A new lanostane-type triterpene with lipid-lowering activity from Ganoderma lucidum and an additional analogue

Non-alcoholic fatty liver disease (NAFLD) represents a chronic liver disorder with widespread global prevalence, primarily attributed to hepatic lipid accumulation, oxidative stress, and inflammatory responses. In the realm of traditional Chinese medicine, Ganoderma lucidum is predominantly utilized for its hepatoprotective properties. The objective of this study was to isolate and identify novel bioactive compounds capable of mitigating hepatic fat accumulation. An in vitro steatosis model was established using oleic acid-induced HepG2 cells to evaluate the total triglyceride (TG) content across various components. Fractionation of the compounds was guided by the observed reduction in TG content, employing multiple chromatographic techniques to successfully isolate ten Ganoderma triterpenes. Structural elucidation was achieved through 1D and 2D NMR spectroscopy, supplemented by additional spectroscopic methods. This investigation led to the identification of two previously unreported lanostane-type triterpenes (1-2) alongside eight known analogues (3-10). Compound 1 and 2 exhibit structural distinctions from the other compounds, primarily in the substituents at positions C-3, C-7, and C-15, as well as in the spatial orientation of these substituents. In vitro experiments were conducted to assess the efficacy of various compounds in inhibiting lipid accumulation. Compound 1-5 demonstrated a significant reduction in TG levels within the OA-induced HepG2 cell model (p < 0.05). In comparison to the model group, Compound 1 demonstrated a moderate lipid-lowering effect, (2.11 mmol/gprot vs. 2.70 mmol/gprot, p < 0.003). Conversely, Compound 2 exhibited a significantly more pronounced lipid-lowering effect, (1.27 mmol/gprot vs. 2.70 mmol/gprot, p < 0.0001). Furthermore, when compared with the positive control drug, the lipid-lowering efficacy of Compound 2 was significantly superior to that of Compound 1. Furthermore, the application of network pharmacology, molecular docking, and molecular dynamics simulations elucidated the mechanism of action underlying the effects of methyl ganoderenic acid A(2).