title: The establishment of efficient bioconversion, extraction, and isolation processes for the production of phyllodulcin, a potential high intensity sweetener, from sweet hydrangea leaves (Hydrangea macrophylla Thunbergii).
abstract: BACKGROUND
  Hydrangea leaf tea has been traditionally consumed in the far-east Asian countries and is favoured for its distinct minty-sweet taste. Phyllodulcin is identified as a key sweet-tasting compound; it is 400-800 times sweeter than sucrose. However, its extraction has not been well-documented. In an effort to optimise phyllodulcin production, pretreatment processes to accumulate phyllodulcin as a final metabolite in leaf tissue were studied, and an efficient process was established for the extraction and purification of phyllodulcin.
  
  
  METHODS
  Phyllodulcin was structurally identified using an LC/MS system. Hydrangea leaves were processed by either hand rolling or mechanical blending, by exposing them at different drying temperatures (25 and 70°C), and even by inducing bioconversion in leaf tissue. The leaf powder was extracted with various solvents (methanol, ethanol, and water) by soaking at 25°C for 12 h, ultrasonication at 35°C for 1 h or accelerated solvent extraction (ASE). Extracts were purified with ion exchange resins and purified using preparative HPLC.
  
  
  RESULTS
  Traditional hand rolling and drying at 70°C significantly increased phyllodulcin accumulation in the leaves. Meanwhile, more phyllodulcin was obtained from the leaves blended mechanically or converted enzymatically compared to traditionally processed ones (P < 0.05). Methanol and ethanol were superior to water as extraction media, and the greatest phyllodulcin yields obtained by ASE, soaking and ultrasonication were 21.28, 21.20 and 19.33 mg/g, respectively, when methanol was used. Highly pure phyllodulcin powder was obtained with a yield of 2.12%.
  
  
  CONCLUSIONS
  This promising result would be beneficial to the industrial utilisation of phyllodulcin as a potential high-intensity sweetener.
authors.affiliation: Department of Food Science & Technology, BK21+ Project Team, and Carbohydrate Bioproduct Research Center, Sejong University, Seoul, 143-747, South Korea.
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Jung
authors.affiliation: Department of Food Science & Technology, BK21+ Project Team, and Carbohydrate Bioproduct Research Center, Sejong University, Seoul, 143-747, South Korea.
authors.forename: Yang
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Food Science & Technology, BK21+ Project Team, and Carbohydrate Bioproduct Research Center, Sejong University, Seoul, 143-747, South Korea.
authors.forename: Min-Soo
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Department of Food Science & Technology, BK21+ Project Team, and Carbohydrate Bioproduct Research Center, Sejong University, Seoul, 143-747, South Korea.
authors.forename: Suyong
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Food Science & Technology, BK21+ Project Team, and Carbohydrate Bioproduct Research Center, Sejong University, Seoul, 143-747, South Korea.
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Yoo
mesh_terms: D002851:Chromatography, High Pressure Liquid; D031966:Hydrangea / Q000378:metabolism*; D049934:Isocoumarins / Q000302:isolation & purification / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D049934:Isocoumarins; C008903:phyllodulcin
keywords: Hydrangea macrophylla; Phyllodulcin; accelerated solvent extraction; high intensity sweetener