Letters in Drug Design & Discovery - Volume 20, Issue 12, 2023

Ferroptosis is an identified form of regulated cell death different from cell necrosis, autophagy, and apoptosis, characterized by iron-dependent accumulation of lipid reactive oxygen species. The processes of ferroptosis are mainly related to iron metabolism disorder, inactivation of glutathione peroxidase 4 (GPX4), and coenzyme Q10-dependent pathway. Inducing ferroptosis is considered a promising strategy to fight against cancers, especially apoptosis-resistant tumors. Epigallocatechin-gallate (EGCG) is the predominately active substance in green tea, which is widely consumed worldwide as a beverage. Recently, EGCG has been proved to play an important role in inducing ferroptosis by modulation of the iron metabolism and promotion of glutathione peroxidase 4 (GPX4) protein degradation. Therefore, this review mainly elaborates the regulating effects of EGCG on ferroptosis, aiming to create a new space for the research and development of novel anticancer drugs.

Background: Curcumin is a polyphenol compound extracted from plant turmeric with high pharmacological activities. The clinical application of curcumin is limited due to the shortcomings of poor water solubility, instability, and low bioavailability. Objective: Modifying the 4', 4''-bit of curcumin is an effective strategy to improve the pharmacological activity of curcumin. Conclusion: In this review, we focused on the strategy of synthesis, medicinal properties, and structurefunction relationship of 4', 4''-bit modified, curcumin derivatives.

Introduction: Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), has its natural history tracing back to 70,000 years. Latent M.tb infection is the reservoir of the TB epidemic. M.tb is becoming more prevalent and acquiring multidrug resistance among the first-line antibiotics. Methods: Methylation is one of the main mechanisms through which bacteria develop resistance, hence targeting methyltransferases provides the opportunity to achieve two-birds-with-one-stone: a) antibiotic: inhibiting the translation activity and b) anti-resistance: eliminating methylation as a mode of resistance. Currently, no known drugs or lead molecules are targeting the methyltransferases, in general, and rRNA Small Subunit Methyltransferase D (RsmD) family, in particular, in M.tb species. Results and Discussion: S-Adenosyl-L-methionine(SAM) is known as the universal donor of a methyl group which is an indispensable cofactor for the proper functioning of SAM-dependent methyltransferases. This in silico study attempts to design and develop novel SAM-analog inhibitors against RsmD, which in turn affects the growth and survival of M.tb in TB patients. The SAM-analogs were designed, after careful study and analysis of RsmD pharmacophore and SAM binding properties. The functional groups such as amide, amine, acetamide, formamide, hydroxyl, fluorine, iodine, and bromine were used to design novel analogs with the aim to improve the binding of analog with RsmD. The analogs that gave better docking scores followed by favourable binding affinities and ADMET properties than native SAM were ranked. Conclusion: Among the library of SAM analogs, the top two analogs with IDs: SAM_172 and SAM_153 need testing and validation for their efficacy through in vitro and in vivo studies.

