Multi-channel recycling counter-current chromatography for natural product isolation: Tanshinones as examples

Recycling is a simple and efficient strategy for improving the peak resolution. In this work, a novel multi-channel recycling counter-current chromatography (CCC) was successfully established and three representative three-channel recycling CCC systems including 1R, 2R, and 3R CCC recycling on one, two, and three channel columns were developed for four typical tanshinones fractions. The results demonstrated that all recycling CCC separations were efficient for the isolation of targeted tanshinones. 1R CCC not only provided the single recycling separation, but also offered two parallel recycling separation or repeated preparation for multiple targets. 2R CCC provided the increased peak resolution and less risk of overlapping. 3R CCC offered versatile elution and recycling modes for multiple targets. Compared to 1R and 2R CCC, 3R CCC was easier to separate the more complex natural products with more targets in the complex natural extracts. In summary, the developed multi-channel recycling CCC systems including 1R, 2R, and 3R CCC were successful and efficient for resolving the complex natural tanshinones. To the best of our knowledge, this is the first document to report the multi-channel recycling CCC methods for the separation of tanshinones. They may be used as new multi-dimensional recycling CCC for targeted and non-targeted isolation of natural products. It may be widely used for current natural drug development and metabolome analysis.