Isolation and structure determination of a new analog of polycavernosides from marine Okeania sp. cyanobacterium

• Kairi Umeda,
• Naoaki Kurisawa,
• Ghulam Jeelani,
• Tomoyoshi Nozaki,
• Kiyotake Suenaga and
• Arihiro Iwasaki

Beilstein J. Org. Chem. 2024, 20, 645–652, doi:10.3762/bjoc.20.57

• from a marine Okeania sp. cyanobacterium. The relative configuration was elucidated primarily by analyzing the two dimensional nuclear magnetism resonance (2D NMR) data. The absolute configuration was clarified by comparing the electronic circular dichroism (ECD) data of 1 with those of known analogs

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• inapplicability of the NOESY experiment. To establish the absolute configuration of compound 1, electron circular dichroism (ECD) calculations were conducted using the time-dependent density functional theory (TDDFT) approach at a B3LYP/6-311G (d,p) (IEFPCM) level (Figure 4). Considering the uncertainty of the

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• using a similar principle [24]. The protection from the solvent of the intercalated Pt guest enables its fluorescence emission and is accompanied by the induction of chirality in the resulting host–guest complex. A significant enhancement of the circular dichroism response of the chiral guest is

• enantiomers (P,P) and (M,M) were separated by chiral HPLC and displayed opposite circularly polarized luminescence (CPL) and electronic circular dichroism (ECD) properties. The addition of ZnCl2 switched the system from a compact conformation to an extended conformation, resulting in a modulation of the

• that enables monitoring by circular dichroism. Upon the addition of Ca(II), a large increase in the binding affinity for halide ions was observed due to the folding of the receptor in a helicoidal form that enabled cooperative interaction with both urea moieties. More flexible coordination responsive

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• multiple chromophore units induces complexity in the interpretation of the resulting circular dichroism (CD) spectra because of the overlap of several exciton couplets. Thus, exciton coupling CD signals were not discernible for 51–55. Further, regarding 56, the exciton coupling CD signal in the ICT region

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• within the binding site. The binding mode of the benzo[c]quinolizinium derivatives 3c,e–g with DNA was further examined with circular dichroism (CD) and linear dichroism (LD) spectroscopy (Figure 6 and Supporting Information File 1, Figures S12–S14). Hence, with increasing ligand-DNA ratio (LDR) weak

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• were obtained on a Jasco J−815 circular dichroism spectrometer (JASCO, Tokyo, Japan). Semi-preparative HPLC was carried out using an Agilent 1260 chromatograph with a 250 mm × 10 mm column, i.d., 5 μm, SEP Basic 120 C18. HRESIMS were measured on a SCIEX X500R QTOF MS spectrometer (Shimadzu Corporation

Asymmetric tandem conjugate addition and reaction with carbocations on acylimidazole Michael acceptors

• Brigita Mudráková,
• Renata Marcia de Figueiredo,
• Jean-Marc Campagne and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 881–888, doi:10.3762/bjoc.19.65

• determined by comparison of experimentally measured electronic circular dichroism (ECD) spectra with those of the DFT-calculated ones (Figure 1 and see Supporting Information File 1 for more details). CD spectra were calculated for the two most populated conformers for both diastereomers of product 4. The

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

• -peptide small molecules, leading to the isolation of six new and three known compounds (Figure 1) from its extract. These structures were determined by 1D and 2D NMR spectra and the experimental and calculated electronic circular dichroism (ECD) spectra. The six new compounds have been named kronopoone A

• obtained using a Shimazu LC-20 CE AB SCIEX QTOF X500R MS spectrometer (Shimadzu Corporation, Tokyo, Japan). Optical rotations (ORD) were collected with a Horiba SEPA-300 polarimeter. Ultraviolet (UV) and circular dichroism (CD) spectra were carried out on a Jasco J-815 CD spectrometer (JASCO). Column

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• 121 in a high yield. Due to the two conformations of cyclooctatetraene saddles, NG 121 is a chiral structure and optically pure enantiomers were separated using chiral high-performance liquid chromatography (HPLC), which featured a perfect mirror-image circular dichroism (CD) for both enantiomers