Background: Torpedo californica acetylcholinesterase (TcAChE) is an important drug development target for Alzheimer's disease (AD) therapeutics. The current in silico study aims to recognise indene methylene-derived compounds acting against TcAChE to gain insight into the molecular interactions. Objective: The current study focused on identifying novel inhibitors for Torpedo californica acetylcholinesterase (TcAChE) by virtual screening, molecular docking, drug-likeness, molecular simulation, and DFT profile for anti-Alzheimer's activity. Methods: Molecular docking, ADMET screening, molecular simulation, and DFT were performed for drug development having anti-Alzheimer's activity related to Torpedo californica acetylcholinesterase (TcAChE). Results: On the AutoDock Vina algorithms, ligands SD-24 [-12.6, -13.1 kcal/mol], SD-30 [-12.5, -12.6 kcal/mol], SD-42 [-11.8, -12.5kcal/mol] showed promising docking and confirmatory redocking scores compared to Donepezil [-8, -10.9 kcal/mol], followed by ADMET screening. The best three complexes were subjected to molecular dynamics simulations (MDSs) over 30 ns to understand the TcAChE dynamics and behavior in a complex with the ligand. MEP and NBO analysis was performed for the DFT/B3LYP theory and 6-311G [d,p] base set and Gaussian 09 package program. For MDSs, the root means square (RMSD) parameter remained stable for 30 ns at 0.25 nm. The ligand-AChE complex formed 2 to 4 satisfactory intermolecular H bonds, which substantiated the stability of the three compounds in the protein binding cluster as potent binders. The LUMO (owest unoccupied molecular orbital)- HOMO (highest occupied molecular orbital) energy gap of the SD24, SD30, and SD42 compounds was 4.0943, 4.2489, and 4.2489 eV, respectively, and stability was ordered as SD24>SD30=SD42. Conclusion: The outcome of in silico studies suggests that SD24, SD30, and SD42 compounds have promising drug-likeness, simulation, and DFT profiles for anti-Alzheimer's activity. However, in vitro and in vivo studies are required to confirm their biological activities.

Background: The research based on natural product herbicides has been increasingly attractive in the field of agriculture. 4-hydroxyphenylpyruvate dioxygenase (HPPD) is one of the most promising compounds in the field of herbicide innovation. Objective: This paper aims to study the relationship between the activity and structure of quinazoline- 2,4-dione derivatives, and to design novel HPPD inhibitors. Methods: A set of quinazoline-2,4-dione derivatives underwent 3D-QSAR studies as well as molecular docking. MOLCAD analysis and 8-point pharmacophore model provided an important reference for us to understand the interaction mode of HPPD and antagonists. Results: The CoMFA (n = 5; q² = 0.778; r² = 0.985) and CoMSIA (n = 6; q² = 0.776; r² = 0.95) models had remarkable stability and predictability. MOLCAD studies and pharmacophore modeling proved the validity of the 3D-QSAR model. On the basis of the gained information, nine novel derivatives as potential candidates of HPPD inhibitors with better predicted activities were designed, mainly binding to HPPD via lipophilic interaction and hydrogen bonding. The key hydrophobic residues of HPPD, Phe381, His308, Asn282, Phe392 and Leu368, were found to be antagonist binding sites that are important factors for the stability of the antagonist binding site. Conclusion: The structural basis and activity of HPPD inhibitors were revealed, which might provide clear and solid insights to guide the rational design of novel HPPD inhibitors.

Background: Miltefosine (MIL), hexadecyl phosphocholine, is the only oral medicine used to treat leishmaniasis. This drug has a major limitation and is expensive and potentially teratogenic. Objective: This study aimed to evaluate the toxic effect of MIL and its niosomal form on human umbilical vein endothelial cells (HUVECs), the expression genes, and the profile associated with apoptosis in the mitochondrial permeabilization regulated. Methods: Miltefosine niosome (MN) prepared by the thin-film hydration method and characterized. HUVECs were treated with MIL (100–1000μg/ml), and MN (10-50μg/ml) for 24, 48, and 72 h, and the persistence was assessed by colorimetric assay flow cytometry and real-time PCR. Results: Lesser toxicity was detected on cell proliferation for MN while both forms decreased Bcl-2 and elevated the expression of Bak/Bax and caspases-3, -8, and -9. The data demonstrated that MIL significantly exerted its cytotoxicity on HUVECs compared to MN. Conclusion: This drug should be considered embryotoxic during pregnancy, while in niosomal form, it released slowly and remained safe. The mechanism of action of MIL associated with programmed cell death.

