Raspberry ketone (4-(4-hydroxyphenyl) butan-2-one; RK) is a major aromatic compound of red raspberry (Rubus idaeus) and is marketed on the Internet as a food supplement. The FDA classified it as GRAS (Generally Recognized as safe) food additives during the 1960s. The structure of RK is similar to the structures of capsaicin and synephrine, compounds known to exert anti-obese actions and alter the lipid metabolism. It was shown, that RK also decreased the weights and hepatic triacylglycerol content in rodents after they had been increased by a high-fat diet. Recently was discovered, that RK may exert anti-adipogenic effects through modulation of the HO-1/Wnt/beta-catenin signaling pathway. Investigations of raspberry ketone in quantitative structure-activity relationship (QSAR) models indicated potential cardiotoxic effects and potential effects on reproduction/development. Taking into account the high intake via supplements, the compound's toxic potential should be clarified with further experimental studies. In UK the pure compound is regarded as novel food requiring authorisation prior to marketing but raspberry ketone is not withdrawn from Internet sites from this country.

Retinyl propionate is a synthetic derivative of a Vitamin A. Upon topical application, retinyl propionate is hydrolyzed by esterases to retinol, which is ultimately converted to retinoic acid. In mouse models, retinyl propionate induced epidermal thickening in mouse tail and promoted collagen formation in UV-irradiated mice. These results encouraged clinical trials of retinyl palmitate against photoaging. Topical retinyl propionate cream (0.15%) did not demonstrate any statistically significant improvement over placebo, but in later studies of combinations of retinyl propionate with climbazole or niacinamide improvements in the appearance of fine lines, wrinkles and age spots were demonstrated.