Total synthesis of 1,4a-di-epi-ent-pancratistatin, exemplifying a stereodivergent approach to pancratistatin isomers.

The total synthesis of 1,4a-di-epi-ent-pancratistatin, a novel stereoisomer of the anti-tumor Amaryllidaceae alkaloid pancratistatin, was achieved in 14 steps starting from D-mannitol. The construction of the pancratistatin skeleton involved conjugate addition of organocuprate to a nitrosoolefin, which was generated in situ from inosose oxime. This was followed by stereoselective reduction of the oxime to an amine and site-selective formylation. Biological evaluations revealed that the newly synthesized compounds exhibit cytotoxicity toward cancer cells and significant ferroptosis inhibitory activity. These compounds constitute a promising small-molecule library for the development of potent bioactive agents.

Design, synthesis, and biological evaluation of new bis-benzylisoquinoline-based analogues as potential neuromuscular blocking agents.

Neuromuscular blocking agents (NMBAs) are widely used in anesthesia for intubation and surgical muscle relaxation. Novel atracurium and mivacurium derivatives were developed, with compounds 18c, 18d, and 29a showing mivacurium-like relaxation at 27.27 nmol/kg, and 15b, 15c, 15e, and 15h having a shorter duration at 272.7 nmol/kg. The structure-activity and configuration-activity relationships of these derivatives and 29a's binding to nicotinic acetylcholine receptors were analyzed through molecular docking. Rabbit trials showed 29a has a shorter duration compared to mivacurium. This suggests that linker properties, ammonium group substituents, and configuration are crucial for NMBA activity and duration, with compound 29a emerging as a potential ultra-short-acting NMBA.

Design, Synthesis, and Investigation of the Pharmacokinetics and Anticancer Activities of Indenoisoquinoline Derivatives That Stabilize the G-Quadruplex in the MYC Promoter and Inhibit Topoisomerase I.

G-quadruplexes are noncanonical four-stranded DNA secondary structures. MYC is a master oncogene and the G-quadruplex formed in the MYC promoter functions as a transcriptional silencer and can be stabilized by small molecules. We have previously revealed a novel mechanism of action for indenoisoquinoline anticancer drugs, dual-downregulation of MYC and inhibition of topoisomerase I. Herein, we report the design and synthesis of novel 7-aza-8,9-methylenedioxyindenoisoquinolines based on desirable substituents and π-π stacking interactions. These compounds stabilize the MYC promoter G-quadruplex, significantly lower MYC levels in cancer cells, and inhibit topoisomerase I. MYC targeting was demonstrated by differential activities in Raji vs CA-46 cells and cytotoxicity in MYC-dependent cell lines. Cytotoxicities in the NCI-60 panel of human cancer cell lines were investigated. Favorable pharmacokinetics were established, and in vivo anticancer activities were demonstrated in xenograft mouse models. Furthermore, favorable brain penetration, brain pharmacokinetics, and anticancer activity in an orthotopic glioblastoma mouse model were demonstrated.

Discovery of novel diaryl substituted isoquinolin-1(2H)-one derivatives as hypoxia-inducible factor-1 signaling inhibitors for the treatment of rheumatoid arthritis.

Since synovial hypoxic microenvironment significantly promotes the pathological progress of rheumatoid arthritis (RA), hypoxia-inducible factor 1 (HIF-1) has been emerged as a promising target for the development of novel therapeutic agents for RA treatment. In this study, we designed and synthesized a series of diaryl substituted isoquinolin-1(2H)-one derivatives as HIF-1 signaling inhibitors using scaffold-hopping strategy. By modifying the substituents on N-atom and 6-position of isoquinolin-1-one, we discovered compound 17q with the most potent activities against HIF-1 (IC50 = 0.55 µM) in a hypoxia-reactive element (HRE) luciferase reporter assay. Further pharmacological studies revealed that 17q concentration-dependently blocked hypoxia-induced HIF-1α protein accumulation, reduced inflammation response, inhibited cellular invasiveness and promoted VHL-dependent HIF-1α degradation in human RA synovial cell line. Moreover, 17q improved the pathological injury of ankle joints, decreased angiogenesis and attenuated inflammation response in the adjuvant-induced arthritis (AIA) rat model, indicating the promising therapeutic potential of compound 17q as an effective HIF-1 inhibitor for RA therapy.

