New taxa and combinations in Malvastrum A. Gray (Malvaceae: Malveae)

The genusMalvastrum A. Gray is interpreted to include 22 taxa in 14 species. Seven taxa are here described as new, namely:M. americanum var.stellatum,M. tomentosum subsp.pautense,M. bicuspidatum subsp.campanulatum,M. bicuspidatum subsp.oaxacanum, M. bicuspidatum subsp.tumidum var.tumidum, M. bicuspidatum subsp.tumidum var.glabrum, andM. coromandelianum subsp.fryxellii. In addition, two new combinations are proposed, namely:M. tomentosum andM. coromandelianum subsp.capitato-spicatum.     

Revision of Plerandra (Araliaceae). I. A synopsis of the genus with an expanded circumscription and a new infrageneric classification

Phylogenetic studies have demonstrated that Schefflera, the largest genus of Araliaceae, is grossly polyphyletic, comprising five distinct clades within the family. In an effort to establish monophyletic genera among the elements that currently comprise Schefflera, the genus Plerandra is expanded to encompass all of the members of one of these clades. In this synoptical revision, a new infrageneric classification is presented (along with a key) in which six subgenera are recognized. Four of these subgenera are newly described (Plerandra subgenera Canacoschefflera, Costatae, Gabriellarum, and Veilloniorum) and a fifth represents a new combination (Plerandra subg. Dizygotheca). A total of 33 species (one with two subspecies) are accepted, one of which is newly described (P. veilloniorum), and 22 new combinations are made (P. actinostigma, P. baillonii, P. cabalionii, P. costata, P. crassipes, P. elegantissima, P. elongata, P. emiliana, P. gabriellae, P. leptophylla, P. nono, P. osyana, P. osyana subsp. toto, P. pachyphylla, P. pancheri, P. plerandroides, P. polydactylis, P. reginae, P. seemanniana, P. tannae, P. vanuatua, P. veitchii). Neotypes are provided for six accepted names and one heterotypic synonym, and lectotypes are designated for 13 accepted names and 16 heterotypic synonyms. For each accepted species, full synonymy is provided along with geographic range and notes.     

Synthesis of some quinolinyl chalcone analogues and investigation of their anticancer and synergistic anticancer effect with doxorubicin

Two derivatives of 2-(4-acetylanilino)quinolines (IIIa, b) were synthesized as scaffolds for synthesis of open chalcone analogues (Va-f) through Claisen-Schmidt condensation with a set of aromatic aldehydes (IVa-d). Derivatives (Va, b) were further manipulated into cyclic ??,??-unsaturated ketones by Michael-addition of acetylacetone and ethylacetoacetate affording derivatives (VI?CVII). Deethoxycarboxylation of derivatives (VIIa, b) afforded cyclohexenons (VIIIa, b) allowing formation of a mini library of ??,??-unsaturated ketones for screening their anticancer and synergistic anticancer effect with doxorubicin using colon cancer cell line (Caco-2). Two open enones, (Vb) and (Ve), showed significant anticancer activity with IC₅₀ of 5.0 and 2.5 ??M respectively. Only one cyclic enone, (VIa) showed synergistic anticancer activity with doxorubicin at 10 ??M.     

Enhanced β-turn conformational stability of tripeptides containing ΔPhe in cis over trans configuration

Conformations of three pairs of dehydropeptides with the opposite configuration of the ΔPhe residue, Boc-Gly-Δ^Z/EPhe-Phe-p-NA (Z- p -NA and E- p -NA), Boc-Gly-Δ^Z/EPhe-Phe-OMe (Z-OMe and E-OMe), and Boc-Gly-Δ^Z/EPhe-Phe-OH (Z-OH and E-OH) were compared on the basis of CD and NMR studies in MeOH, TFE, and DMSO. The CD results were used as the additional input data for the NMR-based calculations of the detailed solution conformations of the peptides. It was found that Z- p -NA, E- p -NA, Z-OMe, and Z-OH adopt the β-turn conformations and E-OMe and E-OH are unordered. There are two overlapping type III β-turns in Z- p -NA, type II’ β-turn in E- p -NA, and type II β-turn in Z-OMe and Z-OH. The results obtained indicate that in the case of methyl esters and peptides with a free carboxyl group, Δ^ZPhe is a much stronger inducer of ordered conformations than Δ^EPhe. It was also found that temperature coefficients of the amide protons are not reliable indicators of intramolecular hydrogen bonds donors in small peptides.     

