Molecular Weight
The sum of the atomic weights of all atoms in a molecule. It is a fundamental descriptor affecting drug-likeness and pharmacokinetic properties.
Max Ring
The number of atoms contained in the largest ring system of the molecule. Larger rings often correlate with increased molecular rigidity and complexity.
Volume
The van der Waals volume of the molecule, calculated from atomic radii and spatial arrangement. It influences molecular packing and interactions with biological targets.
Density
The ratio of molecular weight to molecular volume. It reflects the compactness of the molecular structure.
Formal Charge
The electrical charge assigned to an atom in a molecule, assuming electrons are shared equally in bonds. Optimal values are generally between -4 and +4 for drug-like molecules.
Non-flexible Bonds
The number of bonds that are not freely rotatable, including double bonds and bonds in rings. These bonds contribute to molecular rigidity.
Flexibility
A measure of molecular flexibility, typically calculated as the ratio of rotatable bonds to non-flexible bonds. Higher values indicate a more flexible structure.
nBond
The total count of all covalent bonds in the molecule, including single, double, and triple bonds. Higher counts generally correspond to more complex molecules.
SA Score
The synthetic accessibility score, ranging from 1 to 10. It estimates the difficulty of synthesizing a compound, with higher scores indicating greater difficulty.
Stereo Centers
The number of atoms bonded to four distinct groups, giving rise to stereoisomerism. Fewer stereocenters simplify synthetic and purification processes.
nRing
The total number of rings in the molecular structure. A moderate number of rings is often associated with favorable drug-like properties.
Rotatable Bonds
The number of single bonds that can rotate freely, affecting molecular conformation. Higher values increase molecular flexibility.
Heteroatoms
The count of non-carbon and non-hydrogen atoms in the molecule (e.g., N, O, S). They contribute to polarity, hydrogen bonding, and target interactions.
Heavy Atoms
The total number of non-hydrogen atoms in the molecule. This count is used in various drug-likeness rules.
Hydrogen Bond Acceptors
The number of atoms capable of accepting hydrogen bonds, typically nitrogen and oxygen atoms. It affects solubility and permeability.
Hydrogen Bond Donors
The number of atoms capable of donating hydrogen bonds, typically N-H and O-H groups. It influences pharmacokinetic properties.
NHOHCount
The total count of N-H and O-H functional groups in the molecule. These groups are key hydrogen bond donors.
NOCount
The total number of nitrogen and oxygen atoms in the molecule. These atoms are key hydrogen bond acceptors.
NumAliphaticRings
The number of non-aromatic rings in the molecule. They affect molecular rigidity and three-dimensional shape.
Fraction CSP3
The ratio of sp³-hybridized carbon atoms to the total number of carbon atoms. Higher values indicate greater saturation and three-dimensionality.
LogP
The logarithm of the partition coefficient between n-octanol and water. It is a key descriptor of lipophilicity, affecting solubility, permeability, and metabolism.
QED
Quantitative Estimate of Drug-likeness, a composite score ranging from 0 to 1. It evaluates how closely a compound resembles approved drugs.
TPSA
Topological Polar Surface Area, the sum of the surface areas of polar atoms. It is strongly correlated with molecular permeability and oral absorption.
AvgIpc
Average information content index, a measure of molecular complexity based on Shannon entropy. Higher values indicate greater structural complexity.
BalabanJ
Balaban distance connectivity index, which characterizes molecular branching and shape. It is used in QSAR studies to describe molecular topology.
BertzCT
Bertz molecular complexity index, which quantifies the structural complexity of a molecule. Higher values correspond to more complex structures.
HallKierAlpha
Hall-Kier alpha shape index, which reflects the steric bulk and shape of a molecule. It is useful for predicting biological activity.
Ipc
Molecular information content index, a measure of the complexity of the molecular graph. It is based on the eigenvalues of the adjacency matrix.
LabuteASA
Labute accessible surface area, a measure of the solvent-accessible surface area of polar atoms. It is related to molecular polarity and interactions.
Lipinski Rule
The "Rule of Five", a heuristic for predicting oral bioavailability. Compounds with no more than one violation are generally considered drug-like.
Pfizer Rule
A toxicity risk filter that flags compounds with high lipophilicity and low polarity. Such compounds are associated with higher attrition rates.
GSK Rule
An ADMET favorable rule that recommends molecular weight ≤ 400 and logP ≤ 4. Compounds meeting these criteria often have better pharmacokinetic profiles.
