Two-Phase Electrosynthesis of Dihydroxycoumestans: Discovery of a New Scaffold for Topoisomerase I poison.

Coumestan represents a biologically relevant structural motif distributed in a number of natural products, and the rapid construction of related derivatives as well as the characterization of targets would accelerate lead compound discovery in medicinal chemistry. In this work, a general and scalable approach to 8,9-dihydroxycoumestans via two-electrode constant current electrolysis was developed. The application of a two-phase (aqueous/organic) system plays a crucial role for success, protecting the sensitive o-benzoquinone intermediates from over-oxidation. Based on the structurally diverse products, a primary SAR study on coumestan scaffold was completed, and compound 3r exhibited potent antiproliferative activities and a robust topoisomerase I (Top1) inhibitory activity. Further mechanism studies demonstrates that compound 3r was a novel Top1 poison, which might open an avenue for the development of Top1-targeted antitumor agent.

A facile approach to phenothiazinones via catalytic aerobic oxidation: discovery of an antiproliferative agent.

The production of bioactive pharmaceutical ingredients in a sustainable manner has become essential in the modern academic and industrial community. Herein, we report a chemically robust and sustainable aerobic oxidation for the synthesis of the phenothiazinone framework, using the commercially available TEMPO/HBF4/NaNO2 co-catalytic system under an ambient atmosphere. The reaction is highly efficient with broad scopes and excellent scalability. Preliminary activity screening led to the discovery of compound 3 as a potent antiproliferative agent. The green synthesis of a variety of sulfur containing heterocycles might encourage the pursuit of biologically valuable molecules in the medicinal field.

Electrochemical Synthesis of Phenothiazinone as Fluorophore and Its Application in Bioimaging.

Phenothiazinone is a promising yet underutilized fluorophore, possibly due to the lack of a general accessibility. This study reports a robust and scalable TEMPO-mediated electrochemical method to access a variety of phenothiazinones from 2-aminothiophenols and quinones. The electrosynthesis proceeds in a simple cell architecture under mild condition, and notably carbon-halogen bond in quinones remains compared to conventional methods, enabling orthogonal downstream functionalization. Mechanistic studies corroborate that TEMPO exerts a protective effect in avoiding product decomposition at the cathode. In particular, benzophenothiazinones show intriguing luminescence in both solid and solution state, and thus their photophysical properties are scrutinized in detail. Further bio-imaging of the lipid droplets in living cells highlights the considerable promise of benzophenothiazinones as fluorescent dye in the biomedical fields.

Privileged Biorenewable Secologanin-Based Diversity-Oriented Synthesis for Pseudo-Natural Alkaloids: Uncovering Novel Neuroprotective and Antimalarial Frameworks.

Bioprivileged molecules hold great promise for supplementing petrochemicals in sustainable organic synthesis of a diverse bioactive products library. Secologanin, a biorenewable monoterpenoid glucoside with unique structural elements, is the key precursor for thousands of natural monoterpenoid alkaloids. Inspired by its inherent highly congested functional groups, a secologanin-based diversity-oriented synthesis (DOS) strategy for novel pseudo-natural alkaloids was developed. All the reactive units of secologanin were involved in these operation simplicity protocols under mild reaction conditions, including the one-step enantioselective transformation of exocyclic C8, C8/C11, and C8/C9/C10 as well as the chemoenzymatic manipulation of endocyclic C2/C6 via the attack by various nucleophiles. A combinatory scenario of the aforementioned reactions further provided diverse polycyclic products with multiple chiral centers. Preliminary activity screening of these newly constructed molecules led to the discovery of antimalarial and highly potent neuroprotective skeletons. The application of green biorenewable secologanin in diversity-oriented pseudo-natural monoterpenoid alkaloid synthesis might encourage the pursuit of valuable bioactive frameworks.

Design, Synthesis and Antitumor Assessment of Phenylureas Bearing 5-Fluoroindolin-2-one Moiety.

