New inhibitors of melanogenesis, OH-3984 K1 and K2. II. Physico-chemical properties and structural elucidation.
New melanin synthesis inhibitors, OH-3984 K1 and K2, were isolated from the fermentation broth of Streptomyces sp. OH-3984, and their structures were elucidated by spectroscopic methods and by chemical transformations. OH-3984 K1 (M.W.: 306; C18H26O4) and K2 (M.W.: 308; C18H28O4) have unique gamma-lactone rings, both of which correspond to oxidative products derived from C1-O14 cleavage of the 14-membered lactone group.
Microorganisms as a source of tyrosinase inhibitors: a review
Tyrosinase is the main enzyme responsible for enzymatic browning of fruits post-harvest and melanogenesis in mammals, an undesirable phenomenon. This encouraged researchers to seek potent tyrosinase inhibitors for application in the food and cosmetics industries. Despite an increased knowledge of tyrosinase inhibitors from plants and synthetic sources in the past few years, inhibitors of microbial origin are under-explored. Thus, this article surveys tyrosinase inhibitors produced by microorganisms and hence, serves as an updated database of tyrosinase inhibitors from microbial sources.
Studies on an Antibiotic, Albocycline. V. High Pressure-High Temperature Hydrogenation Products, and Structure Proof of Albocycline
By the catalytic hydrogenation of albocycline in acetic acid under high pressure at elevated temperature, nine reaction products were obtained. They were classified into pairs by their infrared (IR), nuclear magnetic resonance (NMR) and mass spectral data. The eluci dation of structures of these pair products gave the conclusive answers about the positions of O-functions, especially that of a methoxy group, in albocycline molecule. Thus, the structure of albocycline was finally confirmed as Ia.