Construction of Isoquinolone Scaffolds on DNA via Rhodium(III)-Catalyzed C-H Activation.

Isoquinolone is one of the most common heterocyclic core structures in countless natural products and many bioactive compounds. Here, a highly efficient approach to synthesize isoquinolone scaffolds on DNA via rhodium(III)-catalyzed C-H activation has been described. This chemistry transformation is robust and has shown good compatibility with DNA, which is suitable for DNA-encoded library synthesis.

Design, synthesis, and biological evaluation of novel benzo[6,7]indolo[3,4-c]isoquinolines as anticancer agents with topoisomerase I inhibition.

A novel series of benzo[6,7]indolo[3,4-c]isoquinolines 3a-3f was designed by scaffold hopping of topoisomerase I inhibitor benzo[g][1]benzopyrano[4,3-b]indol-6(13H)-ones (BBPIs), which were developed by structural modification of the natural marine product lamellarin. The unconventional pentacycle was constructed by Bischler-Napieralski-type condensation of amide 11 and subsequent intramolecular Heck reaction. In vitro anticancer activity of the synthesized benzo[6,7]indolo[3,4-c]isoquinolines was evaluated on a panel of 39 human cancer cell lines (JFCR39). Among the compounds tested, N-(3-morpholinopropyl) derivative 3e showed the most potent antiproliferative activity, with a mean GI50 value of 39 nM. This compound inhibited topoisomerase I activity by stabilizing the enzyme-DNA complex.

Screening of Chelidonium majus isoquinoline alkaloids reveals berberine and chelidonine as selective ligands for the nuclear receptors RORß and HNF4α, respectively.

The nuclear receptors hepatocyte nuclear factor 4α (HNF4α) and retinoic acid receptor-related orphan receptor-ß (RORß) are ligand-regulated transcription factors and potential drug targets for metabolic disorders. However, there is a lack of small molecular, selective ligands to explore the therapeutic potential in further detail. Here, we report the discovery of greater celandine (Chelidonium majus) isoquinoline alkaloids as nuclear receptor modulators: Berberine is a selective RORß inverse agonist and modulated target genes involved in the circadian clock, photoreceptor cell development, and neuronal function. The structurally related chelidonine was identified as a ligand for the constitutively active HNF4α receptor, with nanomolar potency in a cellular reporter gene assay. In human liver cancer cells naturally expressing high levels of HNF4α, chelidonine acted as an inverse agonist and downregulated genes associated with gluconeogenesis and drug metabolism. Both berberine and chelidonine are promising tool compounds to further investigate their target nuclear receptors and for drug discovery.

Cycloplatinated (II) Complex Based on Isoquinoline Alkaloid Elicits Ferritinophagy-Dependent Ferroptosis in Triple-Negative Breast Cancer Cells.

The development and optimization of metal-based anticancer drugs with novel cytotoxic mechanisms have emerged as key strategies to overcome chemotherapeutic resistance and side effects. Agents that simultaneously induce ferroptosis and autophagic death have received extensive attention as potential modalities for cancer therapy. However, only a limited set of drugs or treatment modalities can synergistically induce ferroptosis and autophagic tumor cell death. In this work, we designed and synthesized four new cycloplatinated (II) complexes harboring an isoquinoline alkaloid C∧N ligand. On screening the in vitro activity of these agents, we found that Pt-3 exhibited greater selectivity of cytotoxicity, decreased resistance factors, and improved anticancer activity compared to cisplatin. Furthermore, Pt-3, which we demonstrate can initiate potent ferritinophagy-dependent ferroptosis, exhibits less toxic and better therapeutic activity than cisplatin in vivo. Our results identify Pt-3 as a promising candidate or paradigm for further drug development in cancer treatment.

Sonochemical synthesis and biological evaluation of isoquinolin-1(2H)-one/isoindolin-1-one derivatives: Discovery of a positive ago-allosteric modulator (PAAM) of 5HT2CR.