New variety and nomenclatural changes in neotropical Gaultheria (ericaceae)

Gaultheria sclerophylla var.hirsuta Luteyn from Ecuador is described, illustrated, and discussed, and the following new combinations are validated:Gaultheria buxifolia var.elassantha (A. C. Smith) Luteyn,G. buxifolia var.secunda (E. J. Remy) Luteyn,G. lanigera var. rufolanata (Sleumer) Luteyn,G. strigosa var.revoluta (A. C. Smith) Luteyn,G. eriophylla var.mucronata (E. J. Remy) Luteyn,G. alnifolia var.grata (A. C. Smith) Luteyn,G. serrata (Vell. Conc.) Sleumer ex Kinoshita-Gouvêa.     

Photophysics of novel coumarin-labeled depsipeptides in solution: sensing interactions with SDS micelle via TICT model

N-Acylbenzotriazoles enable the synthesis (69–92 % yield) of blue to green fluorescent coumarin-labeled depsidipeptides 8a–f (quantum yields 0.004–0.97) and depsitripeptides 12a–d (quantum yields 0.02–0.96). Detailed photophysical studies of fluorescent coumarin-labeled depsipeptides 8a–f and 12a–d are reported for both polar protic and polar aprotic solvents. 7-Methoxy and 7-diethylaminocoumarin-3-ylcarbonyl depsipeptides 8c,f and 12d are highly solvent sensitive. These highly fluorescent compounds could be useful for peptide assays. Further photophysical studies of 7-diethylaminocoumarin-labeled depsipeptides 8c,12d within the micellar microenvironment of SDS reflect their ability to bind with the biological membrane, suggesting potential applications in the fields of bio- and medicinal chemistry.     

New combinations for Panicum subgenus Panicum and subgenus Dichanthelium (Poaceae) of the Southeastern United States

Twenty-two new varietal combinations are made for the treatment of the genusPanicum of the Southeastern United States. The following 3 new combinations are made in the subgenusPanicum:Panicum rigidulum var.elongatum, P. rigidulum var.pubescens, P. rigidulum var.combsii. The following 19 new combinations are made in the subgenusDichanthelium:P. strigosum var.glabrescens P. strigosum var.leucoblepharis, P. dichotomum var.roanokense, P. dichotomum var.lucidum, P. dichotomum var.ramulosum, p. dichotomum var.mattamuskeetense, P. dichotomum var.yadkinense, P. ensifolium var.curtifolium, P. chamaelonche var.breve, P. portoricense var.nashianum, P. acuminatum var.fasciculatum, P. acuminatum var.unciphyllum, P. acuminatum var.columbianum, P. acuminatum var.lindheimeri, P. acuminatum var.densiflorum, P. acuminatum varlongiligulatum, P. acuminatum var.leucothrix, P. ovale var.pseudopubescens, andP. ovale var.villosum.     

New taxa and combinations in neotropical Juncus (Juncaceae)

Juncus arequipensis andJ. breviculmis are described as new species, andJ. ramboi subsp.colombianus as a new subspecies.Juncus arcticus Willd. var.mexicanus (Willd.), var.montanus (Engelm.), and var.andicola (Hook.) are proposed as new combinations.     

Density functional studies on photophysical properties and chemical reactivities of the triarylboranes: effect of the constraint of planarity

The geometric and electronic structures, absorption spectra, transporting properties, chemical reactivity indices and electrostatic potentials of the planar three-coordinate organoboron compounds 1-2 and twisted reference compound Mes ₃ B, have been investigated by employing density functional theory (DFT) and conceptual DFT methods to shed light on the planarity effects on the photophysical properties and the chemical reactivity. The results show that the planar compounds 1-2 exhibit significantly lower HOMO level than Mes ₃ B, owing to the stronger electronic induction effect of boron centers. This feature conspicuously induces a blue shifted absorption for 1, although 1 seemingly possesses more extended conjugation framework than Mes ₃ B. Importantly, the reactivity strength of the boron atoms in 1-2 is much lower than that in Mes ₃ B, despite the fact that the tri-coordinate boron centers of 1-2 are completely naked. The interesting and abnormal phenomenon is caused by the strong p-π electronic interactions, that is, the empty p-orbital of boron center is partly filled by π-electron of the neighbor carbon atoms in 1-2, which are confirmed by the analysis of Laplacian of the electron density and natural bond orbitals. Furthermore, the negative electrostatic potentials of the boron centers in 1-2 also interpret that they are not the most preferred sites for incoming nucleophiles. Moreover, it is also found that the planar compounds 1-2 can act as promising electron transporting materials since the internal reorganization energies for electron are really small.

