NMR

19F-NMR has proved to be a detection mode in fragment-based drug discovery (FBDD) for studies of protein structure and interactions. 19F shows high sensitivity for NMR detection, and the exquisite sensitivity of 19F chemical shifts and linewidths to ligand binding all make it a valuable approach in FBDD.F (Fluorine) -Fragments can be used for 19F-NMR detection after binding to target proteins, and can be used as an effective 19F-NMR tool for FBDD.

MCE designs a unique collection of 5,123 F-fragments, all of which obey a heuristic rule called the “Rule of Three (RO3)”, in which molecular weight ≤300 Da, the number of hydrogen bond donors (H-donors) ≤3, the number of hydrogen bond acceptors (H-acceptors) is ≤3 and cLogP is ≤3. This F-fragments library is an important source of lead-like drugs.

Environmental pollution refers to the process where human activities release harmful chemicals or energy (such as industrial waste, pesticides, and plastic particles) into the natural environment at a rate that exceeds the ecosystem's capacity for self-purification, leading to deterioration in the composition or state of the atmosphere, water bodies, and soil. Environmental pollution is not only a direct threat to biodiversity but also ultimately impacts human health through the bioaccumulation effect of the food chain. Therefore, the accurate identification and dynamic monitoring of pollutants constitute the scientific cornerstone for formulating environmental policies, assessing ecological risks, and promoting green chemistry transformation.

MCE features a collection of 872 environmental pollutants, covering categories such as air pollutants, water pollutants, and pesticides, for research in the field of environmental chemistry.

Lipids are important energy storage substances in the human body. They are involved in the regulation of cell structure and function, as well as signaling pathways and gene expression. Abnormal lipid levels in tissues or their dysregulation can lead to various diseases. These include obesity, type 2 diabetes, non-alcoholic fatty liver disease, neurodegenerative diseases, infections, and cancer. Therefore, maintaining normal levels of lipid metabolism is critical to overall health.

One of the key features of cancer is aberrant lipid metabolism. This includes alterations in lipid uptake, lipid desaturation, neolipogenesis, lipid droplets, and fatty acid oxidation in cancer cells. These changes all contribute to cellular survival in an ever-changing microenvironment. They do this by modulating feed-forward oncogenic signals and key oncogenic functions. Additionally, they affect oxidative stress, other types of stress, immune responses, and intercellular communication. Alterations in lipid metabolism have a strong impact on the properties of cancer stem cells. This includes aspects such as self-renewal, differentiation, invasion, metastasis, drug sensitivity, and resistance. Furthermore, these alterations also modulate T cell responses.

MCE can offer 145 metabolites of lipid metabolism pathways, which can be used for drug screening in cancer, immune-based diseases, metabolic diseases, and other diseases.

Amino acids are the fundamental components that sustain life activities, playing roles in ATP generation, promoting nucleotide synthesis, and maintaining cellular redox balance. Moreover, dysregulation of amino acid consumption is a significant potential regulatory mechanism leading to impaired anti-tumor immunity in immune cells. The normal functioning of immune cells relies on amino acid metabolic pathways to obtain energy and materials, and upon activation, they reprogram their metabolism to support growth, proliferation, and effector functions. Additionally, metabolic disorders of specific amino acids (such as branched-chain amino acids, glutamine, and arginine) can exacerbate mitochondrial dysfunction and oxidative stress, thereby promoting myocardial fibrosis and cardiac cell damage. Therefore, conducting research related to amino acid metabolism holds promise for discovering potential drugs for diseases related to cancer, immunity, and metabolism.

MCE can provide 198 kinds of metabolites of amino acid metabolic pathways, which can be used for drug screening in various diseases such as cancer, immune disorders, metabolic diseases, mitochondrial-targeted diseases

Drug development is both expensive and time-consuming, with approximately one-third of drug discontinuations caused by severe adverse drug reactions (ADRs). Among these, drug-induced cardiotoxicity (DICT) is one of the primary reasons for late-stage clinical drug failures and market withdrawals. To date, cardiotoxicity has been observed in multiple drug classes, such as anticancer drugs, antipsychotics, antidepressants, antibiotics, and neurodegenerative disease medications. To reduce cardiac ADRs, it is crucial to determine the clinical relevance of DICT to treatment, elucidate the underlying molecular mechanisms, identify reliable biomarkers, and develop new diagnostic and therapeutic approaches.

MCE offers 258 cardiotoxicity compounds, including some FDA-approved drugs as well as inhibitors/blockers of the hERG potassium channel.

Kidneys are one of the vital organs in the human body. Due to their exposure to higher concentrations of circulating drugs or metabolites, they are highly susceptible to drug-induced renal injury (DIRI). According to statistics, drug-induced kidney injury accounts for approximately 20% of nephrotoxicity reports and can lead to acute kidney injury (AKI), chronic kidney disease (CKD), or even end-stage renal disease (ESRD). Early detection of drug nephrotoxicity is crucial for preventing irreversible kidney damage. Research into its mechanisms can help optimize clinical medication by adjusting dosages or avoiding combinations of nephrotoxic drugs. Additionally, predicting drug-induced nephrotoxicity in early drug development can reduce the risk of late-stage R&D failure.

