Kazuya Iwai

Enzymatic synthesis of caffeic acid phenethyl ester analogues in ionic liquid

An efficient procedure for transesterification of methyl caffeate was developed to produce caffeic acid phenethyl ester analogues with Candida antarctica lipase B using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, as a solvent. The system provided 48.8mM 2-cyclohexylethyl caffeate and 46.9 mM 3-cyclohexylpropyl caffeate with conversion yields of 97.6% and 93.8%, respectively. Reusability of the system was investigated, and the yield of 4-phenylbutyl caffeate was increased from 30.4 to 45.7 mM when the transesterification was carried out under reduced pressure to remove a by-product, methanol. Additionally, we showed that both 2-cyclohexylethyl caffeate and 3-cyclohexylpropyl caffeate exhibit strong antiproliferative activities, which are comparable to that of 5-fluorouracil by MTT assay.

Inhibitory Activity of Chlorogenic Acids in Decaffeinated Green Coffee Beans against Porcine Pancreas Lipase and Effect of a Decaffeinated Green Coffee Bean Extract on an Emulsion of Olive Oil

A decaffeinated green coffee bean extract (DGCBE) inhibited porcine pancreas lipase (PPL) activity with an IC50 value of 1.98 mg/mL. Six different chlorogenic acids in DGCBE contributed to this PPL inhibition, accounting for 91.8% of the inhibitory activity. DGCBE increased the droplet size and decreased the specific surface area of an olive oil emulsion.

Inhibitory Effect of a Hot Water Extract of Coffee “Silverskin” on Hyaluronidase

Coffee “silverskin” (CS) is a by-product of the roasting procedure for coffee beans. A CS extract (CS-ext) was found to have a high inhibitory effect against hyaluronidase. It seems that the higher-molecular-weight substances in CS-ext contributed most to the hyaluronidase inhibition, while acidic polysaccharides mainly composed of uronic acid played a major role in this hyaluronidase inhibition by CS-ext.