Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

• Moisés Alejandro Alejo Hernandez,
• Katia Pamela Villavicencio Sánchez,
• Rosendo Sánchez Morales,
• Karla Georgina Hernández-Magro Gil,
• David Silverio Moreno-Gutiérrez,
• Eddie Guillermo Sanchez-Rueda,
• Yanet Teresa-Cruz,
• Brian Choi,
• Armando Hernández Garcia,
• Alba Romero-Rodríguez,
• Oscar Juárez,
• Siseth Martínez-Caballero,
• Mario Figueroa and
• Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

• lichenicidin A1 [48], FlvA.1 [42], FlvA.2 [42], BhtA α [49], SmB β [50], Smb α [50], and thusin β [47] (Figure 3B). We find that, especially in the first 20 amino acids of the alignment or the first half of the mature peptide, there are significant sequence differences. Of particular interest, cellulosin forms

• two larger heterocycles (of seven and nine amino acids) in this sequence region, whilst most lanthipeptides only form small ones (up to five) or none at all. As for the second part of the alignment, where most lanthipeptides form various heterocycles, cellulosin shares a very similar profile to

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• ]oxazinan)-6'-one derivatives with two types of molecular diversity as part of their efforts to produce inhibitors of 17β-HSDs [61]. The first type of diversity was achieved by introducing different amino acids through the opening of the oxirane ring on compound 127. After lactonization of compounds 128

• as a 17β-HSD3 inhibitor [42]. The same research group reported a new family of 3-spiromorpholinones derived from ADT bearing hydrophobic substituents [43][62]. The synthetic key step involved a regioselective aminolysis of the oxirane 131 with different ʟ- or ᴅ-amino acids (53–99% yields) to obtain

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• hydrolysis of the ester and oxidation of the phenol rings allowed concise access to jorunnamycin A (103) in just 4 pots from 86 and 101 [102][106]. In subsequent work, Tanifuji and Oguri designed and applied eight variants of the peptidyl aldehyde (e.g., 104, 105) bearing various ʟ- and ᴅ-amino acids in

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• contrast to ribosomal peptide biosynthesis, many non-proteinogenic amino acids can be incorporated as building blocks. However, RiPP pathways are more flexible and they represent interesting biotechnological production routes. In this review, we will focus on post-translational methylation reactions. A

• functionalities. Review Methylation strategies The main section of this paper discusses different RiPP MTs involved in the biosynthesis of methylated peptide natural products. This section serves as an introduction and outlines additional synthetic strategies for methylated amino acids and peptides. There are

• . Additionally, stereoselectivity can be achieved by using potassium bis(trimethylsilyl)amide for deprotonation and methylation with MeI [33][39]. Any of these routes would yield methylated amino acids that can then be incorporated into an oligopeptide in solid-phase peptide synthesis (SPPS). Additionally, N

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• , substituted 3-fluoropyrrolidines, particularly in the form of 2-carboxy derivatives (fluoroprolines), have been extensively explored. These compounds represent valuable nonnatural amino acids, and depending on the regio- and stereochemistry of fluorine substitution, fluoroproline substututions can enhance the

Mining raw plant transcriptomic data for new cyclopeptide alkaloids

• Draco Kriger,
• Michael A. Pasquale,
• Brigitte G. Ampolini and
• Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

• in 1998 [18]. This domain is typically around 300 amino acids in length and has a conserved CHX10CHX25-27CHX25-26CH motif which comprises the active site of the burpitide cyclase. The resulting number of stand-alone transcripts from this filtering step were mapped onto a cladogram of the 647 species

• transcriptome analysis supports the prevalence of cyclopeptide alkaloids in Rhamnaceae with multiple species transcribing 20+ potential split precursor peptides. Alignment of the predicted recognition and core sequences shows the core peptides are 4–5 amino acids in length and appear to exclusively encode for

• . arabica, and Coffea eugenioides (Eugenioides coffee plant) all contained >30 unique transcripts for potential precursor peptides. The core sequences themselves were typically 4 or 5 amino acids in length and most often contained a tyrosine for cyclization. However, a few sequences appeared to have a

