The hepatoprotective efficacy and biological mechanisms of three phenylethanoid glycosides from cistanches herba and their metabolites based on intestinal bacteria and network pharmacology

Echinacoside (ECH), acteoside (ACT), and isoacteoside (ISAT), the typical phenylethanoid glycosides (PhGs) in cistanches herba, have various pharmacological activities. However, the ECH, ACT and ISAT have extremely low oral bioavailability, which is related to their metabolism under the intestinal flora. Previous studies showed that intestinal metabolites were the hepatoprotective substances in vivo, but the research on whether PhGs has effects without intestinal bacteria has not been studied. In this paper, ECH, ACT and ISAT were incubated with human or rat intestinal bacteria for 36 h. After incubating with human bacteria for 36 h, three prototype compounds were not detected and were mainly biotransformed to 3-HPP and HT. In the network pharmacology, a total of 6 common targets were obtained by analysing the prototypes, the metabolites and the liver injury. It was found that the combinations of three metabolites and common targets were more stable than those of the prototypes and common targets by molecular docking. Meanwhile, hepatocellular apoptosis, proliferation, inflammation and oxidative responses might play important roles in the mechanisms of the metabolites exerting hepatoprotective activities. Then normal and pseudo-sterile mice experiments were adopted to further compare the hepatoprotective activities of prototypes and metabolites. Animal experiment results showed that the prototypes and the metabolites in the normal mice had significantly hepatoprotective activity. Interestingly, in the pseudo-germfree mice, the metabolites showed significant hepatoprotective effect, but the prototypes had not effect. It indicated that the prototype cannot exert liver protective activity without the effect of intestinal bacteria.