VOC-Based Probes, a New Set of Analytical Tools to Monitor Patient Health from Blood Sample. Proof of Concept on Tracking COVID-19 Infection.

Induced volatolomics is an emerging field that holds promise for many biomedical applications including disease detection and prognosis. In this pilot study, we report the first use of a cocktail of volatile organic compounds (VOCs)-based probes to highlight new metabolic markers allowing disease prognosis. In this pilot study, we specifically targeted a set of circulating glycosidases whose activities could be associated with critical COVID-19 illness. Starting from blood sample collection, our approach relies on the incubation of VOC-based probes in plasma samples. Once activated, the probes released a set of VOCs in the sample headspace. The dynamic monitoring of the signals of VOC tracers enabled the identification of three dysregulated glycosidases in the initial phase after infection, for which preliminary machine learning analyses suggested an ability to anticipate critical disease development. This study demonstrates that our VOC-based probes are a new set of analytical tools that can provide access to biological signals until now unavailable to biologists and clinicians and which could be included in biomedical research to properly construct multifactorial therapy algorithms, necessary for personalized medicine.

PSL Chemical Biology Symposia Third Edition: A Branch of Science in its Explosive Phase.

This symposium is the third PSL (Paris Sciences & Lettres) Chemical Biology meeting (2016, 2019, 2023) held at Institut Curie. This initiative originally started at Institut de Chimie des Substances Naturelles (ICSN) in Gif-sur-Yvette (2013, 2014), under the directorship of Professor Max Malacria, with a strong focus on chemistry. It was then continued at the Institut Curie (2015) covering a larger scope, before becoming the official PSL Chemical Biology meeting. This latest edition was postponed twice for the reasons that we know. This has given us the opportunity to invite additional speakers of great standing. This year, Institut Curie hosted around 300 participants, including 220 on site and over 80 online. The pandemic has had, at least, the virtue of promoting online meetings, which we came to realize is not perfect but has its own merits. In particular, it enables those with restricted time and resources to take part in events and meetings, which can now accommodate unlimited participants. We apologize to all those who could not attend in person this time due to space limitation at Institut Curie.

Bioorthogonal Drug Release from Nanometric Micelles in Living Cells.

We explored a bioorthogonal approach to release drugs from stimuli-responsive micelles inside tumor cells. The concept relies on sydnonimine-based micelles that undergo quantitative cleavage in presence of cyclooctynes, hence releasing their content within living cells. Four cleavable micelles were developed to allow massive burst release of Entinostat, a potent histone deacetylase inhibitor, following their internalization inside cancer cells. A comparative study on the influence of the bioorthogonal-mediated versus passive drug release from micelles was carried out. The results indicated that a fast release of the drug triggered a stronger antiproliferative activity on tumor cells compared to the passive diffusion of the drug from the micelles core. These finding may be of great interest for the development of new nanomedicines.

Combination of Targeted Therapies for Colorectal Cancer Treatment.

The design of innovative therapeutic strategies enabling the selective destruction of tumor cells while sparing healthy tissues remains highly challenging in cancer therapy. Here, we show that the combination of two targeted therapies, including bevacizumab (Bev), and a ß-glucuronidase-responsive albumin-binding prodrug of monomethyl auristatin E (MMAE), is efficient for the treatment of colorectal cancer implanted in mice. This combined therapy produces a therapeutic activity superior to that of the association of FOLFOX and Bev currently used to treat patients with this pathology. The increased anticancer efficacy is due to either a synergistic or an additive effect between Bev and MMAE selectively released from the glucuronide prodrug in the tumor microenvironment. Since numerous drug delivery systems such as antibody-drug conjugates employ MMAE as a cytotoxic payload, this finding may be of great interest for improving their therapeutic index by combining them with Bev, particularly for the therapy of colorectal cancer.

Stimuli-Responsive Catenane-Based Catalysts.

