Protective Effects of Kakkalide From Flos Puerariae on Ethanol-Induced Lethality and Hepatic Injury Are Dependent on Its Biotransformation by Human Intestinal Microflora

A Comprehensive Review on Biotransformation, Interaction, and Health of Gut Microbiota and Bioactive Components

BACKGROUND

The relationship between gut microbiota and bioactive components has become the research focus in the world. We attempted to clarify the relationship between biotransformation and metabolites of gut microbiota and bioactive components, and explore the metabolic pathway and mechanism of bioactive ingredients in vivo, which will provide an important theoretical basis for the clinical research of bioactive ingredients and rationality of drugs, and also provide an important reference for the development of new drugs with high bioavailability.

METHODS

The related references of this review on microbiota and bioactive components were collected from both online and offline databases, such as ScienceDirect, PubMed, Elsevier, Willy, SciFinder, Google Scholar, Web of Science, Baidu Scholar, SciHub, Scopus, and CNKI.

RESULTS

This review summarized the biotransformation of bioactive components under the action of gut microbiota, including flavonoids, terpenoids, phenylpropanoids, alkaloids, steroids, and other compounds. The interaction of bioactive components and gut microbiota is a key link for drug efficacy. Relevant research is crucial to clarify bioactive components and their mechanisms, which involve the complex interaction among bioactive components, gut microbiota, and intestinal epithelial cells. This review also summarized the individualized, precise, and targeted intervention of gut microbiota in the field of intestinal microorganisms from the aspects of dietary fiber, microecological agents, fecal microbiota transplantation, and postbiotics. It will provide an important reference for intestinal microecology in the field of nutrition and health for people.

CONCLUSION

To sum up, the importance of human gut microbiota in the research of bioactive components metabolism and transformation has attracted the attention of scholars all over the world. It is believed that with the deepening of research, human gut microbiota will be more widely used in the pharmacodynamic basis, drug toxicity relationship, new drug discovery, drug absorption mechanism, and drug transport mechanism in the future.

Biological Potential of Kakkalide in Medicine for the Treatment of Human Disorders: An Overview of Pharmacological Aspects

BACKGROUND

Pueraria lobata is an important herbal medicine of Fabaceae family that has been clinically used in Traditional Chinese Medicine to counteract human disorders and associated secondary complications. Kakkalide also called irisolidone 7-xylosylglucoside is an isoflavonoid of Puerariae flos, Pueraria lobata and Flos Puerariae. Moreover, Kakkalide has a wide range of bioactivities in medicine.

METHODS

Biological potential of kakkalide was investigated in the present work through scientific data analysis of different scientific research work on kakkalide in order to know its therapeutic potential in medicine. Scientific data on Pueraria lobata were collected and analyzed in the present work. All the scientific data were collected from Google, Google Scholar, Scopus, and Science Direct in the present work.

RESULTS

Scientific data analysis of kakkalide revealed its biological importance and therapeutic potential in medicine. The present investigation signified kakkalide's effectiveness in inflammatory diseases, prostaglandin E2 production, liver complication, gastric injury, alcoholism, insulinresistant endothelial dysfunction, aldose reductase enzyme, hyperlipidemia, estrogenic activity, and stroke. In addition, the bioavailability of kakkalide was also discussed in the present paper. Present work also revealed the significance of analytical techniques for the separation, isolation and identification of kakkalide in different biological and non-biological samples.

CONCLUSION

Present paper signified the health-beneficial aspects of kakkalide in medicine.

Oriental traditional herbal Medicine--Puerariae Flos: A systematic review

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria Flos (PF), a traditional herbal medicine, is botanically from the dried flowers of Pueraria lobate (Willd.) Ohwi. (Chinese: ) or Pueraria thomsonii Benth. (Chinese: ). It has a long history of thousands of years in China for awakening the spleen, clearing the lungs, relieving alcohol.

AIM OF THE REVIEW

This review aims to report the up-to-date research progress in ethnopharmacology, phytochemistry, pharmacology and toxicology, metabolism and therapeutic application of PF, so as to provide a strong basis for future clinical treatment and scientific research.

