Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water

• Lorenzo Catti,
• Shinji Aoyama and
• Michito Yoshizawa

Beilstein J. Org. Chem. 2024, 20, 32–40, doi:10.3762/bjoc.20.5

• H2O (2.7 mL), the suspension was sonicated with a probe sonicator (40 kHz, 150 W, 10 min), centrifuged (16,000g, 10 min), and then filtrated (200 nm pore-size membrane filter) to yield a clear brown solution containing host–guest composite (PA-OCH3)n·(C60)m. The UV–visible analysis clearly showed new

Identification of the p-coumaric acid biosynthetic gene cluster in Kutzneria albida: insights into the diazotization-dependent deamination pathway

• Seiji Kawai,
• Akito Yamada,
• Yohei Katsuyama and
• Yasuo Ohnishi

Beilstein J. Org. Chem. 2024, 20, 1–11, doi:10.3762/bjoc.20.1

• recent studies [9][10][11][12][13][14]. Most of them belong to the adenylate-forming enzyme superfamily (ANL superfamily) and utilize ATP to activate nitrous acid by AMPylation, with the only exception being AzpL in alazopeptin biosynthesis, which is a membrane protein that catalyzes diazotization

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• achieved, for example, by immobilizing the catalysts to a solid support [15], e.g., silica gel [16][17][18], organic polymers [19][20][21], magnetic nanoparticles [22][23], or by membrane separation, e.g., using organic solvent nanofiltration (OSN) [24][25][26], which methods can be easily implemented in

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• cell membrane integrity [21]. In the context of cancer therapy development, metal complexes of N-acylhydrazones stand out. For example, Firmino et al. demonstrated that gallium(III) complexes of isoniazid-derived hydrazones exhibit strong cytotoxicity against HL-60 and HCT-116 cancer cell lines [22

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• synthetic and biological membranes and therefore to induce an increase of membrane permeability. However, the effect of cholesterol (CHOL) content in the membrane on the CD permeabilizing effect was not considered yet. Given that an increase in CHOL content reduces the membrane permeability, the aim of this

• work was to reveal how CHOL would modulate the CDs effect on the membrane. Hence, liposomes made of dipalmitoyl phosphatidylcholine (DPPC) and various CHOL contents (DPPC/CHOL 100:10, 100:25, 100:50, and 100:100) encapsulating the hydrophilic fluorophore, sulforhodamine B (SRB), were prepared and

• exposed to the native CDs (α-CD, β-CD, γ-CD) and four β-CD derivatives: the randomly methylated-β-CD (RAMEB), the low methylated-β-CD (CRYSMEB), the hydroxypropyl-β-CD (HP-β-CD) and the sulfobutyl ether-β-CD (SBE-β-CD) at different CD/DPPC molar ratios (1:1, 10:1, and 100:1). The membrane permeability was

Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• often attributed to high binding affinity to DNA, interference with protein biosynthesis, induction of membrane leakage, and affecting GTPase activity in bacteria cell division [12][13][14][15]. Recent reports have also pointed to inhibition of the ‘filamenting temperature-sensitive mutant Z’ (FtsZ

• ]. Similar to berberine, results have demonstrated that the antibacterial activity of chelerythrine can be tied to DNA intercalation and disruption to cell membrane permeability [11][24]. One particular mechanism of action noted for chelerythrine’s antitumor bioactivity is through the inhibition of protein

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

• ) that exhibit promising anticancer properties renew the interest in this class of compounds. Indeed, ether lipid represent a new and promising class of compounds featuring the capacity to modulate selectively the activity of some membrane proteins or, for other compounds, feature antiproliferative

• the endoplasmic reticulum (ER). Then, ELs are spread off in the cell, to the plasma membranes but also in other biomembranes (membrane of mitochondria, ER, nucleus). The occurrence of ELs in tissues was first assessed by Snyder and Woods who reported that neutral ELs and phosphoglycero ELs were