Background: Alzheimer's disease (AD) is one of the major causes of morbidity, affecting more than 36 million population worldwide. Current anti-AD treatments result in limited therapeutic outcomes owing to the complexity of the disease. Some natural promising herbal drugs and phytoconstituents utilized as an alternative treatment for AD have been reported by several researchers for their neuroprotective action. Objective: This study aimed at carrying out molecular docking studies of selected promising flavonoids such as curcumin, quercetin, bilobalide, ferulic acid, reseveratrol for their molecular interactions with multiple AD target proteins and further compare the data with the standard acetylcholine esterase inhibitor drug donepezil. Methods: The molecular docking interactions were studied between the selected actives and the AD target proteins acetylcholine esterase, butyrylcholine esterase, and tau protein using the AutoDock Vina software. The Swiss ADME approach performed prediction of the ADME properties. Binding interactions of the ligands at the target protein binding sites were examined using the Discovery Studio Visualizer 2021. Results: The binding energy for quercetin in the active site of the selected target enzymes acetylcholine esterase, butyrylcholine esterase, and tau protein was -9.5 , -7.8 , and -8.2 kcal/mol, respectively which was much greater than other flavonoids and comparable to the standard drug donepezil binding energy - 10.3, -7.5,-7.9 kcal/mol respectively. Conclusion: This work focuses on recognizing structural features and comparing selected flavonoids and standard acetylcholine esterase (AChEs) inhibitors for molecular docking with three primary targets of AD, namely AChEs, Butyrylcholine esterase, and tau protein. This in silico study concluded that quercetin had significant docking interactions and good pharmacokinetic features, making it a potential therapeutic candidate for the treatment of AD.

Objective: The aim of this study was to determine the vasorelaxant effect of semisynthetic derivatives of ursolic acid, establish the mode of action, and determine the antihypertensive effect of the most active compound. Methods: Isolated aorta rat rings (ex vivo assay), with and without endothelium, were used to determine the vasorelaxant effect of seven semisynthetic derivatives of ursolic acid (UA-01 to UA-07). Then, the effect of the most active compound was studied in ex vivo assay using L-NAME, ODQ and indomethacin to determine its mode action. Finally, the in vivo cardiovascular effect and molecular docking of the most active compound were determined. Results: UA-07 was the most potent compound of the derivatives, since UA-07 induced significant relaxant effect in concentration- and endothelium-dependent manners (Emax = 79.09% and EC50 = 110 μM) on aortic rat rings pre-contracted with noradrenaline (NA, 0.1 μM). Also, endothelium-derived nitric oxide seems to be involved in the mechanism of action of UA-07, because pre-incubation with L-NAME (a NOS inhibitor) and ODQ (a soluble guanylate cyclase inhibitor) significantly reduced its vasorelaxant effect. Further, UA-07 showed a similar binding affinity as ursolic acid on eNOS C1 binding pocket in in silico studies. Finally, treatment with UA-07 (50 mg/Kg) on spontaneously hypertensive rats (SHR) significantly decreased diastolic blood pressure for seven hours. Conclusion: These results demonstrate the significant antihypertensive effect of UA-07, possibly through the NO/cGMP system.

Background: The epidermal growth factor receptor of the tyrosine kinase family has been largely targeted in mutations associated with non-small cell lung cancer. EGFR inhibitors have been produced that bind allosterically to the C797S mutant EGFR enzyme. Objective: Here, the Waterswap tool has been used for the interpretation and visualization of trajectories of mutant EGFR-ligand complexes. Virtual screening of the generated compounds has been carried out along with its molecular docking and ADMET analysis. Methods: Out of the generated library of compounds, the top 15 have been selected. Waterswap calculated the binding free energies of the compounds and thermodynamic properties of the enumerated compounds were compared with that of standard EAI045. Results: It was observed that compound KSK-1 stabilized better than EAI045. Conclusion: Waterswap analysis offers a promising new path in the hunt for improved tools for analyzing and visualizing molecular driving forces in protein-ligand complex simulations.

