Biology subjects

Njoo, E.

Publications and source records attributed to Njoo, E..

7 recordsLinked to original sources

bioRxiv2026

C19 trityl and silyl andrographolide analogs exhibit in vitro anticancer activity in murine cancer models

Andrographolide, a labdane diterpenoid isolated from A. paniculata has been investigated for activity in a broad panel of biological contexts, including its anti-inflammatory, antiviral, and anticancer properties. Previously, A-ring analogs of andrographolide bearing silyl and trityl ethers at C19 have demonstrated improved in vitro anticancer activity in human cancer cell lines, with putative activity through the Wnt1/{beta}-catenin signaling axis. In order to investigate the activity of this series of C19 andrographolide analogs, alongside a cyclic A-ring acetonide analog, as anticancer agents in murine cancer cell models, we evaluated antiproliferative activity of these compounds in B16F10 melanoma, CT26 colorectal adenocarcinoma, Neuro2a neuroblastoma, and 4T1 mammary ductal carcinoma cell lines, and found that most compounds exhibited potent micromolar level anticancer activity. Among these, all trityl ethers exhibited nearly indistinguishable IC50 values of 4-20 M, and generally exhibited greater potency compared to C19 silyl ether analogs. This anticancer activity was further validated through apoptosis flow cytometry, wherein we concluded that our compounds induced apoptosis to a greater extent than the parent compound, andrographolide. Further, we examine the role of modulation of canonical Wnt1/{beta}-catenin signaling in a series of co-delivery assays with CHIR-99021, a selective GSK-3{beta} kinase inhibitor, and MSAB, a selective {beta}-catenin degrader. Finally, we demonstrate that a selection of silyl ether analogs of andrographolide elicit cell cycle arrest by flow cytometry in a manner that is decoupled to in vitro potency trends. Altogether, we report the first in vitro evaluation of trityl and silyl ether analogs of andrographolide within murine adherent cancer cells.

cancer biology↗

bioRxiv2026

A Saturated Aminotriester Lipid Enhances Amonafide Activity in Human Colorectal Cancer Cells

The delivery of small-molecule therapeutics across cellular membranes remains a fundamental challenge in drug development, particularly for compounds whose physicochemical properties limit intracellular bioavailability. Inspired by the low toxicity, biodegradability, and synthetic accessibility of triethanolamine-derived lipids, we investigated a series of C18 aminotriester lipids as excipients for the codelivery of anticancer therapeutics. Four structurally related triester lipids bearing saturated, cis-monounsaturated, trans-monounsaturated, and di-unsaturated C18 tails were synthesized through straightforward esterification reactions with triethanolamine. These lipids were evaluated for their ability to enhance the antiproliferative activity of several anticancer agents, including paclitaxel, doxorubicin, amonafide, homoharringtonine, camptothecin, and SN-38. Across multiple drug classes, the aminotriester lipids exhibited minimal intrinsic cytotoxicity and generally produced limited enhancement of drug potency. However, the fully saturated tris-stearate aminotriester lipid selectively enhanced the antiproliferative activity of amonafide in HCT-116 colorectal cancer cells, particularly at lower concentrations. In contrast, unsaturated lipid analogues displayed negligible enhancement effects, and the activity of the tris-stearate lipid was substantially attenuated in A549 lung adenocarcinoma cells, weakly observed in HT-29 colorectal cancer cells, and absent in CT26 murine colorectal cancer cells. Lactate dehydrogenase release assays indicated that these effects were not associated with membrane lysis or nonspecific cytotoxicity. Further, fluorescence microscopy time course experiments suggest improved membrane trafficking of amonafide when codelivered stoichiometrically with fully saturated C18 aminotriester lipids. Collectively, these findings demonstrate that saturated triethanolamine-based aminotriester lipids may function as selective and biocompatible codelivery excipients for certain small-molecule therapeutics. The observed dependence on both lipid saturation state and cellular context suggests that membrane organization and lipid packing may play important roles in mediating these effects. These results establish a foundation for further mechanistic investigations into aminotriester lipid-assisted small-molecule delivery systems.

cancer biology↗

bioRxiv2025

Synthesis, anticancer properties, and biological profiling of synthetic glycan analogs of proscillaridin A

Several cardiac glycosides, including digoxin, digitoxin, and proscillaridin A, have been originally identified as cardiomyocyte modulators and are currently being investigated for their anticancer properties. These cardiac glycosides are generally classified into cardenolides and bufadienolides, which bear butenolide and pyrone D-ring functionality, respectively, and have exhibited remarkable in vitro toxicity in various cancerous cell lines. As simple modifications on steroidal small molecules have demonstrated success in augmenting bioavailability or enhancing downstream biological activities, we sought to prepare synthetic analogs of proscillaridin A, a bufadienolide isolated from the genus Scilla. We synthesized two novel analogs of proscillaridin A bearing acetate esters or a dimethyl ketal to investigate how strategies of ketalization or acetylation of the A-ring allylic glycoside might alter its anticancer properties. The antiproliferative activity of these compounds was evaluated alongside proscillaridin A and two model cardiac glycosides, digoxin and digitoxin, across several colorectal and liver cancer cell lines. Through a diverse panel of cell viability and cytotoxicity experiments, reporter assays, and cell cycle and protein marker analysis by flow cytometry, we find that ketalization of the glycan of proscillaridin A provides similar, and in some cases enhanced, in vitro potency. This study establishes the foundation for current and further in vitro and in vivo evaluation of glycan analogs of proscillaridin A.

