Extraction, isolation, and aromatase inhibitory evaluation of low-polar ginsenosides from Panax ginseng leaves

A hyphenated accelerated solvent extraction (ASE) technique was elaborately coupled with centrifugal partition chromatography (CPC), ultra-high-performance liquid chromatography (UHPLC), and photo-diode array detector (PDA). This approach was applied to obtain low-polar ginsenoside fractions from the leaves of Panax ginseng. The CPC fractions were isolated and analyzed using the hyphenated technique, and followed by testing and evaluation of their aromatase inhibitory effects. Subsequently, the aromatase inhibition rates of the compositions in the CPC fractions were calculated using a multivariable linear regression model. A biphasic ethyl acetate/n-butanol/ethanol/water solvent system with respective volume ratios of 10:2:2:8 was used for the ASE and CPC separation of 200 g of leaves of P. ginseng raw material. The (lower) aqueous phase of the abovementioned solvent system was used as the extraction solvent. The ginsenosides were subjected to ASE, and the extraction solution was pumped into the sample loop and then directly into the CPC column. The CPC fractions were collected and monitored by an online UHPLC/PDA system at 5-min intervals. The aromatase inhibitory activities of CPC fractions were analyzed by a fluorescence method, with mathematical calculations indicating that the inhibition rates of ginsenosides Rk1, Rg5, Rs5, 20R-Rg3, and Rs4 exceeded 50.00%; indicating that the aforementioned chemical compounds have potential for further development. The results were validated by comparison with authentic standards, indicating that the method used in this research was accurate and advantageous for matrix analysis.