MCE offers 158 nephrotoxicity compounds that have been clearly reported by the FDA to be associated with kidney injury. This library can be used for studying molecular mechanisms of nephrotoxicity or developing novel biomarkers.

Nucleotide metabolism is central to cancer aggressiveness, underpinning uncontrolled proliferation, chemotherapy resistance, immune evasion, and metastasis. It is transcriptionally regulated by oncogenes (e.g., MYC) and tumor suppressors (e.g., pRb). Nucleotide imbalance and nucleoside degradation further regulate cell state transitions, especially following replication stress. Additionally, secretion of nucleotides/nucleosides into the tumor microenvironment modulates immune responses and influences treatment efficacy. Therefore, nucleotide metabolites have roles in disease response and indication in cancer research, and can be utilized to develop cancer-related mechanisms and drugs.

MCE can provide 82 metabolites produced by nucleotide metabolic pathways, which can be used for disease mechanism research and drug research.

Cosmetics are complex mixtures formulated through the rational blending and processing of various natural, synthetic, or extracted raw materials. The ingredients used in cosmetics are diverse in type and functionality. Based on their properties and applications, cosmetic ingredients can generally be classified into two main categories: base materials and auxiliary ingredients. The former constitutes the primary component of cosmetics, accounting for a significant proportion in formulations and serving as the key functional substances. Auxiliary ingredients, on the other hand, play roles in shaping the product, ensuring stability, or imparting color, fragrance, and other specific characteristics.Establishing a systematic ingredient database is of great significance for cosmetic research and development. By analyzing the physicochemical properties (such as oil-water partition coefficients and molecular weight distribution), biological activity mechanisms (such as antioxidant pathways and cellular signaling regulation), and compatibility of ingredients, the database can provide precise guidance for formulation design. This approach helps shorten the development cycle of cosmetic/skincare products and reduces trial-and-error costs.

MCE offers 622 types of cosmetic ingredient compounds, including antioxidants, humectants, emulsifiers, film-forming agents, and more.

Post-translational modifications (PTMs) refer to chemical modifications that occur on amino acid residues of proteins after translation, involving the addition or removal of specific functional groups. These modifications regulate protein activity, localization, folding, and interactions with other biomolecules. By influencing protein function, PTMs play a crucial role in various pathophysiological processes. Common types of PTMs include protein phosphorylation, methylation, acetylation, ubiquitination, glycosylation, and more.

MCE offers 3,698 PTM-targeting compounds, which can be used for drug screening in cancer, neurodegenerative diseases, metabolic disorders, etc.

Linkers play a necessary role in the physicochemical properties and biological activity of the bifunctional molecule. These linkers are not a simply connection of two functional modules together, but its design and nature directly affect the stability, activity, selectivity, pharmacokinetics, and ultimately the therapeutic efficacy of the entire molecule. The length of the linker determines the extent of interaction between the two ligands and thus the maximum activity of the PROTAC molecule.

MCE has collected 0 PROTAC Linkers can be used for the design and synthesis of bifunctional molecules.

Antitussive and antiasthmatic method is a type of treatment strategy in traditional Chinese medicine, mainly used to alleviate symptoms such as coughing and asthma. These symptoms may be caused by various factors, such as: Bronchial asthma, chronic obstructive pulmonary disease, asthmatic bronchitis, cough-induced asthma, and others. Based on existing research in traditional Chinese medicine, many types of Chinese medicinal herbs showed antitussive and antiasthmatic effects. For example: Ardisiae Japonicae Herba, Ginkgo Semen, Amygdalus Communis Vas, Farfarae Flos, Viticis Cannabifoliae Fructus, Eriobotryae Folium etc. Therefore, the active ingredients derived from these traditional Chinese medicine have high medicinal value and have the potential to be developed into drugs for related diseases.

MCE can provide 861 active ingredients that can be obtained from traditional Chinese medicine with antitussive and antiasthmatic functions, which can be applied to drug development and research on disease mechanisms.

Cell death is a core biological process that maintains homeostasis in multicellular organisms, playing a dual role in life activities. On one hand, cell death participates in physiological processes such as cell renewal and damage repair through precise regulation; on the other hand, it actively eliminates damaged, infected, or cancerous cells, thereby blocking pathological progression and preserving organism health. Cell death not only ensures the normal development and growth regulation of organisms but is also closely associated with the occurrence and development of various diseases. Numerous studies have shown that specific types of programmed cell death play critical roles in disease progression, providing an important theoretical basis for developing novel therapeutic strategies by regulating cell death pathways.

MCE offers 22 types of commonly used cell death inhibitors, such as apoptosis, ferroptosis, pyroptosis, and cuproptosis, suitable for use as positive controls in the study of novel cell death mechanisms.