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• different functional groups at the 5-position. The Shi group reported the use of Pd(II) and Selectfluor to enable the enantioselective β-fluorination of α-amino acids (Figure 6) [40]. The presence of 2-(pyridin-2-yl)isopropylamine (PIP) as directing group was essential for the formation of a four-coordinate

• ; however, the methodology was only shown on secondary benzylic positions. The stereoselective benzylic monofluorination of α-amino acids was also reported by Yu and co-workers, employing a similar directing group strategy (Figure 7) [41]. The use of the monodentate directing group 2,3,5,6-tetrafluoro-4

• -(trifluoromethyl)aniline in conjunction with external ligand 5 facilitated the formation of a series of fluorinated α-amino acids. Xu and co-workers also disclosed a palladium-catalysed protocol for the fluorination of simple benzylic substrates bearing a bidentate directing group (Figure 8) [42]. Yields varied

Towards an asymmetric β-selective addition of azlactones to allenoates

• Behzad Nasiri,
• Ghaffar Pasdar,
• Paul Zebrowski,
• Katharina Röser,
• David Naderer and
• Mario Waser

Beilstein J. Org. Chem. 2024, 20, 1504–1509, doi:10.3762/bjoc.20.134

• -selective manner with moderate levels of enantioselectivities (up to 83:17 er). Furthermore, the obtained products can be successfully engaged in nucleophilic ring opening reactions, thus giving highly functionalized α-amino acid derivatives. Keywords: allenoates; amino acids; azlactones; organocatalysis

• ; quaternary ammonium salt catalysis; Introduction The development of asymmetric synthesis routes to access non-natural amino acids has for decades been one of the most heavily investigated tasks in organic synthesis and catalysis-oriented research [1][2][3][4][5][6][7][8][9][10][11][12][13]. As a consequence

• , a broad variety of conceptually orthogonal strategies to access differently functionalized non-natural α-amino acids (α-AA) [2][3][4][5][6][7] as well as β-amino acids (β-AA) [8][9][10][11][12][13] have been introduced and there is still considerable interest in the development of new concepts and

Electrophotochemical metal-catalyzed synthesis of alkylnitriles from simple aliphatic carboxylic acids

• Yukang Wang,
• Yan Yao and
• Niankai Fu

Beilstein J. Org. Chem. 2024, 20, 1497–1503, doi:10.3762/bjoc.20.133

• processes using cyanobenziodoxolones and tosyl cyanide as the cyanating reagents, respectively (Figure 1B, reaction 2). Recently, the Rueping group demonstrated a distinctive use of 4-cyanopyridine as nitrile source for electrochemical decarboxylative cyanation of amino acids [25]. Although these methods

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• plausible that the corresponding biosynthesis involves analogous oxidative ring opening and rearrangement steps. On the other side, in JadG-catalyzed reactions, compound 3 reacts with ʟ-isoleucine or other amino acids, leading to the formation of jadomycin A (6) or analogues, respectively [10]. In the

Direct synthesis of acyl fluorides from carboxylic acids using benzothiazolium reagents

• Lilian M. Maas,
• Alex Haswell,
• Rory Hughes and
• Matthew N. Hopkinson

Beilstein J. Org. Chem. 2024, 20, 921–930, doi:10.3762/bjoc.20.82

• observed (yield = 72%) with analysis by chiral HPLC revealing no erosion of the enantiomeric ratio (er = 99:1). At this stage, the suitability of BT-SCF3-mediated deoxyfluorination for the one-pot formation of peptide linkages between amino acids was investigated (Scheme 3). Treatment of N-Boc-valine under

• under mild and operationally simple conditions while peptide coupling between two amino acids could be efficiently conducted using the longer-chain perfluoroalkyl reagent BT-SC5F11. Mechanistic studies revealed that each equivalent of the benzothiazolium reagent can feasibly generate two equivalents of

• fluoride derivatives. Reactions conducted on a 0.5 mmol scale, isolated yields after column chromatography. One-pot BT-SCF3-mediated deoxygenative coupling of amino acids. Isolated yields after column chromatography. Plausible mechanism for the deoxyfluorination of carboxylic acids with BT-SCF3

Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• , likely acting as its proximal ligand. As described above, the H73A Vs NnlA variant lacked NNG degradation activity and had reduced iron content [21]. The AlphaFold model also predicts a distal pocket composed of Tyr99, Ala101, Ile109, Val111, and Gln127. These amino acids are conserved in an alignment of