Rotaxanes and molecular knots exhibit particular properties resulting from the presence of a mechanical bond within their structure that maintains the molecular components interlocked in a permanent manner. On the other hand, the disassembly of the interlocked architecture through the breakdown of the mechanical bond can activate properties which are masked in the parent compound. Herein, we present the development of stimuli-responsive CuI -complexed [2]catenanes as OFF/ON catalysts for the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The encapsulation of the CuI ion inside the [2]catenanes inhibits its ability to catalyze the formation of triazoles. In contrast, the controlled opening of the two macrocycles induces the breaking of the mechanical bond, thereby restoring the catalytic activity of the CuI ion for the CuAAC reaction. Such OFF/ON catalysts can be involved in signal amplification processes with various potential applications.

A ß-Cyclodextrin-Albumin Conjugate for Enhancing Therapeutic Efficacy of Cytotoxic Drugs.

Enhancing the selectivity of anticancer drugs currently used in the clinic is of great interest in order to propose more efficient chemotherapies with fewer side effects for patients. In this context, we developed a ß-cyclodextrin trimer that binds to circulating albumin to form the corresponding bioconjugate in the bloodstream. This latter can then entrap doxorubicin following its i.v. administration via the formation of a host-guest inclusion complex and deliver the drug in tumors. In this study, we demonstrate that the ß-cyclodextrin trimer improves the therapeutic efficacy of doxorubicin for the treatment of a subcutaneous murine Lewis lung carcinoma (LLC) implanted in C57BL/6 mice. This outcome is associated with an increased deposition of doxorubicin in malignant tissues when used in combination with the ß-cyclodextrin trimer compared to the administration of the drug alone.

Stimuli-Responsive Metal Complexes for Biomedical Applications.

Metal-based compounds have been widely used for biomedical applications. Their unique characteristics make them attractive for both therapeutic and diagnostic purposes. However, numerous issues including toxicity, poor aqueous solubility, and unfavorable biodistribution hamper their widespread use. To overcome these drawbacks, the concept of metal-based prodrugs emerged. This field is particularly developed for applications in oncology. More precisely, tumor-associated stimuli (e.g., pH variation, redox activity, enzyme overexpression, etc.) have been exploited to trigger the selective delivery of active metal-based drugs to the tumor site. The main advances in this area are discussed in this Review.

A Novel Proteomics-Based Strategy for the Investigation of Peptide Sequences in Extraterrestrial Samples.

Method development is one of the objectives of the astrophysical community for characterizing the organic matter in objects of the solar system. In this context, we report on the development of an enzyme-catalyzed stereoselective hydrolysis, inspired by the proteomics discipline, which has enabled the indirect detection of peptide sequences in extraterrestrial samples. A proof of concept has been performed on a Murchison extract. We show that our approach can successfully highlight l- and d-amino acids involved in peptide bonds. While we show that some d-amino acids must have been involved in peptide bonds, we cannot at this stage conclude on the indigenous or exogenous nature of these biopolymers. However, our strategy constitutes the first step toward direct UPLC-MS evidence of peptide sequences in extraterrestrial samples. It should thus contribute to deepening knowledge on the molecules available in the solar system, hence providing new clues about their chemical history, especially on Earth.

Bioorthogonal Reactions in Animals.

The advent of bioorthogonal chemistry has led to the development of powerful chemical tools that enable increasingly ambitious applications. In particular, these tools have made it possible to achieve what is considered to be the holy grail of many researchers involved in chemical biology: to perform unnatural chemical reactions within living organisms. In this minireview, we present an update of bioorthogonal reactions that have been carried out in animals for various applications. We outline the advances made in the understanding of fundamental biological processes, and the development of innovative imaging and therapeutic strategies using bioorthogonal chemistry.

Absolute configuration of a [1]rotaxane determined from vibrational and electronic circular dichroism spectra.

The experimental vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectra were measured for the enantiomers of [1]rotaxane 1. These experimental spectra have been analyzed using predicted VCD and ECD spectra for (S, Rmp ) or (S, Smp ) diastereomers using density functional theory. This comparison allowed for a definitive assignment of the absolute configuration of 1.

Enzyme-Cleavable Linkers for Protein Chemical Synthesis through Solid-Phase Ligations.