MATERIALS AND METHODS

Relevant information on PF was collected from scientific literature databases including PubMed, CNKI and other literature sources (Ph.D. and M.Sc. dissertations and Chinese herbal classic books) by using the keyword "Puerariae".

RESULTS

Briefly, phytochemical research report has isolated 39 flavonoids, 19 saponins and 25 volatile oils from PF. Flavonoids and saponins are the most important bioactive compounds, and most of the quality control studies focus on these two types of compounds. Modern pharmacological studies have revealed their significant biological activities in relieving alcoholism, hepatoprotective, anti-tumor, anti-inflammatory, and anti-oxidation, which provides theoretical support for the traditional use.

CONCLUSIONS

Comprehensive analysis showed that pharmacological activity of most purified compounds from PF had not been reported. Kakkalide, tectoridin and their deglycosylated metabolites (irisolidone and tectorigenin) has been focused on excessively due to their higher content and better activities. This leads to low development and resources waste. Interestingly, PF made a breakthrough in the field of food. Many kinds of fat-lowering foods such as PILLBOX Onaka have been popular in Japan market, which received extensive attention. Therefore, we suggest that future research can be paid attention on the development of the plant's function in the field of food and medicine, as well as the transformation from experimental to clinical.

Herbal Phytomedicine 'Irisolidone' in Chronic Diseases: Biological Efficacy and Pharmacological Activity

BACKGROUND

Plant-derived products have been used in medicine as a source of bioactive molecules, mainly due to their medicinal importance and therapeutic potential. Nowadays, plant derived products have been used in the medicine for the development of novel drug leads. Polyphenols are an important class of secondary metabolites found to be present in plants and their derived products. Polyphenols play an important role in the nutrition of human beings and also have a significant role in plant resistance against pests and diseases. Scientific studies have proven the biological importance of flavonoids in medicine and other allied health sectors. Anti-oxidant, analgesic, anti-microbial, anti-inflammatory, anti-viral, anti-tumor and anti-allergic activities are the important pharmacological features of flavonoids. Irisolidone is an important isoflavone found to be present in Pueraria lobata flowers.

METHODS

To know the medicinal importance and therapeutic potential of irisolidone in the medicine, numerous scientific research data have been collected from Google, Google Scholar, PubMed, Science Direct, and Scopus. Pharmacological activity data of irisolidone has been collected and analyzed in the present works to know their health beneficial aspects in the medicine. Detailed pharmacological activities of irisolidone have been investigated through scientific data analysis of scientific research works.

RESULTS

Scientific research data analysis of irisolidone revealed the anti-inflammatory, antiangiogenic, anti-cancer, anti-platelet, anti-oxidant, anti-hyperlipidemic, immunomodulating, hepatoprotective and estrogenic potential. However, the biological effect of irisolidone on the gastric system, aldose reductase enzymes, malignant gliomas, and JC virus has also been investigated. Scientific data analysis revealed the significance of analytical tools for the separation and identification of irisolidone.

CONCLUSION

Present work signified the biological importance and therapeutic potential of irisolidone in medicine.

Modulation of Hair Growth Promoting Effect by Natural Products

A large number of people suffer from alopecia or hair loss worldwide. Drug-based therapies using minoxidil and finasteride for the treatment of alopecia are available, but they have shown various side effects in patients. Thus, the use of new therapeutic approaches using bioactive products to reduce the risk of anti-hair-loss medications has been emphasized. Natural products have been used since ancient times and have been proven safe, with few side effects. Several studies have demonstrated the use of plants and their extracts to promote hair growth. Moreover, commercial products based on these natural ingredients have been developed for the treatment of alopecia. Several clinical, animal, and cell-based studies have been conducted to determine the anti-alopecia effects of plant-derived biochemicals. This review is a collective study of phytochemicals with anti-alopecia effects, focusing mainly on the mechanisms underlying their hair-growth-promoting effects.

