Separation of Resveratrol and Emodin by Supercritical Fluid-Simulated Moving Bed Chromatography

Ming-Tsai Liang

doi:10.4172/2157-7064.1000175

Abstract

To separate resveratrol and emodin, supercritical carbon dioxide with ethanol was employed as the desorbent for a three-section simulated moving bed with an open-loop design called SF-SMB. Experimental validation of the separation was accomplished in this work. Silica was used as the stationary phase, and a crude extract of Polygonum cuspidatum containing mainly the resveratrol and the emodin, was purchased from a bio-technology company and used as the feedstock for the SF-SMB. Using single column chromatography, the operating conditions for a series of experiments conducted with 18 wt% ethanol were examined. The results were then compared to those predicted by the Triangle theory to determine the separable operating conditions and the dead volume of the SF-SMB unit. The robust operation of the SF-SMB against the concentration fluctuation of ethanol was also examined by conducting experiments with varied ethanol concentrations in different sections. It was found that the system is able to retain robust operation with about a 1.0 wt% ethanol fluctuation. Lowering the ethanol concentration to 15 wt% for each section was expected to relocate the separable operating conditions. A series of experiments with 12 wt% ethanol showed no pure raffinate. This is explained by the fact that the high flow rate of desorbent in the first section needed to obtain pure extract and raffinate would result in a high pressure drop, and lower the efficiency of the SF-SMB. From this study, the SF-SMB is demonstrated as being a useful technology for the separation of natural products, while providing a potentially greener alternative in the development of botanical drugs.

Highlights

Resveratrol is recognized as an active compound extracted mainly from Polygonum cuspidatum and responsible for antibacterial, antioxidantive, anti-virus, and antitumor activity [1,2,3,4]
Since the solvent power of the supercritical fluid significantly changes with the concentration of ethanol, this study investigated the effect of changing the concentration along the six-column to better understand its operation with varying ethanol concentrations
The separation of resveratrol and emodin by supercritical fluidsimulated moving bed (SF-SMB) was conducted at 40°C and 19.3 MPa with ethanol controlled at 18 wt%

Summary

Introduction

Resveratrol is recognized as an active compound extracted mainly from Polygonum cuspidatum and responsible for antibacterial, antioxidantive, anti-virus, and antitumor activity [1,2,3,4]. The crude extract of resveratrol from Polygonum cuspidatum contains large amount of emodin, another bioactive compound. The separation of resveratrol and emodin was conducted using a novel technology known as supercritical fluidsimulated moving bed (SF-SMB). Clavier et al first applied supercritical carbon dioxide as the desorbent to SMB for the separation of GAL (g-linolenic ethyl ester) and DHA (docosahexaenoic ethyl ester). The advantages of using a supercritical fluid as the desorbent include: instant evaporation of carbon dioxide to obtain concentrated products, the adjustment of solvent power by pressure, and the gradient operation of SMB attained by setting different pressures in different sections of the SMB. To apply supercritical carbon dioxide as the desorbent, a more complicated piping design was required; the design and operation were published in prior work [17]. J Chromat Separation Techniq 4: 175. doi:10.4172/2157-7064.1000175

Section III

Results and Discussion

Conclusion