Search Results (2,709)

Surface-enhanced Raman spectroscopy (SERS) amplifies Raman scattering by placing molecules in the near-field of plasmonic nanostructures, enabling label-free molecular fingerprinting. While attractive for living cell phenotyping, many cellular SERS works rely on internalized colloidal nanoparticles, leading to variable uptake/localization, aggregation-driven hotspot fluctuations, and potential cellular perturbation. Here, we report a chip-like Au/SiO₂ nanolaminate SERS substrate that supports direct culture and label-free measurements of living cells on spatially defined hotspots without nanoparticle uptake. The periodic nanolaminate forms dense nanogaps and is engineered for 785 nm excitation, providing uniform enhancement over a large, culture-compatible area with high hotspot uniformity. By engineering the cell–substrate nano–bio interface, the platform enables reproducible acquisition of intrinsic cellular vibrational fingerprints under physiological conditions without Raman tags. Using MCF-7 and MDA-MB-231 breast cancer cells, we collected hundreds of spectra per line, and MDA-MB-231 exhibited broader spectral variations, indicating greater heterogeneity. Principal component analysis and linear discriminant analysis achieved 99% classification accuracy for MCF-7 and MDA-MB-231, and bright-field imaging confirmed preserved adhesion and canonical morphologies. This chip-based, label-free living cell SERS platform enables scalable, nonperturbative phenotyping and may support rapid malignancy classification and treatment response screening across subtle cancer states. Full article

While artemisinin and its derivatives demonstrate broad antitumor potential, the stereochemical influence on the bioactivity of higher-order artemisinin assemblies remains inadequately characterized. Herein, we report the synthesis, chromatographic separation, and structural elucidation of four stereoisomeric artemisinin trimers, followed by systematic evaluation of their antitumor efficacy against MCF-7 and MDA-MB-231 breast cancer cell lines. All trimers exhibited potent cytotoxicity against MCF-7 cells (IC₅₀ < 0.09 μM), with trimer 6a (β, β, β) demonstrating robust antitumor activity in both in vitro and in vivo xenograft models. Remarkably, pronounced stereochemistry-dependent activity emerged against MDA-MB-231 cells: 6a displayed approximately 100-fold greater potency than 6b (β, β, α) and 6.6-fold superiority over gemcitabine. Mechanistic investigations revealed that 6a downregulates Cyclin D1, CDK4, and CDK6 expression, thereby inducing G0/G1 phase cell cycle arrest. These findings underscore the pivotal role of stereochemical configuration in modulating artemisinin trimer bioactivity and provide rational guidance for structure-based design of artemisinin-derived anticancer therapeutics. Full article

Munronia pinnata (Meliaceae), a medicinal plant used in Zhuang traditional medicine, is recognized as a rich source of structurally diverse limonoids. In our continuing investigation of bioactive constituents from Guangxi medicinal plants, four new prieurianin-type limonoids, munropins G–J (1–4), were isolated from their aerial parts. Their structures were determined through comprehensive spectroscopic analysis, including nuclear magnetic resonance and high-resolution mass spectrometry, and further supported by quantum chemical calculations for electronic circular dichroism and statistical probability analysis. Munropins G (1) and H (2) feature an unprecedented C-12 β-D-glucosylated α-methyl-2′-hydroxypentanoate side chain and a C-17 β-substituted furan ring, with 1 being the 7-O-acetyl derivative of 2. Munropins I (3) and J (4) possess a formyl group at C-11, a 3-methyl-2-hydroxypentanoate ester at C-12, and a C-17 γ-hydroxy-α,β-unsaturated γ-lactone unit (21-hydroxy for 3, 23-hydroxy for 4), each existing as an equilibrating mixture of C-21 epimers—a phenomenon observed for the first time within a prieurianin-type framework. The absolute configurations of 1 and 2 were established by quantum chemical electronic circular dichroism calculations, while those of 3 and 4 remain to be assigned. All compounds were evaluated for cytotoxicity against human lung (A549), liver (HepG2), breast (MCF-7), and colon (HCT116) cancer cell lines and for anti-inflammatory activity in lipopolysaccharide-induced RAW 264.7 murine macrophages, but none exhibited significant effects at a concentration of 80 μM. This study expands the chemical diversity of Munronia limonoids and provides new molecular scaffolds for future structure–activity relationship investigations and chemotaxonomic markers for the Meliaceae family. Full article

