The first attempt at simulated-moving-bed separation of medically utilizable ingredients from neoagarooligosaccharides generated through the β-agarase hydrolysis of agarose in red algae

Abstract

Recently, it has been discovered that neoagarohexaose (NA6) contained in neoagarooligosaccharides (NAO), which originate from the β-agarase hydrolysis of agarose in red algae, has various medical effects. This has led to growing interest in establishing an industrial-utilizable process for high-purity separation of NA6 from NAO, which has, however, yet to be realized. To address this issue, we attempt to develop an efficient simulated-moving-bed (SMB) process for continuous-mode separation of NA6 from NAO with high purity and high yield, which was named “NA6-SMB” in this article. It was found first that the most suitable adsorbent for the targeted SMB separation was the ion-exclusion resin of sodium form with 4% crosslinkage, and its proper operating temperature was 60 °C. For the selected absorbent with the aforementioned properties, the intrinsic parameters of all NAO components were determined. Using the resultant parameter values, the configuration and operation parameters of the NA6-SMB were designed such that the high-purity separation of NA6 could be realized and kept stable throughout a long period of SMB operation while maximizing throughput. The separation efficiency of such designed NA6-SMB was first validated by model simulations, and then verified by experiments, which confirmed that the NA6 product of 98.7% purity could be obtained continuously throughout the long-term NA6-SMB processing while keeping its loss below 1%. Finally, an additional SMB was developed to treat the non-product stream of the NA6-SMB for the purpose of producing high-purity NA4 (>99%), which has been considered worthy of testing its medical efficacy and physiological activation in large quantity.