Potential Effects of Dietary Isoflavones on Drug-Induced Liver Injury

Numerous prescribed drugs and herbal and dietary supplements have been reported to cause drug-induced acute liver injury, which is a frequent cause of acute liver failure (ALF). It is a tremendous challenge with ever-increasing drug application in the medication system for huge populations. Drug-induced acute liver injury can lead to diverse pathologies similar to acute and chronic hepatitis, acute liver failure, biliary obstruction, fatty liver disease, and so on. Recently, extensive work demonstrated that isoflavones play an essential and protecting role in drug-induced liver injury (DILI). The isoflavones mediated hepatoprotection by modulating specific genes linked with control of cellular redox homeostasis and inflammatory responses. Isoflavones upregulate oxidative stress-responsive nuclear factor erythroid 2-like 2 (Nrf2), downregulate inflammatory nuclear factor-κB (NF-κB) signaling pathways, and modulate a balance between cell survival and death. Moreover, isoflavones actively inhibit the expression of cytochromes P450 (CYPs) enzyme during drug metabolism. Moreover, isoflavones are also linked with farnesoid X receptor (FXR) activation and signal transducer and activator of transcription factor 3 (STAT3) phosphorylation in hepatoprotection DILI. In vivo and in vitro studies clearly stated that isoflavones bear strong antioxidant potential and promising agents for hepatotoxicity prevention and stressed their potential role as therapeutic supplements in DILI. The current review will elaborate on isoflavones’ preventive and therapeutic potential concisely and highlight various molecular targets to exert a protective effect on DILI.

Tectorigenin attenuates the OGD/R-induced HT-22 cell damage through regulation of the PI3K/AKT and the PPARγ/NF-κB pathways

Tectorigenin (TEC) is an effective compound that derived from many plants, such as Iris unguicularis, Belamcanda chinensis and Pueraria thunbergiana Benth. Evidence suggested that TEC has anti-tumor, anti-oxidant activity, anti-bacterial and anti-inflammatory effects. In addition, there has some evidence indicated that TEC is a potential anti-stroke compound; however, its specific roles and associated mechanism have not yet been elucidated. In the present study, we aimed to investigate the anti-inflammatory, anti-oxidant activity and anti-apoptosis effects of TEC on oxygen-glucose deprivation/reperfusion (OGD/R)-induced HT-22 cells, and clarified the relevant mechanisms. Here, we observed that TEC significantly promoted cell survival, impeded cell apoptosis, inhibited ROS and inflammatory cytokines IL-1β, IL-6, TNF-α production in OGD/R-induced HT-22 cells. Moreover, TEC activated PI3K/AKT signal pathway, increased PPARγ expression and inhibited NF-κB pathway activation in OGD/R-induced HT-22 cells. Further studies indicated that PPARγ inhibitor GW9662 activated NF-κB pathway after TEC treatment in OGD/R-induced HT-22 cells. Also, PI3K/AKT inhibitor LY294002, PPARγ inhibitor GW9662 and NF-κB activator LPS both reversed the effects of TEC on OGD/R-induced HT-22 cell biology. Taken together, this research confirmed that TEC benefit to HT-22 cell survival and against OGD/R damage through the PI3K/AKT and PPARγ/NF-κB pathways. These results indicated that TEC might be an effective compound in the treatment for ischemic brain injury.

Gut microbial transformation, a potential improving factor in the therapeutic activities of four groups of natural compounds isolated from herbal medicines

Herbal medicines (HMs) have attracted widespread attention because of their significant contributions to the prevention and treatment of many human diseases. Recently, gut microbiota has become an important frontier to understand the therapeutic mechanisms of medicines. Gut microbiota-mediated transformation is a microbial metabolic form after oral administrations of HMs compounds. A great number of studies showed that gut microbiota could transform some HMs compounds by the variation of chemical structures into several active metabolites, which exerted better bioavailabilities and therapeutic activities than their parent compounds. Among these HMs compounds, alkaloids, flavonoids, polyphenols and terpenoids were the representative ones. However, there is no systemic review focusing on the potential improved therapeutic activities of these natural compounds caused by gut microbial transformation. Here, this review summarizes the therapeutic activities that are more potent in microbial transformed metabolites than in their parent compounds (alkaloids, flavonoids, polyphenols and terpenoids) from HMs. We hope this review will be conducive to deepening the understanding of the relationship between gut microbial transformation and therapeutic activities of HMs compounds.