Breast cancer remains a major global health challenge, requiring novel therapeutic strategies that can overcome drug resistance and improve treatment efficacy. This study investigates the synergistic antitumor effects of etoposide, a conventional chemotherapeutic agent, and resveratrol, a natural polyphenol with anticancer properties, in human breast cancer cell lines, with particular focus on their ability to activate the parthanatos cell death pathway. Using MCF-7 (estrogen receptor-positive) and MDA-MB-231 (triple-negative) breast cancer cells, we assessed cell viability via MTT assays and evaluated parthanatos activation through multiple complementary approaches including AIF translocation determined by subcellular fractionation, NAD+ depletion measurement, and gene expression analysis. Synergy was quantified using the Chou–Talalay method across multiple effect levels (ED50, ED75, ED90). To establish causality, Olaparib PARP inhibitor experiments were performed to confirm that PARP-1 hyperactivation is essential for the observed cytotoxic effects. The results demonstrated that the etoposide–resveratrol combination significantly enhanced cell death and inhibited proliferation compared to single-agent treatments, with combination index (CI) values indicating strong synergism (CI = 0.62–0.75 for MCF-7; CI = 0.58–0.71 for MDA-MB-231). This synergy was associated with robust parthanatos activation, evidenced by increased PARP-1 expression, AIF nuclear translocation confirmed by subcellular fractionation, and significant NAD+ depletion. Critically, Olaparib pre-treatment (3 µM) significantly rescued cells from combination-induced death, restored NAD+ levels to near-control values, and prevented AIF translocation, establishing a causal link between PARP-1 hyperactivation and parthanatos-mediated cytotoxicity. The combination also induced significant DNA fragmentation, elevated oxidative stress, and cell death with morphological features consistent with parthanatos, while caspase activity remained low, confirming caspase-independent cell death. These findings suggest that targeting parthanatos with etoposide and resveratrol could offer a promising therapeutic strategy for breast cancer, potentially overcoming resistance and improving efficacy. Further in vivo studies and clinical investigations are needed to validate these results and explore translational applications. Full article

Phyllanthus emblica (amla) exhibits anticancer activity, but its extracts often suffer from poor stability and bioavailability. This study developed amla extract-loaded niosomes to enhance delivery and evaluate their anticancer activity against MCF-7 and HCT116 cell lines, supported by in silico analyses. Methodology: Amla extract was prepared using a 50% aqueous–alcoholic solvent system and lyophilized. Niosomes were prepared by the thin-film hydration method and characterized for physicochemical properties. Anticancer activity was evaluated through in vitro cytotoxicity studies, supported by molecular docking and in silico pharmacokinetic analyses. Results: Optimized niosomes exhibited spherical morphology, good homogeneity (PDI < 0.30), anionic surface charge, high entrapment efficiency (70.5 ± 5.9%), and sustained diffusion-controlled release. In vitro cytotoxicity demonstrated a strong concentration-dependent anticancer activity of amla-loaded niosomes across a range of concentrations (31.25–1000 µg/mL) against both MCF-7 and HCT116 cell lines. At 1000 µg/mL, cell viability decreased to 7.0% and 5.4% in MCF-7 and HCT116 cells, respectively, with calculated IC₅₀ values of 245 µg/mL and 158 µg/mL. Molecular docking and pharmacokinetic predictions supported the potential multi-target anticancer relevance of major phytochemicals, including hydrolyzable tannins, phenolic acids, flavonoid aglycones and glycosides, and highlighted bioavailability limitations for certain high-affinity glycosylated flavonoids, reinforcing the rationale for vesicular encapsulation. Conclusions: Amla extract-loaded niosomes represent a promising vesicular system for enhanced, sustained delivery of anticancer activity in vitro, with complementary in silico findings supporting mechanistic plausibility and translational rationale. Further studies are warranted to evaluate their performance in vivo. Full article

