A novel off-line multi-dimensional high-speed countercurrent chromatography strategy for preparative separation of bioactive neolignan isomers from Piper betle. L

Separation and purification of naturally occurring isomers from herbs are still challenging. High-speed counter-current chromatography (HSCCC) has been applied to isolate natural products. In this study, an off-line multi-dimensional high-speed counter-current chromatography (multi-D HSCCC) strategy was developed utilizing the in situ concentration technique with online storage recycling elution to rapidly separate bioactive isomeric neolignans from chloroform-partitioned samples of the plant Piper betle L. In the procedure, the crude sample (105 mg) was implemented using the online storage recycling technique in a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (7: 5: 12: 3), which first simply afforded a neolignane kadsurenone (1, 5.3 mg) and its epimer (-)-denudatin B (2, 6.4 mg). Then, the remains fr a was subjected to the second-dimensional HSCCC elution using the in situ concentration technique with online storage recycling technique in another solvent system of petroleum ether-ethyl acetate-methanol-water (5: 5: 11, 15). As a result, kadsurenin I (3, 0.6 mg) and its regioisomer pibeneolignan C (4, 5.0 mg), together with the fractional remaining fr b and fr c, were obtained. Thirdly, the fr c was reloaded to allow the HSCCC for recycling elution with the former solvent system employing the in situ concentration strategy and yielded a pair of epimers, (7R,8S,1'S)-1'-allyl-5-methoxy-8-methyl-7-piperonyl-7,8,3,6-tetrahydro-2-oxobenzofuran (5, 10.2 mg), and 3-epi-(-)-burchullin (6, 2.6 mg). Finally, the three pairs of less amount and the structurally similar isomers 1-6 were isolated from the crude fraction of P. betle with a high HPLC purity of over 95.0 % for compound 2, 4-6 and 92.5 % for compound 1, 91.0 % for 3, while the purity of 1 and 3 in 1H NMR were 89.9 % and 91.1 %, respectively. The whole isolation process was quick and efficient. Compounds 1, 2, 4 and 5 showed significantly synergistic activities combining several antibiotics against five drug-resistant Staphylococcus aureus with FICIs from 0.156 to 0.375. This novel off-line multi-dimensional HSCCC strategy could be broadened to application for the rapid separation of complex natural products.

Integrative countercurrent chromatography for the target isolation of lysine-specific demethylase 1 inhibitors from the roots of Salvia miltiorrhiza

The ability to separate bioactive compounds from herbal medicines, which contain abundant components, is crucial for drug discovery. Conventional Countercurrent chromatography (CCC) methods for separating bioactive compounds are labor intensive and show low efficiency. Here, we present a novel integrative CCC method for separating lysine-specific demethylase 1 (LSD1) inhibitors from the roots of Salvia miltiorrhiza (RSM). The methanol extracts of RSM were separated into hydrosoluble and liposoluble fractions, which were online stored in coils. Subsequently, the targeting LSD1 constituents were isolated using isocratic, gradient, or recycling elution mode. All separation processes could be accomplished using one CCC apparatus. Using our separation strategy, two phenylpropanoids and four tanshinones were isolated, which were determined to be new classes of natural LSD1 inhibitors. Salvianolic acid B, which showed the most potent inhibitory activity with an IC50 of 0.11 μM, exhibiting a considerable potential as an anticancer agent. Promisingly, the integrative CCC could be a crucial tool for the target separation of enzyme inhibitors from herbal medicines.