Maltobionic acid is comprised of one molecule of glucose attached via an ether-type linkage to one molecule of gluconic acid (R). It is a stereoisomer of lactobionic acid (R), and is obtained from the chemical or enzymatic oxidation of maltose (R, R, R). Like lactobionic acid, it is an aldobionic acid but is often called a polyhydroxy bionic acid due to its multiple hydroxyl groups.
Maltobionic acid's molecular weight of 358 daltons has been claimed to be sufficiently low to allow it to penetrate the skin (R), but we are not aware of any published studies with actual permeation data.