Nomenclatural changes in Myrteola and Myrceugenia (Myrtaceae)

The following new combinations are made:Myrteola phylicoides (Benth.) Landrum,Myrteola phylicoides var.glabrata (Berg) Landrum,Myrceugenia alpigena var.fuliginea (Berg) Landrum,Myrceugenia ovata var.regnelliana (Berg) Landrum, andMyrceugenia pilotantha var.nothorufa (Legrand) Landrum.     

New taxa and nomenclatural changes in arceuthobium (viscaceae)

The following new taxa are recognized inArceuthobium: subgeneraArceuthobium andVaginata; sectionsVaginata, Campylopoda, andMinuta; seriesCampylopoda,Rubra, andStricta; speciesA. apachecum,A. californicum,A. guatemalense,A. hondurense, andA. pini; new formae spécialesA. abietinum f. sp.concoloris,A. abietinum f. sp.magnificae. New combinations:A. abietinum (Engelm.) Hawksworth & Wiens, andA. microcarpum (Engelm.) Hawksworth & Wiens.     

New combinations and one new variety among the genera Indigofera,Robinia, and Tephrosia (Leguminosae)

This report includes: a new variety,Indigofera miniata var.florida, and five new combinations.I. mucronata var.keyensis, Robinia hispida var.kelseyi, Tephrosia angustissima var.corallicola, T. angustissima var.curtissii, andT. × floridana.     

Synthesis of modified fragments of fibrinogen and their effect on the activity of proteolytic enzymes

New analogues of the Gly-Pro-Arg and Arg-Gly-Asp fragments of fibrinogen were synthesized: Gly-Pro-Arg-Pro (I), Gly-Pro-Arg-Pro-Met-OMe (II), Gly-Pro-Arg-Pro-Phe (III), Gly-Pro-Arg-Pro-Asp (IV), Gly-Pro-Arg-Pro-Glu (V), and Arg-Asn-Trp-Asp (VI). Their effect on the activity of proteases of various types was studied with the method of lysis of fibrin plates. All the peptides were found to inhibit plasmin activity (by 60–85%) and the γ-subunit of nerve growth factor (by 55–93%). Tetrapeptide (VI) proved to be an effective inhibitor of tissue activator of plasminogen and the γ-subunit of nerve growth factor (by 96 and 93%, respectively). The peptides exerted practically no effect on the activity of urokinase and moderately inhibited the activity of streptokinase [(III), IV), and (VI)], papain [(I), (II), IV), and (VI)], subtilisin [(V) and (VI)], α-chymotrypsin [(III), (V), and VI)], and Bacillus subtilis metalloprotease (VI). They inhibit trypsin [except for (I) and (III)] when applied on fibrin plates at a concentration of 1 × 10^?2 M, while, at the concentration of 1 × 10^?3 M, (I) and (II) induced an increase in proteolytic activity by 35 and 47%, respectively.     

Driving and retarding forces in a chemical reaction

The reaction force F(ξ) is the negative gradient of the potential energy of a chemical process along the intrinsic reaction coordinate ξ. We extend the rigorous concept of F(ξ) to the “activation strain model” of Bickelhaupt et al., to formulate the “strain” force F _str(ξ) that retards a reaction and the “interaction” force F _int(ξ) that drives it. These are investigated for a group of Diels-Alder cycloadditions. The results fully support the interpretation of the minimum of F(ξ) as defining the beginning of the transition from deformed reactants to eventual products.     

Mycopteris,a new neotropical genus of grammitid ferns (Polypodiaceae)

Mycopteris, a new genus of grammitid ferns, is described and combinations are made for the species that belong to it. Mycopteris is diagnosed by castaneous rhizome scales with turgid cells, usually pectinate laminae, blackish petioles and rachises, blackish pinna costae and veins, reddish setae, cretaceous hydathodes, glabrous sporangia, and the presence of Acrospermum ascomes. It is entirely neotropical, ranging from Mexico east into the West Indies and south to Bolivia. Mycopteris is one of two genera of grammitid ferns that are consistently associated with Acrospermum, an epibiotic ascomycete that produces black clavate fruiting bodies. Seventeen species of Mycopteris are recognized here, including one new species (M. longipilosa) and one elevated from the rank of variety to species (M. costaricensis). The following additional combinations are made here: M. alsopteris, M. amphidasyon, M. attenuatissima, M. cretata, M. grata, M. leucolepis, M. leucostica, M. longicaulis, M. pirrensis, M. praeceps, M. semihirsuta, M. steyermarkii, M. subtilis, M. taxifolia, and M. zeledoniana. Lectotypes are chosen for Ctenopteris leucosticta, Polypodium amphidasyon, and Polypodium pectinatum var. hispidum. For each accepted species, full synonymy and geographical range are provided. Taxonomic discussion is provided for species not widely recognized in previous treatments.     