Golden Triangle
A drug-likeness optimization range defined by molecular weight and lipophilicity. Compounds within this range tend to have favorable properties and developability.
PAINS
Pan-assay interference compounds, substructures known to cause false positives in biological assays. Compounds containing these alerts are often problematic.
BMS Rule
A filter for undesirable reactive and toxic substructures identified by Bristol-Myers Squibb. It aims to eliminate compounds with potential safety liabilities.
ALARM NMR Rule
A filter for compounds prone to causing false positives in NMR-based screening, often due to aggregation or reactivity. It helps identify problematic early hits.
LogS
The logarithm of aqueous solubility, typically in mol/L. It is a critical property for drug absorption and formulation development.
LogD
The logarithm of the distribution coefficient between octanol and water at a specific pH. It accounts for the ionization state of the molecule.
LogP
The logarithm of the partition coefficient between n-octanol and water. It is a key descriptor of lipophilicity, affecting solubility, permeability, and metabolism.
LogVP
The logarithm of vapor pressure, a measure of a compound's volatility. Lower values indicate lower volatility and higher stability.
Melting Point
The temperature at which a solid transitions to a liquid state. It is related to molecular packing and crystal lattice energy.
Boiling Point
The temperature at which the vapor pressure of a liquid equals the external pressure. It reflects the intermolecular forces within the liquid.
Hydration Free Energy
The change in free energy when a molecule is transferred from the gas phase to water. It is a measure of the affinity of the molecule for water.
Bioavailability
The fraction of an administered dose of a drug that reaches the systemic circulation. It is a critical parameter for oral drug efficacy.
Caco-2 Permeability
A measure of a compound's ability to cross a monolayer of human colon adenocarcinoma cells, used as an in vitro model of intestinal absorption.
Bioavailability
The probability of a compound having low oral bioavailability. A higher value indicates a greater risk of poor absorption.
Caco-2 Permeability
The probability of a compound having high permeability across Caco-2 cells. It predicts the potential for good intestinal absorption.
HIA
Human Intestinal Absorption, the probability that a compound will be well absorbed by the human intestine. It is a key ADMET parameter.
HOB
Human Oral Bioavailability, the probability that a compound will have high oral bioavailability. It is critical for oral drug delivery.
MDCK Permeability
The probability of high permeability across Madin-Darby Canine Kidney cells. It is an in vitro model for assessing permeability.
PAMPA
Parallel Artificial Membrane Permeability Assay, the probability of high passive permeability across an artificial membrane.
PPB
Plasma Protein Binding, the percentage of drug bound to proteins in the blood. Only unbound drug is pharmacologically active.
VD
Volume of Distribution, a theoretical volume that represents the distribution of a drug throughout the body. It is calculated as the ratio of amount in the body to plasma concentration.
BBB Penetration
The probability that a compound can cross the blood-brain barrier. This is essential for drugs targeting the central nervous system.
CYP450 1A2 Inhibition
The potential of a compound to inhibit the Cytochrome P450 1A2 enzyme. Inhibition can lead to drug accumulation and toxicity.
CYP450 3A4 Inhibition
The potential of a compound to inhibit the Cytochrome P450 3A4 enzyme, the most common drug-metabolizing enzyme.
P-gp Inhibition
The potential of a compound to inhibit P-glycoprotein, an efflux pump that limits drug absorption and distribution.
CYP450 1A2 Inhibitor
The probability that a compound inhibits the Cytochrome P450 1A2 enzyme. Inhibition can cause drug-drug interactions.
CYP450 2C19 Inhibitor
The probability that a compound inhibits the Cytochrome P450 2C19 enzyme. It is a major site of drug metabolism.
CYP450 2C9 Inhibitor
The probability that a compound inhibits the Cytochrome P450 2C9 enzyme. It can lead to altered drug metabolism.
CYP450 2C9 Substrate
The probability that a compound is a substrate for the Cytochrome P450 2C9 enzyme. It indicates the likelihood of being metabolized by this enzyme.
CYP450 2D6 Inhibitor
The probability that a compound inhibits the Cytochrome P450 2D6 enzyme. Polymorphism in this enzyme leads to variable drug response.
CYP450 2D6 Substrate
The probability that a compound is a substrate for the Cytochrome P450 2D6 enzyme. Metabolism by this enzyme can lead to variable efficacy.