Background: Predicting protein-peptide binding affinity is one of the leading research subjects in peptide drug design and repositioning. In previous studies, models constructed by researchers just used features of peptide structures. These features had limited information and could not describe the proteinpeptide interaction mode. This made models and predicted results lack interpretability in pharmacy and biology, which led to the protein-peptide interaction mode not being reflected. Therefore, it was of little significance for the design of peptide drugs. Objective: Considering the protein-peptide interaction mode, we extracted protein-peptide interaction interface characteristics and built machine learning models to improve the performance and enhance the interpretability of models. Methods: Taking MHC-I protein and its binding peptides as the research object, protein-peptide complexes were obtained by molecular docking, and 94 protein-peptide interaction interface characteristics were calculated. Then ten important features were selected using recursive feature elimination to construct SVR, RF, and MLP models to predict protein-peptide binding affinity. Results: The MAE of the SVR, RF and MLP models constructed using protein-peptide interaction interface characteristics are 0.2279, 0.2939 and 0.2041, their MSE are 0.1289, 0.1308 and 0.0780, and their R² reached 0.8711, 0.8692 and 0.9220, respectively. Conclusion: The model constructed using protein-peptide interaction interface characteristics showed better prediction results. The key features for predicting protein-peptide binding affinity are the bSASA of negatively charged species, hydrogen bond acceptor, hydrophobic group, planarity, and aromatic ring.

Isoxazole derivatives are one of the heterocyclic structures that have various biological activities. Objective: This study aimed to design and synthesize novel isoxazole derivatives and evaluate their cytotoxic, cyclooxygenase (COX) inhibitory, and antimicrobial activities. Methods: Coupling reactions of aniline derivatives and isoxazole carboxylic acid have been established to synthesize chloro-fluorophenyl-isoxazole carboxamide derivatives. The synthesized compounds were characterized using ¹H, ¹³C-NMR, IR, and HRMS spectrum analysis and evaluated by MTS, COX kit, and antimicrobial microdilution assays. Results: The synthesized compounds showed moderate to potent cytotoxic activity against all the screened cancer cell lines (except 2b against HepG2) with an IC50 range of 0.107-77.83 μg/ml. The results showed that the most potent compound against cervical cancer cell line (HeLa) was the 2b compound, with an IC50 value of 0.11±0.10 μg/ml, which is less than the IC50 for the potent anticancer drug Doxorubicin. While the 2a and 2b compounds have potential antiproliferative activities against Hep3B with IC50 doses of 2.774±0.53 and 3.621±1.56 μg/ml, respectively. Furthermore, 2c compound was the most active against MCF7, with an IC50 value of 1.59±1.60 μg/ml. In addition, the most potent isoxazole derivative against the COX1 enzyme was the 2b compound, with an IC50 value of 0.391 μg/ml, and compound 2a had a good selectivity ratio of 1.44 compared to the Ketoprofen positive control. However, compound 2c showed antifungal activity against Candida albicans with an MIC value of 2.0 mg/ml in comparison to the antifungal drug Fluconazole (MIC = 1.65 mg/ml). Conclusion: The synthesized compounds could be candidates for anticancer drugs in the future, and other analogues and cytotoxicity evaluations should be conducted

