Comment on isolation and identification of compounds from Penthorum chinense Pursh with antioxidant and antihepatocarcinoma properties: pinocembrin and its rapidly emerging neuroprotective effects

Polyphenol-enriched Penthorum chinense Pursh ameliorates alcohol-related liver injury through Ras/Raf/MEK/ERK pathway: Integrating network pharmacology and experiment validation

ETHNOPHARMACOLOGICAL RELEVANCE

Penthorum chinense Pursh (PCP) has acknowledged as an edible herbal medicinal plant for the prevention and treatment of alcoholic liver injury (ALI). However, only few of researches focus on the chemical material basis and potential mechanisms of PCP against ALI.

AIM OF THE STUDY

Herein, we explored the therapeutic effects of PCP extract against ALI based on the integration of network pharmacology, molecular docking, and experiment validation.

METHODS

Based on the standard quality control of PCP herbs by UPLC fingerprint and quantitative determination, 80% ethanol extract fraction of PCP containing more polyphenols, compared to aqueous extract fraction of PCP, were chosen for further experiments. After oral administration of PCP ethanol extract, serum pharmacochemistry based on UPLC-Q-Exactive-MS analysis was implemented to evaluate the potential effective compounds. These absorbed prototypes in PCP were used to construct network pharmacology and predict the potential mechanisms of PCP extract against ALI. Then, the predicted targets and biological mechanisms of PCP extract were validated using animal experiments and molecular docking analysis.

RESULTS

Although totally 19 polyphenol compounds were identified in PCP ethanol extract by UPLC-MS analysis, only 18 absorbed prototypes were found in the serum collected from mice at 1 h post-administration with PCP extract. These candidate active compounds were further screened into 13 compounds to construct network pharmacology and 433 targets were identified as PCP targets. GO and KEGG pathway enrichment analyses indicated that the effects of PCP extract would involve in Ras signaling pathway. The animal experiments on chronic ALI model mice shown that the oral administration of PCP can alleviate ALI by attenuating hepatic oxidative stress, inflammation and down-regulating the target proteins in Ras/Raf/MEK/ERK pathway. Molecular docking analysis revealed the good binding ability between the three polyphenols (i.e. quercetin, apigenin, thonningianin B) in PCP with the top contribution in network pharmacology, and these target proteins (Ras, Raf, MEK1/2, and ERK1/2).

CONCLUSION

Our results clarified that PCP ethanol extract could effectively alleviate ALI by down-regulating Ras/Raf/MEK/ERK signaling pathway promisingly. Quercetin, apigenin, and thonningianin B may be the active compounds of PCP, attributing to the intervention benefits of PCP against ALI.

The active components derived from Penthorum chinensePursh protect against oxidative-stress-induced vascular injury via autophagy induction

Oxidative stress-induced damage has been proposed as a major risk factor for cardiovascular disease and is a pathogenic feature of atherosclerosis. Although autophagy was reported to have a protective effect against atherosclerosis, its mechanism for reducing oxidative stress remains un-elucidated. In this study, we have identified 4 novel autophagic compounds from traditional Chinese medicines (TCMs), which activated the AMPK mediated autophagy pathway for the recovery of mitochondrial membrane potential (MMP) to reduce the production of reactive oxygen species (ROS) in Human umbilical vein endothelial cells (HUVECs). In this study, 4 compounds (TA, PG, TB and PG1) identified from Penthorum chinense Pursh (PCP) were demonstrated for the first time to possess binding affinity to HUVECs cell membranes via cell membrane chromatography (CMC) accompanied by UHPLC-TOF-MS analysis, and the 4 identified compounds induce autophagy in HUVECs. Among the 4 autophagic activators identified from PCP, TA (Thonningianin A, Pinocembrin dihydrochalcone-7-O-[3″-O-galloyl-4″,6″-hexahydroxydiphenoyl]-glucoside) is the major chemcial component in PCP, which possesses the most potent autophagy effect via a Ca²⁺/AMPK-dependent and mTOR-independent pathways. Moreover, TA efficiently reduced the level of ROS in HUVECs induced by H₂O₂. Additionally, the expression of pro- and cleaved-IL-1β in the aortic artery of ApoE-KO mice were also alleviated at the transcription and post-transcription levels after the administration of TA, which might be correlated to the reduction of oxidative-stress induced inflammasome-related Nod-like receptor protein3 (NLRP3) in the aortic arteries of ApoE-KO mice. This study has pinpointed the novel autophagic role of TA in alleviating the oxidative stress of HUVECs and aortic artery of ApoE-KO mice, and provided insight into the therapeutic application of TA in treatment of atherosclerosis or other cardiovascular diseases.