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.

Tectorigenin attenuates the MPP+-induced SH-SY5Y cell damage, indicating a potential beneficial role in Parkinson's disease by oxidative stress inhibition

Tectorigenin is a plant isoflavonoid primarily derived from the flowers of Pueraria thomsonii Benth. Although various biological properties of tectorigenin have been reported, such as its antioxidant activity, the effects of tectorigenin on the cellular models of Parkinson's disease have not yet been elucidated. The aims of the current study were to investigate whether tectorigenin prevents neurotoxicity induced by MPP⁺ (also known as 1-methyl-4-phenylpyridinium) in SH-SY5Y cells and to elucidate the underlying protective mechanism. Cell viability and lactate dehydrogenase release were measured. The morphological changes of apoptotic cells were observed by Hoechst 33258 staining. Caspase-3, superoxide dismutase, catalase and glutathione peroxidase activity was measured using commercially available ELISA kits. The expression of cytochrome c, Bax, Bcl-2 and NADPH oxidase were detected by western blot analysis. The results indicated that treatment with MPP⁺ causes a significant decrease in the viability of cells and an increase in apoptosis, as evidenced by the upregulation of apoptotic cells, caspase-3 activity and cytochrome c expression. By contrast, these effects were all reversed by pretreatment with tectorigenin in SH-SY5Y cells. Tectorigenin also inhibited the MPP⁺-induced changes of Bax and Bcl-2 levels. In addition, pretreatment with tectorigenin mitigated the MPP⁺-caused increases in the levels of reactive oxygen species and NADPH oxidase protein in SH-SY5Y cells. Simultaneously, tectorigenin abolished the downregulation of antioxidant enzymes, including superoxide dismutase, catalase and glutathione peroxidase, that was induced by MPP⁺. In conclusion, the present study data indicate that the neuroprotective effect of tectorigenin against MPP⁺-induced cytotoxicity and apoptosis may be involved in attenuating oxidative stress and enhancing antioxidant defense.

Methylamine irisolidone, a novel compound, increases total ATPase activity and inhibits apoptosis in vivo and in vitro

We propose to further research the protective effect of MMI on myocardium ischemic rat model and H9c2 cells that underwent cell apoptosis induced by hypoxia. We established the myocardium ischemic rat model via the cardiac surgical procedures in vivo and treated the model rats with different concentration of MMI. In vitro, with the pretreatment of MMI for 12 h in the model of Na2S2O4-induced hypoxia injury, the H9c2 cells viability was determined by MTT assay. We found that MMI had significantly improved cardiac function of the myocardial ischemia, and significantly decreased the reactive oxygen species level. The expression of P53, Bcl-2, Bax, and caspase-9 was also induced by MMI. In vitro study revealed a concentration-dependent increase in cell viability associated with MMI pretreatment. Annexin V-FITC and PI staining results showed that MMI had a preventive effect on hypoxia-induced apoptosis in H9c2 cells. MMI also inhibited the mitochondrial membrane potential decrease and increased total ATPase activity during hypoxia in H9c2 cells. In conclusion, MMI can enhance the cardiac function in myocardial ischemic rat and increase cell viability and attenuate the apoptosis in H9c2 cells induced by hypoxia, which was associated with inhibiting MMP decreasion and increasing total ATPase activity.

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.

The effect of gut microbiota on drug metabolism

INTRODUCTION

Numerous drugs and toxicants must be metabolized to an active form. Metabolic activation by host tissues, such as the liver, has been well studied. However, drug and toxicant metabolism by the intestinal microbiota is an unexplored, but essential, field of study in pharmacology and toxicology. The taxonomic diversity and sheer numbers of the intestinal microbiota, and their capacity to metabolize xenobiotics, underscore the importance of this mode of metabolism.

AREAS COVERED

Metabolism by the intestinal microbiota has focused on the natural products of glycosides hydrolyzed by intestinal microbiota enzymes, but not by host tissues. Metabolism of synthetic drugs by the intestinal microbiota has been less-intensively investigated. This review provides an overview of xenobiotic metabolism by the intestinal microbiota of both natural products and synthetic drugs.

