Synergistic effects of trans-p-coumaric acid isolated from the ethanol extract of Gynura procumbens in promoting intestinal absorption of chlorogenic acid and reversing alcoholic fatty liver disease.

ETHNOPHARMACOLOGICAL RELEVANCE: Our previous studies found that the ethanol extract of Gynura procumbens (EEGS) reduced hepatic steatosis in alcoholic fatty liver disease (AFLD). AIM OF THE STUDY: To explore the active ingredients from EEGS and their relevant mechanism of action in alleviating alcoholic liver injuries. AIM OF THE STUDY: To explore the active ingredients from EEGS and their intestinal absorption characteristics as an approach for understanding mechanism of action in alleviating alcoholic liver injuries. MATERIALS AND METHODS: Monitored by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC), chemical constituents from the prepared EEGS were isolated by means of solvent extraction, repeated column chromatography, preparative HPLC and other methods, and their structures were identified based on spectroscopic methods. The in vivo intestinal absorption rate of chlorogenic acid (CA), the active component of the EEGS, both in a single form and in the EEGS were monitored by the single-pass intestinal perfusion (SPIP) method in rats. The protective effect of EEGS and its active components on alcoholic liver injuries was evaluated in the alcoholic liver injury model of C57BL/6J male mice induced by Lieber-DeCarli alcohol liquid feed. RESULTS: Three noncaffeoyl quinic acid components were isolated and identified from the EEGS, namely, 3-trans-p-coumaroyl quinic acid (0.9%), 3-cis-p-coumaroyl quinic acid (2.7%), and trans-p-coumaric acid (0.6%). In vivo intestinal absorption of CA decreased with the increase of pH value of perfusion solution in the range of 5.5-7.8. The maximum absorption percentage of CA alone was 6.7 ± 2.4%, while the maximum absorption percentage of CA in the EEGS was 16.0 ± 2.2%, which was 2.4 times higher than that of CA alone. The results of animal experiments showed that the degree of fatty liver of mice treated with EEGS was significantly lower than that of the CA, trans-p-coumaric acid, and the combination group of CA and trans-p-coumaric acid alone. CONCLUSION: The above results indicated that trans-p-coumaric acid isolated from the dried stems of Gynura procumbens assisted CA being absorbed into the body and worked together with CA to improve the function of liver lipid metabolism, reduce hepatic lipid accumulation in a mouse model of AFLD and effectively counteract alcohol-induced fatty liver disease.

Chronic high-dosage fish oil exacerbates gut-liver axis injury in alcoholic steatohepatitis in mice: the roles of endotoxin and IL-4 in Kupffer cell polarization imbalance.

In the present study, intestinal tight junctions (TJs) and Kupffer cell polarization were investigated in an alcoholic steatohepatitis (ASH) mouse model to uncover the potential side effects of overexposure to fish oil or omega-3 fatty acids. The mice were fed ad libitum with a liquid diet containing ethanol and fish oil. In the meantime, ethanol was given every 5-7 days by gavage to simulate binge drinking. After the 7th binge, steatosis, necrosis, inflammatory infiltration, and bridging fibrosis were observed in the liver by histological staining. After the 13th binge, the inducers, markers and other downstream genes/proteins of the Kupffer cell M1/M2 phenotype in the liver, serum, and small intestine were analysed. The results suggested that a chronic high dosage of fish oil alone reduced the mRNA levels of most genes tested and showed a tendency to damage the intestinal zonula occludens-1 localization and reduce the number of M2 Kupffer cells. Meanwhile, the combination of fish oil and ethanol damaged the intestinal TJs, resulting in an increased endotoxin level in the liver. Gut-derived endotoxin polarized Kupffer cells to the M1 phenotype, whereas the number of cells with the M2 phenotype (markers: CD163 and CD206) was decreased. Interleukin-4 (IL-4), an M2 Kupffer cell inducer, was also decreased. Moreover, in vitro experiments showed that IL-4 reversed eicosapentaenoic acid-induced CD163 and CD206 mRNA suppression in RAW 264.7 cells. Overall, our results showed that a chronic high dosage of fish oil exacerbated gut-liver axis injury in alcoholic liver disease in mice, and endotoxin/IL-4-induced Kupffer cell polarization imbalance might play an important role in that process.

Gynura procumbens Reverses Acute and Chronic Ethanol-Induced Liver Steatosis through MAPK/SREBP-1c-Dependent and -Independent Pathways.

The present study aimed to evaluate the hepatoprotective effect and mechanism of action of Gynura procumbens on acute and chronic ethanol-induced liver injuries. Ethanol extract from G. procumbens stems (EEGS) attenuated acute ethanol-induced serum alanine aminotransferase levels and hepatic lipid accumulation. Therefore, EEGS was successively extracted by petroleum, ethyl acetate, and n-butyl alcohol. The results showed that the n-butyl alcohol extract was the active fraction of EEGS, and hence it was further fractionated on a polyamide glass column. The 60% ethanol-eluted fraction that contained 13.6% chlorogenic acid was the most active fraction, and its effect was further evaluated using a chronic model. Both the n-butyl alcohol extract and the 60% ethanol-eluted fraction inhibited chronic ethanol-induced hepatic lipid accumulation by modulating lipid metabolism-related regulators through MAPK/SREBP-1c-dependent and -independent signaling pathways and ameliorated liver steatosis. Our findings suggest that EEGS and one of its active ingredients, chlorogenic acid, may be developed as potential effective agents for ethanol-induced liver injury.