New species and combinations in neotropical Lecythidaceae

Lecythis barnebyi Mori andCorythophora amapaensis Pires ex Mori & Prance are described and the following new combinations are coined:Lecythis brancoensis (R. Knuth) Mori,L. schwackei (R. Knuth) Mori,L. alutacea (A. C. Smith) Mori,L. lurida (Miers)Mori, L. holcogyne (Sandwith)Mori, L. corrugata Poiteau subsp.rosea (Spruce ex Berg) Mori, andCorythophora labriculata (Eyma) Mori & Prance.     

New genera and species of ericaceae (Vaccinieae) from Costa Rica and Panama

Two new monotypic genera,Didonica andUtleya, are described, withD. pendula from Panama andU. costaricensis from Costa Rica.Disterigma trimera (Panama),D. utleyorum (Costa Rica, Panama, Colombia, and Ecuador),Lateropora santafeensis (Panama),Lysiclesia panamensis (Panama),Macleania talamancensis (Costa Rica),Themistoclesia costaricensis (Costa Rica) andT. horquetensis (Panama),Vaccinium costaricense andV. orosiense (both from Costa Rica) and V.jefense (Panama) are all described as new. New combinations are provided for the PanamanianVaccinium floccosum (=Symphysia floccosa) and the West IndianVaccinium racemosum (=Symphysia racemosa). Keys are provided for the Central American species ofDisterigma andThemistoclesia, the species ofLateropora andLysiclesia, and the Costa Rican and Panamanian species ofVaccinium. Six new species are illustrated.     

Synthesis of 1,6-Diaryl-5,7-dioxo(dithio)imidazo[1,2-a] [1,3,5]triazines. A Novel Pathway for Imidazo[1,2-a] [1,3,5]triazine Systems Obtained via 1-(Imidazolin-2-yl)urea and Thiourea Derivatives

Novel 1,6-diaryl-5,7(1H)dioxo(dithio)-2,3-dihydroimidazo[1,2-a][1, 3, 5]triazines 8, and 9 were synthesized by cyclization of the respective 1-(imidazolin-2-yl)ureas 4 or thioureas 6 with phosgene or thiophosgene in the presence of bases. 1-Aryl-2-aminoimidazolines 1 reacting with arylisocyanates 2 or arylisothiocyanates 3 form a mixture of isomeric imidazolin-2-yl 4 and 6 and imidazolin-3-yl 5 and 7 urea or thiourea derivatives. Isomers 4 and 6 can be easily separated and used for the cyclization reaction. The structures of the main intermediates and the final target compounds were confirmed by ¹H-NMR spectral analysis. Discussion of the possible course of the reactions is also presented.     

Generic delimitations of Central American Bignoniaceae

Generic delimitations in the Bignoniaceae are discussed, a number of Central American genera are reduced to synonymy, and a new genusPseudocatalpa is proposed. Generic mergers includeLevya withCydista, Saldanhaea withCuspidaria, Doxantha withMacfadyena, Pseudocalymma withPachyptera, andPhaedranthus withDistictis. New combinations necessitated by these mergers include the following:Arrabidaea costaricensis (Kränzl.) Gentry,A. pubescens (L.) Gentry,Cuspidaria floribunda (DC.) Gentry,C. weberbaueri (Spr.) Gentry,Cydista aequinoctialis var.hirtella (Benth.) Gentry,Distictis buccinatoria (DC.) Gentry,Macfadyena unguiscati (L.) Gentry,Melloa quadrivalvis (Jacq.) Gentry,Pachyptera alliacea (Lam.) Gentry,P. hymenaea (DC.) Gentry,P. kerere var.incarnata (Aubl.) Gentry,P. standleyi (Steyerm.) Gentry, andPseudocatalpa caudiculata (Standl.) Gentry. In addition, the fruits of several species are described for the first time, and their taxonomic significance is discussed.     

New taxa from the Venezuelan Guayana

Seven new taxa, mainly from the Guayana Highland of Venezuela, are described. These include four new species (Cottendorfia atrorosea, Navia emergens, Navia ovoidea, and Pitcairnia nematophora) and one new variety (Cottendorfia brachyphylla var. angustior) of Bromeliaceae, one new species (Swartzia cowanii) of Leguminosae, and one new species (Marlierea pudica) of Myrtaceae.