HPLC profile analysis of hepatoprotective oleanene-glucuronides in Puerariae Flos

Systematic characterization of Puerariae Flos metabolites in vivo and assessment of its protective mechanisms against alcoholic liver injury in a rat model

Puerariae Flos, a representative homology plant of medicine and food for alcoholism, has a long history of clinical experience and remarkable curative effect in the treatment of alcoholic liver disease (ALD). However, its effective forms and hepatoprotective mechanisms remain unknown. In the present study, a strategy based on UPLC-QTOF MS combined with mass defect filtering technique was established for comprehensive mapping of the metabolic profile of PF in rat plasma, urine, bile, and feces after oral administration. Furthermore, the absorbed constituents into plasma and bile with a relatively high level were subjected to the network analysis, functional enrichment analysis, and molecular docking to clarify the potential mechanism. Finally, the therapeutic effect of PF on ALD and predicted mechanisms were further evaluated using a rat model of alcohol-induced liver injury and Western blot analysis. In total, 25 prototype components and 82 metabolites, including 93 flavonoids, 13 saponins, and one phenolic acid, were identified or tentatively characterized in vivo. In addition, glucuronidation, sulfation, methylation, hydroxylation, and reduction were observed as the major metabolic pathways of PF. The constructed compound–target–pathway network revealed that 11 absorbed constituents associated with the 16 relevant targets could be responsible for the protective activity of PF against ALD by regulating nine pathways attributable to glycolysis/gluconeogenesis, amino acid metabolism, and lipid regulation as well as inflammation and immune regulation. In addition, four active ingredients (6″-O-xylosyltectoridin, genistein-7-glucuronide-4′-sulfate, tectoridin-4′-sulfate, and 6″-O-xylosyltectoridin-4′-sulfate) as well as two target genes (MAO-A and PPAR-α) were screened and validated to play a crucial role with a good molecular docking score. The present results not only increase the understanding on the effective form and molecular mechanisms of PF-mediated protection against ALD but also promote better application of PF as a supplement food and herbal medicine for the treatment of ALD.

Potential Anti-Diabetic Activity of Pueraria lobata Flower (Flos Puerariae) Extracts

Pueraria lobata (Wild.) Ohwi. (P. lobata) flowers known as ‘Kudzu flower’ contain isoflavonoids and essential oil components. They have a wide range of biological and pharmacological activities, including protective effects against non-alcoholic fatty liver disease, hyperglycemia, and hypolipidemia, anti-mutagenic effects, and benefits for weight loss. However, the molecular mechanism of these effects remains unclear. Our study aimed to systematically examine the effects of flos puerariae crude extract (FPE) as an anti-diabetic agent using in vitro assays. The cytotoxicity of FPE was evaluated using MTS assay in L6 rat myocyte and 3T3-L1 murine fibroblast cell lines. PPARγ binding activity and adipogenesis were examined using dual-luciferase and differentiation assays, respectively. For investigating the anti-diabetic activity, glucose utilization, including GLUT4 protein expression, glucose uptake assay, and GLUT4 translocation using immunofluorescence microscopy were conducted in L6 cells. Furthermore, we assessed the antioxidant and anti-inflammatory activities of FPE. Our results demonstrated the ability to augment glucose uptake in L6 cells and enhance glucose utilization activity by increasing the expression of glucose transporter type 4 (GLUT4). In summary, our findings suggest that FPE may be a potential anti-diabetic substance for the treatment of diabetic patients and can prevent inflammatory or oxidation-related diseases.

New hepatoprotective isoflavone glucosides from Pueraria lobata (Willd.) Ohwi

Two new isoflavone glucosides, 3'-methoxyneopuerarin A (1) and 3'-methoxyneopuerarin B (2), together with nine known isoflavones including puerarin (3), neopuerarin A (4), neopuerarin B (5), daidzin (6), daidzein (7), 3'-methoxypuerarin (PG-3) (8), puerarin xyloside (9), mirificin (10), 3'-hydroxypuerarin (11) were isolated from the water extraction of the dried roots of Pueraria lobata (Willd.) Ohwi. Their structures were elucidated by the means of spectroscopic and chromatographic analysis methods. All compounds were evaluated for their hepatoprotective activity on HepG2 cells. All of them showed statistically significant hepatoprotective effect.

New triterpenoid saponins from the flowers of Pueraria thomsonii

Two new oleanane-type triterpenoid saponins, kakkasaponin II (1) and kakkasaponin III (2), were isolated from the methanol extract of the flowers of Pueraria thomsonii (Leguminosae), together with seven known oleanane-type triterpenoid saponins, phaseoside IV (3), sophoradiol monoglucuronide (4), kakkasaponin I (5), kaikasaponin III (6), soyasaponin I (7), soyasaponin III (8), and soyasaponin IV (9). The structures of 1 and 2 were elucidated by spectroscopic methods including IR, ESI-TOF-MS, and 1D and 2D NMR experiments.