CYP450 3A4 Inhibitor
The probability that a compound inhibits the Cytochrome P450 3A4 enzyme. It is responsible for the metabolism of a large fraction of drugs.
CYP450 3A4 Substrate
The probability that a compound is a substrate for the Cytochrome P450 3A4 enzyme. It indicates susceptibility to metabolism by this enzyme.
P-gp Inhibitor
The probability that a compound inhibits P-glycoprotein. This can increase the bioavailability of co-administered drugs.
P-gp Substrate
The probability that a compound is a substrate for P-glycoprotein. This can lead to reduced absorption and distribution.
BCRP Inhibitor
The probability that a compound inhibits Breast Cancer Resistance Protein. This efflux pump affects drug disposition.
OATP1B1 Inhibitor
The probability that a compound inhibits Organic Anion Transporting Polypeptide 1B1. It is involved in hepatic drug uptake.
OATP1B3 Inhibitor
The probability that a compound inhibits Organic Anion Transporting Polypeptide 1B3. It mediates hepatic uptake of various drugs.
OCT2 Inhibitor
The probability that a compound inhibits Organic Cation Transporter 2. It plays a key role in renal secretion.
HLM
Human Liver Microsomal stability, the probability that a compound will be unstable in human liver microsomes. It predicts metabolic clearance.
BZR Inhibition
The potency of a compound to inhibit benzodiazepine receptors. Such activity is associated with central nervous system side effects.
COX-2 Inhibition
The potency of a compound to inhibit Cyclooxygenase-2, an enzyme involved in inflammation. Inhibition is the mechanism of action for NSAIDs.
ER Inhibition
The potency of a compound to inhibit the Estrogen Receptor. Such activity can lead to endocrine disruption.
LC50DM
The median lethal concentration (LC50) for Daphnia magna, expressed as -log₁₀(mol/L). It is a measure of aquatic toxicity.
LC50FM
The median lethal concentration (LC50) for fathead minnow, expressed as -log₁₀(mol/L). It is a standard test for fish toxicity.
LD50Rat
The median lethal dose (LD50) for rats, expressed as -log₁₀(mol/kg). It is a measure of acute systemic toxicity.
LogBCF
The logarithm of the Bioconcentration Factor, which measures a compound's tendency to accumulate in living organisms.
LogHD50
The logarithm of the half-maximal hypnotic dose. It is a measure of the sedative potency of a compound.
IGC50
The median inhibitory concentration for growth of Tetrahymena pyriformis, expressed as -log₁₀(mol/L). It is used as a model for general toxicity.
Man Oral TDLo
The lowest published toxic dose for humans following oral administration. It is a reference point for potential human toxicity.
Mammal Intraperitoneal LD50
The median lethal dose for mammals following intraperitoneal administration. It is a measure of acute toxicity.
Mammal Oral LD50
The median lethal dose for mammals following oral administration. It is a primary measure of acute oral toxicity.
Mammal Subcutaneous LD50
The median lethal dose for mammals following subcutaneous administration. It assesses toxicity via the subcutaneous route.
Mouse Intramuscular LD50
The median lethal dose for mice following intramuscular administration. It is a measure of toxicity via the muscle route.
Mouse Intravenous LD50
The median lethal dose for mice following intravenous administration. It assesses acute systemic toxicity.
Mouse Oral LD50
The median lethal dose for mice following oral administration. It is a common test for acute oral toxicity.
Mouse Oral LDLo
The lowest published lethal dose for mice following oral administration. It represents the minimum lethal exposure.
Mouse Parenteral LD50
The median lethal dose for mice following parenteral administration. It includes routes other than oral.
Rat Intraperitoneal LD50
The median lethal dose for rats following intraperitoneal administration. It is a standard test for acute toxicity.
Rat Intravenous LD50
The median lethal dose for rats following intravenous administration. It measures toxicity via direct systemic exposure.
Rat Intravenous LDLo
The lowest published lethal dose for rats following intravenous administration. It represents the threshold of lethality.
Rat Oral LD50
The median lethal dose for rats following oral administration. It is a key indicator of acute oral toxicity.
Rat Skin LD50
The median lethal dose for rats following dermal application. It assesses skin absorption and toxicity.
Rat Subcutaneous LD50
The median lethal dose for rats following subcutaneous administration. It is a measure of toxicity via this route.