Circulating tumor cells (CTCs) are valuable liquid-biopsy biomarkers, yet their extreme rarity makes high-purity, high-throughput enrichment challenging. In spiral inertial microfluidics, high cell loading induces long-range hydrodynamic interactions that broaden the focused blood-cell stream; consequently, a subpopulation completes the ~0.5 and ~1.0 Dean-cycle migrations with a phase delay, compressing the CTC–blood cell gap and degrading purity. Here we propose a Dean-cycle phase-regulated double-spiral design informed by this phenomenon. This design aims to mitigate the stream-broadening effect by boosting the Dean number during the first half-cycle to promote synchronized blood-cell migration and shifting the CTC equilibrium position near one full cycle to further widen the CTC–blood cell separation. We implement this strategy in a second-generation double-spiral microfluidic chip (SDMC) and scale it to a four-channel parallel array (ASDMC). Under optimized conditions, ASDMC processes diluted whole blood (hematocrit = 4%) without the need for red blood cell (RBC) lysis or antibody labeling, achieving a sample throughput of 1200 μL·min⁻¹. Specifically, it exhibits a mean recovery rate of 98.8% across three spiked tumor cell lines (MCF-7, PC-9, and Mahlavu) and a mean white blood cell (WBC) depletion efficiency of 93.3%. In a pilot clinical testing of 20 patients (NSCLC and HCC), enriched fractions enabled immunofluorescence identification of CK⁺CD45⁻DAPI⁺ CTCs, with an exploratory trend of increasing CTC counts with advanced disease stage (4–34 cells·mL⁻¹). These results describe a scalable, label-free platform, and the observed purification performance aligns with our proposed mechanism: Dean-cycle phase regulation to mitigate blood-cell migration lag. Our findings support further technical validation and clinical assessment in larger cohorts. Full article

Background: Breast cancer (BC) remains the most prevalent malignancy among women worldwide, with one in eight at risk during their lifetime. Platinum-based chemotherapeutic drugs, despite of their binding to the DNA of cancer cells, are plagued by toxicity and resistance, necessitating the need for safer and more effective alternatives, such as organometallic complexes. Both synthetic organometallic complexes and natural compounds have attracted attention in this regard. Organotin(IV) complexes are promising chemotherapeutics due to their structural versatility and bioactivity, while vitamins such as Vitamin D (VD) and Vitamin E (VE) exhibit antiproliferative, anti-inflammatory, and antioxidant properties, making them valuable candidates for combination therapy. Methodology: In this study, six novel organotin(IV) dithiocarbamate complexes [LMe₃Sn (Complex 1), LBu₃Sn (Complex 2), LPh₃Sn (Complex 3), LMe₂SnCl (Complex 4), LBu₂SnCl (Complex 5), and L₂Me₂Sn (Complex 6), where L = (E)-4-styrylpiperazine-1-carbodithioate], were synthesized and characterized by FT-IR, ¹H-, ¹³C-NMR, and elemental analysis. Results: Structural studies confirmed penta- and hexacoordination geometries. In silico docking against six BC-related proteins identified Complexes 2 and 4 with both vitamins as promising candidates, exhibiting strong binding affinities, with stable interaction profiles. However, integration of pharmacokinetic, antioxidant, and anti-inflammatory analyses highlighted Complex 4 with both vitamins as the most potent candidate owing to its superior ADME characteristics and balanced biological properties. Subsequent in vitro assays confirmed these findings, as Complex 4 demonstrated strong cytotoxic activity against both MCF-7 (>1.16-fold) and MDA-MB-231 (>1.46-fold) cell lines, surpassing the efficacy of cisplatin. Remarkably, co-administration of VD or VE with Complex 4 further enhanced its anticancer potential, with Chou–Talalay combination index values < 1 (0.66–0.91) indicating a synergistic interaction. Conclusions: Collectively, these results identify Complex 4 as a promising lead compound, and its synergistic activity with natural vitamins may promote cell death, likely through apoptosis induction and modulation of oxidative stress, underscoring its potential as an effective and less toxic therapeutic strategy for breast cancer management. Full article