Background: Buruli ulcer (BU), caused by Mycobacterium ulcerans is a neglected tropical disease characterized by necrotic skin lesions. Antibiotic therapy and excision of the lesions are the treatments for this chronic disease. During the management of the disease, the emergence of drug resistance in these bacilli is a major challenge. Therefore, there is a need to identify new drug targets against this important pathogen. Objective: The study aimed to investigate novel drug targets exploring virulence factors of M. ulcerans by in silico analysis. Methods: Virulence proteins encoded by the chromosome of Mycobacterium ulcerans strain Agy99 were retrieved and analyzed for their cellular localization, human non-homology and essentiality. Further, proteins were analyzed for their physio-chemical characterization, drug resistance analysis, protein interaction analysis, metabolic pathway prediction, and druggability prediction by various databases and online software to find their suitability as drug targets. The structure of the predicted drug targets was also modeled and validated. Among three predicted drug targets, MUL_4536 was subjected to molecular docking with some known inhibitor compounds also. Receptor-ligand complex with the highest binding energy was selected for molecular dynamic (MD) simulation to determine the structural stability of the complex. Results: Three virulence proteins MUL_4536, MUL_3640, and MUL_2329 encoding enzymes iso-citrate lyase, lysine-N-oxygenase, pup-protein ligase, respectively were predicted as a drug target against M. ulcerans. Isocitrate lyase has been identified as a potential drug target in many other mycobacterial and non-mycobacterial diseases. Lysine-N-oxygenase is the enzyme of mycobactin biosynthesis pathway and pup-protein ligase is associated with the pup-proteasome system. Proteins of these pathways have been studied as attractive drug targets in previous research works, which further support our predictions. Conclusion: Our computational analysis predicted new drug targets, which could be used to design drugs against M. ulcerans. However, these predicted proteins require further experimental validation for their potential use as drug targets.

Aims: Synthesis of 4-fluorobenzohydrazide Schiff bases and 1,3,4-oxadiazole analogs has a DPPH radical scavenging potential. Background: Synthetic antioxidants are widely used because they are effective and cheaper than natural antioxidants. Based on the literature survey, this present study is mainly focused on the study of the free radical scavenging activity of the Schiff base and oxadiazole motifs. Methods: In this research work, Schiff’s base (4a-4g) and 1,3,4-oxadiazole (5a-5g) derivatives based on 4-fluorobenzoic acid were synthesized through multistep reactions. Initially, 4-fluorobenzoic acid was esterified in the presence of sulphuric acid (H2SO4) in ethanol solvent, and then it was reacted with an excess of hydrazine hydrate to obtain the desired 4-fluorobenzohydrazide. Various aromatic aldehydes were reacted with 4-fluorobenzo hydrazide in the presence of a catalytic amount of acetic acid to obtain the desired hydrazones. Finally, different substituted hydrazones were cyclized in the presence of iodine and potassium carbonate in DMSO to obtain substituted 1,3,4-oxadiazoles. The progress of all reactions was checked using thin-layer chromatography. The compounds were recrystallized from ethanol with good yield. The synthesized compounds were characterized with the help of EI-MS and ¹H-NMR spectroscopy. Results: The synthesized Schiff bases (4a-4g) and oxadiazole derivatives (5a-5g) of 4-fluorobenzoic acid demonstrated good free radical scavenging activity. Among the series, Compound 4f (IC50 = 25.57 ± 7.41 μM), showed comparable activity when compared with the standard Vitamin C (IC50 = 19.39 ± 12.57 μM). Similarly Compound 4a (IC50 = 40.90 ± 1.92 μM), 4b (IC50 = 34.77 ± 1.03 μM), 4c (IC50 = 90.2 ± 2.90 μM), 4e (IC50 = 78.62 ± 9.64 μM), 4g (IC50 = 80.65 ± 1.80 μM), 5a (IC50 = 52.67 ± 4.98 μM) and 5f (IC50 = 89.45 ± 9.11 μM) showed moderate antioxidant activity. Furthermore compounds, 4d (IC50 = 102.55 ± 10.4 μM), 5b (IC50 = 123.76 ± 12.34 μM), 5d (IC50 = 701.62 ± 1.06 μM), and 5e (IC50 = 102.87 ± 7.98 μM) displayed less significant anti-oxidant potential, while compounds 5c and 5g were found inactive. Conclusion: Schiff’s base (4a-4g) and substituted 1,3,4-oxadiazole (5a-5g) derivatives based on 4- fluorobenzoic acid scaffolds were synthesized using standard pathways. All compounds were structurally characterized through EI-MS and ¹H-NMR spectroscopy and evaluated for their in vitro DPPH free radical scavenging activity. In-vitro study reveals that the newly prepared derivatives of 4-fluorobenzoic acid have potent antioxidant potential. Whereas compound 5c and 5g were found inactive, this study has recognized a series of potential molecules as antioxidant agents and is useful in the field of medicinal chemistry.