• = 844 000 M−1 cm−1 at 573 nm). A pair of enantiomers, (M,M)- and (P,P)-configuration was revealed by single crystal X-ray diffraction and optically pure samples of 125 were isolated by chiral HPLC. Meanwhile, a record high electronic circular dichroism (ECD) signal in the visible spectral range (Δε

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• UV–vis spectrophotometer. ECD spectra were acquired on a JASCO J-1500 circular dichroism spectrometer. FTIR spectra were obtained using a PerkinElmer FTS FT-IR spectrophotometer. NMR spectra were obtained on a Bruker NEO 500 MHz NMR Ultra Shield. Chemical shifts are referenced in parts per million (δ

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

• -dependent, and the flexibility of the linker can alter that [13]. Further, pyrene-guanidiniocarbonylpyrrole discriminated DNA and RNA by different spectroscopic (induced circular dichroism signal and fluorescent signal) responses [14]. Also, we recently reported a pyrene–quinoline conjugate molecule that

• and probability of contact, including steric shielding and charge–charge interactions [41]. Circular dichroism (CD) experiments CD spectroscopy was chosen to monitor conformational changes of polynucleotide's secondary structure induced by small molecule binding [42]. Compounds Phen-Py-1 and Phen-Py-2

CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview

• Dileep Kumar Singh

Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29

• ascorbate in DMSO (Scheme 9). According to UV–vis and circular dichroism (CD) spectrum measurements, the authors state that the formation of the dimer of porphyrin 50 can be attributed to DNA hybridization and through-space electronic interactions. In this investigation, it was found that the DNA serves as

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• compound was determined based on calculated electronic circular dichroism (ECD) spectra that were compared to the experimental ECD spectra of (+)-1 and (+)-2. Although these natural products did not exhibit antimicrobial activity or cytotoxicity against HeLa cells, their biological activities in other

Characterization of a new fusicoccane-type diterpene synthase and an associated P450 enzyme

• Jia-Hua Huang,
• Jian-Ming Lv,
• Liang-Yan Xiao,
• Qian Xu,
• Fu-Long Lin,
• Gao-Qian Wang,
• Guo-Dong Chen,
• Sheng-Ying Qin,
• Dan Hu and
• Hao Gao

Beilstein J. Org. Chem. 2022, 18, 1396–1402, doi:10.3762/bjoc.18.144

• derived from 1, the relative configuration of 4 was assigned as 2S*,3S*,10R*,11R*. And as the experimental electronic circular dichroism (ECD) spectrum of 4 resembled the calculated ECD spectrum of (2S,3S,10R,11R)-4, the absolute configuration of 4 was determined to be 2S,3S,10R,11R (Supporting

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• -dependent density functional theory/electronic circular dichroism (TDDFT-ECD) calculations or X-ray diffraction analysis. A plausible biosynthetic pathway of these sesquiterpenoids and their internal correlation were proposed and discussed. In an in vitro bioassay, (+)-aristolone (3) exhibited promising

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• carbohelicenes has led to the synthesis of double, triple, quadruple, quintuple, and sextuple molecules, the chiro-optical properties of these molecules, such as their circular dichroism (CD) and circularly polarized luminescence (CPL), have also been widely studied [1][2][3][4][5][6][7][8]. The development of

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• electronic circular dichroism (ECD) data with those of compound 3, whereas that of compound 2 was proposed based on biosynthetic considerations. The structures of the known compounds were further confirmed by comparison of their 1H and 13C NMR spectroscopic data, specific rotations, and ECD data with those

Synthesis and bioactivity of pyrrole-conjugated phosphopeptides

• Qiuxin Zhang,
• Weiyi Tan and
• Bing Xu

Beilstein J. Org. Chem. 2022, 18, 159–166, doi:10.3762/bjoc.18.17

• dephosphorylation of 6b (Supporting Information File 1, Figure S33) after the addition of ALP. In addition to the TEM images, we used circular dichroism (CD) to reveal the secondary structures of the assemblies before and after enzymatic action. The spectra show a significant change in the signal upon ALP treatment