Flavonones from Penthorum chinense Ameliorate Hepatic Steatosis by Activating the SIRT1/AMPK Pathway in HepG2 Cells

Pinocembrin-7-O-β-d-glucoside (PCBG), pinocembrin (PCB), and 5-methoxy-pinocembrin-7-O-β-d-glucoside (MPG) are three flavonones isolated from Penthorum chinense Pursh (P. chinense). The effects of the three flavonones on hepatic steatosis and their molecular mechanisms in HepG2 cells were investigated in this study for the first time. A model of hepatic steatosis in HepG2 cells was induced by free fatty acid (FFA), and co-treated with the three flavonones as mentioned. Intracellular lipid droplets were detected by Oil Red O staining. PCB, PCBG, and MPG suppressed oxidative stress by decreasing malondialdehyde (MDA) levels and increasing superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. The levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were ameliorated. Moreover, these flavonones enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and the expression of silent mating type information regulation 2 homolog 1 (SIRT1) and peroxisome proliferator-activated receptor α (PPARα), and reduced the expression of sterol regulatory element binding protein-1c (SREBP1c) and the downstream targets fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and stearoyl-CoA desaturase 1 (SCD1). Molecular docking was used to predict the interaction and combination patterns between the three flavonones and the enzymes above. The results revealed that the SIRT1/AMPK pathway is involved in the functions of the three flavonones, and the most effective flavonone against hepatic steatosis might be PCBG, followed by MPG and PCB. Therefore, the three flavonones from P. chinense were found to exert preventive effects against hepatic steatosis by regulating the SIRT1/AMPK pathway.

Bacterial Translocation Is Linked to Increased Intestinal IFN-γ, IL-4, IL-17, and mucin-2 in Cholestatic Rats

Background and rationale for the study. Bacterial translocation is an important triggering factor of infection and mortality in cirrhosis. In a rat model using bile duct ligation (BDL), bacterial translocation appears within 24 h after ligation. The dynamic between TH1/TH2/TH17 cytokines and the integrity of the colonic mucosa in the context of cirrhosis is little known. This study aims to determine the link between bacterial translocation and intestinal inflammation in a cholestasis model. Additionally, alterations of the colonic mucus layer and the bacterial load were also addressed.

RESULTS

Bacterial translocation detected by microbiological cultures and MALDI-TOF showed that Escherichia coli predominates in mesenteric lymph nodes of BDL rats. Intestinal bacterial load analyzed by qPCR indicates a dramatic Escherichia/Shigella overgrowth at 8 and 30 days post-BDL. IFN-γ, IL-4, and IL-17 evaluated by Western blotting were increased at 8 and 30 days in the small intestine. In the colon, in contrast, only IFN-γ was significantly increased. The colonic mucus layer and mucin-2 expression determined by Alcian blue staining and immunohistochemistry surprisingly showed an increase in the mucus layer thickness related to increased mucin-2 expression during the entire process of liver damage. Hepatic enzymes, as well as collagen I, collagen III, TNF-α, and IL-6 liver gene expression were increased. In conclusion, bacterial overgrowth associated with bacterial translocation is linked to the over-expression of IFN-γ, IL-4, IL-17 and mucin-2. These molecules might facilitate the intestinal permeability through exacerbating the inflammatory process and disturbing tight junctions, leading to the perpetuation of the liver damage.

Using functional and molecular MRI techniques to detect neuroinflammation and neuroprotection after traumatic brain injury

This study was designed to investigate whether functional and molecular MRI techniques are sensitive biomarkers for assessment of neuroinflammation and drug efficacy after traumatic brain injury (TBI) in rats. We subjected rats to a controlled cortical impact model and used behavioral tests, histology, and immunofluorescence to assess whether flavonoid pinocembrin provides cerebral protection and improves functional recovery. Most importantly, we used multiple noninvasive structural, functional, and molecular MRI techniques to examine whether the pinocembrin-related neuroprotection and attenuation of neuroinflammation can be detected in vivo. Significant increases in cerebral blood flow (CBF) and amide proton transfer-weighted (APTw) MRI signals were observed in the perilesional areas in untreated TBI rats at 3days and could be attributed to increased glial response. In addition, increased apparent diffusion coefficient and decreased magnetization transfer ratio signals in untreated TBI rats over time were likely due to edema. Post-treatment with pinocembrin decreased microglial/macrophage activation at 3days, consistent with the recovery of CBF and APTw MRI signals in regions of secondary injury. These findings suggest that pinocembrin provides cerebral protection for TBI and that multiple MRI signals, CBF and APTw in particular, are sensitive biomarkers for identification and assessment of neuroinflammation and drug efficacy in the TBI model.