BACKGROUND: The development of novel antineoplastic agents remains highly desirable. OBJECTIVE: This study focuses on the design, synthesis, and antitumor evaluation of phenyl ureas bearing 5-fluoroindolin-2-one moiety. METHODS: Three sets of phenylureas were designed and synthesized and their antiproliferative ability was measured against four human carcinoma cell lines (Hela, Eca-109, A549, and MCF-7) via MTT assay. In vivo anticancer activity was further evaluated in xenograft models of human breast cancer (MCF-7). RESULTS: A total of twenty-one new compounds were synthesized and characterized by means of 1H and 13C NMR as well as HR-MS. Three sets of compounds (1a‒1c, 2a‒2c, and 3a‒3c) were initially constructed, and preliminary antiproliferative activities of these molecules were evaluated against Hela, Eca-109, A549 and MCF-7, highlighting the meta-substituted phenylureas (1a‒1c) as the most cytotoxic set. A series of meta-substituted phenylureas derivatives (1d‒1o) were then designed and synthesized for structure-activity relationship study. Most of the new compounds showed desirable cytotoxicity, among which compound 1g exhibited the most remarkable cytotoxic effects against the tested human cancer cells with IC50 values ranging from 1.47 to 6.79 µM. Further studies showed that compound 1g suppressed tumor growth in human breast cancer (MCF- 7) xenograft models without affecting the body weight of its recipients. CONCLUSION: In this study, twenty-one new compounds, containing the privileged structures of phenylurea and 5-fluoroindolin-2-one, were designed and synthesized. Subsequent structureactivity studies showed that 1g was the most bioactive antitumor agent among all tested compounds, hence a potentially promising lead compound once given further optimization.

Strictosidine Synthase Triggered Enantioselective Synthesis of N-Substituted (S)-3,14,18,19-Tetrahydroangustines as Novel Topoisomerase I Inhibitors.

Monoterpenoid indole alkaloids (MIAs) comprise an important class of molecules for drug discovery, and they have variant carbon skeletons with prominent bioactivities. For instance, in spite of limitations to their use, camptothecins are the only clinically approved topoisomerase I (Top1) inhibitors. The enzyme strictosidine synthase, which is key for MIA biosynthesis, was applied to the enantioselective preparation of three N-substituted (S)-3,14,18,19-tetrahydroangustine (THA) derivatives. These non-camptothecin MIAs were shown to have moderate in vitro HepG2 cytotoxicity and Top1 inhibition activities. The (S)-configured MIAs had stronger cytotoxicity and Top1 inhibition than their chemically synthesized (R)-enantiomers, which aligned with the results of molecular dynamics simulations. A series of N-substituted (S)-THAs were then chemoenzymatically synthesized to investigate structure-activity relationships. The most active analogue observed was the N-(2-Cl benzoyl)-substituted derivative (7i). Insight into the binding mode of 7i and a Top1-DNA covalent complex was investigated by molecular dynamics simulations, which will facilitate future efforts to optimize the Top1 inhibitory activities of non-camptothecin MIAs.

Design, synthesis, and biological evaluation of novel piperidine-4-carboxamide derivatives as potent CCR5 inhibitors.

Based on a putative 'Y shape' pharmacophore model of CCR5 inhibitors, a series of novel piperidine-4-carboxamide derivatives were designed and synthesized using a group-reverse strategy. Among synthesized target compounds, 16g (IC50 = 25.73 nM) and 16i (IC50 = 25.53 nM) showed equivalent inhibitory activity against CCR5 to that of the positive control maraviroc (IC50 = 25.43 nM) in calcium mobilization assay. Selected compounds were further tested for their antiviral activity in HIV-1 single cycle assay. Two compounds, 16g and 16i, displayed antiviral activity with IC50 values of 73.01 nM and 94.10 nM, respectively. Additionally, the pharmacokinetic properties and inhibitory potency against hERG of 16g were evaluated, providing a foundation for ongoing optimization.