Breast carcinoma represents the most frequent malignancy in women in Canada, and intrinsic or acquired drug resistance significantly increases the risk of recurrence and metastasis. Although front-line therapy is multimodal, chemoresistance remains a major hurdle in treatment and therapy, and the intake of natural compounds resulting from fermentation processes is currently considered an effective strategy to overcome this problem. This study investigated the effect of extracellular vesicles (EVs) from Mesenchymal Stromal/stem cells (MSCs) pretreated with cultured Lentinula edodes extract (AHCC) on reducing chemoresistance and modulating microRNAs in the MCF-7 and MCF-7/DOX cell lines. EV characterization was performed using nanoparticle tracking analysis, and microRNAs and the formation of cancer stem cells were studied. The miRNA analysis revealed that AHCC significantly downregulated oncogenic miR-155 but upregulated the tumor-suppressive microRNAs miR-34a, miR-Let7a, and miR-200c. In vitro experiments showed inhibition of cancer stem cell proliferation after challenging the cells with AHCC-pretreated EVs. Conclusion: Our data demonstrated that AHCC may contribute to modulation of the tumor microenvironment, thus influencing the development of cancer stem cells. Full article

Background: Cancer patients are highly susceptible to microbial infections due to immune suppression, necessitating therapeutic strategies that integrate anticancer efficacy with effective antimicrobial intervention. Chalcone-derived nitrogen-fused heterocycles represent a promising platform for developing multi-target agents with relevance to antimicrobial drug delivery, particularly for localized infections. Methods: A series of chalcone-based pyrazoline-thiadiazole nitrogen-fused azole hybrids was synthesized via thiosemicarbohydrazide-functionalized intermediates and fully characterized. Antiproliferative activity was evaluated against MCF-7, HepG-2, HeLa, and HCT-116 cell lines, alongside selectivity toward WI-38 normal fibroblasts. Antibacterial, antibiofilm, and in vivo efficacy were assessed against methicillin-resistant Staphylococcus aureus (MRSA USA300) and Acinetobacter baumannii AB5057. Mechanistic investigations included cell-cycle analysis, apoptosis assays, ERK2, RIPK3, p53, BAX/Bcl-2 quantification, DNA gyrase inhibition, molecular docking, molecular dynamics simulations, and density functional theory calculations. Results: Compound 13 exhibited potent cytotoxicity, particularly against MCF-7 (IC₅₀ = 3.87 ± 0.2 µM), outperforming doxorubicin (IC₅₀ = 4.17 ± 0.2 µM), with high selectivity indices (SI = 10.7 for MCF-7). Mechanistically, compound 13 induced G₂/M arrest (40.16% vs. 14.15% control), increased apoptosis to 32.89%, up-regulated ERK2 (3.17-fold), RIPK3 (11.97-fold), and p53 (3.54-fold), and markedly increased the BAX/Bcl-2 ratio (~42-fold). Compounds 7 and 13 displayed bactericidal activity against MRSA and A. baumannii (MIC/MBC = 10 mg/mL), potent antibiofilm effects, and significant in vivo efficacy in an MRSA skin infection model. Compound 13 reduced bacterial load by ~5 log units, outperforming vancomycin. DNA gyrase inhibition (IC₅₀ = 17.10 ± 0.17 µM) and computational studies supported target engagement. Conclusions: Pyrazoline-thiadiazole-based nitrogen-fused azole hybrids, particularly compound 13, demonstrated quantifiable anticancer and antimicrobial efficacy with strong in vivo validation, supporting their potential as multi-target candidates relevant to antimicrobial drug delivery in infection-prone cancer patients. Full article

