AcceptOROH

AcceptOROH is a term used in chemical informatics and related fields to denote a hydrogen-bond acceptor feature associated with a hydroxyl group (OH) in a molecule. In many descriptor sets and pharmacophore models, molecules are annotated with hydrogen-bond donors and hydrogen-bond acceptors to help predict interactions, solubility, and bioavailability. AcceptOROH specifically refers to the oxygen of a hydroxyl group acting as a hydrogen-bond acceptor.

In neutral organic molecules, each hydroxyl group provides one acceptor site via the lone pairs on the oxygen, so acceptorOH is typically counted as one per OH group. This is distinct from the hydroxyl’s role as a hydrogen-bond donor, where the same OH group donates a hydrogen atom in H-bonding. Some datasets or software may separately track acceptorOH as a subset of all hydrogen-bond acceptors to emphasize OH-based interactions or to distinguish them from other acceptors such as carbonyl, ether, or nitro oxygens.

Applications include drug-likeness assessment, quantitative structure–activity/property relationship (QSAR/QSPR) modeling, and ADMET prediction, where accurate counting of H-bond donors and acceptors influences predicted solubility, permeability, and binding properties. Limitations arise from pH effects, tautomerism, and intramolecular hydrogen bonding, which can alter the effective H-bond accepting ability of hydroxyl groups in certain environments.

See also: hydrogen bond donor, hydrogen bond acceptor, Lipinski’s rules, pharmacophore.