Kudzu root: traditional uses and potential medicinal benefits in diabetes and cardiovascular diseases

Kudzu root (Gegen in Chinese) is the dried root of Pueraria lobata (Willd.) Ohwi, a semi-woody, perennial and leguminous vine native to South East Asia. It is often used interchangeably in traditional Chinese medicine with thomson kudzu root (Fengen in Chinese), the dried root of P. thomsonii, although the Chinese Pharmacopoeia has separated them into two monographs since the 2005 edition. For more than 2000 years, kudzu root has been used as a herbal medicine for the treatment of fever, acute dysentery, diarrhoea, diabetes and cardiovascular diseases. Both English and Chinese literatures on the traditional applications, phytochemistry, pharmacological activities, toxicology, quality control and potential interactions with conventional drugs of both species have been included in the present review. Over seventy phytochemicals have been identified in kudzu root, with isoflavonoids and triterpenoids as the major constituents. Isoflavonoids, in particular puerarin, have been used in most of the pharmacological studies. Animal and cellular studies have provided support for the traditional uses of kudzu root on cardiovascular, cerebrovascular and endocrine systems, including diabetes and its complications. Further studies to define the active phytochemical compositions, quality standards and clinical efficacy are warranted. Strong interdisciplinary collaboration to bridge the gap between traditional medicine and modern biomedical medicine is therefore needed for the development of kudzu root as an effective medicine for the management of diabetes and cardiovascular diseases.

Microbial transformation and bioactivation of isoflavones from Pueraria flowers by human intestinal bacterial strains

The flowers from Pueraria, which are called Puerariae Flos, have been used since ancient times for recovery from alcohol intoxication. We elucidated the microbial transformation of the main isoflavones (1, 1a and 2) by using 29 commercially available human intestinal bacterial strains together with the bioactivation of the hepatoprotective activity of their metabolites. Tectoridin (1a), which contains only one glucosyl moiety, was metabolized to its aglycone 1b by various bacterial strains. On the other hand, the metabolism of 1 and 2, which both have disaccharide groups, was limited to specific bacterial strains. The metabolites 1c and 2c obtained from the Peptostreptococcus productus strain were completely different from those produced by the other strains. These metabolites were identified as 6-hydroxygenistein and 6-hydroxybiochanin A, respectively. The glycosides 1, 1a and 2 did not show any hepatoprotective activity, whereas aglycones 1b and 2b showed moderate activity. Furthermore, the hepatoprotective activity of the demethylated metabolites 1c and 2c was extremely potent. Although not all people have P. productus in their gastrointestinal tract, the O-demethylated compounds might become one of the bioactivated metabolites when Puerariae Flos is administered orally.

Hepatoprotective Effects of Irisolidone on tert-Butyl Hyperoxide-Induced Liver Injury

To clarify the hepatoprotective effects of kakkalide and its metabolite irisolidone by human fecal microflora, their effects on tert-butyl hydroperoxide (t-BHP)-injured HepG2 cells and mice were investigated. Irisolidone protected HepG2 cells against cytotoxicity induced by t-BHP. However, kakkalide did not protect cytotoxicity. When kakkalide 100 mg/kg was orally administered to mice injured by t-BHP, it significantly inhibited the increase in plasma alanine aminotransferase and aspartate aminotransferase activities by 84% and 85% of t-BHP-treated control group, respectively. The inhibitory effect of kakkalide is much more potent than that of silybin, a hepatoprotective agent. However, intraperitoneally administered kakkalide did not exhibit hepatoprotective activity. When irisolidone was intraperitoneally administered to mice, it exhibited potent hepatoprotective activity. Based on these findings, irisolidone can be hepatoprotective and kakkalide may be a prodrug transformed to irisolidone.

[Search for functions of natural oligoglycosides--Solanaceae and Leguminosae origin glycosides]

Our extensive investigation of the isoprenoidal glycosides in Solanaceae and Leguminosae folk medicines to verify their effectiveness, antiherpes and anti-HSV-1 activities, and hepatoprotective action has resulted in the elucidation of their structure-activity relationships. We present the respective optimum models here.

The bioactivity of saponins: triterpenoid and steroidal glycosides

Triterpenoid and steroidal glycosides, referred to collectively as saponins, are bioactive compounds present naturally in many plants. They have considerable potential as pharmaceutical and/or nutraceutical agents in natural or synthetic form. Saponins, from a variety of sources, have been shown to have hypocholesterolemic, anti-coagulant, anticarcinogenic, hepatoprotective, hypoglycemic, immunomodulatory, neuroprotective, anti-inflammatory and anti-oxidant activity. This paper reviews saponin research of the last decade, focussing on developments in understanding their mechanism of action and structure-activity relationships. Virtually all of this work has used animal and in vitro models. To date there are very few human data.