• functions of ether lipids offer an interesting overview of the current knowledge of the effect of plasmalogen and ELs on membrane properties at a molecular scale. Shortly, according to molecular dynamics simulation, PE-plasmalogens form thicker, compressed and rigid bilayers when compared to PE-diacyl

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• . Carpenter and co-workers also proposed, but did not test, recycling their amine with electrochemistry and light [32]. They cited a work by Itoh et al. who modified a proton exchange membrane electrolyzer with a Rh–Pt catalyst to generate hydrogen from water to hydrogenate benzene to cyclohexane in one

• of artificial photosynthesis research investigating the compartmentalization of different reactions using liposomes and membranes [38]. Another alternative could be to use redox-active polymers as recyclable donors which would allow microporous membrane separation. Redox-active polymers are a very

• active area of research for aqueous and non-aqueous RFBs [59][60]. This is because often the most expensive component of an RFB is the ion-exchange membrane used to prevent the mixing of charged species and recombination. Microporous membranes are much less expensive, and the particulate size of redox

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• into the cell through membrane receptors and transporters. Eventually, the bound metal is released through reductive or hydrolytic mechanisms [2]. In the past years, β-proteobacteria have received increasing attention as producers of siderophores with interesting chemical features. For instance

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• in the cell membrane. Keywords: dipeptidyl peptidase enzyme; excimer; molecular dynamics simulations; phenanthridine; polynucleotide; pyrene; Introduction The design of small molecules that can selectively bind and discriminate different biomolecular structures (polynucleotides vs proteins, DNA or

• membrane (Figure S26, Supporting Information File 1). The compound showed not to be toxic to the HeLa cells as no visible damage was detected. Interactions of Phen-Py-1 and Phen-Py-2 with ds-polynucleotides and enzyme dipeptidyl peptidase III in an aqueous medium Interactions of Phen-Py-1 and Phen-Py-2

Recommendations for performing measurements of apparent equilibrium constants of enzyme-catalyzed reactions and for reporting the results of these measurements

• Robert N. Goldberg,
• Robert T. Giessmann,
• Peter J. Halling,
• Carsten Kettner and
• Hans V. Westerhoff

Beilstein J. Org. Chem. 2023, 19, 303–316, doi:10.3762/bjoc.19.26

• units used. All important aspects of the reactants, the reaction, and the catalyst should be included in the discussion, e.g., if reactants are bound to a membrane or surface or in equilibrium with a solid. 3.5. Definition of equilibrium constants and specification of standard states Attention to

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• charge upon chitosan coating enhances this membrane binding ability. However, there was no significant difference in IC50 values against HT29 cells between 6-O-capro-β-CD and CS-(6-O-capro-β-CD) groups. Due to the increased biological membrane interaction, the amount of drug transported into the cell may

• aliphatic groups on the surfaces of CD derivatives play a direct role in the interaction time with the cell and cell membrane components [50]. It is well established that positively charged nanoparticles interact with the cell membrane more favorably than negatively charged ones. However, their passing

• through the cell membrane is challenging because of the agglomeration of positive charge on the cell membrane [51]. This knowledge might explain why the 6-O-capro-β-CD nanoparticle IC50 values are lower at 48 hours than those of the poly-β-CD-C6 nanoparticles. Besides, chitosan coating on nanoparticles

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• –517. Keywords: Appel reaction; azidolysis; cholesterol; crystal structure; Walden inversion; Introduction 3β-Hydroxycholest-5-ene (cholesterol) is a structural and physiologic amphipathic steroid in human and animals as well. Cholesterol is an essential component of the plasma membrane, where it

• butter provide the body with its daily needs of cholesterol. In addition, hepatocyctes synthesize cholesterol through the mevalonate pathway. Dietary cholesterol is absorbed into the blood stream through a specific membrane bound protein named Niemann-Pick C1-Like 1 (NPC1L1) on the gastrointestinal tract

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

• Adwoa P. Nartey,
• Aboagye K. Dofuor,
• Kofi B. A. Owusu,
• Anil S. Camas,
• Hai Deng,
• Marcel Jaspars and
• Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

