea and shows the potential of using the pollen grains sterility as an indicators of heavily radionuclide-contaminated water bodies. Additionally, we observed gradual changes in a pollen allometric length-to-width coefficient as the radiation dose level increases., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dmitri Gudkov reports financial support was provided by National Research Foundation of Ukraine. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The specificity of inhibition by 6,6′-dihydroxythiobinupharidine (DTBN) on cysteine proteases was demonstrated in this work. There were differences in the extent of inhibition, reflecting active site structural-steric and biochemical differences. Cathepsin S (IC50 = 3.2 μM) was most sensitive to inhibition by DTBN compared to Cathepsin B, L and papain (IC50 = 1359.4, 13.2 and 70.4 μM respectively). DTBN is inactive for the inhibition of Mpro of SARS-CoV-2. Docking simulations suggested a mechanism of interaction that was further supported by the biochemical results. In the docking results, it was shown that the cysteine sulphur of Cathepsin S, L and B was in close proximity to the DTBN thiaspirane ring, potentially forming the necessary conditions for a nucleophilic attack to form a disulfide bond. Covalent docking and molecular dynamic simulations were performed to validate disulfide bond formation and to determine the stability of Cathepsins-DTBN complexes, respectively. The lack of reactivity of DTBN against SARS-CoV-2 Mpro was attributed to a mismatch of the binding conformation of DTBN to the catalytic binding site of Mpro. Thus, gradations in reactivity among the tested Cathepsins may be conducive for a mechanism-based search for derivatives of nupharidine against COVID-19. This could be an alternative strategy to the large-scale screening of electrophilic inhibitors.

Little attention has been paid to how aquatic habitat characteristics affect the traits of plant species. Nuphar lutea (L.) Sm. is a keystone species distributed across temperate regions of Europe, northwest Africa and western Asia. Its apparently low phenotypic variability compared to other aquatic plants led us to test whether the species exhibited significant phenotypic variability and whether trait values correlated to environmental parameters. The hypotheses were that (1) the environmental variation within our set of wetlands (both water and sediment characteristics) led to significant variation among four sets of traits related respectively to growth, reproduction, defence and storage and (2) that nutrient limitation (nitrogen and especially phosphorus) should affect plant traits towards a higher investment in storage and defence and a lower investment in growth and reproduction, thereby negatively affecting the success of N. lutea. To test these hypotheses, 11 populations of N. lutea were sampled in wetlands differing in physicochemical characteristics and spread along three rivers. A total of 15 traits, grouped into four sets (growth, reproduction, storage and defence), were measured during the growing season. Most N. lutea traits were related to the environmental characteristics of wetlands. The growth and reproduction traits were mostly positively related to habitat resource conditions, whereas the defence traits were positively correlated with both ammonium concentration and temperature, outlining possible anoxic stress (habitat adversity). Nitrogen or phosphorus limitation led to the variation of only a few traits: the rhizome starch content was higher in phosphorus-limited wetlands, while the rhizome length and volume, and the number of flowers were higher in nitrogen-limited wetlands.

Chronic Kidney Disease (CKD) associated complications are associated with increased inflammation through the innate immune response, which can be modulated with anti-inflammatory agents. An active ingredient derived from the Nuphar lutea aquatic plant, 6,6'-dihydroxythiobinupharidine (DTBN) has anti-inflammatory properties, mainly through the inhibition of NF-κB. We tested the effects of DTBN on mice with CKD. After preliminary safety and dosing experiments, we exposed 8 weeks old male C57BL/6J mice to adenine diet to induce CKD. Control and CKD animals were treated with IP injections of DTBN (25 μg QOD) or saline and sacrificed after 8 weeks. Serum urea and creatinine were significantly decreased in CKD-DTBN Vs CKD mice. Kidney histology showed a decrease in F4/80 positive macrophage infiltration, damaged renal area, as well as decreased kidney TGF-β in CKD-DTBN Vs CKD mice. Kidney inflammation indices (IL-1β, IL-6 and P-STAT3) were significantly decreased in CKD-DTBN as compared to CKD mice. DTBN treatment showed no apparent damage to tissues in control mice, besides a decrease in weight gain and mild hypoalbuminemia without proteinuria. Thus, DTBN significantly improved renal failure and inflammation indices in CKD mice. Therefore, this and similar substances may be considered as an additional treatment in CKD patients., (© 2024. The Author(s).)