Efforts have been devoted for the discovery and development of positive allosteric modulators (PAMs) of 5-HT2CR because of their potential advantages over the orthosteric agonist like Lorcaserin that was withdrawn from the market. On the other hand, pursuing a positive ago-allosteric modulator (PAAM) is considered as beneficial particularly when an agonist is not capable of affecting the potency of the endogenous agonist sufficiently. In search of a suitable PAAM of 5-HT2CR we adopted an in silico based approach that indicated the potential of the 3-(1-hydroxycycloalkyl) substituted isoquinolin-1-one derivatives against the 5-HT2CR as majority of these molecules interacted with the site other than that of Lorcaserin with superior docking scores. These compounds along with the regioisomeric 3-methyleneisoindolin-1-one derivatives were prepared via the Cu(OAc)2 catalyzed coupling of 2-iodobenzamide with 1-ethynylcycloalkanol under ultrasound irradiation. According to the in vitro studies, most of these compounds were not only found to be potent and selective agonists but also emerged as PAAM of 5-HT2CR whereas Lorcaserin did not show PAAM activities. According to the SAR study the isoquinolin-1(2H)-ones appeared as better PAAM than isoindolin-1-ones whereas the presence of hydroxyl group appeared to be crucial for the activity. With the potent PAAM activity for 5-HT2CR (EC50 = 1 nM) and 107 and 86-fold selectivity towards 5-HT2C over 5-HT2A and 5-HT2B the compound 4i was identified as a hit molecule. The compound showed good stability in male BALB/c mice brain homogenate (∼85 % remaining after 2 h), moderate stability in the presence of rat liver microsomes (42 % remaining after 1 h) and acceptable PK properties with fast reaching in the brain maintaining âˆ¼ 1:1 brain/plasma concentration ratio. The compound at a dose of 50 mg/kg exhibited decreased trend in the food intake starting from day 3 in S.D. rats, which reached significant by 5th day, and the effect was comparable to Lorcaserin (10 mg/kg) on day 5. Thus, being the first example of PAAM of 5-HT2CR the compound 4i is of further medicinal interest.

A Concise Total Synthesis of the Fungal Isoquinoline Alkaloid TMC-120B.

Recent reports of antiepileptic activity of the fungal alkaloid TMC-120B have renewed the interest in this natural product. Previous total syntheses of TMC-120B comprise many steps and have low overall yields (11-17 steps, 1.5-2.9% yield). Thus, to access this compound more efficiently, we herein present a concise and significantly improved total synthesis of the natural product. Our short synthesis relies on two key cyclization steps to assemble the central scaffold: isoquinoline formation via an ethynyl-imino cyclization and an intramolecular Friedel-Crafts reaction to form the furanone.

A Three-Component Synthesis of 3-Functionally Substituted 5,6-Dihydropyrrolo[2,1-a]isoquinolines.

Synthesis of novel C3-substituted 5,6-dihydropyrrolo[2,1-a]isoquinolines via a three-component domino reaction of 1-aroyl-3,4-dihydroisoquinolines, terminal alkynes and CH-acids under microwave irradiation in dry acetonitrile is described. The method developed enables the obtainment of highly functionalized compounds with pharmacophore groups, which are potentially biologically active.

Design, synthesis and anti-hepatocellular carcinoma activity of 3-arylisoquinoline alkaloids.

This article describes the syntheses and biological activity of five 3-arylisoquinoline natural products corydamine (1), N-formyl Corydamine (2), hypecumine (3), Decumbenine B (XW) and 2-(1,3-dioxolo [4,5-h]isoquinolin-7-yl)-4,5-dimethoxy-N-methyl-Benzeneethanamine (A), and twelve analogues. Among them, 1, 2, and A were synthesized for the first time. In vitro screening for anti-proliferative activity showed that derivative 1a could significantly inhibit the proliferation of HCC cells (IC50 = 9.82 µM on Huh7 cells and 6.83 µM on LM9 cells), and arrest cell cycle at G2/M phase. The mechanistic studies further suggested compound 1a was a dual inhibitor of Topo I and Topo II, and Topo II inhibitory activity was superior to etoposide. In addition, 1a could significantly inhibit the invasion and migration of cancer cells by inhibiting the expression of MMP-9, and induce apoptosis through inhibiting the activation of the PI3K/Akt/mTOR signaling pathway. Moreover, in vivo studies demonstrated 1a could obviously reduce the growth of xenograft tumor and possessed good pharmacokinetic parameters, which indicated the potential value of 1a in treating liver cancer.

