The juice extracted from Prunus mume (Mei-Gin) is in the form of a highly concentrated dark black syrup. It is a common health supplement in Asia. The active component, 5-hydroxymethylfurfural (HMF), manifested a
concentration-dependent effect on the inhibition of β-hexosaminidase degranulation upon antigen-sensitized RBL-2H3 cells. In order to investigate HMF (1) of P. mume extract, HMF was isolated and the HPLC profiles of 23 commercial Mei-Gin products (6 types) were qualitatively and quantitatively analyzed for HMF content. The samples included 10 Taiwanese Mei-Gin products, 3 Japanese Mei-Gin products, 5 specific-processing Mei-Gin products, 2 commercial plum drinks, 1 fresh mature plum extract, and 2 heat-processed samples. The HPLC profiles showed that the commercial products contained various amounts of HMF. Among them, the water extract of P. mume showed better yield of HMF. The yields from such products may differ due to different Mei-Gin original materials and different extraction and manufacturing procedures.