Little attention has been paid to how aquatic habitat characteristics affect the traits of plant species. Nuphar lutea (L.) Sm. is a keystone species distributed across temperate regions of Europe, northwest Africa and western Asia. Its apparently low phenotypic variability compared to other aquatic plants led us to test whether the species exhibited significant phenotypic variability and whether trait values correlated to environmental parameters. The hypotheses were that (1) the environmental variation within our set of wetlands (both water and sediment characteristics) led to significant variation among four sets of traits related respectively to growth, reproduction, defence and storage and (2) that nutrient limitation (nitrogen and especially phosphorus) should affect plant traits towards a higher investment in storage and defence and a lower investment in growth and reproduction, thereby negatively affecting the success of N. lutea. To test these hypotheses, 11 populations of N. lutea were sampled in wetlands differing in physicochemical characteristics and spread along three rivers. A total of 15 traits, grouped into four sets (growth, reproduction, storage and defence), were measured during the growing season. Most N. lutea traits were related to the environmental characteristics of wetlands. The growth and reproduction traits were mostly positively related to habitat resource conditions, whereas the defence traits were positively correlated with both ammonium concentration and temperature, outlining possible anoxic stress (habitat adversity). Nitrogen or phosphorus limitation led to the variation of only a few traits: the rhizome starch content was higher in phosphorus-limited wetlands, while the rhizome length and volume, and the number of flowers were higher in nitrogen-limited wetlands. [ABSTRACT FROM AUTHOR]

Premise of research. Although the Nymphaeaceae are an ancient angiosperm family, fossil leaves with nymphaeacean affinities from the Paleogene have nearly always been assigned to modern genera. Yet during the diversification of this group, it is extremely likely that transitional forms in this family evolved since its origin over 100 million years ago and should show up in the fossil record. Here, we describe an extinct genus of nymphaeacean leaf with transitional characters from the Eocene Lake Messel locality, which is, according to phylogenetic analysis, a member of the main Nymphaeaceae clade excluding Nuphar. Methodology. Over 39 fossil leaves from the Messel Pit near Darmstadt, Germany, were studied, coded for 40 of 55 morphological and leaf architecture characters, and analyzed phylogenetically. Analyses were run with PAUP* of the Messel leaf morphotype combined with living taxa and then together with previously described fossil Nymphaeales. Pivotal results. Inclusion of the Messel leaf with living taxa results in three trees with similar topology except for the relationship within Nuphar. Bootstrap data strongly support inclusion of the Messel leaf in the order Nymphaeales and the family Nymphaeaceae. In analyses with only living taxa, the Messel leaf places beyond Nuphar within the remaining Nymphaeaceae. In analyses with living and other fossil taxa, it places at the base of the Nuphar clade. Based on its suite of characters, the Messel leaf is recognized here as an intermediate between existing genera and described as a new extinct genus and species. Conclusions. The Eocene water lily from Messel is described here as a new genus and species, Nuphaea engelhardtii Gee and David W. Taylor gen. et sp. nov., and is represented by leaves with characters that are transitional to those of modern Nuphar , Nymphaea , and other Nymphaeaceae. This study offers new evidence of greater biodiversity in Nymphaeaceae in the Cenozoic. [ABSTRACT FROM AUTHOR]