Background: Cancer still remains a disease of concern with various side effects of synthetic chemotherapeutic agents. Hence, there is a continued need to develop safer therapies with fewer side effects. Erythroxylum species is a widely available source of various phytoconstituents, especially terpenoids. Objective: To carry out the docking studies of a few terpenoids on validated targets like EGFR, VEGFR, CDK, and tubulin protein which are overexpressed in many types of cancers, and to estimate the pharmacokinetic and drug-likeness properties of these molecules using in silico techniques. Materials: Protein structures were retrieved from Protein Data Bank, and the terpenoids were docked on each of the protein targets using Autodock 4.2. SwissADME was used to predict the pharmacokinetic and drug-likeness properties. Results: Compounds show good binding affinity and inhibition constant for all targets except for tubulin, where few ligands could bind. They exhibit an excellent pharmacokinetic profile, and no significant violations in drug-likeness parameters were observed. Conclusion: Compound 2 was found to be the most active agent against VEGFR, CDK, and tubulin, whereas compound 7 was most effective at EGFR. These compounds can be continued for further studies.

Background: Prediction of toxicity of imidazo[4,5-b]pyridine derivatives is carried out using GA-MLR and BPANN methods. Objective: A quantitative structure-property relationship (QSPR) was determined based on methods, including genetic algorithm-multiple linear regression (GA-MLR) and backpropagation artificial neural network (BP-ANN). These methods were employed for modeling and predicting the anticancer potency of imidazo[4,5-b]pyridine derivatives. Materials and Methods: A dataset of imidazo[4,5-b]pyridine derivatives was randomly divided into two groups, training and test sets consisting of 75% and 25% of data points, respectively. The optimized conformation of compounds was obtained using the DFT-B3LYP method and 6-31G* basis sets level with Gaussian 09 software. A large number of molecular descriptors were calculated using Dragon software. The QSAR models were optimized using multiple linear regressions (MLR). Results: The most relevant molecular descriptors were obtained using the genetic algorithm (GA) and backward stepwise regression. The predictive powers of the GA-MLR models were studied using leaveone- out (LOO) cross-validation and an external test set. Conclusion: The obtained results of statistical parameters showed the BP-ANN model to have better performance compared to the GA-MLR model. To assess the predictive ability of QSAR models, many statistical terms, such as correlation coefficient (R²), leave-one-out cross-validation (LOOCV), root mean squared error (RMSE), and external and internal validation were used. The results of validation methods demonstrate the QSAR model to be robust and with high predictivity.

Background: Targeting intracellular signaling molecules in nervous tissue progenitors is a promising basis for the development of novel neurodegenerative disease therapy approaches. Naphthoquinone shikonin from the root of Lithospermum erythrorhizon is known to have inhibitory effects on NF-ΚB and STAT3. Objective: This study aimed to explore the influence of shikonin on the functioning of progenitors of nervous tissue and its neuroprotective properties in the modeling of alcoholic encephalopathy (AE). Methods: Experiments were performed on C57B1/6 male mice. AE was modeled by prolonged intragastric administration of ethanol. We studied the exploratory behavior and conditioned reflex activity in laboratory animals, as well as the functioning of neural stem cells (NSCs) and neuronal committed progenitors (NCPs) of the subventricular zone of the cerebral hemispheres. NCPs were obtained using the immunomagnetic separation method. The direct in vitro effects of the shikonin on the colony-forming capacity of progenitors, their proliferative activity, and intensity of specialization were compared with the effects of synthetic NF-ΚB and STAT3 inhibitors. Results: Results of in vitro experiments showed that the influence of phytochemicals was similar to the effects of synthetic NF-ΚB and STAT3 inhibitors. Shikonin stimulated the proliferation of NSCs and NCPs. In vivo shikonin administration caused the normalization of exploratory behavior and conditioned reflex activity of mice with AE. These effects developed after an increase in NSCs and NCPs content in the subventricular zone of the cerebral hemispheres due to an increase in their proliferative activity. The intensity of specialization of progenitors was also accelerated Conclusion: The findings indicated the promise of developing a novel approach to the treatment of AE based on shikonin-mediated inhibiting of NF-ΚB/STAT3.