EXPERT OPINION

Metabolism by the intestinal microbiota might result in a different metabolite profile than that produced by host tissues. This could potentially result in either activation or inactivation of the pharmacological and/or toxicological actions of the compound in question. The contribution of the intestinal microbiota to drug metabolism remains relatively unexplored. Therefore, studies of xenobiotic metabolism by the intestinal microbiota need to be included in new drug development as well as classical studies of host tissue metabolism.

Kakkalide ameliorates endothelial insulin resistance by suppressing reactive oxygen species-associated inflammation

BACKGROUND

Kakkalide is the predominant isoflavone derived from the flowers of Pueraria lobata (Willd.) Ohwi. The aim of the present study was to investigate the effects of kakkalide on insulin resistance in the endothelium.

METHODS

Human umbilical vein endothelial cells (HUVEC) were stimulated with 100 μmol/L palmitate (PA) for 30 min and the effects of 30 min pretreatment with 0.1-10 μmol/L kakkalide on reactive oxygen species (ROS)-associated inflammation in cells were evaluated by western blot analysis and reverse transcription-polymerase chain reaction. Furthermore, we investigated the biomodulation of insulin signaling by kakkalide along the insulin receptor substrate (IRS)-1/Akt/endothelial nitric oxide synthase (eNOS) pathway. We also determined the effects of 30 min pretreatment with 0.1-10 μmol/L kakkalide on insulin-mediated endothelium-dependent vasodilation of rat aorta in vitro following stimulation with 100 μmol/L PA.

RESULTS

Kakkalide inhibited ROS overproduction and effectively restored mitochondrial membrane potential, demonstrating its chemoprotection of mitochondrial function. In addition, kakkalide inhibited ROS-associated inflammation in the endothelium by inhibiting tumor necrosis factor-α and interleukin-6 production and gene expression, as well as suppressing the phosphorylation of c-Jun N-terminal kinase and IκB kinase β/nuclear factor-κB. Inflammation impaired insulin phosphatidylinositol 3-kinase (PI3K) signaling and reduced insulin-mediated NO production in endothelial cells. Kakkalide facilitated PI3K signaling by positively regulating serine/tyrosine phosphorylation of IRS-1.

CONCLUSIONS

Kakkalide inhibited ROS-associated inflammation and ameliorated insulin-resistant endothelial dysfunction by beneficial effects on IRS-1 function.

Aldose Reductase Inhibitors fromViola hondoensisW. Becker et H Boss

The isolation and characterization of rat lens aldose reductase inhibitors from the Viola hondoensis W. Becker et H Boss were conducted. The extracts and organic fractions from V. hondoensis were tested. The MeOH extract and EtOAc fraction were found to exhibit potent rat lens aldose reductase inhibition in vitro, their IC50being 1.2 and 0.6 μg/ml, respectively. One major isoflavonoid glycoside was isolated from the ethyl acetate soluble fraction of V. hondoensis. Kakkalide was found to be the potential rat lens aldose reductase inhibitor (IC50= 0.34 μg/ml), and may be useful for the prevention and/or treatment of diabetic complications.

Kakkalide and its metabolite irisolidone ameliorate carrageenan-induced inflammation in mice by inhibiting NF-κB pathway

The anti-inflammatory activities of kakkalide, a major constituent of the flower of Pueraria thunbergiana, and irisolidone, a metabolite of kakkalide produced by intestinal microflora, against carrageenan-induced inflammation in air pouches on the backs of mice and in lipopolysaccharide (LPS)-stimulated peritoneal macrophages were investigated. Kakkalide and irisolidone down-regulated the gene expression of cytokines [tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β)] and cyclooxygenase-2 (COX-2) and the production of pro-inflammatory cytokines, TNF-α and IL-1β, and inflammatory mediators, NO and prostaglandin E(2) (PGE(2)), in LPS-stimulated peritoneal macrophages. These agents also inhibited the phosphorylation of IκB-α and the nuclear translocation of nuclear factor-kappa B (NF-κB). Orally administered kakkalide and irisolidone significantly reduced carrageenan-induced inflammatory markers, leukocyte number, and protein amount in the exudates of the air pouch. These constituents also inhibited PGE(2) production and COX-2 inducible nitric oxide synthase, IL-1β, and TNF-α expression. These agents also inhibited NF-κB activation. The anti-inflammatory effects of irisolidone were more potent than those of kakkalide. Based on these findings, kakkalide and irisolidone may inhibit inflammatory reactions via NF-κB pathway, and irisolidone, a metabolite of kakkalide, may more potently inhibit these inflammatory reactions.

