NOVELTY - Pyrimidine carboxylic acid compound, comprising a cationic and an anionic component, is new, where the pyrimidine carboxylic acid compound excludes ectoin hydrochloride.    USE - The pyrimidine carboxylic acid compound is useful as ionic liquid; as cosmetically active agent; and in pharmaceutical-, cosmetic- or dermatological formulation (claimed). The pyrimidine carboxylic acid compound is useful e.g. as a solvent or solvent additive for many synthetic and catalytic reactions such as Friedel-Crafts acylation and alkylation, Diels-Alder cycloadditions, transition metal- or enzyme catalyzed-, hydrogenation- and oxidation-, Heck-, Suzuki- couplings-, esterification-, isomerization-, hyroformylation-, oligomerization- reaction; as an extractant, heat source, surfactant, plasticizer, lubricant, antistatic agent, flame retardant, a non-aqueous electrolyte, plasticizers in polymeric materials, flame retardants for a variety of materials and applications, supporting electrolyte or additive in various cells and electrochemical applications, such as capacitors or in fuel cells. The pyrimidine carboxylic acid compound is useful to treat: aged or dry skin; and hair. The pyrimidine carboxylic acid compound has antiaging-, antiphotoaging-, antioxidative-, melanogenesis promoting- and skin-lightening-, anticellulite-, antiacne-, anticancer-, anti-inflammatory effect. The pyrimidine carboxylic acid compound is useful for the stabilization of the p53 gene. The pyrimidine carboxylic acid compound is useful for the preparation of a medicament or a dermatological preparation for topical prophylaxis and treatment of skin diseases, preferably atopic dermatitis. No biological data given.    ADVANTAGE - The pyrimidine carboxylic acid compound exhibits high solubility and bioavailability.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) preparation of the pyrimidine carboxylic acid compound;    (2) preparation comprising the pyrimidine carboxylic acid compound; and    (3) process for the manufacture of the preparation comprising mixing the pyrimidine carboxylic acid compound with a suitable cosmetic, dermatological, pharmaceutical or foodstuff material.