Kurozu melanoidin, a novel oligoglucan-melanoidin complex from Japanese black vinegar, suppresses adipogenesis in vitro

Abstract

• This study identifies an anti-adipogenic factor in the black vinegar kurozu. • The factor, kurozu melanoidin (KZM), consists of an oligoglycan and a melanoidin. • KZM inhibits adipocyte differentiation of 3 T3-L1 cells in vitro . • KZM may, in part, account for anti-obesity effects of kurozu. The black vinegar “kurozu” has an anti-obesity potential, but its active principle is unknown. Here, we isolate and characterize a novel oligoglucan-melanoidin complex, designated kurozu melanoidin (KZM), that suppresses adipogenesis in vitro . KZM was isolated by organic solvent extraction, followed by size-exclusion chromatography. Its average molecular mass was estimated to be 1,090 ± 30 Da using polyethylene glycols as standards. The combination of spectroscopic and chemical analyses revealed the presence of an oligoglucan and a melanoidin structures in KZM. The glucan moiety consisted mainly of 1 → 4 linkage. The MALDI-TOF-MS analysis identified an array of ion peaks that differed in m / z by ~ 162.055 [C 6 H 12 O 6 − H 2 O], indicating a variation of glucan chain length. Prominent signals around m / z 500–600 that were unassignable to glucan units suggested ion peaks for the melanoidin moiety. KZM significantly suppressed adipogenesis of 3T3-L1 preadipocytes at 100 μM.