Design and Synthesis of Indenoisoquinolines Targeting Topoisomerase I and Other Biological Macromolecules for Cancer Chemotherapy.

The discovery that certain indenoisoquinolines inhibit the religation reaction of DNA in the topoisomerase I-DNA-indenoisoquinoline ternary complex led to a structure-based drug design research program which resulted in three representatives that entered Phase I clinical trials in cancer patients at the National Cancer Institute. This has stimulated a great deal of interest in the design and execution of new synthetic pathways for indenoisoquinoline production. More recently, modulation of the substitution pattern and chemical nature of substituents on the indenoisoquinoline scaffold has resulted in a widening scope of additional biological targets, including RXR, PARP-1, MYC promoter G-quadruplex, topoisomerase II, estrogen receptor, VEGFR-2, HIF-1α, and tyrosyl DNA phosphodiesterases 1 and 2. Furthermore, convincing evidence has been advanced supporting the potential use of indenoisoquinolines for the treatment of diseases other than cancer. The rapidly expanding indenoisoquinoline knowledge base has provided a firm foundation for further advancements in indenoisoquinoline chemistry, pharmacology, and therapeutics.

Analogs of TIQ-A as inhibitors of human mono-ADP-ribosylating PARPs.

The scaffold of TIQ-A, a previously known inhibitor of human poly-ADP-ribosyltransferase PARP1, was utilized to develop inhibitors against human mono-ADP-ribosyltransferases through structure-guided design and activity profiling. By supplementing the TIQ-A scaffold with small structural changes, based on a PARP10 inhibitor OUL35, selectivity changed from poly-ADP-ribosyltransferases towards mono-ADP-ribosyltransferases. Binding modes of analogs were experimentally verified by determining complex crystal structures with mono-ADP-ribosyltransferase PARP15 and with poly-ADP-ribosyltransferase TNKS2. The best analogs of the study achieved 10-20-fold selectivity towards mono-ADP-ribosyltransferases PARP10 and PARP15 while maintaining micromolar potencies. The work demonstrates a route to differentiate compound selectivity between mono- and poly-ribosyltransferases of the human ARTD family.

Derivatives of montanine-type alkaloids and their implication for the treatment of Alzheimer's disease: Synthesis, biological activity and in silico study.

Alzheimers disease (AD) is the most common neurodegenerative disorder, characterized by neuronal loss and cognitive impairment. Currently, very few drugs are available for AD treatment, and a search for new therapeutics is urgently needed. Thus, in the current study, twenty-eight new derivatives of montanine-type Amaryllidaceae alkaloids were synthesized and evaluated for their ability to inhibit human recombinant acetylcholinesterase (hAChE) and butyrylcholinesterase (hBuChE). Three derivatives (1n, 1o, and 1p) with different substitution patterns demonstrated significant selective inhibitory potency for hAChE (IC50 < 5 µM), and one analog, 1v, showed selective hBuChE inhibition activity (IC50 = 1.73 ± 0.05 µM). The prediction of CNS availability, as disclosed by the BBB score, suggests that the active compounds in this survey should be able pass through the blood-brain barrier (BBB). Cytotoxicity screening and docking studies were carried out for the two most pronounced cholinesterase inhibitors, 1n and 1v.

CuCl2-catalyzed inexpensive, faster and ligand/additive free synthesis of isoquinolin-1(2H)-one derivatives via the coupling-cyclization strategy: Evaluation of a new class of compounds as potential PDE4 inhibitors.