Antioxidant mechanism of isoflavone metabolites in hydrogen peroxide-stimulated rat primary astrocytes: critical role of hemeoxygenase-1 and NQO1 expression

The brain is highly vulnerable to oxidative stress, thus controlling oxidative stress is considered to be an important therapeutic target for neurodegenerative diseases. In this study, we found that two isoflavone metabolites (tectorigenin and glycitein) inhibited hydrogen peroxide-induced reactive oxygen species (ROS) generation and subsequent cell death in rat primary astrocytes. The isoflavone metabolites increased the expression of phase II antioxidant enzymes, such as hemeoxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1), and pre-treatment of cells with their specific inhibitors or small interfering RNA (siRNA) reversed the antioxidant and cytoprotective effects of isoflavones. The results suggest that the antioxidant/cytoprotective effects of isoflavone metabolites are at least because of increased HO-1 and NQO1 expression. Further mechanistic studies revealed that isoflavones increase the binding of transcription factors [nuclear factor-E2-related factor 2 (Nrf2) and c-Jun] to the antioxidant response element (ARE) on HO-1 and NQO1 promoters. Down-regulation of Nrf2 and/or c-Jun using dominant-negative mutants (DNMs) or siRNA diminished the expression of HO-1 and NQO1, suggesting that Nrf2 and c-Jun are key transcription factors modulating HO-1/NQO1 expression. Moreover, PI3 kinase and mitogen-activated protein kinase (MAPK) signaling pathways were shown to be involved in HO-1 and/or NQO1 expression by isoflavones. Our data collectively suggest that HO-1 and NQO1 play a critical role in antioxidant effects of isoflavone metabolites in rat brain astrocytes.

Protective effects of salecan against carbon tetrachloride-induced acute liver injury in mice

Carbon tetrachloride (CCl₄) is a well-established model for screening hepato-protective drugs. The aim of the present study was to evaluate the potential protective effects of a novel soluble β-glucan salecan on acute liver injury induced by CCl₄ in mice and to further explore the underlying mechanisms. Mice were given salecan (40 mg kg⁻¹) or phosphate-buffered saline for 3 days prior to treatment with a single intraperitoneal dose of CCl₄ (1 ml kg⁻¹ body weight). Animals were sacrificed at 0, 12, 24, 48, 72 and 96 h post-injection of CCl₄. Serum liver enzyme levels, histology, lipid peroxidation, glutathione (GSH) content, expression of antioxidant enzymes and hepatocyte proliferation were subsequently evaluated. The serum levels of hepatic enzyme markers were markedly reduced in the salecan pretreatment group compared with the control group. Histopathological examination of the livers revealed that hepatocellular degeneration and necrosis were significantly attenuated at an early stage during CCl₄ intoxication and liver recovery was markedly accelerated at a later stage in salecan pre-administered mice. Furthermore, salecan administration remarkably alleviated lipid peroxidation and restored GSH depletion. Meanwhile, the expression of antioxidant genes was significantly elevated in the salecan-treated group. Interestingly, the administration of salecan remarkably enhanced hepatocyte proliferation in the recovery phase after CCl₄ injection. Taken together, these results demonstrated that salecan exhibits a protective action on acute hepatic injury induced by CCl₄ through attenuating oxidative stress and accelerating hepatocyte regeneration.