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

•  1). Results and Discussion Syntheses of C60–oligopeptides 5a–c The oligopeptides 2a–c were synthesized on resin using Fmoc-protected amino acids with a standard SPPS method (Figure 1a) [43]. A moderate loading (0.4 mmol⋅g−1) of the initial amino acid was used. After synthesizing the pentamer of Lys

Chemoenzymatic synthesis of macrocyclic peptides and polyketides via thioesterase-catalyzed macrocyclization

• Senze Qiao,
• Zhongyu Cheng and
• Fuzhuo Li

Beilstein J. Org. Chem. 2024, 20, 721–733, doi:10.3762/bjoc.20.66

• , resulting in daptomycin (12) formation with a ratio of cyclization to hydrolysis of 3:1 (Scheme 4a). The significance of single amino acids for daptomycin bioactivity was evaluated, for instance, the substitution of ʟ-3-MeGlu12 by ʟ-Glu12 in Dap yielded a 7-fold increase of the MIC against B. subtilis

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• multicomponent reaction protocol. Keywords: carboamination; diazo chemistry; palladium catalysis; radical-polar crossover; three-component reaction; Introduction Since the discovery of the existence of non-canonical amino acids (AAs) in organisms, such structural motifs have attracted considerable attention

Recent developments in the engineered biosynthesis of fungal meroterpenoids

• Zhiyang Quan and
• Takayoshi Awakawa

Beilstein J. Org. Chem. 2024, 20, 578–588, doi:10.3762/bjoc.20.50

• terpenoid moiety is held in a substrate pocket consisting of hydrophobic amino acids, and the polyketide moiety is retained by a loop structure serving as a lid. The conformation of the terpenoid moiety can be easily altered by mutations to the enzyme’s substrate retention site, thereby changing the

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• (SORHA), Triticum aestivum (TRZAS), and Zea mays (ZEAMX). LpFAT A expression and purification: The fat a03 gene from Lemna paucicostata, in which the N-terminal amino acids representing the chloroplast transit peptide were replaced by an N-terminal 6xHis-tag, was cloned into a pET24 vector [3]. The LpFAT

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• HCl. The obtained amino acid (alanine) and authentic amino acids were modified using Nα-(5-fluoro-2,4-dinitrophenyl)-ᴅ-leucinamide (ᴅ-FDLA). The LC–MS analysis of ᴅ-FDLA derivatives revealed that the chiral center of the amino acid in 1 had ʟ configuration (Figure S7, Supporting Information File 1

• . Advanced Marfey’s analysis A volume of 20 µL of 1 M NaHCO3 was added to each 50 µL of the hydrolysate of the de-sulfurized derivative of 1 and 1 mM standard amino acids (ʟ- and ᴅ-alanine). Then, 50 µL of ᴅ-FDLA (10 mg·mL−1 in acetone) was added to the mixtures and mixed well (the color changed from yellow

Development of a chemical scaffold for inhibiting nonribosomal peptide synthetases in live bacterial cells

• Fumihiro Ishikawa,
• Sho Konno,
• Hideaki Kakeya and
• Genzoh Tanabe

Beilstein J. Org. Chem. 2024, 20, 445–451, doi:10.3762/bjoc.20.39

• (Figure 1) [3]. The adenylation (A) domain in NRPSs is responsible for the selection and activation of amino acids, hydroxy acids, and aryl acids upon ATP consumption (Figure 2a) [4]. The activated aminoacyladenosine monophosphate (AMP) is transferred to the thiol group of a phosphopantetheine prosthetic

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• with aryl thiols [70]. Further studies showed that 4-(trifluoromethyl)thiophenol (97) could act as a catalytic reductant in the aminodecarboxylation reaction of NHPI esters derived from α-amino acids [71] (Scheme 19). Accordingly, visible light irradiation of a mixture consisting of N-Boc-alanine NHPI

• forming an iminium intermediate 101. Finally, nucleophilic addition of phthalimide anion 102 afforded the amination product 103. Bosque and Bach reported the use of 3-acetoxyquinuclidine (q-Ac) as a catalytic donor for the activation of TCNHPI esters derived from α-amino acids [72] (Scheme 20). Treatment

