Identification of the bioactive components of orally administered Lithocarpus polystachyus Rehd and their metabolites in rats by liquid chromatography coupled to LTQ Orbitrap mass spectrometry

Toxicological safety assessment of a water extract of Lithocarpus litseifolius by a 90-day repeated oral toxicity study in rats

Lithocarpus litseifolius although known as "Sweet Tea" (ST), has been traditionally accepted as a daily beverage and used as a folk medicine in southern China with little understanding of its potential toxicity. This study evaluated the safety of a water extract of ST by a subchronic toxicity study in Sprague-Dawley rats. A total of 80 rats were randomized divided into 4 groups with 10 males and 10 females in each group, treated with 2000, 1,000, 500 and 0 mg/kg body weight of ST extract by gavage for 90 days, respectively. The results of the study showed that ST extract did not induce treatment-related changes in the body and organ weight, food intake, blood hematology and serum biochemistry, urine indices, and histopathology in rats. The NOAEL of ST extract was observed to be 2000 mg/kg/day for rats of both sexes. These results indicated that ST extract was of low toxicity in the experimental conditions of the current study and had the potential for application in food-related products.

Metabolic Investigation on the Interaction Mechanism between Dietary Dihydrochalcone Intake and Lipid Peroxidation Product Acrolein Reduction

SCOPE

Acrolein (ACR), a lipid peroxidation product, pathologically participates in various chronic diseases. In vitro evidence suggestes that dietary dihydrochalcones (DHCs) potentiate safe and alternative therapeutics to synthetic pharmaceuticals for ACR scavenging. Here, to investigate whether ingested DHCs could trap ACR and thereof result in reductions in endogenous ACR in mice is aimed.

METHODS AND RESULTS

Three doses of phloretin (25, 100, and 400 mg kg-1 ), a major dietary DHC, are orally administrated to mice and 24 h urine and fecal samples are collected, respectively. High-resolution MS-based targeted metabolomics reveal for the first time that phloretin and its oxidized metabolite are able to trap endogenous ACR via formation of ACR conjugates. Quantification further demonstrate that a) more than 13% of ingested phloretin can dose-dependently trap 0.77-9.92 nmol of ACR within 24 h; b) phloretin ingestion leads to marked reductions in both free ACR and ACR metabolites in mouse urine compared to control; and c) trapping reactions by phloretin can account for up to 20.1% of the total decreases in endogenous ACR, depending on the administration doses.

CONCLUSION

Findings from this study indicate that regular consumption of DHCs-rich diets holds great promise to alleviate the development of ACR-associated chronic diseases.

Deciphering mechanism of the herbal formula WuShen in the treatment of postinfarction heart failure

BACKGROUND

Numerous clinical studies reported the effectiveness of herbal formula WuShen (WS) in treating cardiovascular diseases, yet relevant basic research was rarely conducted.

METHODS AND RESULTS

Twelve main bioactive compounds of WS decoction were identified using the ultra-performance liquid chromatography-LTQ-Orbitrap mass spectrometer. A total of 137 active compounds with 613 targets were predicted by network pharmacology; their bioinformatic annotation and human microarray data suggested that wounding healing, inflammatory response, and gap junction were potentially the major therapeutic modules. A rat model of post-myocardial infarction (MI) heart failure (HF) was used to study the effects of WS on cardiac function, adverse cardiac remodeling, and experimental arrhythmias. Rats treated with WS led to a significantly improved pump function and reduced susceptibility to both ventricular tachycardia and atrial fibrillation, and restricted adverse cardiac remodeling partly via inhibiting TGFβ1/SMADs mediated extracellular matrix deposition and Rac1/NOX2/CTGF/Connexin43 -involved gap junction remodeling.

CONCLUSIONS

The present study highlights that WS can be applied to the treatment of heart failure and the upstream therapy for atrial fibrillation and ventricular tachycardia through its preventive effect on adverse cardiac remodeling.

The Bioavailability, Extraction, Biosynthesis and Distribution of Natural Dihydrochalcone: Phloridzin

Phloridzin is an important phytochemical which was first isolated from the bark of apple trees. It is a member of the dihydrochalcones and mainly distributed in the plants of the Malus genus, therefore, the extraction method of phloridzin was similar to those of other phenolic substances. High-speed countercurrent chromatography (HSCCC), resin adsorption technology and preparative high-performance liquid chromatography (HPLC) were used to separate and purify phloridzin. Many studies showed that phloridzin had multiple pharmacological effects, such as antidiabetic, anti-inflammatory, antihyperglycaemic, anticancer and antibacterial activities. Besides, the physiological activities of phloridzin are cardioprotective, neuroprotective, hepatoprotective, immunomodulatory, antiobesity, antioxidant and so on. The present review summarizes the biosynthesis, distribution, extraction and bioavailability of the natural compound phloridzin and discusses its applications in food and medicine.