Background: Flavones are potential anticancer agents that act by different mechanisms and have multiple targets to exert anticancer effects. Nitrogen-containing heterocyclic rings have remarkable chemical characteristics as well as a wide range of biological activities. Substitution of the N-heterocyclic ring on the flavon structure may potentiate its anticancer effect. Objective: A series of flavon derivatives with an N-heteroaryl ring at the 4' position of the B ring of flavon were designed, prepared, and evaluated for anticancer activity. Methods: Different flavon derivatives were created by cyclizing chalcones, and chalcones were synthesized by Claisen-Schmidt condensation of substituted aldehydes and 2-hydroxyacetophenone. Structures of all compounds were confirmed by ¹HNMR, ¹³CNMR, FTIR, and MS spectra. Molecular docking was used to study the binding interactions of the synthesized compounds with the multiple targets ER-α, EGFR, and VEGFR-2. Anticancer activity was evaluated by Brine shrimp assay, MTT assay, and SRB assay on breast cancer (MCF-7, MDA-MB-231, and MDA-MB-468) and cervical cancer (HeLa). An apoptosis study was carried out on MCF-7 cell lines for the active compounds. Results: Among all compounds, 6c and 5f showed potent growth inhibition of ER-positive breast cancer cell lines. Compounds 5b, 5c, 5g, and 6f displayed good anticancer activity against cervical cancer. In triple-negative breast cancer cell lines, compounds 5c, 6b, and 6c showed remarkable anticancer activity. The potent flavones identified against breast cancer cell lines were 5f and 6c. Anticancer study results were analogous to the results obtained by the molecular docking study. Conclusion: This study offers a viable reference point for improving the design of flavon-incorporated Nheterocyclic ring derivatives as anticancer compounds.

Background: Breast cancer is one of the most common malignant tumors. Signal transduction and activators of transcription 3 (STAT3) have been demonstrated to play important roles in breast cancer. However, no direct inhibitor of STAT3 has been approved by the FDA for clinical use. Objective: LL1 is a newly designed STAT3 inhibitor that we identified. In this study, we investigated the cytotoxic effect of LL1 on breast cancer cells and its potential mechanisms. Methods: Colony formation and CCK-8 assay were used to detect the anti-proliferation of LL1. Flow cytometry was used to evaluate mitochondrial membrane potential and apoptosis in breast cancer cells following the treatment of LL1. The expression of proteins was analyzed using western blot, and the invasion and migration of cells were analyzed by wound healing assay and transwell assay. The xenograft model was used to evaluate the anti-cancer effect of LL1 in vivo. Results: LL1 selectively inhibited the expression of p-STAT3, but had no obvious effect on total STAT3. LL1 exhibited great potential in suppressing the proliferation of breast cancer in vitro. Moreover, LL1 induces apoptosis and the decrease of mitochondrial membrane potential in breast cancer cells. LL1 can also inhibit the invasion and migration of breast cancer cells. These cell biology changes may be induced via the regulation of Bcl-2, Bax, cleaved-caspase3, Survivn, Mmp-2, Mmp-9, N-cadherin, E-cadherin, vimentin, c-myc and cyclin D1 by LL1. In addition, LL1 exhibited great antitumor activity in vivo. Conclusion: Our study suggested that LL1 can be considered a promising candidate for the treatment of breast cancer.