The total synthesis of long proteins requires the assembly of multiple fragments through successive ligations. The need for intermediate purification steps is a strong limitation, particularly in terms of overall yield. One solution to this problem would be solid-supported chemical ligation (SPCL), for which a first peptide segment must be immobilized on a SPCL-compatible solid support through a linker that can be cleaved under very mild conditions to release the assembled protein. The cleavage of SPCL linkers has previously required chemical conditions sometimes incompatible with sensitive protein targets. Herein, we describe an alternative enzymatic approach to trigger cleavage under extremely mild and selective conditions. Optimization of the linker structure and use of a small enzyme able to diffuse into the solid support were key to the success of the strategy. We demonstrated its utility by the assembly of three peptide segments on the basis of native chemical ligation to afford a 15 kDa polypeptide.

The Lossen rearrangement from free hydroxamic acids.

The Lossen rearrangement, that allows the conversion of hydroxamic acids into isocyanates, was discovered almost 150 years ago. For more than a century, this transformation was supposed to occur exclusively in the presence of stoichiometric amounts of activating reagents devoted to promoting the dehydration of primary hydroxamic acids. Very recently, it was demonstrated that the Lossen rearrangement can take place directly from free hydroxamic acids offering a renewal of interest for such a reaction. This short review summarizes advances in this field by describing successively the metal-assisted, the self-propagative and the promoted self-propagative Lossen rearrangement with a special emphasis on their mechanisms.

Volatile Organic Compound Based Probe for Induced Volatolomics of Cancers.

The development of efficient protocols for cancer diagnosis remains highly challenging. An emerging approach relies on the detection in exhaled breath of volatile organic compounds (VOC) produced by tumours. In this context, described here is a novel strategy in which a VOC-based probe is converted selectively in malignant tissues, by a tumour-associated enzyme, for releasing the corresponding VOC. The latter is then detected in the exhaled breath as a tumour marker for cancer diagnosis. This approach allows the detection of several different tumours in mice, the monitoring of tumour growth and tumour response to chemotherapy. Thus, the concept of "induced volatolomics" provides a new way to explore biological processes using VOC-based probes that could be adapted to many biomedical applications.

Controlled Release of a Micelle Payload via Sequential Enzymatic and Bioorthogonal Reactions in Living Systems.

A bioorthogonal approach is explored to release the content of nanoparticles on demand. Exploiting our recently described click-and-release technology, we developed a new generation of cleavable micelles able to disassemble through a sequential enzymatic and bioorthogonal activation process. Proof-of-concept experiments showed that this new approach could be successfully used to deliver the substances encapsulated into micelles in living cells as well as in mice by two complementary targeted strategies.

Diminished oligomerization in the synthesis of new anti-angiogenic cyclic peptide using solution instead of solid-phase cyclization.

The design and synthesis of novel peptides that inhibit angiogenesis is an important area for anti-angiogenic drug development. Cyclic and small peptides present several advantages for therapeutic application, including stability, solubility, increased bio-availability and lack of immune response in the host cell. We describe here the synthesis and biological evaluations of a new cyclic peptide analog of CBO-P11: cyclo(RIKPHE), designated herein as CBO-P23M, a hexamer peptide encompassing residues 82 to 86 of VEGF which are involved in the interaction with VEGF receptor-2. CBO-P23M was prepared using in solution cyclization, therefore reducing the peptide cyclodimerization occurred during solid-phase cyclization. The cyclic dimer of CBO-P23M, which was obtained as the main side product during synthesis of the corresponding monomer, was also isolated and investigated. Both peptides markedly reduce VEGF-A-induced phosphorylation of VEGFR-2 and Erk1/2. Moreover, they exhibit anti-angiogenic activity in an in vitro morphogenesis study. Therefore CBO-P23M and CBO-P23M dimer appear as attractive candidates for the development of novel angiogenesis inhibitors for the treatment of cancer and other angiogenesis-related diseases. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 368-375, 2016.

An Enzyme-Responsive Self-Immolative Recognition Marker for Manipulating Cell-Cell Interactions.