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• moreover, explains the increased binding affinity to β-catenin as P5 is more likely to be found in an active conformation. Analysis of the secondary structure by circular dichroism: CD spectra of both isomers of stapled peptide P5 (P5.1 and P5.2) and linear references (aAxWt, P6) (c = 100 µM) at 20 °C in

Nomimicins B–D, new tetronate-class polyketides from a marine-derived actinomycete of the genus Actinomadura

• Zhiwei Zhang,
• Tao Zhou,
• Taehui Yang,
• Keisuke Fukaya,
• Enjuro Harunari,
• Shun Saito,
• Katsuhisa Yamada,
• Chiaki Imada,
• Daisuke Urabe and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2194–2202, doi:10.3762/bjoc.17.141

• (Table S1, Supporting Information File 1) and 3JHH coupling constants [15]. The absolute configuration of 1 was deduced to be the same as 4 in consideration of the overall similarity of the electronic circular dichroism (ECD) spectra of 1 and 4 (Figure 4). This proposition was evidenced by the density

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• -modified PNA monomers (Figure 5) slightly reduced PNA binding affinity, with ᴅ-amino acids being somewhat better accommodated in the backbone than ʟ-amino acids and ᴅ-Lys being the only α-backbone modification that slightly increased PNA’s binding affinity to complementary DNA (but not RNA) [67]. Circular

• dichroism studies showed that the ᴅ-Lys modification induced a right-handed helical conformation favorable for DNA binding while the ʟ-Lys modification induced a left‐handed helical conformation that disfavored PNA binding to DNA [69]. Interestingly, a crystal structure of PNA having three α-ᴅ-Lys

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• 5a–e in the presence of ct DNA were examined with flow linear dichroism (LD) and circular dichroism (CD) spectroscopy (Figure 5, Figure S6, Supporting Information File 1). The binding of ligands 5a–e resulted in the development of negative LD signals at 350–355 nm and 420–429 nm clearly indicating an

• = 77.2 ppm). Elemental analyses: HEKAtech EUROEA combustion analyzer, determined by Rochus Breuer, Organische Chemie I, Universität Siegen. Mass spectra (ESI): Finnigan LCQ Deca (U = 6 kV; working gas: Ar; auxiliary gas: N2; temperature of the capillary: 200 °C). Circular dichroism (CD) and linear

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• '-stereoisomer of FANA, FRNA also demonstrates improved binding to RNA, relative to DNA [185]. Circular dichroism spectra of FANA/RNA and ANA/RNA duplexes show similarity to that of DNA/RNA [178][183]. Both ANA and FANA demonstrate good stability to nucleases [183][186]. Hybrid duplexes of ANA and FANA with

Synthesis and properties of oligonucleotides modified with an N-methylguanidine-bridged nucleic acid (GuNA[Me]) bearing adenine, guanine, or 5-methylcytosine nucleobases

• Naohiro Horie,
• Takao Yamaguchi,
• Shinji Kumagai and
• Satoshi Obika

Beilstein J. Org. Chem. 2021, 17, 622–629, doi:10.3762/bjoc.17.54

• affected the ΔTm values, though further investigations are needed for the details. CD spectral analyses of duplexes modified with GuNA[Me]-G To analyze the structures of the duplexes containing GuNA[Me], circular dichroism (CD) spectra were measured for ON2/ssRNA and ON2/ssDNA duplexes (Figure 2). The CD

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• dichroism, which assesses the backbone folding [121][122]. Changes in the denaturing conditions can be tracked by circular dichroism or fluorescence-based assays very easily. Alterations in the regular fold would usually be associated with alterations in the energy of the folding. These observations created

• stability of proteins containing fluoroprolines In the context of biochemical science, it is common to assume that structural changes and stability differences correlate with each other. For a protein, an overall sum of the secondary structures can be easily evaluated by chiroptic methods, such as circular