Ultrasound-assisted extraction, enrichment, and hypolipidemic potential of triterpenes from Grifola frondosa mycelia.

Triterpenes (GFTs) are the main secondary metabolites of Grifola frondosa, which is a famous porous fungus with multiple biological actions. To enhance the yield of GFTs, the parameters for ultrasound-assisted extraction (UAE) of GFTs were first optimized. As a result, the highest amount of GFTs (25.44 mg/g) was achieved under the optimized parameters (ultrasound time, 55.4 min; ultrasonic power, 135 W; temperature, 40 ℃; ethanol concentration, 90.4%; solid-liquid ratio, 1:45 g·mL). Then, different comparative analyses, including extraction kinetics and scanning electron microscopy detection, were carried out between UAE and traditional maceration extraction, and the data suggest that ultrasound treatment is beneficial for the dissolution of target products from the mycelia. Furthermore, AB-8 resins followed by silica gel column chromatography were employed to purify the GFTs, and three purified fractions (Fr1, Fr2, and Fr3) were acquired. A total of 4, 12, and 15 triterpenoids were identified in Fr1, Fr2, and Fr3, respectively, using ultra-performance liquid chromatography and tandem mass spectrometry. Additionally, the three purified fractions, especially Fr2, exhibited remarkable hypolipidemic activities in vitro. In conclusion, the triterpenes with hypolipidemic potential were purified from G. frondosa, and these findings would be beneficial for promoting the utilization of these triterpenes.