The relationship between invasive plant functional traits and their invasiveness is still the subject of scientific investigation, and the backgrounds of transition from non-native to invasive species in ecosystems are therefore poorly understood. Furthermore, our current knowledge on species invasiveness is heavily biased toward terrestrial species; we know much less about the influence of allochthonous plant traits on their invasiveness in aquatic ecosystems. In this paper, we present the results of a study on physiological and ecological traits of two introduced and three native macrophyte species in the Mantua lakes system (northern Italy). We compared their photophysiology, pigment content, leaf reflectance, and phenology in order to assess how the invasive Nelumbo nucifera and Ludwigia hexapetala perform compared to native species, Nuphar lutea , Nymphaea alba , and Trapa natans. We found L. hexapetala to have higher photosynthetic efficiency and to tolerate higher light intensities than N. nucifera and the native species especially at extreme weather conditions (prolonged exposure to high light and higher temperatures). Chlorophyll a and b, and carotenoids content of both allochthonous species were substantially higher than those of native plants, suggesting adaptive response to the ecosystem of Mantua lakes system. Higher variability of recorded data in invasive species was also observed. These observations suggest advanced photosynthetic efficiency of the invasive species, especially L. hexapetala , resulting in faster growth rates and higher productivity. This was supported by the evaluation of seasonal dynamics mapped from satellite remote sensing data. This study provides empirical evidence for the relationship between specific plant physiological traits and invasiveness of aquatic plant species, highlighting the importance of trait studies in predicting ecosystem-level impacts of invasive plant species. [ABSTRACT FROM AUTHOR]

Direct or incidental ingestion of fruits or seeds by freshwater turtles can facilitate seed dispersal within and between bodies of water. Here, we evaluate Chrysemys picta (Eastern painted turtles) as a dispersal mode for hydrophytes and aimed to determine: 1) factors that drive diversity and abundance of egested seeds, 2) if certain regionally-common seed taxa more frequently occur in feces, and 3) assess the viability of seeds that passed through the turtle digestive system. Close to half of the turtles captured were found to egest seeds with a high proportion of these seeds (85–94%) apparently unaffected by the digestive process. In all, 5859 seeds (ranging from 1 to 1081 per feces) were recovered representing four plant taxa. Most seeds recovered from either pond, in terms of overall quantity, density, and frequency, were those of the locally-common Nymphaea odorata , followed by Nuphar variegata , suggesting these items may be actively targeted as food items. Analyses indicate neither turtle sex nor health had an effect on overall seed number or seed richness of feces. While germination levels varied by turtle and locality, defecated N. odorata seeds were capable of germinating at high capacities. When compared to control, however, trials suggest C. picta ingestion has an inhibitory effect. Our evidence supports a complementary bi-modal dispersal system implicating the mobile C. picta with hydrochory to enhance the transport of aquatic plants like N. odorata . The seed treatment and high mobility afforded by C. picta makes it an effective vector to overcome interpond limitations of hydrochory and ichthyochory, and potential seed mistreatment by some waterbirds. [ABSTRACT FROM AUTHOR]

Possible routes in which aquatic plants have spreaded across their vast ranges from ancestral areas and refugia still remain poorly known. We have chosen Eurasian yellow water-lilies ( Nuphar Sm. sect. Nuphar , Nymphaeaceae) as a model group for a wide-scale phylogeographical study as they represent a common component of the continental freshwater flora. To elucidate the history of diversification of the section Nuphar , we sequenced nuclear ribosomal ITS and chloroplast intergenic spacers ( trn H- psb A, trn L –trn F) from 117 localities from almost all the section area. Sequence data were analysed with a statistical parsimony approach using the network algorithm. We also incorporated data on morphological variation and pollen viability. The section Nuphar originated and diversified into several evolutionary lineages in Eastern Asia. Two lineages, represented by N. pumila and N. lutea , spread from the Russian Far East westwards to Siberia and further to Europe. Nuphar pumila also migrated from the Far East to North America (where it is referred to as N. microphylla ). Nuphar lutea colonized deglaciated north-eastern Europe not only from the south, but also from the Siberian refugia. Nuphar lutea and N. pumila hybridize rarely in Eastern Europe and Asia and warrant species status. We provide the first evidence, based on a phylogeographical approach, for the origin and diversification of aquatic flowering plants in Eastern Asia. Our results indicate that phylogeographic analysis on the area-wide scale is one of the most efficient ways to deduce possible routes in which aquatic plants have spread across their total range from ancestral areas and refugia. [ABSTRACT FROM AUTHOR]