cancer biology↗

bioRxiv2025

Synthetic derivatives of vinpocetine as antiproliferative agents

Vincamine is an indole alkaloid initially isolated from plants of the Vinca genus and has previously been demonstrated to have antioxidant, hypoglycemic, and hypolipidemic activities. Vinpocetine, a synthetic derivative of vincamine with an enhanced pharmacological profile, has demonstrated promising antiproliferative properties. While previously reported vinpocetine derivatives have undergone extensive investigation for their pharmacological properties, the role of the E-ring ethyl ester in the anticancer properties of compounds with this scaffold has not yet been fully described. Here, we report the antiproliferative activity of two vinpocetine analogs with modifications at the E-ring. MTT assays revealed that reduction of the ethyl ester to an alcohol exhibited strong dose-dependent antiproliferative activity across five mammalian cell lines, but did not induce significant markers of apoptosis or necrotic death as determined by FITC/Annexin V and cell cycle flow cytometry, respectively. We further observe that vinpocetine and both analogs exhibit dose-dependent modulation of a TCF/LEF reporter cell, which appears to be decoupled from trends in antiproliferative activity Altogether, this work demonstrates the potential for E-ring modifications of vinpocetine as anticancer agents.

cancer biology↗

bioRxiv2025

Anticancer synthetic arylsulfonamides with Wnt1-modulating activity

Dysregulation of the Wnt1/{beta}-catenin signaling pathway has been demonstrated to be a driving factor in the propagation of several human cancers. Previous studies have discovered methyl 3-{[(4-methylphenyl)sulfonyl]amino}benzoate (MSAB) as a selective inhibitor of the Wnt1/{beta}-catenin signaling pathway, which putatively functions through direct engagement of {beta}-catenin. To understand how changes to the identity and position of the methyl ester affect the in vitro potency of this compound in Wnt1-driven mammalian cell lines, we prepared and evaluated three analogs of MSAB with 3- and 4-substituted methyl and ethyl esters. In MTT assays, analogs with methyl esters showed significantly more activity than their ethyl ester counterparts and both 4-substituted esters exhibited significantly attenuated antiproliferative activity, with MSAB exhibiting dose-dependent activity across cancerous cell lines. Further analysis by flow cytometry reveals low-Annexin V signal, suggesting that these compounds do not function via a pro-apoptotic pathway. Additionally, through a TCF/LEF-activated luciferase reporter cell assay, we observe that the 4-substituted methyl ester analogous to MSAB exhibits slightly diminished Wnt1-inhibitory activity, while 3- and 4-substituted ethyl esters exhibit minimal Wnt1-inhibitory activity. This difference in potency with a simple ester substitution might be attributed to several factors that ultimately drive antiproliferative activity, prompting the investigation of other potential substituents to further investigate the structure-activity relationship of these compounds as Wnt1-based antiproliferative agents.

cancer biology↗

bioRxiv2024

Direct expression of CPT1a enables a high throughput platform for the discovery of CPT1a modulators

Carnitine palmitoyltransferase 1 (CPT1), which catalyzes the rate-limiting step of fatty acid oxidation, has been implicated in therapeutic approaches to several human diseases characterized by aberrant lipid metabolism. Isoform-specific quantification of CPT1 activity is essential in the characterization of small molecule inhibitors of CPT1, but several existing means to quantify enzymatic activity, including the use of radioisotope labeled carnitine, are not amenable to scalable, high throughput screening. Here, we demonstrate that mitochondrial extracts from Expi293 cells transfected with a CPT1a plasmid are a reliable and robust source of catalytically active human CPT1. Moreover, with a source of catalytically active enzyme in hand, we modified a previously reported colorimetric method of coenzyme A (CoA) easily scalable to a 96-well format for the screening of CPT1a inhibitors. This assay platform was validated by two previously reported inhibitors of CPT1a: R-etomoxir and perhexiline. To further demonstrate the applicability of this method in small molecule screening, we prepared and screened a library of 87 known small molecule APIs, validating the inhibitory effect of chlorpromazine on CPT1. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/628575v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1f69f0corg.highwire.dtl.DTLVardef@43eb95org.highwire.dtl.DTLVardef@11fa21corg.highwire.dtl.DTLVardef@1cbe405_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Synthesis and Evaluation of Carmofur Analogs as Antiproliferative Agents, Inhibitors to the Main Protease (Mpro) of SARS-CoV-2, and Membrane Rupture-Inducing Agents

Initially developed as a derivatized analog of 5-fluorouracil for the treatment of colorectal cancer, carmofur has more recently demonstrated potent covalent inhibition of the main protease (Mpro) of SARS-CoV-2. Harnessing our previously described workflow for the optimized preparation of carmofur using benchtop 19F NMR spectroscopy, here, we prepared and evaluated a synthetic library of nine carmofur analogs with a selection of side chain motifs or single-atom substitution to explore the diversifiability of these compounds as Mpro inhibitors, where we discovered that a hexyl carbamate analog outperformed carmofur, and as antiproliferative agents in model human cell lines to identify differences in potency when the carbonyl electrophilicity and/or alkyl side chains are modified. Finally, we describe a novel workflow for the evaluation of membrane-rupturing small molecules through imaging of fluorescently labeled giant unilamellar vesicles (GUVs), and through this, we identified two lipophilic urethane analogs of carmofur bearing dodecyl urethane and octadecyl urethane side chains that have potent membrane-rupturing capability in the nanomolar range, providing insight into a potential mechanism for the in vitro activities of lipidated 5-fluorouracil analogs.

biochemistry↗