In spite of possessing a wide range of pharmacological properties the anti-inflammatory activities of isoquinolin-1(2H)-ones were rarely known or explored earlier. PDE4 inhibitors on the other hand in addition to their usefulness in treating inflammatory diseases have been suggested to attenuate the cytokine storm in COVID-19 especially TNF-α. In our effort, a new class of isoquinolin-1(2H)-ones derivatives containing an aminosulfonyl moiety were designed and explored as potential inhibitors of PDE4. Accordingly, for the first time a CuCl2-catalyzed inexpensive, faster and ligand/additive free approach has been developed for the synthesis of these predesigned isoquinolin-1(2H)-one derivatives via the coupling-cyclization strategy. Thus, the CuCl2-catalyzed reaction of 2-iodobenzamides with appropriate terminal alkynes proceeded with high chemo and regioselectivity affording the desired compounds in 77-84% yield within 1-1.5 h. The methodology also afforded simpler isoquinolin-1(2H)-ones devoid of aminosulfonyl moiety showing a broader generality and scope of this approach. Several of the synthesized compounds especially 3c, 3k and 3s showed impressive inhibition (83-90%) of PDE4B when tested at 10 µM in vitro whereas compounds devoid of aminosulfonyl moiety was found to be less active. In spite of high inhibition showed at 10 µM these compounds did not show proper concertation dependent inhibition below 1 µM that was reflected in their IC50 values e.g. 2.43 ± 0.32, 3.26 ± 0.24 and 3.63 ± 0.80 µM for 3k, 3o and 3s respectively. The anti-inflammatory potential of these compounds was indicated by their TNF-α inhibition (60-50% at 10 µM). The in silico docking studies of these molecules suggested good interactions with PDE4B and selective inhibition of PDE4B by 3k over PDE4D that was supported by in vitro assay results. These observations together with the favorable ADME and safety predicted for 3kin silico not only suggested 3k as an interesting hit molecule for further studies but also reveal the first example of isoquinolin-1(2H)-one based inhibitor of PDE4B.

In Vivo Induction of P-Glycoprotein Function can be Measured with [18F]MC225 and PET.

P-Glycoprotein (P-gp) is an efflux pump located at the blood-brain barrier (BBB) that contributes to the protection of the central nervous system by transporting neurotoxic compounds out of the brain. A decline in P-gp function has been related to the pathogenesis of neurodegenerative diseases. P-gp inducers can increase the P-gp function and are considered as potential candidates for the treatment of such disorders. The P-gp inducer MC111 increased P-gp expression and function in SW480 human colon adenocarcinoma and colo-320 cells, respectively. Our study aims to evaluate the P-gp inducing effect of MC111 in the whole brain in vivo, using the P-gp tracer [18F]MC225 and positron emission tomography (PET). Eighteen Wistar rats were treated with either vehicle solution, 4.5 mg/kg of MC111 (low-dose group), or 6 mg/kg of MC111 (high-dose group). Animals underwent a 60 min dynamic PET scan with arterial-blood sampling, 24 h after treatment with the inducer. Data were analyzed using the 1-tissue-compartment model and metabolite-corrected plasma as the input function. Model parameters such as the influx constant (K1) and volume of distribution (VT) were calculated, which reflect the in vivo P-gp function. P-gp and pregnane xenobiotic receptor (PXR) expression levels of the whole brain were assessed using western blot. The administration of MC111 decreased K1 and VT of [18F]MC225 in the whole brain and all of the selected brain regions. In the high-dose group, whole-brain K1 was decreased by 34% (K1-high-dose = 0.20 ± 0.02 vs K1-control = 0.30 ± 0.02; p < 0.001) and in the low-dose group by 7% (K1-low-dose = 0.28 ± 0.02 vs K1-control = 0.30 ± 0.02; p = 0.42) compared to controls. Whole-brain VT was decreased by 25% in the high-dose group (VT-high-dose = 5.92 ± 0.41 vs VT-control = 7.82 ± 0.38; p < 0.001) and by 6% in the low-dose group (VT-low-dose = 7.35 ± 0.38 vs VT-control = 7.82 ± 0.37; p = 0.38) compared to controls. k2 values did not vary after treatment. The treatment did not affect the metabolism of [18F]MC225. Western blot studies using the whole-brain tissue did not detect changes in the P-gp expression, however, preliminary results using isolated brain capillaries found an increasing trend up to 37% in treated rats. The decrease in K1 and VT values after treatment with the inducer indicates an increase in the P-gp functionality at the BBB of treated rats. Moreover, preliminary results using brain endothelial cells also sustained the increase in the P-gp expression. In conclusion, the results verify that MC111 induces P-gp expression and function at the BBB in rats. An increasing trend regarding the P-gp expression levels is found using western blot and an increased P-gp function is confirmed with [18F]MC225 and PET.

