Cryptophycin unit B analogues

• Thomas Schachtsiek,
• Jona Voss,
• Maren Hamsen,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40

• isolation from cyanobacteria [2], their extraordinarily high cytotoxicity was apparent and attracted attention, not least because of their still high efficacy against multidrug-resistant (MDR) cells [3]. Cryptophycin-52, a synthetic development candidate by Eli Lilly based on the initially discovered

• cryptophycin-1, failed in clinical studies as a cytotoxic drug on its own due to severe side effects [4]. However, the embedment of cryptophycins as payloads in drug conjugates, increases specificity and minimises adverse effects [5][6]. Drug conjugates usually consist of three units, where the payload is

• relationship (SAR) studies between derivatisations of all four units (A to D) (Figure 1A) of cryptophycin-52 analogues with functional groups [8]. While many modifications of cryptophycin decrease the cytotoxicity drastically, some viable attachment points for conjugation were found, mainly including the para

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

• options for treating vinca alkaloid- and taxol-resistant cancers [79]. Therefore, the pharmaceutical investigation of these natural products started for the first time when they were isolated in the early 1990s and has lasted until the present. A synthetic analog, cryptophycin 52, completed phase I

• 2005, Sherman and co-workers reported a chemoenzymatic approach through the stereospecific macrocyclization based on the identification of the thioesterase domain (CrpTE) from the cryptophycin biosynthetic pathway, which demonstrated that the CrpTE has both high efficiency in generating the 16-membered

• diverse range of heteroaromatics. For instance, incorporation of a 4-methylpyrazole ring (64a) showed nearly complete conversion to product with no measurable starting substrate or hydrolytic byproducts. After producing these cryptophycin analogs utilizing the CrpTE, the selective epoxidation using wild

Novel unit B cryptophycin analogues as payloads for targeted therapy

• Eduard Figueras,
• Adina Borbély,
• Mohamed Ismail,
• Marcel Frese and
• Norbert Sewald

Beilstein J. Org. Chem. 2018, 14, 1281–1286, doi:10.3762/bjoc.14.109

• cryptophycin analogues. The O-methyl group of the unit B D-tyrosine analogue was replaced by an O-(allyloxyethyl) moiety, an O-(hydroxyethyl) group, or an O-(((azidoethoxy)ethoxy)ethoyxethyl) substituent. While the former two maintain cytotoxicity in the subnanomolar range, the attachment of the triethylene

• glycol spacer with a terminal azide results in a complete loss of activity. Docking studies of the novel cryptophycin analogues to β-tubulin provided a rationale for the observed cytotoxicities. Keywords: cryptophycin; cytotoxic agents; novel payloads; tubulin inhibitors; tumour targeting; Introduction

• [2][3]. Their high cytotoxicity prompted manifold studies that were initially focussed on the total synthesis and structure–activity relationships [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. This work resulted in the identification of cryptophycin-52, a highly biologically active

Total synthesis and biological evaluation of fluorinated cryptophycins

• Christine Weiß,
• Tobias Bogner,
• Benedikt Sammet and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 2060–2066, doi:10.3762/bjoc.8.231

• against multi-drug-resistant tumor cell lines. As fluorinated pharmaceuticals have become more and more important during the past decades, fluorine-functionalized cryptophycins were synthesized and evaluated in cell-based cytotoxicity assays. The unit A trifluoromethyl-modified cryptophycin proved to be

• ; fluorinated natural product analogues; structure-activity relationship; Introduction Cryptophycins form a class of cytotoxic sixteen-membered macrocyclic depsipeptides. Cryptophycin-1 (1) was isolated for the first time in 1990 from cyanobacteria Nostoc sp. ATCC 53789 [1] (Figure 1). Moore et al. isolated

• cryptophycin-1 from the related Nostoc strain GSV 224, investigated the stereochemistry, and described the cytotoxicity [2]. At the same time Kobayashi et al. succeeded in a full structural analysis and described the first total synthesis of another member of the cryptophycin family [3][4]. Twenty-eight

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• -tail linkage [56]. Cryptophycin Cryptophycins were shown to be produced by terrestrial strains of Nostoc that are either free living or associated with a lichen symbiont. Cryptophycin 1 (15) is the most potent tubulin-destabilizing compound ever discovered and serves as a leading product for the

A two step synthesis of a key unit B precursor of cryptophycins by asymmetric hydrogenation

• Benedikt Sammet,
• Mathilde Brax and
• Norbert Sewald

Beilstein J. Org. Chem. 2011, 7, 243–245, doi:10.3762/bjoc.7.32

• enantioselectivity, and avoids hazardous reaction conditions. Keywords: amino acid; asymmetric hydrogenation; cryptophycin; DuPhos; Introduction Cryptophycins are macrocyclic depsipeptides, which show very high cytotoxicity even against multidrug-resistant cell lines. They inhibit mitosis of eukaryotic cells by

• modified α-amino acids, such as the classical Schöllkopf-method [10] or catalytic approaches [11][12]. The unit B precursor of cryptophycin is a phenylalanine derivative. An asymmetric hydrogenation approach for the synthesis of such α-amino acids is well-established [12]. In the first step of the

• cryptophycin unit B precursor 4 is disclosed based on a HWE reaction followed by a highly enantioselective [(COD)Rh-(R,R)-Et-DuPhos]BF4 mediated asymmetric hydrogenation. This high-yielding access is more convenient and avoids hazardous chemicals in contrast to the established method. The four building blocks

2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β²-amino acids

• Markus Nahrwold,
• Arvydas Stončius,
• Anna Penner,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43

• ]. Examples are cryptophycin-1 (a highly cytotoxic depsipeptide produced by cyanobacteria Nostoc sp. GSV224 and ATCC53789) [11][12][13][14] as well as a class of lipopeptides isolated from various fungi, comprising topostatin (a topoisomerase I and II inhibitor) [15], YM-170320 (an inhibitor of ergosterol