Diarrhea is a disease symptom, and the pathophysiologic basis of diarrhea is a disturbance in intestinal water and electrolyte balance, which may be due to increased secretion of osmotically active electrolytes (secretory diarrhea) or increased intake of osmotically active substances (osmotic diarrhea). Food poisoning, pathogenic bacterial infections, and intestinal-related diseases can all contribute to the development of diarrhea. Traditional Chinese Medicine (TCM) considers diarrhea to be a symptom of an imbalance in the body's systems, particularly related to the functions of the spleen and stomach. Spleen qi deficiency, dampness-heat, liver and spleen disharmony are closely related to diarrhea. Many types of Chinese herbs regulate the function of diarrhea, such as: Dysosmae Verspiellis Rhixoma Et Radix, Ginkgo Semen, Forsythiae Fructus, and Campsis Flos.

MCE can provide 2,459 active monomers that can be obtained from TCM herbs with diarrhea-regulating functions, which can be applied to drug development and disease mechanism research.

Boronic acid and boronic ester represent a relatively novel and promising chemical structure in drug design. Boronic acid exists in an sp²-hybridized state, possessing an empty p-orbital that can act as a Lewis acid to accept lone pairs from heteroatoms (O, N, or S). This Lewis acidity enables it to form reversible covalent bonds with amino acid residues such as lysine, serine, threonine, and histidine. Currently, five FDA-approved drugs containing boronic acid or boronic ester predominantly involve such covalent binding mechanisms in their interactions with target proteins. Furthermore, boronic acid can serve as a bioisostere for carboxylic acids, phosphates, and phenolic groups, utilized to improve pharmacokinetic properties and enhance drug efficacy.

To date, five boron-containing drugs have been approved by the FDA. The unique properties of boronic acids and boronic esters confer significant potential in drug design, with applications spanning cancer therapy (e.g., multiple myeloma), anti-infectives (e.g., fungal infections, tuberculosis), anti-inflammatory treatments (e.g., atopic dermatitis), antibacterial agents (e.g., carbapenem-resistant bacterial infections), and Reactive Oxygen Species (ROS)-responsive prodrugs, among others. The MCE Boronic Acid/Boronic Ester Fragment Library, which contains 1,488 compounds, serves as a valuable tool for the development of boron-containing drugs.

Amino acids are indispensable building blocks for life activities and are widely involved in key biological processes such as cell signal transduction, energy metabolism, gene expression regulation, and neurotransmitter synthesis. As components of proteins, 20 kinds of amino acids make up over one million kinds of proteins in the human body. These amino acids can be classified into nine types of "essential amino acids" that the human body cannot synthesize on its own and must obtain from food, as well as eleven types of "non-essential amino acids" that the human body can synthesize on its own.

MCE offers 20 kinds of amino acids provided which can be applied in research fields such as the study of amino acid metabolic processes, metabolite identification, food/cosmetic ingredient research, and the development of nutritional supplements.

Biotoxins, also referred to as natural toxins, are chemical substances produced by plants, animals, or microorganisms that exert toxic effects on other living organisms. Due to unique biological activities, biotoxins have been widely applied in molecular biology, physiology, pharmacology, and the clinical diagnosis and treatment of various human diseases, becoming an important source of natural drug development. Biotoxins can specifically bind to and interfere with intracellular signaling molecules or receptors, thereby altering cellular signaling processes. Leveraging this characteristic, biotoxins can be used to study the regulatory mechanisms of cellular signaling pathways. For example, neurotoxins such as snake venom peptides can be used to investigate the functional regulation of neurotransmitter receptors and ion channels. Additionally, biotoxins have demonstrated significant potential in drug development across various fields, including neurological diseases, cardiovascular diseases, anticoagulation, and anti-cancer therapies. With advancements in high throughput screening, structural optimization, and antibody-toxin conjugation technologies, numerous biotoxins or their structural analogs have been successfully brought to market, such as Ziconotide, Captopril, Bivalirudin, and Eptifibatide.

MCE offers 90 types of biotoxins, including neurotoxins, cardiotoxins, mycotoxins, and more.

Antimicrobial Peptides (AMPs), also known as antimicrobial peptides or antibiotic peptides, are a class of polypeptides encoded by specific genes in various biological cells and induced by external stimuli. They exhibit broad-spectrum bioactivity against bacteria, fungi, viruses, protozoa, and even tumor cells. AMPs serve as crucial effector molecules in the host's innate immune system.Due to their wide antimicrobial spectrum, low toxicity to normal cells of higher animals, high safety profile, low tendency to induce resistance, and additional benefits such as immune enhancement and antioxidant effects, antimicrobial peptides hold significant promise in new drug development.

MCE offers 58 types of antimicrobial peptides, which can be applied in high-throughput screening for research in anti-infection therapies, immunotherapy, anticancer drug development, and agricultural disease control.

Targeted protein degradation(TPD) is a novel and promising approach to new drug discovery and development. It shows great potential for treating diseases with “undruggable” pathogenic protein targets and for overcoming drug resistance. Molecular glues and PROTACs are both targeted protein degraders that have attracted the most attention.

