Design, synthesis, and cytotoxic activity of novel 7-substituted camptothecin derivatives incorporating piperazinyl-sulfonylamidine moieties

The recent developments of camptothecin and its derivatives as potential anti-tumor agents

This review article focuses on the research progress made in the structural modifications of camptothecin (CPT), a potent cytotoxic natural alkaloid. CPT possesses a unique 5-fused ring structure and exhibits various beneficial activities such as anti-proliferative, anti-fungal, insecticidal, and anti-SARS-CoV-2 properties. CPT and its analogs, including Topotecan and Irinotecan, have been successfully developed and marketed as topoisomerase I inhibitors. To enhance the therapeutic potential of CPT, researchers have undertaken structural modifications primarily on the A, B, and E rings of the CPT core structure. These modifications aim to improve the efficacy, selectivity, and pharmacokinetic properties of CPT derivatives. The article reviews the advancements in hybridizing CPT with other bioactive compounds, the synthesis of novel CPT analogs, and their associated biological activities. Moreover, the structure-activity relationship (SAR) of these modified CPT derivatives is summarized to gain insights into their structure-function correlations. In addition to discussing the modifications and biological activities of CPT derivatives, the article also touches upon the mechanism of parent drug release. Many CPT derivatives are prodrugs, meaning they require metabolic activation to generate the active form of the drug. It is a resource for researchers interested in developing novel anti-tumor agents based on CPT, addressing the limitations associated with the parent drug, and exploring various aspects of CPT modifications.

Lead/Drug Discovery from Natural Resources

Natural products and their derivatives have been shown to be effective drug candidates against various diseases for many years. Over a long period of time, nature has produced an abundant and prosperous source pool for novel therapeutic agents with distinctive structures. Major natural-product-based drugs approved for clinical use include anti-infectives and anticancer agents. This paper will review some natural-product-related potent anticancer, anti-HIV, antibacterial and antimalarial drugs or lead compounds mainly discovered from 2016 to 2022. Structurally typical marine bioactive products are also included. Molecular modeling, machine learning, bioinformatics and other computer-assisted techniques that are very important in narrowing down bioactive core structural scaffolds and helping to design new structures to fight against key disease-associated molecular targets based on available natural products are considered and briefly reviewed.

Camptothecin's journey from discovery to WHO Essential Medicine: Fifty years of promise

Nature represents a rich source of compounds used for the treatment of many diseases. Camptothecin (CPT), isolated from the bark of Camptotheca acuminata, is a cytotoxic alkaloid that attenuates cancer cell replication by inhibiting DNA topoisomerase 1. Despite its promising and wide spectrum antiproliferative activity, its use is limited due to low solubility, instability, acquired tumour cell resistance, and remarkable toxicity. This has led to the development of numerous CPT analogues with improved pharmacodynamic and pharmacokinetic profiles. Three natural product-inspired drugs, namely, topotecan, irinotecan, and belotecan, are clinically approved and prescribed drugs for the treatment of several types of cancer, whereas other derivatives are in clinical trials. In this review, which covers literature from 2015 to 2020, we aim to provide a comprehensive overview and describe efforts that led to the development of a variety of CPT analogues. These efforts have led to the discovery of potent, first-in-class chemotherapeutic agents inspired by CPT. In addition, the mechanism of action, SAR studies, and recent advances of novel CPT drug delivery systems and antibody drug conjugates are discussed.

Piperazine skeleton in the structural modification of natural products: a review

Piperazine moiety is a cyclic molecule containing two nitrogen atoms in positions 1 and 4, as well as four carbon atoms. Piperazine is one of the most sought heterocyclics for the development of new drug candidates with a wide range of applications. Over 100 molecules with a broad range of bioactivities, including antitumor, antibacterial, anti-inflammatory, antioxidant, and other activities, were reviewed. This article reviewed investigations regarding piperazine groups for the modification of natural product derivatives in the last decade, highlighting parameters that affect their biological activity.