N,C-Coupled naphthylisoquinoline alkaloids: a versatile new class of axially chiral natural products.

Covering: up to April 2021During the past decades, a plethora of natural products with restricted rotation about a biaryl axis have been discovered, among them the naphthylisoquinoline (NIQ) alkaloids, mostly C,C-coupled and having remarkable bioactivities. Within this fascinating class of naturally occurring biaryl compounds, NIQ alkaloids bearing an N,C-heterobiaryl axis have attracted particular attention. They are structurally and biosynthetically unprecedented, with interesting stereochemical implications and biological activities. In contrast to existing articles and reviews about axially chiral - yet C,C-coupled - natural products, this is the first, comprehensive review on the new subclass of N,C-coupled NIQs, their isolation and structural elucidation, their N,C-axial chirality, their biosynthetic origin, their promising antiparasitic and antileukemic activities, and their total synthesis.

Synthesis and Biological Screening of New Cyano-Substituted Pyrrole Fused (Iso)Quinoline Derivatives.

Several new cyano-substituted derivatives with pyrrolo[1,2-a]quinoline and pyrrolo[2,1-a]isoquinoline scaffolds were synthesized by the [3 + 2] cycloaddition of (iso)quinolinium ylides to fumaronitrile. The cycloimmonium ylides reacted in situ as 1,3-dipoles with fumaronitrile to selectively form distinct final compounds, depending on the structure of the (iso)quinolinium salt. Eleven compounds were evaluated for their anticancer activity against a panel of 60 human cancer cell lines. The most potent compound 9a showed a broad spectrum of antiproliferative activity against cancer cell lines representing leukemia, melanoma and cancer of lung, colon, central nervous system, ovary, kidney, breast and prostate cancer. In vitro assays and molecular docking revealed tubulin interaction properties of compound 9a.

Palladium-mediated synthesis and biological evaluation of C-10b substituted Dihydropyrrolo[1,2-b]isoquinolines as antileishmanial agents.

The development of new molecules for the treatment of leishmaniasis is, a neglected parasitic disease, is urgent as current anti-leishmanial therapeutics are hampered by drug toxicity and resistance. The pyrrolo[1,2-b]isoquinoline core was selected as starting point, and palladium-catalyzed Heck-initiated cascade reactions were developed for the synthesis of a series of C-10 substituted derivatives. Their in vitro leishmanicidal activity against visceral (L. donovani) and cutaneous (L. amazonensis) leishmaniasis was evaluated. The best activity was found, in general, for the 10-arylmethyl substituted pyrroloisoquinolines. In particular, 2ad (IC50 = 3.30 µM, SI > 77.01) and 2bb (IC50 = 3.93 µM, SI > 58.77) were approximately 10-fold more potent and selective than the drug of reference (miltefosine), against L. amazonensis on in vitro promastigote assays, while 2ae was the more active compound in the in vitro amastigote assays (IC50 = 33.59 µM, SI > 8.93). Notably, almost all compounds showed low cytotoxicity, CC50 > 100 µg/mL in J774 cells, highest tested dose. In addition, we have developed the first Perturbation Theory Machine Learning (PTML) algorithm able to predict simultaneously multiple biological activity parameters (IC50, Ki, etc.) vs. any Leishmania species and target protein, with high values of specificity (>98%) and sensitivity (>90%) in both training and validation series. Therefore, this model may be useful to reduce time and assay costs (material and human resources) in the drug discovery process.