• hydrophilic biological environments. Repeated studies on the bioactivity of lipopeptides have shown that the primary mechanism of action of these peptides involves interactions with the double layer of lipids and proteins that constitute the cell membrane [24][25][26]. This mechanism of action is important

Inline purification in continuous flow synthesis – opportunities and challenges

• Jorge García-Lacuna and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 1720–1740, doi:10.3762/bjoc.18.182

• factors to consider [50]. In addition, these membranes are available in different sizes, and they can operate in series to improve separation. Some examples using them in a counter-current way and their application as solvent swap technology are also discussed below. Though examples of using membrane

• to another step. At this stage it appears that almost all reports use membrane separators at lab scale, which is a limitation of these membranes. Industrial applications often seek to intensify the workup process whereby an aqueous quench might be combined with an extraction, which necessitates

• membrane-based liquid–liquid separators the ability to gradually adjust the pH of the crude material stands out as an option to enable continuous purification. Though this approach does not apply to all substrates, it allows for tuning of parameters and sequential removal of impurities. Thorough

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• ][36]. The psammaplysin structure class has also had antimalarial [28], cytotoxicity [37] and antimicrobial data reported, albeit with low to moderate potencies [7]. More recently psammaplysin F and several semi-synthetic analogues have been shown to cause loss of mitochondrial membrane potential

Molecular and macromolecular electrochemistry: synthesis, mechanism, and redox properties

• Shinsuke Inagi and
• Mahito Atobe

Beilstein J. Org. Chem. 2022, 18, 1505–1506, doi:10.3762/bjoc.18.158

• , polymer electrolyte membrane electrolysis technology, and new methods coupled with photoredox catalysts or transition metal catalysis, resulting in remarkable progress in organic electrosynthetic processes. Theoretical calculations have also led to a better understanding of the electron transfer behavior

Make or break: the thermodynamic equilibrium of polyphosphate kinase-catalysed reactions

• Michael Keppler,
• Sandra Moser,
• Henning J. Jessen,
• Christoph Held and
• Jennifer N. Andexer

Beilstein J. Org. Chem. 2022, 18, 1278–1288, doi:10.3762/bjoc.18.134

• model enzymes for PPK1 and PPK2 [9][10]. From a structure perspective, PPK1 enzymes form tetramers in solution with a mass of approximately 80 kDa for the monomer (Figure 2b). Although not being an integral membrane protein, the enzyme is described to be membrane-associated [11][12][13]. The phosphate

• , clearly demonstrating the necessity of the residues for catalysis [14]. PPK2-I enzymes are of lower molecular weight than their PPK1 counterparts, with an approximate molecular mass of 40 kDa for a monomer (Figure 2c) [5]. They form dimers or tetramers in solution and are not purified from membrane

Synthesis of tryptophan-dehydrobutyrine diketopiperazine and biological activity of hangtaimycin and its co-metabolites

• Houchao Xu,
• Anne Wochele,
• Minghe Luo,
• Gregor Schnakenburg,
• Yuhui Sun,
• Heike Brötz-Oesterhelt and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1159–1165, doi:10.3762/bjoc.18.120

• growth occurred up to the highest concentration tested (256 µg/mL). In the Gram-negative Escherichia coli, the outer membrane protects the cells from the impact of 1. When the integrity of the outer membrane was compromised by adding the outer-membrane permeabilizing polymyxin B nonapeptide (PMBN, 10 μg

• lowest concentration of an antibacterial agent inhibiting visible bacterial growth (no turbidity detected by the naked eye) after overnight incubation. Only when the outer membrane was permeabilised by polymyxin B nonapeptide (PMBN), 1 inhibited growth of E. coli sufficiently to yield a clear MIC. GC

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• proton-exchange membrane reactor is described. The reduction of enones proceeded smoothly under mild conditions to afford ketones or alcohols. The reaction occurred chemoselectively with the use of different cathode catalysts (Pd/C or Ir/C). Keywords: enone; hydrogenation; iridium; palladium; PEM