Quinoline anticancer agents active on DNA and DNA-interacting proteins: From classical to emerging therapeutic targets

Quinoline is one of the most important and versatile nitrogen heterocycles embodied in several biologically active molecules. Within the numerous quinolines developed as antiproliferative agents, this review is focused on compounds interfering with DNA structure or with proteins/enzymes involved in the regulation of double helix functional processes. In this light, a special focus is given to the quinoline compounds, acting with classical/well-known mechanisms of action (DNA intercalators or Topoisomerase inhibitors). In particular, the quinoline drugs amsacrine and camptothecin (CPT) have been studied as key lead compounds for the development of new agents with improved PK and tolerability properties. Moreover, notable attention has been paid to the quinoline molecules, which are able to interfere with emerging targets involved in cancer progression, as G-quadruplexes or the epigenetic ones (e.g.: histone deacetylase, DNA and histones methyltransferase). The antiproliferative and the enzymatic inhibition data of the reviewed compounds have been analyzed. Furthermore, concerning the SAR (structure-activity relationship) aspects, the most recurrent ligand-protein interactions are summarized, underling the structural requirements for each kind of mechanism of action.

Redox-sensitive dimeric camptothecin phosphatidylcholines-based liposomes for improved anticancer efficacy

Aim: A redox-triggered camptothecin (CPT) liposomal system was developed for an improved clinical potential in tumor therapy. Materials & methods: CPT–phosphorylcholine conjugates (CPT–SS–GPCs: CPT–SS–3–GPC and CPT–SS–11–GPC) were synthesized by conjugating CPT to glycerylphosphorylcholine via disulfide bond linker. CPT–SS–GPCs could be assembled into liposomes. Different in vitro and in vivo analyses were used to evaluate the anticancer activities of CPT–SS–GPCs. Results: CPT–SS–GPCs liposomes exhibited extremely high drug loading and uniform size of 150–200 nm. Moreover, the rapid release of parent CPT in reductive condition and high cellular uptake of CPT–SS–GPCs liposomes were observed. At last, in vitro and in vivo anticancer assay showed the enhanced efficacy of CPT–SS–GPCs liposomes. Conclusion: Redox-triggered CPT–SS–GPC liposomes have great potential in tumor therapy.

Design and synthesis of novel 7-[(N-substituted-thioureidopiperazinyl)-methyl]-camptothecin derivatives as potential cytotoxic agents

As part of continuing our research on diverse C-7 derivatives of camptothecin (CPT), 16 CPT derivatives bearing piperazinyl-thiourea chemical scaffold and different substituent groups have been designed, synthesized and evaluated in vitro for cytotoxicity against five tumor cell lines (A-549, MDA-MB-231, MCF-7, KB and KBvin). As a result, all the synthesized compounds showed promising in vitro cytotoxic activity against the five tumor cell lines tested, and were more potent than irinotecan. Importantly, compounds 13 g (IC₅₀ = 0.514 μM) and 13o (IC₅₀ = 0.275 μM) possessed similar or better antiproliferative activity against the multidrug-resistant (MDR) KBvin subline than that of topotecan (IC₅₀ = 0.511 μM) and merit further development as anticancer candidates for clinical trail. With these results in hand, we have a reason to conclude that incorporating piperazinyl-thiourea motifs into position-7 of camptothecin confers well cytotoxic activity against cancer cell lines, probably resulting in new anticancer drugs.

Structure-Based Drug Design and Identification of H2O-Soluble and Low Toxic Hexacyclic Camptothecin Derivatives with Improved Efficacy in Cancer and Lethal Inflammation Models in Vivo

Camptothecin (CPT) has been shown to block disassembly of the topoisomerase I (Topo I)/DNA cleavable complex. However, the poor aqueous solubility, intrinsic instability, and severe toxicity of CPTs have limited their clinical applications. Herein, we report the design and synthesis of H₂O-soluble and orally bioavailable hexacyclic CPT derivatives. By analysis of a virtual chemical library and cytotoxicity screening in vitro, 9 and 11 were identified as potential prodrugs and chosen for further characterization in vivo. Both compounds exhibited remarkable anticancer and anti-inflammation efficacies in animals and improved drug-like profiles.

N-Sulfonyl acetylketenimine as a highly reactive intermediate for the synthesis of N-sulfonyl amidines

A highly reactive intermediate N-sulfonyl acetylketenimine was generated from a 3-butyn-2-one participating CuAAC/ring-opening method. Its high reactivity due to bearing two EWGs allowed us to offer the first example of a reaction between ketenimine and amide to synthesize N-sulfonyl amidines efficiently.