Research was carried out on fruits and seeds of Nymphaea and Nuphar taxa collected from Poland, Latvia and Estonia. The aim of the research was to establish diagnostic features which could enable identification of the examined taxa on the basis of the fruit and seed structure and creating a key to identify them. The examined organs were observed through an optic microscope and scanning electron microscope (SEM). New diagnostic features were discovered: spotting of fresh pericarp, the range of the fruit shape coefficient, the colour of the rays in the fruit stigma disc, the thickness of the seed testa, ribs in the seeds, and occurrence of the “puzzle shaped” cells on the surface of the testa. The discovered features were used in the taxonomic characteristics.

The alkaloid from the yellow waterlily nuflein, whose preparation is described here, has cytotoxic activity against HeLa cervical cancer tumor cells. Suppression of the viability of normal fibroblasts requires nuflein concentrations 67 times greater than suppression of the viability of the same number of HeLa tumor cells. Cytotoxic activity is mediated by induction of the mitochondrial apoptosis pathway, as nuflein induces opening of mitochondrial pores and release of cytochrome c, which activates caspases. Nuflein also inhibits cellular energy generation due to uncoupling of oxidative phosphorylation in mitochondria and inhibition of mitochondrial respiration. The cytotoxic action of nuflein has been suggested to result from the properties of the sulfur atom in the thioether bond in the pharmacophore molecule. Utilization of the chemical properties of nuflein, allowing its steric structure to be 'tuned,' may lead to the creation of a whole series of probes with different activities directed at modifying or inhibiting biologically important thiols. The greater selectivity of the antiproliferative activity of nuflein in relation to tumor cells as compared with the known antitumor substance cisplatin points to a specific antitumor nature for the activity of nuflein. [ABSTRACT FROM AUTHOR]

An asymmetric total synthesis of (+)-6- hydroxythiobinupharidine (1b) and (-)-6-hydroxythionuphlutine (2b), a set of hemiaminal containing dimeric sesquiterpenes isolated from yellow water lilies of the Nuphar genus, is described. The central bis-spirocyclic tetrahydrothiophene ring was forged through the Stevens rearrangement of a sulfonium ylide, generated in situ from the coupling of a copper-carbene with a spirocyclic thietane. This strategy diverges both from the proposed biosynthesis¹ and previous syntheses of this family of alkaloids,2,3 all of which employ dimerization of symmetric monomers to form the aforementioned thiaspirane. The coupling of unsymmetrical monomers allowed access to the unsymmetrically oxidized product 2b for the first time. [ABSTRACT FROM AUTHOR]

A new genus and species, Notonuphar antarctica, is described from the Eocene of Seymour (Marambio) Island, the Antarctic Peninsula and assigned to the Nymphaeales based on well-preserved seeds. This is the first record of a water lily from Antarctica and the first record of a Gondwanan plant with close link to the genus Nuphar (Nymphaeaceae), which is restricted today to the Northern Hemisphere. Critical features for systematic placement of Notonuphar are the presence of a germination cap with closely spaced hilar scar and micropyle, anatropous, bitegmic and exotestal seed organization, exotesta composed of one cell layer of high sclerenchymatic palisade-shape cells, mesotesta of smaller, low parenchymatic cells, a few cell layers deep, and a thin tegmen. The seeds of Notonuphar are particularly similar to seeds of extant and fossil Nuphar in the straight, unfolded anticlinal wall of the exotestal cells and the presence of a narrow zone of exotestal tissue between hilum and micropyle. Other seed features including the very tall exotestal cells and strongly thickened cell walls of exotesta also link Notonuphar to Brasenia and related fossil taxa (Cabombaceae). This character mosaic observed in Notonuphar corroborates the transitional position of Nuphar between Cabombaceae and Nymphaeaceae. Notonuphar is the only member of Nymphaeales recorded from Antarctica and so far the only fossil seeds of Nymphaeales known from the Southern Hemisphere. The discovery of this extinct Gondwanan taxon with features suggesting close relationship with extant Northern Hemisphere genus Nuphar is a further evidence for the relictual nature of the extant group. [ABSTRACT FROM AUTHOR]