The development of innovative strategies for cell membranes engineering is of prime interest to explore and manipulate cell-cell interactions. Herein, an enzyme-sensitive recognition marker that can be introduced on cell surface via bioorthogonal chemistry is designed. Once functionalized in this fashion, the cells gain the ability to assemble with cell partners coated with the complementary marker through non-covalent click chemistry. The artificial cell adhesion induces natural biological processes associated with cell proximity such as inhibiting cancer cell proliferation and migration. On the other hand, the enzymatic activation of the stimuli-responsive marker triggers the disassembly of cells, thereby restoring the tumor cell proliferation and migration rates. Thus, the study shows that the ready-to-use complementary markers are valuable tools for controlling the formation and the breaking of bonds between cells, offering an easy way to investigate biological processes associated to cell proximity.

An enzyme-responsive system programmed for the double release of bioactive molecules through an intracellular chemical amplification process.

The rise of chemical biology has led to the development of sophisticated molecular devices designed to explore and manipulate biological processes. Within this framework, we developed the first chemical system programmed for the selective internalization and subsequent enzyme-catalyzed double release of bioactive compounds inside a targeted population of cells. This system is composed of five distinct units including a targeting ligand, an enzymatic trigger, a self-immolative linker and two active compounds articulated around a chemical amplifier. Designed as such, this molecular assembly is capable in an autonomous manner to recognize a selected population of cells, penetrate into the intracellular medium through endocytosis and transform a single enzymatic activation step into the release of two active units. Demonstrating that an enzyme-catalyzed amplification process can occur spontaneously under the conditions prevailing within the cells could be an important step toward the development of innovative molecular systems for a diverse range of applications spanning drug delivery, biological sensors and diagnostics.

Induced-volatolomics for the design of tumour activated therapy.

The discovery of tumour-associated markers is of major interest for the development of selective cancer chemotherapy. Within this framework, we introduced the concept of induced-volatolomics enabling to monitor simultaneously the dysregulation of several tumour-associated enzymes in living mice or biopsies. This approach relies on the use of a cocktail of volatile organic compound (VOC)-based probes that are activated enzymatically for releasing the corresponding VOCs. Exogenous VOCs can then be detected in the breath of mice or in the headspace above solid biopsies as specific tracers of enzyme activities. Our induced-volatolomics modality highlighted that the up-regulation of N-acetylglucosaminidase was a hallmark of several solid tumours. Having identified this glycosidase as a potential target for cancer therapy, we designed an enzyme-responsive albumin-binding prodrug of the potent monomethyl auristatin E programmed for the selective release of the drug in the tumour microenvironment. This tumour activated therapy produced a remarkable therapeutic efficacy on orthotopic triple-negative mammary xenografts in mice, leading to the disappearance of tumours in 66% of treated animals. Thus, this study shows the potential of induced-volatolomics for the exploration of biological processes as well as the discovery of novel therapeutic strategies.

NDMA formation by chloramination of ranitidine: kinetics and mechanism.

The kinetics of decomposition of the pharmaceutical ranitidine (a major precursor of NDMA) during chloramination was investigated and some decomposition byproducts were identified by using high performance liquid chromatography coupled with mass spectrometry (HPLC-MS). The reaction between monochloramine and ranitidine followed second order kinetics and was acid-catalyzed. Decomposition of ranitidine formed different byproducts depending on the applied monochloramine concentration. Most identified products were chlorinated and hydroxylated analogues of ranitidine. In excess of monochloramine, nucleophilic substitution between ranitidine and monochloramine led to byproducts that are critical intermediates involved in the formation of NDMA, for example, a carbocation formed from the decomposition of the methylfuran moiety of ranitidine. A complete mechanism is proposed to explain the high formation yield of NDMA from chloramination of ranitidine. These results are of great importance to understand the formation of NDMA by chloramination of tertiary amines.

The first generation of ß-galactosidase-responsive prodrugs designed for the selective treatment of solid tumors in prodrug monotherapy.

Massive attack: Galactoside prodrugs have been designed that can be selectively activated by lysosomal ß-galactosidase located inside cancer cells expressing a specific tumor-associated receptor. This efficient enzymatic process triggers a potent cytotoxic effect, releasing the potent antimitotic agent MMAE and allowing the destruction of both receptor-positive and surrounding receptor-negative tumor cells.