Isoflavonoid glycosides from the flowers of Pueraria lobata

Pueraria lobata flower is a medicinal herb for treating intoxication, hepatic, and gastrointestinal tract lesions induced by alcohol. This study aims to investigate the isoflavonoid glycosides in P. lobata flowers. Two new isoflavone compounds were isolated from the extract of P. lobata flowers. Their structures were determined to be 5,6,7,4'-tetrahydroxyisoflavone-6,7-di-O-β-D-glucopyranoside and 5,6,7-trihydroxy-4'-methoxyisoflavone-6,7-di-O-β-D-glucopyranoside on the basis of spectroscopic means including HR-ESI-MS, UV, IR, ¹H, and ¹³C NMR.

Quantitative analysis of two isoflavones in Pueraria lobata flowers from eleven Chinese provinces using high performance liquid chromatography

Background

Pueraria lobata flower (Gehua) is a medicinal herb to treat intoxication, hepatic and gastrointestinal tract lesion induced by alcohol. This study aims to develop a new HPLC method for the determination of two major isoflavones in P. lobata flowers, namely tectoridin and 6"-O-xylosyl-tectoridin.

Methods

A high performance liquid chromatography (HPLC) method with a C₁₈ column (250 mm × 4.6 mm, 5 μm) was developed for the quantitative analysis of tectoridin and 6"-O-xylosyl-tectoridin, the main isoflavone components in P. lobata flower. A simple gradient of acetonitrile/water (0 min 15:85; 35 min 50:50; 36 min 15:85; 40 min 15:85; v/v) was used, and 265 nm was selected as detection wavelength. Tectoridin and 6"-O-xylosyl-tectoridin were used as the external standards in quality control of P. lobata flower for the first time. The method was applied to practical use in quality assessment of eleven batches of P. lobata flower samples in Chinese herbal medicine market.

Results

The peak area response was linear for tectoridin in the 11.8-236.4 μg/mL range with a correlation coefficient of 0.9996 (P < 0.001), and for 6"-O-xylosyl-tectoridin in the 10.33-185.99 μg/mL range with a correlation coefficient of 0.9984 (P < 0.001) respectively. The average recoveries were 102.7-103.7% for tectoridin and 95.7-103.2% for 6"-O-xylosyl-tectoridin (RSDs < 3%), and the intra-day and inter-day RSDs of the two components were less than 2%. This HPLC method was applied to assess the quality of P. lobata flower from eleven provinces in China. P. lobata flowers from northern China contained 26.46-43.28 mg/g of tectoridin and 30.90-48.23 mg/g of 6"-O-xylosyl-tectoridin comparing to 10.00-19.81 mg/g of tectoridin and 11.08-37.03 mg/g of 6"-O-xylosyl-tectoridin in those from southern China.

Conclusion

The results showed that P. lobata flowers from northern China contained more tectoridin and 6"-O-xylosyl-tectoridin than those from southern China.

Cardioprotective effect of 'methylamine irisolidone', a new compound, in hypoxia/reoxygenation injury in cultured rat cardiac myocytes

'Methylamine irisolidone' (=5,7-dihydroxy-6-methoxy-3-(4-methoxyphenyl)-8-[(methylamino)methyl]-4H-[1]benzopyran-4-one), a new compound, is a structurally modified kakkalide with good water solubility. In this study, we investigated its effect on hypoxia/reoxygenation (H/R) injury in cultured rat cardiac myocytes. The results showed that methylamine irisolidone could significantly inhibit lactate dehydrogenase (LDH) release, enhance the mitochondrial membrane potential, decrease intracellular calcium (Ca(2+)) associated with the attenuation of reactive oxygen species (ROS) generation, reduce contents of malondialdehyde (MDA), and increase the activity of superoxide dismutase (SOD) after H/R in a dose-dependent manner. The present study demonstrated that methylamine irisolidone can directly protect cardiomyocytes against H/R injury, primarily as a result of reduction of the intracellular Ca(2+) overload coincident with an attenuation of ROS generation and ROS-mediated lipid peroxidation, which may contribute to the preservation of mitochondrion function and antioxidant against H/R injury.

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.