Molecular glues are small molecular degraders that mainly induce novel interaction between an E3 ligase and a target protein to form a ternary complex, leading to protein ubiquitination and subsequent proteasome degradation. Compared with PROTACs, molecular glues generally possess more favorable drug-like properties, such as lower MW, higher cell permeability, and better oral absorption. Molecular glues are emerging as a promising new therapeutic strategy.

MCE supplies a unique collection of 105 molecular glues which target various proteins. MCE Molecular Glue Compound Library is a useful tool to conduct scientific research and disease mechanism study.

In drug discovery and development (R&D) area, target binding and druggability optimization are core processes. Among these attributes, high solubility is critical for a compound to achieve druggability, as it directly impacts the progress of drug R&D. Superior solubility ensures the rapid dissolution and uniform distribution of drug molecules in vivo, thereby enhancing bioavailability and effectively mitigating issues such as suboptimal efficacy, increased dosage requirements, or exacerbated toxic and side effects arising from insufficient solubility.

From the perspective of medicinal chemistry, high-solubility drug fragments serve as high-quality "molecular building blocks". Based on these fragments, lead compounds with potential druggability can be rapidly screened out, which significantly shortens the drug R&D cycle and reduces R&D costs. Meanwhile, the high-solubility drug fragment library can provide diverse options for drug development in different therapeutic areas, offer solutions for the solubility defects of existing clinical drugs, and facilitate the development of novel, highly effective targeted drugs with higher bioavailability and better safety profiles.

MCE has collected and compiled 2,527 experimentally validated small-molecule fragments with high solubility. These fragments can be directly used for drug molecular design, providing high-quality pre-validated solubility fragments that significantly improve the efficiency of lead compound screening and accelerate the progress of drug R&D.

The TCA cycle (tricarboxylic acid cycle)—is also known as the Krebs cycle or the citric acid cycle (CAC). The TCA cycle is a series of chemical reactions that release stored energy through the oxidation of acetyl-CoA in carbohydrates, fats, and proteins.

For decades, the TCA cycle has been considered as the central pathway for cell oxidative phosphorylation to produce energy and biosynthesis. Research shows that TCA cycle is associated with many diseases, especially cancer. In colon carcinoma, liver cancer and other cancers, there are mutations that lead to the imbalance of TCA cycle metabolites, indicating that TCA cycle may be related to the occurrence of cancer. Understanding the role and molecular mechanism of TCA cycle in inhibiting or promoting cancer progression will promote the development of new metabolite-based cancer treatment methods in the future.

MCE supplies a unique collection of 26 key intermediates of the TCA cycle, which can be utilized for TCA-related research and metabolomics identification studies.

Plant hormones are natural signaling molecules synthesized by plants themselves, serving as crucial chemical messengers that exert physiological effects on plants at extremely low concentrations. They coordinate cellular growth, division, differentiation, and organ formation, helping plants adapt to environmental changes. Major categories include abscisic acid, auxins, gibberellins, cytokinins, ethylene, and brassinosteroids, among others.

MCE has included 45 plant hormones, which can be used for identification in plant metabolomics and related botanical research.

Ionizable lipids are a class of specialized, functional lipid molecules with pH-sensitive charge characteristics. They are primarily divided into two major categories: ionizable cationic lipids and ionizable anionic lipids, though the term typically specifies ionizable cationic lipids within the biomedical field. Structurally, these lipids consist of an ionizable hydrophilic headgroup, a biodegradable linker, and hydrophobic tails. Their primary application is serving as the key delivery vehicle in lipid nanoparticles (LNPs) to encapsulate negatively charged nucleic acid macromolecules, such as mRNA vaccines, siRNA therapeutics, and CRISPR gene-editing components. In a physiological, neutral environment, they remain electrically neutral to minimize systemic toxicity and prolong circulation time. Upon entering the acidic microenvironment of cellular endosomes, however, they undergo protonation to become positively charged, thereby inducing membrane fusion and enabling the highly efficient intracellular release of the nucleic acid cargo. Consequently, they serve as the technological cornerstone for bringing nucleic acid therapies into clinical application.

To accelerate the translational process of cutting-edge nucleic acid drugs, MCE has meticulously constructed an ionizable lipid compound library containing 95 high-performance molecules, aiming to provide researchers and pharmaceutical professionals with a high-throughput, multi-dimensional lipid screening platform.

Cysteine proteases (CPs), a key enzyme family regulating physiological metabolism and mediating pathological processes (e.g., abnormal bone resorption, tumour invasion, and pathogen infection), represent a core therapeutic target for disease intervention via the development of specific inhibitors. Currently reported CP covalent inhibitors encompass diverse structural types, including epoxides, aziridine, and activated double bonds (vinyl sulphones, α,β-unsaturated ketones), providing clear structural references for the development of novel CP covalent inhibitors.

This compound library contains multiple warheads that specifically target cysteine proteases, serving as a powerful tool for the efficient discovery of novel covalent inhibitors against this enzyme family.

The most prominent mechanism of action of kinase inhibitors is their competition with ATP by binding to the hinge region of the kinase protein. Once the kinase is blocked by an inhibitor, it loses the ability to transfer phosphate groups from ATP to other molecules, resulting in the loss of kinase activity.