Rat Subcutaneous LDLo
The lowest published lethal dose for rats following subcutaneous administration. It is the minimum lethal dose.
Tetrahymena pyriformis Toxicity
The toxicity of a compound to Tetrahymena pyriformis, a protozoan used as a model organism. It correlates with general toxicity.
Neurotoxicity
The potential of a compound to cause damage to the nervous system. It is a major safety concern in drug development.
Ames Toxicity
The probability that a compound is mutagenic in the Ames test. A positive result indicates potential genotoxicity.
Biodegradation
The probability that a compound is readily biodegradable in the environment. It is an indicator of environmental safety.
Carcinogenicity
The probability that a compound is carcinogenic. This is a critical safety endpoint in drug development.
Genotoxicity
The probability that a compound causes damage to DNA. It is a major concern for drug safety.
ClinTox
The probability that a compound is associated with clinical toxicity. It is based on known adverse drug reactions.
DILI
Drug-Induced Liver Injury, the probability that a compound causes liver damage. It is a leading cause of drug withdrawal.
Hepatotoxicity
The probability that a compound is toxic to the liver. It is a key safety concern for drug candidates.
Eye Corrosion
The probability that a compound causes irreversible damage to the eye. It is a serious safety hazard.
Eye Irritation
The probability that a compound causes reversible irritation to the eye. It is assessed for topical and systemic drugs.
Respiratory Toxicity
The probability that a compound causes damage to the respiratory system. It is a concern for inhaled and systemic drugs.
Skin Sensitization
The probability that a compound induces an allergic reaction upon skin contact. It is important for topical drugs.
FDAMDD
The probability that a compound is similar to FDA-approved drugs. It is used as a druggability filter.
Fish Toxicity
The probability that a compound is toxic to fish. It is an indicator of environmental impact.
Honey Bee Toxicity
The probability that a compound is toxic to honey bees. It is a concern for environmental safety, especially for agrochemicals.
hERG Inhibitor
The probability that a compound inhibits the hERG potassium channel. This is a primary risk factor for QT prolongation and cardiotoxicity.
NR-AhR
The probability that a compound activates the Aryl Hydrocarbon Receptor. It is involved in xenobiotic metabolism and toxicity.
NR-AR-LBD
The probability that a compound binds to the Androgen Receptor Ligand Binding Domain. It can disrupt endocrine function.
NR-AR
The probability that a compound activates the Androgen Receptor. It is associated with endocrine-disrupting effects.
NR-Aromatase
The probability that a compound inhibits the Aromatase enzyme. This affects estrogen production and hormonal balance.
NR-ER
The probability that a compound activates the Estrogen Receptor. It is linked to endocrine-disrupting activity.
NR-PPAR-gamma
The probability that a compound activates the Peroxisome Proliferator-Activated Receptor gamma. It is a target for metabolic diseases.
NR-ER-LBD
The probability that a compound binds to the Estrogen Receptor Ligand Binding Domain. It can mimic or block estrogen action.
SR-ARE
The probability that a compound activates the Antioxidant Response Element pathway. It is related to oxidative stress response.
SR-ATAD5
The probability that a compound activates the ATAD5 stress response pathway. It is a marker for DNA damage.
SR-HSE
The probability that a compound activates the Heat Shock Element pathway. It is involved in the cellular stress response.
SR-MMP
The probability that a compound causes changes in Mitochondrial Membrane Potential. It is an indicator of mitochondrial toxicity.
SR-p53
The probability that a compound activates the p53 pathway. It is a key regulator of the DNA damage response.
Micronucleus
The probability that a compound induces micronucleus formation, a marker of chromosome damage. It is used to assess genotoxicity.
Nephrotoxicity
The probability that a compound causes damage to the kidneys. It is a significant safety concern in drug development.
RLM
Rat Liver Microsomal stability, the probability that a compound will be unstable in rat liver microsomes. It is used to predict metabolic stability.
PIH
The probability that a compound poses a risk of hERG inhibition. It is a simplified risk assessment for cardiotoxicity.
PIV
The probability that a compound causes ion channel toxicity. It is a broad assessment of potential cardiotoxicity.
T_Acute_Oral_Toxicity
Acute oral toxicity reflects the lethal risk of compounds after acute oral exposure, used to evaluate short-term oral safety.
T_Human_Oral_TDLo
Human oral lowest published toxic dose, the minimum oral dose causing toxic effects in humans, supporting clinical safety assessment.