In-vivo absorption of pinocembrin-7-O-β-D-glucoside in rats and its in-vitro biotransformation

Pinocembrin-7-O-β-D-glucoside (PCBG), a flavonoid isolated from Penthorum chinense Pursh., has significant liver-protecting effects. The pharmacokinetics of PCBG and its major metabolite pinocembrin (PCB) in rats were investigated in this study. A sensitive and accurate UPLC-MS/MS method was developed and validated for the simultaneous quantitative determination of PCBG and PCB in rat plasma after oral and intravenous administration of PCBG. After intravenous administration, PCBG was the main form in plasma. In contrast, after oral administration, the concentration of PCB was about 4-fold higher than that of PCBG, indicating that PCBG was metabolized to PCB. We also investigated the biotransformation of PCBG in vitro in order to understand whether the pH and the intestinal flora of gastrointestinal tract could affect the metabolism of PCBG. PCBG was incubated in rat plasma, liver homogenization, gastrointestial contents, liver microsomes (RLM) and hepatocytes in vitro. The data showed that PCB was quickly formed in the gastrointestinal incubation but PCBG was converted to PCB gradually in other incubations. The results indicated that the majority of PCBG was converted to its aglycone PCB in digestive system after oral administration, and PCB could be the active ingredient in the body.

Traditional Chinese Herbal Medicine Penthorum chinense Pursh: A Phytochemical and Pharmacological Review

Penthorum chinense Pursh (ganhuangcao), a traditional Chinese medicine, is used for the prevention and treatment of liver diseases, including hepatitis B, hepatitis C, and alcoholic liver damage. A wide range of investigations have been carried out on this herbal medicine from pharmacognosy to pharmaceuticals, as well as pharmacology. The extract of P. chinense was reported to have significant liver protective effects through anti-oxidation, reduction of key enzyme levels, inhibition of hepatitis B virus DNA replication, and promotion of bile secretion. Based on the current knowledge, flavonoids and phenols are considered to be responsible for P. chinense's bioactivities. The main purpose of this review is to provide comprehensive and up-to-date knowledge of the phytochemical and pharmacological studies performed on P. chinense during the past few decades. Moreover, it intends to provide new insights into the research and development of this herbal medicine.

Pharmacokinetics, safety, and tolerability of single and multiple-doses of pinocembrin injection administered intravenously in healthy subjects

ETHNOPHARMACOLOGICAL RELEVANCE

Pinocembrin is the most abundant flavonoid in propolis. Preclinical studies have suggested that pinocembrin protects rat brain against oxidation and apoptosis induced by ischemia-reperfusion both in vivo and in vitro. To investigate the safety, tolerability and pharmacokinetics of a new neuroprotective agent, pinocembrin.

MATERIALS AND METHOD

A double-blind, placebo-controlled, randomized study was carried out in 58 healthy subjects. Single ascending doses of pinocembrin (20-150 mg) were evaluated in 5 cohorts. Multi-dose was studied at pinocembrin 60 mg.

RESULTS

Pinocembrin was well tolerated. No serious adverse events occurred. No subjects were discontinued because of a treatment emergent AE. Treatment related adverse event was acute urticaria. Two subjects in 150 mg cohort developed grade II urticaria during the study. One subject discontinued after 3 days at 60 mg bid because of diarrhea. In the single-dose study, the mean peak plasma pinocembrin concentration was obtained at the end of the 30-min infusion. The Cmax ranged from 0.28 μg mL(-1) to 2.46 μg mL(-1). AUC (0,∞) ranged from 10.34 μg mL(-1) min to 89.34 μg mL(-1) min. The T1/2 was similar across 5 dose groups, ranging from 40 to 55 min. Both urinary and feces excretion levels of pinocembrin were extremely low and similar among each dose groups, with mean values ranging from 0.07% to 0.17% and 0.94% to 1.94% of the administered dose, respectively. Linear increases in Cmax and AUC(0,∞) were observed. The pharmacokinetics of pinocembrin in multiple-dose was similar to those observed in the single-dose study, with no evidence of accumulation. Both urinary and feces excretion levels of pinocembrin were extremely low.

CONCLUSIONS

Pinocembrin displayed linear plasma pharmacokinetics over the dose range, 20-150 mg and was well tolerated up to 120 mg day(-1) when administered intravenously to healthy adults. No major safety concerns were identified that would preclude further clinical development of pinocembrin injection.