Separation of targeted ganoderic acids from Ganoderma lucidum by reversed phase liquid chromatography with ultraviolet and mass spectrometry detections

Abstract

Ganoderic acids are valuable bioactive secondary metabolites produced by a traditional medicinal mushroom Ganoderma lucidum (“Ling-zhi” in Chinese and “Reishi” in Japanese). In this work, a fast and efficient method for the recovery and purification of ganoderic acid T (GA-T) and ganoderic acid Me (GA-Me) from triterpene-enriched extracts of G. lucidum mycelia was developed by using reversed phase HPLC (RP-HPLC) on a C 18 column with an acidified methanol–water mobile phase in combination with ultraviolet (UV) detection and electrospray ionization mass spectrometry (ESI-MS). The presence of each targeted GA (GA-T and GA-Me) in its corresponding peak was easily identified and confirmed by UV and MS. The chemical structures of the purified GA-T and GA-Me were further confirmed by 1H NMR. The retention behaviors of the two GAs over a temperature range of 15–55 °C were also investigated. From the retention time data, van’t Hoff plots were obtained. The estimated enthalpy (Δ H) and entropy (Δ S) data suggest that the retention time difference between GA-T and GA-Me might be driven by an enthalpy difference. Furthermore, a semi-preparative HPLC purification was achieved on a semi-preparative C 18 column using the conditions optimized for the analytical column. The method presented in this work can be a valuable tool for the rapid semi-preparative purification of targeted GAs, and it may also be applicable to some other natural products.