Pressured Microwave-assisted Hydrolysis of Crude Glycyrrhizic Acid for Preparation of Glycyrrhetinic Acid

Abstract

A pressured microwave-assisted hydrolysis (PMAH) technique has been developed for hydrolyzing the crude glycyrrhizic acid (GA) extracted from licorice root to prepare glycyrrhetinic acid (GRA). In order to optimize the efficiency of PMAH, several experimental parameters were investigated, including liquid-solid ratio, hydrolysis time, sulfuric acid concentration and hydrolysis temperature. The optimized hydrolysis conditions were as follows: pressured microwave-assisted hydrolysis of crude GA for 21 min (taking 15 min to reach 150 ºC, and holding it for 6 min) at 150 ºC (at a radiation power of 450 W) in 3%-5% sulfuric acid solution with the liquid-solid (ml•g −1 crude GA) ratio of 25︰1. As a result of the considerable saving in time and higher product yields (up to 90%), PMAH was proved more effective than conventional methods.

The mechanism of hydrothermal hydrolysis for glycyrrhizic acid into glycyrrhetinic acid and glycyrrhetinic acid 3- O -mono-β- d -glucuronide in subcritical water

“…A high level of GA formation ratio was obtained at higher temperature in a shorter time, for instance, 220°C for 10 min or at lower temperature in a longer time, for example, 120°C for 80 min. A longer holding time at a higher reaction temperature caused some undesirable reactions, such as carbonization, which was evident by the visible brown color of the hydrolysate and emission of a scorched flavor, a similar result was also reported by Wang et al (2012).…”

“…The appropriate temperature for producing GA was similar to that of a pressured microwave-assisted hydrolysis of crude glycyrrhizic acid, which was at a temperature of 150°C for 22 min. Compared with subcritical water technology, its time was shorter, this might be due to H 2 SO 4 used as a catalyst in pressured water with microwaveassist hydrolysis (Wang et al, 2012).…”

“…1a), is a natural sweetener in liquorice (Cinatl et al, 2003) and has been widely used in the tobacco, food and pharmaceutical industries (Wang et al, 2012). GL also possesses many useful pharmacological activities, such as anti-cancer, anti-inflammatory and anti-bacterial properties (Zhang & Ye, 2009).…”

Numerical Analysis of Ultimate Bearing Capacity of Embedded Foundation

“…In domestic, Luan Miaotian derived ultimate bearing capacity of layered non-homogeneous subgrade [2]. The results show that bearing capacity of subsoil was almost increased linearly with increasing buried depth.…”