• hydrogenation of enones using homogeneous and heterogeneous catalysts. Meanwhile, electrochemical systems using a proton-exchange membrane (PEM) reactor have been shown to be powerful tools for electrochemical hydrogenation [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. A PEM reactor

• consists of a membrane called a membrane electrode assembly (MEA), which can act as supporting electrolyte, electrode, and heterogeneous catalyst. Therefore, the further addition of a supporting electrolyte is not necessary for the electrochemical reactions using a PEM reactor, which offers clean and

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• suggest their participation in this step. Ady6 shows weak homology to DUF4260 (PF14079.9), a family of integral membrane proteins with unknown functions, while Ady8 is similar to the ferritin-like superfamily protein (IPR009078). Ady6/Ady8 are homologous to VlmO/VlmB and SRO_1835/SRO_1837 in the

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• , 20 mM imidazole, pH 8.0). After ultrasonic cell crushing, the cells were centrifuged at 24,000 rpm for 60 min to remove cell fragments. The supernatant was filtered through 0.22 μm of the filter membrane and then loaded into the nickel column of the rebalanced lysate (HisTraqTM FF, GE Healthcare

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• from the anodic electroactivity of the electrogenerated carbene. In order to have NHC accumulation in the catholyte, the Nafion membrane (cell separator) was pretreated with an alkaline solution. The formation of NHC was quantified as its reaction product with elemental sulfur. The NHC was successfully

• -permeable membrane (Nafion® 438) was inserted to separate the cathode and anode chambers, and a spacer was used on each compartment [36]. The initial goal of this work was to demonstrate the possibility to achieve NHC formation starting from 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4), by

• membrane, under N2 atmosphere, at room temperature, under galvanostatic conditions (I = 134 mA) with continuous flow rate of 36 mL/min, studying the effect of cathode material, anode solution and number of Faradays per mole of IL supplied (Table 1). At the end of the electrolysis, excess elemental sulfur

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• and, thus, a large interface between the phases. Subsequently, the biphasic system is directly separated, employing a PTFE membrane separator, to afford a solution of isoamyl acetate in n-heptane, while the aqueous layer containing the lipase could be recycled. At 60 °C with a residence time of 8.6

• formation of hydrazone 28. As one equivalent of water is formed in this condensation process, which is detrimental for the subsequent Shapiro reaction, water is continuously removed by in-line separation of the reaction mixture using a PTFE-membrane separator. The organic layer is then mixed with a solution

• %. Thus, Brenna and co-workers developed a cis-selective synthesis of 54 via a biocatalytic process in flow (Scheme 12) [45]. In the first step, a mixture of cyclohexanone 51, NADH, and isopropanol in an aqueous phosphate buffer (pH ≈ 7) is pumped through a continuously stirred membrane reactor at 30 °C

Identification of the new prenyltransferase Ubi-297 from marine bacteria and elucidation of its substrate specificity

• Jamshid Amiri Moghaddam,
• Huijuan Guo,
• Karsten Willing,
• Thomas Wichard and
• Christine Beemelmanns

Beilstein J. Org. Chem. 2022, 18, 722–731, doi:10.3762/bjoc.18.72

• binding abilities to target proteins [3]. The prenylation reaction, most often a C–C-bond-forming step between an aromatic acceptor moiety and a prenyl chain, is catalyzed by dedicated dominantly membrane-bound prenyltransferases (Ptases) [4][5][6][7]. Ptases belonging to the UbiA-superfamily are

• % pairwise identity) displayed similarities to geranylgeranylglyceryl phosphate synthases (EC 2.5.1.42), which are involved in the formation of polar membrane lipids of archaea and other bacteria [20], while group G4 contained close homologs of the protoheme IX farnesyltransferase (EC 2.5.1.141) (23–100

• (33% identity) and a 4-hydroxybenzoate octaprenyltransferase (ubiquinone-8 (UQ-8), 23% identity) from Shewanella woodyi ATCC 51908. Additionally, UbiA-297 showed sequence identity to a membrane-bound Ptase from the plant Avena sativa (31%) [26]. We then compared the genetic environment of the coding