The hinge-binding region of kinase inhibitors mimics the interaction pattern between the ATP nucleobase and the kinase. MCE extracted thousands of kinase inhibitors from the ChEMBL database and isolated their molecular fragments. In certain cases, the amino and amide groups on the molecular fragments are crucial for binding in the hinge region. Therefore, we enhanced the diversity of the collected results by adding these two groups to unoccupied positions on the ring system. Subsequently, the fragments were assessed for their hinge region binding ability via docking at distinct kinases, we also applied pharmacophore constraints to ensure interactions with key amino acids in the kinase hinge region, ultimately obtaining kinase-related molecular fragments.

MCE provides over 12,412 kinase fragment molecules that meet the above requirements and are available off the shelf, serving as an effective tool for screening and developing drugs targeting kinases.

Nucleoside and nucleotide analogues are synthetic, chemically modified compounds that have been developed to mimic their physiological counterparts in order to exploit cellular metabolism and subsequently be incorporated into DNA and RNA to inhibit cellular division and viral replication. In addition to their incorporation into nucleic acids, nucleoside and nucleotide analogues can interact with and inhibit essential enzymes such as human and viral polymerases (that is, DNA-dependent DNA polymerases, RNA-dependent DNA polymerases or RNA-dependent RNA polymerases), kinases, ribonucleotide reductase, DNA methyltransferases, purine and pyrimidine nucleoside phosphorylase and thymidylate synthase. These actions of nucleoside and nucleotide analogues have potential therapeutic benefits — for example, in the inhibition of cancer cell growth, the inhibition of viral replication as well as other indications.

MCE offers a unique collection of 572 nucleotide compounds including nucleotide, nucleoside and their structural analogues. MCE Nucleotide Compound Library is a useful tool to discover anti-cancer and antiviral drugs for high throughput screening (HTS) and high content screening (HCS).

MCE Novel Bioactive Compound Library consists of 2,981 bioactive compounds with validated bioactivities tested by cell-based assays or biochemical assays. All compounds in this library are structurally novel and bioactivity diverse which makes it easier to discover new lead compounds. MCE Novel Bioactive Compound Library, as a supplement of MCE bioactive compound library (HY-L001), is a useful tool to screen new lead compounds.

Flavors and fragrances serve as indispensable enhancing elements in modern industries, playing multidimensional roles in the fields of food, cosmetics, and pharmaceutical development. In the food industry, flavors and fragrances are not only used to compensate for flavor loss during processing but also to create novel sensory experiences and enhance product appeal. Natural flavors such as vanilla and citrus oils impart rich, layered aromas to foods, while synthetic flavors can precisely replicate specific tastes, meeting the demands of standardized production and extending the flavor stability of food products. In the cosmetics sector, flavors and fragrances are key to emotional design. They enhance product recognition and elevate the pleasure of use through pleasant scents. In pharmaceutical development, the application of flavors and fragrances focuses on improving compliance. Especially in formulations such as oral liquids and chewable tablets, the addition of mint, fruit, and other flavoring components effectively masks the bitter or irritating taste of medications, increasing patient acceptance. Additionally, some natural flavors may themselves possess auxiliary therapeutic benefits.

MCE contains 500 kinds of flavors and fragrances, which can be used in fields such as food, cosmetics and drug development.

Unnatural amino acids (UAAs), also referred to as non-canonical amino acids (ncAAs) or non-proteinogenic amino acids, are a class of amino acids that are distinct from the 20 standard natural amino acids. They can be obtained through chemical synthesis, biosynthesis, and other approaches, with structural diversity far exceeding that of natural amino acids. UAAs are mainly including naturally occurring non-canonical amino acids, chemically synthesized amino acids, and biosynthetic amino acids, which provide a molecular basis for protein function design.

UAAs exhibit significant value in multiple fields. They can optimize the pharmacokinetic properties of peptide drugs and peptidomimetics, modify enzyme functions and endow them with new biological activities, thereby overcoming the limitations of traditional peptide drugs and expanding the chemical space . Meanwhile, UAAs can serve as molecular probes to analyze protein-protein interactions and investigate the regulatory mechanisms of protein functions.

MCE has compiled a UAAs Fragment Library comprising nearly a thousand unnatural amino acid fragments with extensive coverage of chemical space and enhanced structural diversity. This compound library can be widely applied in peptide synthesis, drug design, and protein engineering.

Animal drug (also veterinary drug) refers to a drug intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in animals. Animal Drugs @ FDA is a searchable online database that includes most FDA-approved and conditionally approved animal drugs. The major classes of veterinary drugs include antibiotics, anthelmintics, coccidiostats, nonsteroidal anti-inflammatory drugs, sedatives, corticosteroids, beta-agonists, and anabolic hormones.

MCE has collected 167 FDA-approved veterinary drug compounds for use in scientific research.

