The methanolic extract from the flower buds of Prunus mume, cultivated in Zhejiang province, China, showed an inhibitory effect on aldose reductase. From the methanolic extract, five new acylated sucroses, mumeoses F-J, were isolated together with 29 known compounds. The chemical structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects of the isolated compounds on aldose reductase were also investigated. Acylated quinic acid analogs, which are one of the major compounds of the flower buds of P. mume, were shown to substantially inhibit aldose reductase. In particular, mumeic acid-A was found to exhibit a potent inhibitory effect [IC 50 =0.4 µm].Key words Prunus mume; mumeose; acylated sucrose; medicinal flower; aldose reductase; acylated quinic acid analogIn the course of our studies on bioactive constituents from medicinal flower, 2-6) we previously reported the isolation and structure elucidation of acylated sucroses named prunoses I (11), II (12), and III (13) with inhibitory effects on platelet aggregation and aldose reductase and radical scavenging effect from the flower buds of Prunus (P.) mume Sieb. et Zucc.(Rosaceae) cultivated in Wakayama prefecture, Japan. 7,8) In addition, the methanolic (MeOH) extract from the flower buds of P. mume cultivated in Zhejiang province, China, showed inhibitory effects on melanogenesis. From the MeOH extract, five new acylated sucroses, mumeoses A (6), B (7), C (8), D (9), and E (10), and three new acylated quinic acid analogs, mumeic acid-A (15) and its methyl ester (16) and 5-O-(E)-pcoumaroylquinic acid ethyl ester (22), were isolated and their structures as well as the inhibitory effects on melanogenesis were characterized.