Endophytic fungi associated with date fruits (Phoenix dactylifera) are mostly under-explored, despite their potential as reservoirs of natural compounds. The aims of this study were to characterize the endophytic fungus Aspergillus terreus (SU5) isolated from date fruits, and to investigate its biological activities and chemical profile for the first time. Morphological and molecular methods were utilized to identify Aspergillus terreus. A liquid chromatography–mass spectrometry analysis (LC/MS/MS) was conducted to determine the chemical profile of the crude extract. Biological properties were investigated through acetylcholine esterase and butyrylcholine esterase inhibition, cytotoxicity assays against MCF-7 and MCF-7/Adr, and antioxidant assays. LC/MS/MS of the fungal extract resulted in the detection of 39 of established secondary metabolites, primarily comprising polyketides, quinones, and phenolic derivatives. The crude extract demonstrated significant antioxidant activity, especially in the ABTS assay (IC₅₀ = 50.18 μg/mL), considerable cytotoxicity against MCF-7 breast cancer cells, diminished efficacy against the drug-resistant MCF-7/Adr cell line, and preferential inhibition of butyrylcholinesterase compared to acetylcholinesterase. While none of the identified compounds are novel, numerous metabolites are documented here for the first time from an endophytic A. terreus associated with date fruits. The findings underscore date fruits as a prospective ecological niche for a chemically varied endophytic fungus with potential pharmaceutical significance. Full article

Oleocanthal (OC), an anti-inflammatory and antioxidant phenolic compound exclusively found in extra virgin olive oil (EVOO), has emerged as a potential anticancer agent through multiple mechanisms of action, yet its impact on key processes such as cellular metabolism remains insufficiently characterized. Here, we investigated the metabolic and mitochondrial responses to OC across different breast cancer molecular subtypes. Triple-negative (MDA-MB-231) and luminal (MCF7, T47D) breast cancer cell lines were treated with OC to evaluate cell viability, cell cycle progression, metabolic enzyme expression, mitochondrial respiration, and mitochondrial network organization. OC responsiveness differed, being highest in MDA-MB-231 and lowest in T47D cells. Lactate dehydrogenase levels decreased in all cell lines, while mitochondrial response varied. MDA-MB-231 mitochondrial function was fully impaired, while MCF7 cells showed increased respiratory activity, with marked mitochondrial fragmentation, and T47D cells largely preserved mitochondrial integrity and function. Notably, the magnitude of OC effects correlated with MET expression, an established target of OC and a prognostic factor associated with reduced relapse-free survival within the triple-negative subtype. Collectively, these findings identify OC as a modulator of cancer cell metabolism and mitochondrial dynamics, with particular relevance in MET-high triple-negative breast cancers. Full article