Nuphar submersa (Nymphaeaceae) is a critically endangered freshwater macrophyte indigenous to central Japan, with only four small extant populations represented across its entire range. We investigated the genotypic and genetic diversity as well as the genetic structure of all extant individuals of N. submersa based on analysis of 15 microsatellite loci. Among 278 individual ramets, 52 multilocus genotypes were detected: 30 genotypes in Nikko City (NIK), 18 in Nasukarasuyama City (NAS), 3 in Mooka City (MOK), and 1 in Sakura City (SAK). The average number of alleles per locus ranged from 1.20 to 1.93, whereas the observed and expected heterozygosities ranged from 0.11 to 0.33 and from 0.10 to 0.24, respectively. With the exception of SAK, all populations contained multiple clones, but our results indicated low levels of within-population genetic diversity. The populations NIK and NAS comprised few large or middle-sized genets and many small genets. The populations NIK and NAS were suggested to comprise large old, old fragmented, and/or young small genets resulting from seedling establishment. All four populations were differentiated, and gene flow between the populations was restricted (average level of gene flow ( Nm) = 0.122, G' = 0.639). Of the total genetic diversity, 67.20 and 9.13% were attributable to inter- and intra-population diversity, respectively. STRUCTURE analysis revealed two or three well-differentiated groups of populations. Cluster I comprised one population (NIK) and cluster II comprised the remaining populations at K = 2. The populations NIK, NAS, and the remaining populations were assigned to clusters I, II, and III, respectively, at K = 3. For conservation practices, we recommend that each cluster be regarded as a different management unit. We further suggest that artificial gene flow among MOK and SAK populations is an appropriate option, whereas NIK should not be reinforced with genotypes from the remaining populations. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the occurrence of micromycetes associated with disease symptoms on the leaves and flowers of three plant species, Nymphaea alba (NA), Nymphaea candida (NC), and Nuphar lutea (NL), forming nympheid phytocoenoses on Lake Płociczno in Drawa National Park during the years 2009 to 2012. From all collected plant specimens, an overall number of 38 distinct taxa of fungi and chromistan fungal analogues was isolated. The largest diversity of taxa was found on NL (37 taxa), the lowest was on NC (4 taxa), and NA contained 12 taxa. Each year, anamorphic forms of Ascomycota were dominant in the taxonomic structure. For the first time in Poland, Septoria nupharis (NA, NL, NC) and Colletotrichum nymphaeae (NL, NC) were found on their spotted leaves. For both of the mentioned pathogens, Nymphaea candida is a new host plant in Poland. Botrytis cinerea, Elongisporangium undulatum (= Pythium undulatum), Epicoccum nigrum, Fusarium incarnatum (= F. semitectum), and Gibberella avenacea (= Fusarium avenaceum) were found each year in the studied phytocoenoses. The confirmation of NA and NL flower infections by Botrytis cinerea, which leads to gangrene, is an important aspect of the gray mold epidemiology. Until now, the occurrence of smut fungi on nympheids in Drawa National Park was not observed. The taxonomic structure and the predomination of asexual stages of fungi, as well as the similarity coefficients, suggest that the seasonal decomposition of nympheids run naturally and contribute to maintaining the stability of the lake ecosystem.

