HPLC-DAD analysis of arbutin produced from hydroquinone in a biotransformation process in Origanum majorana L. shoot culture

Abstract

The hydroquinone glucoside arbutin is a plant derived compound medically applied due to its uroantiseptic activity. It also has skin whitening properties and thus is widely used in dermatology and cosmetology. Origanum majorana L. (Lamiaceae) is known to produce arbutin, however the content of the compound in cultivated plants is very variable and low. Since plant cell and tissue cultures are capable to perform specific biotransformation reactions including glucosylation, this investigation targeted the formation of arbutin from hydroquinone in agitated O. majorana shoot cultures. For this purpose different doses of hydroquinone (96, 144, 192, 288 and 384mg/L of medium) were added to the culture flasks in one, two or three portions. Arbutin was qualitatively and quantitatively determined in methanol extracts from dry biomass and lyophilized media using HPLC-DAD. Cells of O. majorana shoot cultures efficiently converted hydroquinone into arbutin. The product was accumulated in the biomass and was not observed (or in trace amounts) in the medium samples. Different doses as well as portioning of the precursor had a significant impact on the biotransformation process. Arbutin accumulation increased from 0.23±0.03mg/g DW up to 52.6±4.8mg/g DW in the biomass. The highest product content was observed after the addition of 192mg/L hydroquinone in three portions. The highest efficiency of the biotransformation process, i.e. 67.5±5.2% was calculated for a dose of 96mg/L precursor divided into three portions. After further optimization of the biotransformation process, O. majorana shoot cultures could serve as a rich source of arbutin.