Humulus lupulus L. (hops), belonging to the Cannabaceae family, is grown mainly for brewing, with 98% of global production directed to this sector. Moreover, large volumes of female cone residues are generated as by-products, representing a valuable source of bioactive compounds that can be valorized under green chemistry principles. This study aimed to extract bioactive compounds from hop cone residues sourced from craft breweries using ultrasound-assisted (EH-UA) and microwave-assisted (EH-MA) extraction methods. Hydroalcoholic extracts (70%) were analyzed for chemical composition, antioxidant, antimicrobial, antiproliferative, nitric oxide (NO)-production inhibition, and photoprotective activities. GC-MS identified 32 compounds in EH-MA and 30 in EH-UA, including terpenes, sesquiterpenes, oxygenated sesquiterpenes, and fatty acids. Both extracts demonstrated strong antioxidant activity in cell-based (TBARS, OxHLIA) and chemical (DPPH, ABTS, FRAP) assays, particularly EH-MA. Significant antibacterial activity was observed, especially against Enterobacter cloacae, Pseudomonas aeruginosa, and Staphylococcus aureus (MIC 1–10 mg/mL), as well as antifungal activity against Aspergillus brasiliensis (MIC 2–2.5 mg/mL). Selective antiproliferative activity was observed against tumor cell lines Caco-2 and MCF-7 (GI₅₀ 25 μg/mL), without cytotoxicity toward nontumor cell lines Vero and PLP2 (GI₅₀ > 400 μg/mL). All extracts inhibited the production of the inflammation mediator NO, with EH-MA showing the most potent effect (IC₅₀ of 35 μg/mL), followed by EH-UA (IC₅₀ of 55 μg/mL). Photoprotective potential was also demonstrated, with SPF values of 19 (EH-MA) and 18 (EH-UA). In conclusion, hop cone residues can yield multifunctional extracts with antioxidant, antimicrobial, antiproliferative, anti-inflammatory, and photoprotective activities, which support their sustainable upcycling for pharmacological, nutraceutical, and cosmetic applications. Full article

Agapanthus africanus (L.) Hoffmanns. is a medicinal plant traditionally used in South Africa for its promise as a source of bioactive compounds with anticancer properties. This study aimed to investigate the apoptotic effects of A. africanus fractions on cancer cell lines and to identify the bioactive phytochemical constituents using gas chromatography-mass spectrometry analysis. To test for cytotoxicity, MCF-7, A549, and HeLa cancer cells were treated with crude extract, n-hexane, n-butanol, dichloromethane, and aqueous fractions of A. africanus extracts at different concentrations (0.00–1000 µg/mL). Total apoptosis was quantified using Annexin V/PI staining. The 4′,6-diamidino-2-phenylindole was used to detect nuclear morphological changes and the Caspase-GLO 3/7 assay was employed to check the caspase activation in the cancer cells. Expression of apoptosis-related (caspase-3, bax, bcl-2) genes was evaluated using real time-polymerase chain reaction. The crude extract of A. africanus exhibited dose-dependent cytotoxicity against MCF-7, A549, and HeLa cells, with IC₅₀ values of 130 µg/mL, 380 µg/mL, and <125 µg/mL, respectively. Among the tested fractions, the n-butanol fraction showed cytotoxicity towards MCF-7 cells with an IC₅₀ value of <870 µg/mL. In contrast, n-hexane, dichloromethane and the aqueous fractions exhibited higher IC₅₀ values against cancer cells. Flow cytometry analysis, which was applied to quantify total apoptosis, revealed that the crude extract of A. africanus induced apoptosis by (~60%) compared to the n-butanol fraction, which exhibited a moderate apoptotic effect (~27%). DAPI nuclear staining showed nuclear shrinkage and chromatin condensation in the MCF-7 cell line, whereas in Caspase-GLO 3/7, the crude extract and n-butanol fraction resulted in significant luminescence, indicating activation of caspase-3/7. Caspase-3/7 analysis showed A. africanus treatments produced varying levels of apoptotic activation. The crude extract increased caspase activity by 2.9-fold, while the n-butanol fraction induced a 1.7-fold rise compared with untreated cells. GC-MS chromatograms detected and identified 16 compounds in the fractionated n-butanol and 23 compounds from the crude extract of A. africanus. The major compounds identified from the n-butanol fraction included n-hexadecanoic acid; α-tocopherol and 9,12,15-octadecatrienoic acid, while the GC–MS profile of the crude extract was dominated by 6,10,14-trimethylpentadecan-2-one; 1,3,5-Triphenylcyclohexane and phytol. The study indicates the pro-apoptotic potential of A. africanus, particularly in its crude form, supporting its ethnopharmacological use and suggesting its relevance as a candidate for anticancer drug discovery. Full article