Cancer is a multi-step process which involves initiation, promotion and progression. Chemical carcinogens can alter any of these processes to induce their carcinogenic effects. People are continuously exposed exogenously to varying amounts of chemicals that have been shown to have carcinogenic or mutagenic properties in experimental systems. Exposure can occur exogenously when these agents are present in food, air or water, and also endogenously when they are products of metabolism or pathophysiologic states such as inflammation. The administration of chemical carcinogens is one of the most commonly used methods to induce tumors in several organs in laboratory animals in order to study oncologic diseases of humans. MCE offers a unique collection of 143 chemical carcinogens which have been identified with carcinogenic activity either in humans or in animal models. MCE Tumorigenesis-Related Compound Library is a powerful tool for studying oncologic diseases of humans. Standard opration based on safety data sheet will not cause harm to the body.

Proteolysis-targeting chimera (PROTAC) has been developed to be a useful technology for targeted protein degradation. PROTACs consist of a ligand for E3 ligase (E3 ligase binder), a linker and a ligand (mostly small-molecule inhibitor) for protein of interest（target binder）. Upon binding to the target protein, the PROTACs can recruit E3 for target protein ubiquitination, which is subjected to proteasome-mediated degradation.

Although there are more than 600 E3 ubiquitin ligases, only several with small molecule ligands have been used for designing PROTACs, including Skp1-Cullin-F box complex containing Hrt1 (SCF), Von Hippel-Lindau tumor suppressor (VHL), Cereblon (CRBN), inhibitor of apoptosis proteins (IAPs), and mouse double minute 2 homolog (MDM2).

MCE carefully prepared a unique collection of 174 ligands for E3 ligase, which have been reported to be used in PROTAC design. MCE E3 ligase ligand library is a useful tool for PROTAC development.

Lipids are a diverse and ubiquitous group of compounds which have many key biological functions, such as acting as structural components of cell membranes, serving as energy storage sources and participating in signaling pathways. Several studies suggest that bioactive lipids have effects on the treatment of some mental illnesses and metabolic syndrome. For example, DHA and EPA are important for monoaminergic neurotransmission, brain development and synaptic functioning, and are also correlated with a reduced risk of cancer and cardiovascular disease in clinical and animal studies.

MCE supplies a unique collection of 1,266 lipid and lipid derivative related compounds including triglycerides, phospholipids, sphingolipids, steroids and their structural analogues or derivatives. MCE lipid compound library can be used for research in bioactive lipids, and high throughput screening (HTS) and high content screening (HCS).

Glycosides are compounds in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond. Many biologically active compounds are glycosides. Glycosides comprise several important classes of compounds such as hormones, sweeteners, alkaloids, flavonoids, antibiotics, etc. The glycosidic residue can be crucial for their activity or can only improve pharmacokinetic parameters. Glycosides, which exhibit anti-inflammatory, anti-infection, anti-cancer and anti-oxidative properties, play numerous important roles in living organisms, such as streptomycin, as an aminoglycoside antibiotic, has anti-infection activity. Anthracyclines possess good antibacterial and anti-cancer activities.

MCE Glycoside Compound Library contains a unique collection of 894 glycoside compounds and is a useful tool to discovery glycoside drugs.

Cyclic peptides are polypeptide chains taking cyclic ring structure, which exhibit diverse biological activities, such as antibacterial activity, immunosuppressive activity and anti-tumor activity. Cyclic peptides, with the features of good binding affinity, target selectivity and low toxicity, show great success as therapeutics. Multiple cyclic peptides are currently in clinical use, for examples, gramicidin and tyrocidine with bactericidal activity, cyclosporin A with immunosuppressive activity, and vancomycin with antibacterial activity. Furthermore, cyclic peptides usually have the sufficient size and a balanced conformational flexibility/rigidity for binding to flat protein-protein interaction (PPI) interfaces, which have potential to develop PPI drugs.

MCE offers a unique collection of 97 cyclic peptides, all of which have good bioactivities. MCE Cyclic Peptide Library is a powerful tool for drug discovery and PPI inhibitor screening.

Chinese Baijiu is one of the oldest alcoholic beverages in the world, with a history of over 2,000 years. It can be classified into 12 aroma types based on its fragrance and flavor characteristics. The specific flavor profile of Baijiu is determined by the composition and concentration of certain compounds. These trace compounds, present in low concentrations yet rich in esters, alcohols, acids, lactones, aldehydes, ketones, acetals, alkenes, and others, significantly influence the flavor of Baijiu. Additionally, some active components in Baijiu possess antioxidant properties, and moderate consumption may help reduce the risk of cardiovascular diseases, dementia, and insulin resistance. Therefore, studying the chemical composition of Baijiu is crucial for promoting its fermentation process and enhancing its flavor and quality.

MCE has compiled included 671 Chinese Baijiu components, which can be used for drug development, Baijiu fermentation, and research related to Baijiu flavor and aroma.

Cysteine proteases (CPs), a key enzyme family regulating physiological metabolism and mediating pathological processes (such as abnormal bone resorption, tumour invasion, and pathogen infection), represent a core therapeutic target for developing specific inhibitors in disease intervention. Currently reported CP inhibitors primarily achieve their inhibitory function by precisely binding to CP active pockets (e.g., S1-S4 non-primed regions or S1'-S2' primed regions) and forming covalent/non-covalent interactions with the active site cysteine residues, providing clear structural references for the development of novel inhibitors.

