Separation of alkaloids from herbs using high-speed counter-current chromatography

Alkaloids represent a most widespread group of bioactive natural products. Because of their alkalinity and structural diversity, the fractionation and purification of the alkaloids from herbs can often present a number of practical difficulties using the conventional chromatographic techniques. High-speed counter-current chromatography (HSCCC) is a liquid-liquid partition chromatography with a support-free liquid stationary phase, and is gaining more and more popularity as a viable separation technique for bioactive compounds from natural resources. In the present review, focus is placed on the separation of alkaloids by both conventional HSCCC and pH-zone-refining counter-current chromatography (CCC) techniques from herbs. The review presents the separation of over 120 different alkaloid compounds from more than 30 plant species by the conventional HSCCC and pH-zone-refining CCC. Based on the data from the literature, the proper solvent systems for the separation of alkaloids by the conventional HSCCC and pH-zone-refining CCC are also summarized.

Countercurrent separation of natural products

An assessment of the technology and method development in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CS), is provided. More than six decades of CS theory and applications are critically reviewed and developed into a practical guide to CS for natural products research. The necessary theoretical foundation is given for better use of CS in the separation of biological molecules of any size, small to large, and from any matrix, simple to complex. The three operational fundamentals of CS--instrumentation, biphasic solvent systems, and theory--are covered in a prismatic fashion. The goal of this review is to provide the necessary background and references for an up-to-date perspective of CS and to point out its potential for the natural products scientist for applications in natural products chemistry, metabolome, and proteome research involving organisms from terrestrial and marine sources.

Natural product isolation

Since the 1990s, interest in natural product research has increased considerably. Following several outstanding developments in the areas of separation methods, spectroscopic techniques, and sensitive bioassays, natural product research has gained new attention for providing novel chemical entities. This updated review deals with sample preparation and purification, recent extraction techniques used for natural product separation, liquid-solid and liquid-liquid isolation techniques, as well as multi-step chromatographic operations. It covers examples of papers published since the NPR review 'Modern separation methods' by Marston and Hostettmann,1 with major emphasis on methods developed and the research undertaken since 2000.