Counter-current chromatography for the separation of terpenoids: a comprehensive review with respect to the solvent systems employed

Abstract

Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid–solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids—one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications.

Superior anticancer activity is demonstrated by total extract of Curcuma longa L. as opposed to individual curcuminoids separated by centrifugal partition chromatography

“…CPC is a novel purification tool that enables fast and effective separation of compounds from mixtures, regardless of their nature, depending on their affinity to each of the phases in a given biphasic solvent system (Kukula‐Koch & Mroczek, ; Skalicka‐Wozniak & Garrard, ). The differences in the solubility between the stationary and mobile phases affect the separation of a sample on a rotating column, which is constructed from a cascade of cable channels and cartridges surrounding the main axis of a rotor.…”

“…The two axes of rotations of the holder in the HSCCC chromatograph—about its own axis and simultaneously around the major centrifuge axis—create mixing and settling zones in the coil tube that interchange with each other (Skalicka‐Wozniak & Garrard, ). The induced conditions mean that extraction and settling are time and space separated.…”

Isolation of cytotoxic diterpenoids from the Chilean medicinal plantAzorella compactaPhil from the Atacama Desert by high-speed counter-current chromatography

“…17,18 The isolation of new substances from natural sources on a preparative or semi-preparative scale is frequently necessary for further investigation of plant-derived bioactive compounds. In this sense, high-speed counter-current chromatography (HSCCC) is a support-free liquid-liquid partition chromatographic technique that employs two immiscible liquid phases in which the stationary phase is retained in the column with the aid of a centrifugal force field while the mobile phase is passed through the stationary phase and thus eliminates the problem of the adsorption of a sample onto a solid support 19 and has been widely used for the purification of natural products 20 including a variety of terpenoids. 19,21 -24 In the continuing efforts made by our laboratory in the search for new metabolites from the genus Azorella, 5,7,25 three new mulinane diterpenoids (compounds 1-3, Fig.…”

Crystal Structure of 3,4-Dihydroxy-5-Geranyl-Benzoic Acid

“…2 High speed counter current chromatography (HSCCC) is a support free liquidliquid partition chromatographic technique which eliminates the problem of the adsorption of a sample onto a solid support and has been widely used for the purification of natural products including a variety of flavonoids 3 . In the continuing efforts made by our laboratory in the search for new interesting metabolites from Paposo flora, 4-5 several flavonoids and one new benzoic acid derivative (compounds 1-5, Fig.…”