Background/Objectives: There is a clear need for more options to control the progression of breast cancer and prevent the occurrence of breast cancer in minority populations that have a higher rate of mortality due to triple-negative breast cancer (TNBC) subtypes. Prevalent nutraceuticals such as Ashwagandha (also known as the Indian Winter Cherry) have anti-inflammatory and apoptotic capabilities, as well as the ability to inhibit cancer growth. The purpose of this study is to analyze the novel combination of withaferin A (derived from the Indian Winter Cherry and known to have histone deacetylase inhibition capabilities) and sodium butyrate (a short-chain fatty acid produced from the gut microbiome and known to have DNA methyltransferase inhibition capabilities) treatment on breast cancer-derived cell lines. There is a scientific gap of possible causality of decreasing breast cancer progression when treated with sodium butyrate and withaferin A. Methods: Two in vitro cell viability assays were utilized consisting of [MTT (4,5 Dimethylthiazol-2-yl)] and the neutral red assay to analyze the impact of treatment of compounds alone and in combination on breast cancer cells for 72 h. The Highest Single Agent (HSA) combination analysis was utilized to derive combination indexes for our breast cancer cell types. Protein and gene expression was investigated for Class 1 histone deacetylases, de novo DNA methyltransferase, the p65 subunit of NF-κB, and NFκB1. Lastly, DNA methyltransferase enzymatic activity was analyzed via the Epigentek DNMT Activity/Inhibition ELISA Easy Kit. Results: Through the cell viability assay [MTT (4,5 Dimethylthiazol-2-yl)], MCF−7, MDA−MB−231, and MDA−MB−157 cells were found to have a decrease in cell viability due to combinatorial treatment with withaferin A and sodium butyrate. Western blot results depicted a decrease in protein expression levels for DNA methyltransferases due to the administration of 2.5 mM sodium butyrate and 0.2 µM withaferin A alone and in combination for breast cancer cell lines MCF−7, MDA-MB-231, and MDA−MB−157. Additionally, the combination of these two components have successfully inhibited the progression of the NFκB1 gene within analysis through the quantitative polymerase chain reaction (qPCR). Conclusions: The novel combination of withaferin A and sodium butyrate have markedly reduced the progression of breast cancer-derived cell lines for cell viability, epigenetic DNMT gene expression, as well as inhibiting NFκB1 signaling on the gene expression level. Full article

Background/Objectives: Oral squamous cell carcinoma (OSCC) is a major cause of human cancer. The enzyme, nicotinamide N-methyltransferase (NNMT), is overexpressed in a variety of human cancers, including OSCC. Our objective was to target NNMT with novel inhibitors and determine their anti-cancer efficacy while shedding light on their possible mechanism of action. Methods: We identified two small molecule inhibitors of NNMT (AG-670 and AO-022) based on a pharmacophore of the in silico nicotinamide binding site. These inhibitors were investigated for (i) potency to inhibit the activity of the isolated NNMT enzyme (EC₅₀ values), (ii) cytotoxicity (IC₅₀ values) against the human OSCC cell line, SCC-4, and (iii) ability to affect cellular energy metabolism, as measured by oxygen consumption, in SCC-4 cells (plus dysplastic oral keratinocytes (DOK) cells and breast cancer MCF-7 cells). Immunoblotting was used to determine whether NNMT was expressed in the aforementioned cells. Results: NNMT is expressed in SCC-4 and DOK cells (and primary human oral keratinocytes) but not MCF 7 cells. The NNMT inhibitors inhibit isolated NNMT enzyme activity and were cytotoxic to SCC-4 cells (EC₅₀ and IC₅₀ values in the micromolar range). Sublethal doses of the inhibitors were demonstrated to inhibit in situ mitochondrial oxygen consumption in SCC-4 and DOK cells but not in MCF-7 cells. It was demonstrated that the NNMT inhibitors do not directly inhibit mitochondrial electron transport chain activity. Thus, we deduce that the NNMT inhibitors affect mitochondrial activity indirectly via NNMT. Conclusions: It is concluded that NNMT is a potential drug target for oral cancer. Full article