Field studies and conceptual work on hybridization-mediated extinction risk in climate relicts are extremely rare. Nuphar pumila (Nymphaeaceae) is one of the most emblematic climate relicts in Europe with few isolated populations in the Alpine arc. The extent of introgression with related lowland and generalist species Nuphar lutea has never been studied using molecular methods. All biogeographical regions where N. pumila naturally occurs in the neighbourhood of the Alpine arc were sampled and studied using nuclear microsatellite markers. Furthermore, we used forward-in-time simulations and Approximate Bayesian Computation to check whether an introgression scenario fits with the observed admixture patterns and estimated the demographic parameters associated with this process. Our study confirms ongoing hybridization between N. pumila and N. lutea and validates it by the use of population models. More than 40 % of investigated N. pumila individuals were admixed and hybrids were found in over 60 % of studied populations. The introgression is bidirectional and is most likely a result of very recent gene flow. Our work provides strong evidence for rapid extinction risk and demographic swamping between specialized climatic relicts and closely related generalists. The remaining pure populations of N. pumila are rare in the Alpine arc and deserve high conservation priority. [ABSTRACT FROM AUTHOR]

Concise, scalable, and enantioselective formal syntheses of eight dimeric and three monomeric nuphar alkaloids were achieved, along with the construction of a stereochemically diverse collection of the first known monomeric analogues having apoptotic activity. The syntheses involved the development of highly enantioselective Brønsted acid catalyzed vinylogous Mukaiyama-Mannich reactions, which feature the unprecedented use of a supersilyl group to control the regio-, enantio- and diastereoselectivity. Biological studies reveal that several of these novel nuphar analogues are even more potent than their dimeric natural product counterparts. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the occurrence of micromycetes associated with disease symptoms on the leaves and flowers of three plant species, Nymphaea alba (NA), Nymphaea candida (NC), and Nuphar lutea (NL), forming nympheid phytocoenoses on Lake Płociczno in Drawa National Park during the years 2009 to 2012. From all collected plant specimens, an overall number of 38 distinct taxa of fungi and chromistan fungal analogues was isolated. The largest diversity of taxa was found on NL (37 taxa), the lowest was on NC (4 taxa), and NA contained 12 taxa. Each year, anamorphic forms of Ascomycota were dominant in the taxonomic structure. For the first time in Poland, Septoria nupharis (NA, NL, NC) and Colletotrichum nymphaeae (NL, NC) were found on their spotted leaves. For both of the mentioned pathogens, Nymphaea candida is a new host plant in Poland. Botrytis cinerea, Elongisporangium undulatum (= Pythium undulatum), Epicoccum nigrum, Fusarium incarnatum (= F. semitectum), and Gibberella avenacea (= Fusarium avenaceum) were found each year in the studied phytocoenoses. The confirmation of NA and NL flower infections by Botrytis cinerea, which leads to gangrene, is an important aspect of the gray mold epidemiology. Until now, the occurrence of smut fungi on nympheids in Drawa National Park was not observed. The taxonomic structure and the predomination of asexual stages of fungi, as well as the similarity coefficients, suggest that the seasonal decomposition of nympheids run naturally and contribute to maintaining the stability of the lake ecosystem. [ABSTRACT FROM AUTHOR]

Herein, we describe the first total syntheses of five members of the dimeric nuphar alkaloids: (+)-6,6′-dihydroxythiobinupharidine (+)- 1 a, (+)-6-hydroxythiobinupharidine (+)- 1 b, (−)-6,6′-dihydroxythionuphlutine (−)- 2 a, (−)-6,6′-dihydroxyneothiobinupharidine (−)- 3 a, and (+)-6,6′-dihydroxyneothionuphlutine (+)- 4 a. The latter two have not been found in nature. We have also made each of their enantiomers (−)- 1 a- b, (+)- 2 a, (+)- 3 a, and (−)- 4 a. The key step in these syntheses was the dimerization of an α-aminonitrile (a hydrolytically stable surrogate for its corresponding hemiaminal) with chiral Lewis acid complexes. We have also reassigned the literature structures of (+)- 1 a- 1 b-for those instances in which the NMR spectra were obtained in CD3OD-to their corresponding CD3O-adducts. Our efforts provide for the first time apoptosis data for (−)- 3 a, (+)- 4 a, and all five non-natural enantiomers prepared. The data indicate high apoptotic activity regardless of the enantiomer or relative stereochemical configuration at C7 and C7′. [ABSTRACT FROM AUTHOR]