Evaluation of Two Parts of Lithocarpus polystachyus Rehd. from Different Chinese Areas by Multicomponent Content Determination and Pattern Recognition

The purpose of this work is to establish a new method using high-performance liquid chromatography-diode array detection (HPLC-DAD) with chemometrics analysis to determine the content of catechin, isoquercetin, astragalin, phloridzin, trilobatin, and phloretin for one flavanol and five flavonoids, filter out the key compounds, and evaluate the quality of 26 batches of tender leaves and flower spikes of Lithocarpus polystachyus Rehd. (LP) from ten areas in China. The result showed that the HPLC-DAD method had excellent performance for accurate quantification analysis. S3 (tender leaf from Lushan, Sichuan) had the highest contents for six measured chemicals with trilobatin content of up to 27.82% in dry weight. S22 (flower spike from Liangping, Chongqing) had the highest content of phloridzin (up to 7.28%). All samples were divided into three types based on spatial distribution using principal component analysis. The result showed that the tender leaves and flower spikes from the same areas had many similar properties, and there were significant differences between the samples from different regions. Furthermore, phloridzin and trilobatin were identified as chemical markers for quality evaluation of two parts with different tender leaves and flower spikes of LP from geographical areas by orthogonal partial least squares discrimination analysis. These results will be helpful to establish an effective and comprehensive evaluation system of the development and utilization of LP resources.

Regioselective Hydroxylation of Phloretin, a Bioactive Compound from Apples, by Human Cytochrome P450 Enzymes

Phloretin, the major polyphenol compound in apples and apple products, is interesting because it shows beneficial effects on human health. It is mainly found as a form of glucoside, phlorizin. However, the metabolic pathway of phloretin in humans has not been reported. Therefore, identifying phloretin metabolites made in human liver microsomes and the human cytochrome P450 (P450) enzymes to make them is interesting. In this study, the roles of human liver P450s for phloretin oxidation were examined using human liver microsomes and recombinant human liver P450s. One major metabolite of phloretin in human liver microsomes was 3-OH phloretin, which is the same product of a bacterial CYP102A1-catalyzed reaction of phloretin. CYP3A4 and CYP2C19 showed k_cat values of 3.1 and 5.8 min^-1, respectively. However, CYP3A4 has a 3.3-fold lower K_m value than CYP2C19. The catalytic efficiency of a CYP3A4-catalyzed reaction is 1.8-fold higher than a reaction catalyzed by CYP2C19. Whole-cell biotransformation with CYP3A4 was achieved 0.16 mM h^-1 productivity for 3-OH phlorein from 8 mM phloretin at optimal condition. Phloretin was a potent inhibitor of CYP3A4-catalyzed testosterone 6β-hydroxylation activity. Antibodies against CYP3A4 inhibited up to 90% of the microsomal activity of phloretin 3-hydroxylation. The immunoinhibition effect of anti-2C19 is much lower than that of anti-CYP3A4. Thus, CYP3A4 majorly contributes to the human liver microsomal phloretin 3-hydroxylation, and CYP2C19 has a minor role.

The PI3K/Akt and NF-κB signaling pathways are involved in the protective effects of Lithocarpus polystachyus (sweet tea) on APAP-induced oxidative stress injury in mice

Acetaminophen (APAP)-induced acute liver injury (ALI) is a health issue that has gradually attracted attention, and is often regarded as a model of drug-induced hepatotoxicity. The leaves of Lithocarpus polystachyus Rehd. (named as “sweet tea”, ST) usually serve as tea drink and folk medicine for healthcare in the southwest part of China. In previous reports, it has been proven to protect various animal models, except for APAP-induced liver injury model. Therefore, this study initially explored the protective effect of ST leaf extract (STL-E) on hepatotoxicity induced by APAP in ICR mice. STL-E of 50 and 100 mg kg⁻¹ were given to each group for 7 days. ALI was intraperitoneally induced by APAP treatment (i.p. 250 mg per kg body weight). Biochemical markers, levels of inflammatory factors, histopathological staining and western blotting were used to analyze the inflammation and apoptosis of liver tissues. Interestingly, the treatment with STL-E significantly attenuated APAP-induced liver injury (p < 0.05). Moreover, STL-E partially mitigated APAP-induced liver injury by effectively activating the PI3K/Akt pathway and inhibiting the NF-κB pathway. In a word, STL-E protected liver against APAP-induced hepatotoxicity by inhibiting the PI3K/Akt-mediated apoptosis signal pathway and inhibiting the NF-κB-mediated signaling pathway.

Acetaminophen (APAP)-induced acute liver injury (ALI) is a health issue that has gradually attracted attention, and is often regarded as a model of drug-induced hepatotoxicity.

