Design, semisynthesis and potent cytotoxic activity of novel 10-fluorocamptothecin derivatives

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.

Improved anti-tumor activity of fluorinated camptothecin derivatives 9-fluorocamptothecin and 7-ethyl-9-fluorocamptothecin on hepatocellular carcinoma by targeting topoisomerase I

Primary liver cancer is one of the most common malignant cancers of the digestive system that lacks effective chemotherapeutic drugs in clinical settings. Camptothecin (CPT) and its derivatives have been approved for cancer treatment; however, their application is limited by their systemic toxicity. For lead optimization in new drug discovery stages, fluorination is an effective and robust approach to increase the bioavailability and optimize the pharmacokinetics of candidate compounds, thereby improving their efficacy. To obtain new and highly active CPT derivatives, we designed, synthesized, and evaluated two new fluorinated CPT derivatives, 9-fluorocamptothecin (A1) and 7-ethyl-9-fluorocamptothecin (A2), in this study. In vitro, A1 and A2 exhibited more robust anti-tumor activity than topotecan (TPT) in various cancer cells, particularly hepatocellular carcinoma (HCC) cells. In vivo, A1 and A2 exhibited greater anti-tumor activity than TPT in both AKT/Met induced primary HCC mouse models and implanted HepG2 cell xenografts. Acute toxicity tests revealed that A1 and A2 were not lethal and did not cause significant body weight loss at high doses. Moreover, A1 and A2 exhibited no significant toxicity in the mouse liver, heart, lung, spleen, kidney, and hematopoietic systems at therapeutic doses. Mechanistically, A1 and A2 blocked HCC cell proliferation by inhibiting the enzymatic activity of Topo I, subsequently inducing DNA damage, cell cycle arrest, and apoptosis. In summary, our results indicate that fluorination improves the anti-tumor activity of CPT while decreasing its toxicity and highlight the application potential of fluorination products A1 and A2 in clinical settings.

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.

Synthesis and in vitro anticancer activities of biotinylated derivatives of glaucocalyxin A and oridonin

Fourteen glaucocalyxin A biotinylated derivatives, one glaucocalyxin C biotinylated derivative, and two oridonin biotinylated derivatives were designed and synthesized. Their structures were confirmed from ¹H NMR, ¹³C NMR and HRMS data. The derivatives were evaluated for cytotoxic activities against lung (A549), cervical cancer cell line HeLa derivative (KB), multidrug-resistant KB subline (KB-VIN), triple-negative breast (MDA-MB-231), and estrogen receptor-positive breast (MCF-7) cancer cell lines.[Formula: see text].

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.

Application of Amino Acids in the Structural Modification of Natural Products: A Review

Natural products and their derivatives are important sources for drug discovery; however, they usually have poor solubility and low activity and require structural modification. Amino acids are highly soluble in water and have a wide range of activities. The introduction of amino acids into natural products is expected to improve the performance of these products and minimize their adverse effects. Therefore, this review summarizes the application of amino acids in the structural modification of natural products and provides a theoretical basis for the structural modification of natural products in the future. The articles were divided into six types based on the backbone structures of the natural products, and the related applications of amino acids in the structural modification of natural products were discussed in detail.

Design, Synthesis and Biological Activity of (20S,21S)-7-Cyclohexyl-21-fluorocamptothecin Carbamates as Potential Antitumor Agents

(20S,21S)-7-Cyclohexyl-21-fluorocamptothecin was discovered by a fluorine drug design strategy with potent antitumor activity and increased metabolic stability. In continuous efforts to find novel antitumor agents derived from natural product camptothecin, 20-carbamates of the active compound (20S,21S)-7-cyclohexyl-21-fluorocamptothecin have been designed and synthesized. Among them, one compound with the diethylamino group showed greater antiproliferative activity than the other 20-carbamate derivatives. The following biological activity assays indicated that the above compound is a valuable lead compound with excellent Topo I inhibitory activity and solution stability.

Unnatural spirocyclic oxindole alkaloids biosynthesis in Uncaria guianensis

Spiro-oxindole scaffolds have been studied due to their promising therapeutic potential. In the Amazon rainforest there are two important Uncaria species known as “cat’s claw”, which biosynthesize spirocyclic oxindole alkaloids; Uncaria tomentosa (Willd. ex Schult.) DC. and Uncaria guianensis (Aublet) Gmell. We carried out a precursor-directed biosynthesis approach with U. guianensis and successfully obtained oxindole alkaloid analogues with molecular mass corresponding to the addition of a methyl or fluorine group on the oxindole ring using tryptamine analogue precursors. Two of these novel oxindole alkaloid analogues (3b-7-methyl-isomitraphylline and 3c-6-fluoro-isomitraphylline) were isolated and characterized by NMR spectroscopy and ESI-QTOF-MS/MS. Having established a substrate feeding protocol for these plantlets, the biosynthetic route for mitraphylline (1), rhynchophylline (2), isomitraphylline (3) and isorhynchophylline (4) was also investigated using ¹³C-precursors (1-¹³C-D-glucose, 2-¹³C-tryptophan, 1-¹³C-DL-glyceraldehyde, and methyl-¹³C-D-methionine).