• reported in recent years, including decarboxylative alkynylations [76][77][78] and the C(sp3)–H alkylation of α-amino acids [79]. The ability of NHPI esters to act as dual reagents was also investigated by Glorius and co-workers in the context of a photoinduced Pd-catalyzed aminoalkylation of 1,4-dienes

Discovery of unguisin J, a new cyclic peptide from Aspergillus heteromorphus CBS 117.55, and phylogeny-based bioinformatic analysis of UngA NRPS domains

• Sharmila Neupane,
• Marcelo Rodrigues de Amorim and
• Elizabeth Skellam

Beilstein J. Org. Chem. 2024, 20, 321–330, doi:10.3762/bjoc.20.32

• heptapeptides isolated predominantly from Aspergillus sp. [1][2][3][4][5][6][7][8]. Distinctive features of these cyclic peptides include the non-proteinogenic amino acid γ-aminobutyric acid (GABA) and the incorporation of up to five ᴅ-amino acids (Figure 1) [1][2][3][4][5][6][7][8]. The amino acids at

• positions 1 (ᴅ-Ala) and 7 (GABA) are conserved but there is considerable variability at positions 2–6, including the incorporation of additional non-proteinogenic amino acids β-methylphenylalanine (βMePhe) and kynurenine (Kyn) [3][4]. So far, no significant biological activities have been reported for these

• bond formation. Additional common domains include epimerization (E) domains for converting naturally occurring ʟ-amino acids to ᴅ-amino acids, methyltransferase (MT) domains that typically methylate specific N atoms, and terminal condensation (CT) domains which cyclize the growing peptide chain and

Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin

• Jon Lundstrøm,
• Emilie Gillon,
• Valérie Chazalet,
• Nicole Kerekes,
• Antonio Di Maio,
• Ten Feizi,
• Yan Liu,
• Annabelle Varrot and
• Daniel Bojar

Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31

• amino acids and is predicted to fold into two linked β-trefoil domains belonging to carbohydrate-binding module family 13 (CBM13) and placing it into the group of R-type lectins. Both CBM13 domains are likely to exhibit carbohydrate-binding activity due to the conservation of key amino acids in at least

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• compatibility and efficiency of a diverse range of redox-active esters 3, deriving from various aliphatic carboxylic acids (including primary, secondary, and tertiary acids), as well as α-amino acids. Impressively, these redox-active esters exhibited exceptional compatibility, high effectiveness, and remarkable

• -anion catalysis under visible light irradiation, as depicted in Scheme 9. Subsequent investigations revealed that redox-active esters 3 and Katritzky salts 15 derived from amino acids could be effectively employed in decarboxylative/deaminative cross-coupling reactions [15]. These reactions enabled the

• route for the synthesis of unnatural amino acids and amines. Remarkably, the procedure exhibited excellent compatibility with a wide range of alkyl radicals, including primary, secondary, tertiary, and α-heterosubstituted radicals generated from corresponding redox-active esters 3. Concurrently, Shang

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• acid-catalyzed hydrocyanation of trifluoromethylated acylhydrazones, in which the product was the precursor for the preparation of chiral fluorinated amino acids [104] (Scheme 17a). Meanwhile, Hu et al. provided a novel and efficient process for the synthesis of polysubstituted 3-trifluoromethyl-1,2,4

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• Pharmacy, Changzhou University, Changzhou 213164, China 10.3762/bjoc.19.123 Abstract The [3 + 2] cycloadditions of stabilized azomethine ylides (AMYs) derived from amino esters are well-established. However, the reactions of semi-stabilized AMYs generated from decarboxylative condensation of α-amino acids

• with arylaldehydes are much less explored. The [3 + 2] adducts of α-amino acids could be used for a second [3 + 2] cycloaddition as well as for other post-condensation modifications. This article highlights our recent work on the development of α-amino acid-based [3 + 2] cycloaddition reactions of N–H

• aldehydes and α-amino esters (via dehydration) or α-amino acids (via decarboxylation) could be classified based on the substitution groups on the N atom to: 1) N-substituted (N–R type), 2) hydrogen containing (N–H type), and 3) metal complexes (N–M type) (Figure 1) [16][17]. These AMYs could also be