This compound library, designed based on the core strategy of "similarity-based known active structures", contains over 200 cysteine protease inhibitors. Leveraging AI-driven molecular screening technology, it retains the critical pharmacological and shape features of reported CP inhibitors, serving as a specialized tool for efficiently discovering novel cysteine protease inhibitors.

Lysine is the second most common target residue used in the design of TCIs and related covalent ligands. Its appeal lies in its abundance in human proteins, which is approximately three times higher than that of cysteine (5.8% vs. 1.9%). This significantly increases the number of proteins suitable for covalent targeting, especially given that many human proteins lack ligandable cysteine residues. Moreover, it has been suggested that functional lysines have a lower probability of being replaced by mutation, as they often play a crucial role in catalysis by acting as bases or nucleophiles. Additionally, lysines are essential for maintaining the structural integrity of proteins and for regulating post-translational modifications (PTMs). Consequently, targeting lysine has garnered significant interest in recent years.

Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 445 fragment molecules which can target lysine residue and can be used for fragment-based covalent drug discovery.

Recently, significant advancements in tyrosine-targeting electrophiles have primarily occurred in the field of protein-protein interactions (PPIs), where cysteine residues are often underrepresented and novel chemistries are needed to address these interfaces. In this context, tyrosines are frequently more accessible compared to more buried binding sites. Moreover, they are commonly found at "hot spots," which are functional epitopes of PPIs, with 12.3% of the residues consisting of tyrosines. This prevalence is likely due to the hydrophobic nature of tyrosine, its ability to participate in aromatic π-interactions, and its capacity for hydrogen bonding. Beyond PPIs, some progress has also been made in covalent tyrosine targeting in other areas where more commonly addressed side chains are lacking. Even though tyrosine has a slightly lower pKa value compared to the protonated lysine side chain (approximately 10 vs. 10.5 for the unprotected amino acid side chains), significantly less progress has been made in the development of tyrosine-targeted covalent ligands compared to lysine. This is likely due to the reduced flexibility of the tyrosine side chain and the greater steric hindrance of its hydroxy group, which makes it more challenging to adopt suitable reaction geometries.

Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 124 fragment molecules which can target tyrosine residue and can be used for fragment-based covalent drug discovery.

Macrocycles, molecules containing 12-membered or larger rings, are receiving increased attention in small-molecule drug discovery. The reasons are several, including providing access to novel chemical space, challenging new protein targets, showing favorable ADME- and PK-properties. Macrocycles have demonstrated repeated success when addressing targets that have proved to be highly challenging for standard small-molecule drug discovery, especially in modulating macromolecular processes such as protein–protein interactions (PPI). Otherwise, the size and complexity of macrocyclic compounds make possible to ensure numerous and spatially distributed binding interactions, thereby increasing both binding affinity and selectivity.

MCE offers a unique collection of 448 macrocyclic compounds which can be used for drug discovery for high throughput screening (HTS) and high content screening (HCS). MCE Macrocyclic Compound Library is a useful tool for discovering new drugs, especially for “undruggable” targets and protein–protein interactions.

In the progression of various diseases, metabolic reprogramming has emerged as a key hallmark. Lactate, as an important metabolic signaling molecule, is widely involved in tumorigenesis, immune regulation, and inflammatory responses. Particularly within the tumor microenvironment, the abnormal accumulation of lactate not only affects cellular energy metabolism but also promotes disease progression by modulating immune cell functions and mediating protein lactylation, thereby participating in epigenetic regulation and signaling networks. Therefore, systematic investigation of lactate metabolic pathways and their associated metabolites is of great significance for understanding disease mechanisms and developing novel therapeutic strategies.

The MCE lactic acid metabolite compound library contains 63 compounds and is constructed around key metabolic pathways involving lactate production, transport, and utilization. This library systematically includes core intermediates from glycolysis, the tricarboxylic acid (TCA) cycle, and the lactate cycle. Focusing on disease-associated metabolic reprogramming, it is suitable for research in oncology, inflammation, and metabolic disorders. The library can be used to elucidate the roles of lactate in tumor microenvironment regulation, immune evasion, and epigenetic modifications (such as protein lactylation). In addition, it provides high-quality small-molecule resources for drug screening, facilitating the discovery of potential modulators targeting key enzymes (such as LDH) or transporters (such as MCTs) involved in lactate metabolism.

A diverse compound library with favorable ADMET properties (Absorption, Distribution, Metabolism, Excretion, and Toxicity) is crucial in drug discovery. Early evaluation of ADMET properties allows for the exclusion of molecules with unfavorable profiles at the initial stages, thereby reducing the risk of late-stage development failures, lowering R&D costs, and accelerating optimization of lead compounds. Based on predictions from ADMET-related AI algorithms, the compounds in this library are predicted to exhibit favorable oral bioavailability (F > 30%), reasonable plasma protein binding (PPB < 98%), minimized CYP3A4 inhibition potential (inhibition probability < 50%, CYP3A4 is the most critical drug-metabolizing enzyme in the cytochrome P450 family) , low toxicity profiles, with 140 potentially toxic substructures pre-identified and excluded via substructure searching to eliminate compounds containing hazardous fragments. The diversity library enables broad applicability in high-throughput screening (HTS) and high-content screening (HCS).

