In glycyrrhetinic acid, the functional group (R) is a hydroxyl group. Research in 2005 demonstrated that with a proper functional group a very effective glycyrrhetinic artificial sweetener can be obtained. When R is an anionic NHCO(CH2)CO2K side chain, the sweetening effect is found to 1200 times that of sugar (human sensory panel data). A shorter or longer spacer reduces the sweetening effect. One explanation is that the taste bud cell receptor has 1.3 nanometers (13 angstroms) available for docking with the sweetener molecule. In addition the sweetener molecule requires three proton donor positions of which two reside at the extremities to be able to interact efficiently with the receptor cavity.