Intestinal phase-II metabolism of quercetin in HT29 cells, 3D human intestinal tissues and in healthy volunteers: a qualitative comparison using LC-IMS-MS and LC-HRMS

Flavonoids are a large class of dietary molecules, among which quercetin is the most ubiquitous, which undergo an extensive intestinal phase-II metabolism. We compared the in vivo metabolism of quercetin in healthy volunteers with two in vitro models, HT29 cells and 3 D human intestinal tissues. Supernatants of the in vitro experiments and the human intestinal fluids (HIF) were analyzed by LC-IMS-MS and LC-HRMS in a qualitative way. Quercetin glucuronides, sulfates and their methyl conjugates were detected in all three systems. The metabolic profiles were found to be different, both in terms of the metabolites produced and their relative proportions. In particular, quercetin sulfates were almost absent in supernatants from HT29 cells incubations while they were a major metabolite in HIF and also found in 3 D intestinal tissues incubations. IMS provided structural information as well as a third dimension of characterization, while HRMS brought increased sensitivity and MS/MS confirmation. HT29 cells are a useful tool to generate phase-II metabolites but do not represent the in vivo situation. 3 D intestinal tissues appear as a more relevant tool to study the intestinal phase-II metabolism of flavonoids.

Evaluation of toxicity studies of flavonoid fraction of Lithocarpus polystachyus Rehd in rodents

The aim of the study was to evaluate the safety of flavonoid fraction of Lithocarpus polystachyus Rehd (Sweet Tea-F, ST-F) in mice and rats through acute and sub-chronic toxicity studies respectively. For acute toxicity study, a single dose of 5000 mg/kg of ST-F was given orally to healthy KM mice. The mice were observed mortality and toxic symptoms for 24 h, then once a day up to 14 days. In the sub-chronic toxicity study, ST-F was administered orally at doses of 0, 70, 140, 560 mg/kg/day to rats for 26 weeks. Body weight and food intake were recorded weekly. Hematological, biochemical, coagulation and organ parameters were analyzed at the end of 26 weeks administration. Vital organs were evaluated by histopathology. In the acute toxicity study, ST-F caused neither significant toxic symptoms, nor mortality in mice. In sub-chronic toxicity study, daily oral administration of ST-F at the dose of 70 mg/kg resulted in a significant increase (P < 0.05) in the relative body weight at the 10-week, and the same situation brought at the dose of 140 mg/kg/day at the 22-week. Hematological and biochemical showed significant changes (P < 0.01 or P < 0.05) in WBC, GLU, ALP, AST and serum electrolytes levels at the dose of 560 mg/kg/day. The amount of RBC decreased significantly (P < 0.05) while the content of PLT slightly increased (P < 0.05) at the dose of 140 mg/kg/day. In additional, no obvious histological changes were observed in vital organs of ST-F treated animals compared to control group. The ST-F may be exit slight side effects at the dose of 560 mg/kg/day in rats. Thus, the overall results show that the no-observed adverse effect level (NOAEL) of ST-F was considered to be 140 mg/kg for male SD rats.

Immunomodulatory activities of phlorizin metabolites in lipopolysaccharide-stimulated RAW264.7 cells

The immunomodulatory effects of two new phlorizin metabolites, phloretin 4-O-β-d-glucuronide (1), 6-methoxyl-phloretin-2-O-β-d-glucuronide (2), together with phloretin-2-O-β-d-glucuronide (3) on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells were determined. 1-3 (1-5μg/ml) significantly inhibited the production of NO (p<0.01). At the concentration of 5μg/ml, 2 and 3 further inhibited iNOS mRNA expression (p<0.01 or 0.05), and 1-3 inhibited iNOS protein expression (p<0.01). Conversely, they all promoted the proinflammatory cytokine TNF-α mRNA expression (p<0.01). For IL-10 mRNA, 1 and 3, which are main metabolism forms in rat plasma, obviously promoted its expression (p<0.01), while metabolite 2, which was only detected in rat urine, showed inhibitory activity, but 1-3 alone without LPS stimulation had no effect on the expression of both TNF-α and IL-10 mRNA expression. 1 further inhibited VEGF, CCL2 and CXCL1 mRNA expression at the concentration of 5-25μg/ml (p<0.01). These results indicated phloretin's metabolites with different structural forms showed different immunomodulatory activities.

Metabolic profiling analysis of berberine, palmatine, jatrorrhizine, coptisine and epiberberine in zebrafish by ultra-high performance liquid chromatography coupled with LTQ Orbitrap mass spectrometer

1. Zebrafish has been used in metabolic study of drugs as a powerful tool in recent years. In this study, we make a feasible metabolism investigation of five protoberberine alkaloids (PBAs) applied in zebrafish model for the first time, including berberine (BBR), palmatine (PAL), jatrorrhizine (JAT), coptisine (COP) and epiberberine (EBBR). 2. After exposure for 24 hours, 19 metabolites were identified by LTQ Orbitrap mass spectrometer, including 9 phase I metabolites and 10 phase II metabolites. Demethylation, hydroxylation, sulfation and glucuronidation were the major metabolic transformation of PBAs in zebrafish, which were similar to mammals. Compared with reported literatures, BBR and JAT showed high consistency between human and zebrafish in metabolic pathways. 3. To our knowledge, this is the first time to study in vivo metabolism of COP, which provides useful information to other researchers. 4. This study indicated that zebrafish model is feasible and reasonable to predict the metabolism of PBAs. It showed great potential for developing a novel and rapid method for predicting the metabolism of trace compounds of botanical drugs, with the advantages of lower cost, higher performance and easier set up.