A stereodivergent approach to the central thiolane subunit of Nuphar sesquiterpene thioalkaloids has been developed. This approach features a rhodium-catalyzed Stevens-type rearrangement in conjunction with an enzyme resolution reaction. Further elaboration into a polycyclic ring system via alcohol oxidation and ring-closing metathesis is also described. [ABSTRACT FROM AUTHOR]

Floral organ identity genes, most of which are MADS-box genes, play key roles in flower development and floral organ identity determination. To specify the identities of different floral organ types, proteins of the floral MADS-box genes need to form dimers and higher-level complexes before they bind to the control regions of downstream genes and regulate their expression. Previous studies have shown that understanding the evolution of the interactions among proteins of the floral MADS-box genes may be an excellent step towards uncovering the underlying mechanisms of the origin of the flower. Yet, due to the lack of such information in early-branching angiosperm lineages, it has been difficult to determine the evolutionary changes of the protein-protein interactions (PPIs) before and after the origin of the flower. In this study, we first isolated counterparts of the floral MADS-box genes from Nuphar pumila (Timm) D.C., a representative of the basalmost angiosperms Nymphaeales, and investigated the interactions among their proteins by carrying out yeast two-hybrid assays. We then estimated the PPIs in the most recent common ancestor of extant angiosperms by using two different methods: ancestral character state reconstruction and ancestral sequence reconstruction followed by yeast two-hybrid assay. Based on these results, we examined the evolutionary transitions of the PPIs before and after the occurrence of extant angiosperms, and discussed their contributions to the origin of the flower. We found that duplication and diversification of floral MADS-box genes, as well as non-random losses of some once-existed PPIs, have been the driving force of the origin of the flower. [ABSTRACT FROM AUTHOR]

Background Multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), cause serious infections at clinical sites, for which the development of new drugs is necessary. We screened candidates for new antibiotics and investigated its action mechanism. Methods An antimicrobial compound was isolated from an extract of Nuphar japonicum . Its chemical structure was determined by NMR, MS, and optical rotation. We measured its minimum inhibitory concentration (MIC) using the microdilution method. The effects of the compound on DNA gyrase and DNA topoisomerase IV were investigated with DNA supercoiling, decatenation, and cleavage assay. Results We isolated and identified 6,6′-dihydroxythiobinupharidine as the antimicrobial compound. The MIC of this compound was 1–4 μg/mL against various MRSA and VRE strains. We also demonstrated that this compound inhibited DNA topoisomerase IV (IC 50 was 10–15 μM), but not DNA gyrase in S. aureus , both of which are known to be the targets of quinolone antibiotics and necessary for DNA replication. However, this compound only exhibited slight cross-resistance to norfloxacin-resistant S. aureus , which indicated that DTBN might inhibit other targets besides topoisomerase IV. These results suggest that 6,6′-dihydroxythiobinupharidine may be a potent candidate or seed for novel antibacterial agents. Conclusions DTBN from N. japonicum showed anti-MRSA and anti-VRE activities. DTBN might be involved in the inhibition of DNA topoisomerase IV. General significance DTBN might be useful as a seed compound. The information on the inhibition mechanism of DTBN will be useful for the modification of DTBN towards developing novel anti-MRSA and anti-VRE drug. [ABSTRACT FROM AUTHOR]