Proteolysis-targeting chimera (PROTAC) has been developed to be a useful technology for targeted protein degradation. PROTACs consist of a ligand for E3 ligase (E3 ligase binder), a linker and a ligand (mostly small-molecule inhibitor) for protein of interest（target binder）. Upon binding to the target protein, the PROTACs can recruit E3 for target protein ubiquitination, which is subjected to proteasome-mediated degradation. Therefore, PROTACs execute their functions by degrading the target proteins rather than inhibiting them, which has a great superiority in overcoming resistance caused by target mutation or overexpression. To date, PROTAC technology has been applied to a variety of targets, including AR, ER, BTK, BET, and BCR-ABL to overcome resistance.

MCE carefully prepared a unique collection of 94 ligands for target proteins, which have been reported to be used in PROTAC design. MCE Target Protein Ligand Library is a useful tool for PROTAC development.

Covalent inhibitors are small molecules that can bind specifically to target proteins through covalent bonds and inhibit their biological functions. Although for a long time, covalent targeting has been playing a subordinate role in drug discovery, with an increasing number of reports on successful clinical applications of such drugs, the potential of these agents is now being acknowledged.

Covalent ligands rely on reactive groups (“warheads”), and new warheads are key to expanding the scope of covalent modalities. Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 8,900 fragment molecules with covalent modification potential, which can target various reactive amino acid residues and can be used for fragment-based covalent drug discovery.

Protein lactylation, an emerging post-translational modification identified in recent years, plays a critical role in linking cellular metabolic reprogramming, epigenetic regulation, and signaling networks. Based on a systematic framework encompassing lactate metabolism, lactylation, and downstream signaling pathways, this compound library comprehensively targets multiple regulatory layers, including histone modification enzymes (such as p300 and HDACs), key glycolytic enzymes (such as PKM2, LDHA, and GAPDH), transcriptional regulators (such as STAT3, HMGB1, and p53), as well as central signaling pathway nodes including HIF-1α, NF-κB, and PI3K-AKT-mTOR. This integrated design enables a comprehensive representation of the regulatory roles of lactylation across the “metabolism–epigenetics–signaling” axis.

MCE has assembled a collection of 5,860 known bioactive compounds and potential functional molecules, making this library suitable for a wide range of applications, including high-throughput drug screening, inhibitor identification, and mechanistic studies. It can be used to systematically evaluate the functional roles of lactylation in biological processes such as tumor metabolism, immune regulation, and inflammatory responses, and to efficiently identify small-molecule candidates with regulatory potential, thereby facilitating the development of innovative therapeutics targeting the interplay between metabolism and epigenetic regulation.

MCE-18 stands for Medicinal Chemistry Evolution 2018, which was first published in Journal of Medicinal Chemistry in 2019 for assessing molecular novelty and three-dimensional complexity. Developed based on Clarivate global pharmaceutical patent database, this descriptor was constructed via big-data analysis covering 28,161 patented lead compounds, 1,370 approved drugs and nearly 30,000 preclinical-to-phase III drug candidates from 23 top pharmaceutical companies worldwide between 1950 and 2018, followed by structural clustering and removal of redundant outdated scaffolds for data denoising. Its scoring system integrates five core structural features including aromatic ring (AR), aliphatic heterocycle (NAR), chiral center (CHIRAL), spiro atom (SPIRO), cyclic and acyclic sp³ carbon ratio together with a quadratic topological correction factor. Breaking the limitations of the single Fsp³ parameter, MCE-18 effectively distinguishes conventional flat aromatic scaffolds from modern 3D-enriched novel chemotypes, overcoming typical drawbacks of traditional compound libraries such as scaffold redundancy, low screening hit rates and poor compatibility with allosteric and PPI-related difficult targets.

This library contains over 37,000 structurally diverse compounds with favorable overall drug-likeness, suitable for high-throughput screening against canonical targets including kinases, GPCRs and proteases as well as challenging allosteric and PPI targets. Compounds comply with the developmental trend of modern novel drug discovery, supporting routine primary screening as well as early hit identification of allosteric modulators and PPI inhibitors, serving as an efficient screening resource for early-stage innovative drug discovery.

In the research of covalent inhibitors targeting serine and threonine, scientists have found that the nucleophilicity of these hydroxyl groups is significantly enhanced due to the influence of their surrounding environment. This results in higher activity during catalytic reactions. Aspirin, which targets the non-catalytic domain serine (Ser529 in human COX1) of cyclooxygenase, exerts its anti-inflammatory effect through covalent binding. β-lactam antibiotics, which targets the catalytic domain serine of penicillin-binding proteins, interferes with bacterial cell wall synthesis.

Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 3,300 fragment molecules which can target serine and threonine residues and can be used for fragment-based covalent drug discovery.