Optimization of extraction and characterization of triterpenoids from wild Ganoderma lucidum in Guilin based on antioxidant capacity

Abstract To obtain Ganoderma lucidum triterpenoids (GLTs) with high antioxidant capacity, a new method of enzymatic extraction using pectinase and cellulase enzymes was developed and tested. The experiment involved single-factor exploration encompassing five variables: enzyme ratio, enzyme concentration, pH, temperature, and time. The GLTs extraction process was optimized using response surface methodology. The in vitro antioxidant capacity of the GLTs, which served as an evaluation index for extraction, was investigated using ELISA. The results unveiled the optimum conditions for enzymatic GLTs extraction, including an enzyme ratio of 2:1 (cellulase and pectinase), enzyme concentrations of 2.5%, enzymatic temperature of 30 ℃, enzymatic time of 30 min, enzymatic pH of 5.0, and a material-liquid ratio of 1:60 (g/mL). Under these conditions, the predicted value of the antioxidant capacity of GLTs was 0.12 µmol/mL, and the measured mean antioxidant capacity was 0.117 ± 0.011 µmol/mL. The close correspondence between the anticipated and actual detection values highlights the capability of the regression model to effectively optimize the extraction conditions. Subsequently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was employed to identify the triterpenoids in the extracts of wild-cultivated Ganoderma lucidum (G. lucidum). The results showed that the extract from wild-cultivated G. lucidum contained 19 triterpenoid fractions, including ganoderic acid A, ganoderic enoic acid B, and lucidenic acid A. These findings suggest that enzymatic extraction is an efficient method for extracting GLTs with an improved capability to scavenge reactive oxygen species, and wild cultivated G. lucidum could potentially serve as a valuable natural source of triterpenoids.