Anti-Inflammatory Mechanisms of Isoflavone Metabolites in Lipopolysaccharide-Stimulated Microglial Cells

The microglial activation plays an important role in neurodegenerative diseases by producing several proinflammatory cytokines and nitric oxide (NO). We found that three types of isoflavones and their metabolites that are transformed by the human intestinal microflora suppress lipopolysaccharide (LPS)-induced release of NO and tumor necrosis factor (TNF)-alpha in primary cultured microglia and BV2 microglial cell lines. The inhibitory effect of the isoflavone metabolites (aglycon form) was more potent than that of isoflavones (glycoside form). The RNase protection assay showed that the isoflavone metabolites regulated inducible nitric oxide synthase (iNOS) and the cytokines at either the transcriptional or post-transcriptional level. A further molecular mechanism study was performed for irisolidone, a metabolite of kakkalide, which had the most potent anti-inflammatory effect among the six isoflavones tested. Irisolidone significantly inhibited the DNA binding and transcriptional activity of nuclear factor (NF)-kappaB and activator protein-1. Moreover, it repressed the LPS-induced extracellular signal-regulated kinase (ERK) phosphorylation without affecting the activity of c-Jun N-terminal kinase or p38 mitogen-activated protein kinase. The level of NF-kappaB inhibition by irisolidone correlated with the level of iNOS, TNF-alpha, and interleukin (IL)-1beta suppression in LPS-stimulated microglia, whereas the level of ERK inhibition correlated with the level of TNF-alpha and IL-1beta repression. Overall, the repression of proinflammatory cytokines and iNOS gene expression in activated microglia by isoflavones such as irisolidone might have therapeutic potential for various neurodegenerative diseases including ischemic cerebral disease.

Natural medicines for alcoholism treatment: a review

Alcoholism is a serious problem throughout the world. The development of alcoholism remedies have medical, social and economical significance. In view of the pitfalls of psychological dependence and adverse behavioural effects of synthetic drugs, the development of low toxicity and high efficiency medicines derived from natural products exhibits expansive market prospects. Based on these considerations, we summarize briefly folk application of traditional hangover remedies and clinical application of herbal complex and patent medicines for alcoholism treatment. We have reviewed the effects of natural medicines on intake, absorption and metabolism of alcohol, as well as the protective effects on alcohol-induced acute and chronic tissue injury.

Irisolidone, an isoflavone metabolite, represses JC virus gene expression via inhibition of Sp1 binding in human glial cells

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease that results from an oligodendrocyte infection caused by the JC virus. Therefore, inhibiting the expression of JC virus is important for preventing and/or treating PML. This study found that irisolidone, an isoflavone metabolite, significantly inhibited the JC virus expression in primary cultured human astrocytes and glial cell lines. Studies examining the underlying mechanism revealed that a mutation of the Sp1 binding site downstream of the TATA box (Sp1-II) dramatically diminished the inhibitory activity of irisolidone. In addition, an irisolidone treatment repressed Sp1 binding to Sp1-II site, which is important for the basal JC virus promoter activity. The results suggest that the inhibitory effect of irisolidone against the JC virus may be attributed at least in part to the suppression of Sp1 binding to the JC virus promoter region. Therefore, the inhibition of the JC virus expression by irisolidone might provide therapeutic potential for PML caused by the JC virus.

Estrogenic Effect of Main Components Kakkalide and Tectoridin of Puerariae Flos and Their Metabolites

To understand the relationship between the metabolism and estrogenic activity of kakkalide and tectoridin, main isoflavones in the flower of Pueraria thunbergiana (family Leguminosae), these isoflavones and their metabolites by human intestinal microflora as well as their estrogenic effects were investigated. All human fecal specimens metabolized kakkalide and tectoridin. All isolated kakkalide-hydrolyzing intestinal bacteria also hydrolyzed kakkalide and tectoridin to irisolidone and tectorigenin, respectively. When the estrogenic effects of kakkalide and tectoridin were compared with those of their metabolites irisolidone and tectorigenin, the metabolites more potently increased proliferation of MCF-7 cells than kakkalide and tectoridin. These metabolites also potently induced estrogen-response c-fos and pS2 mRNA expression. These results suggest that kakkalide and tectoridin may be metabolized mainly to irisolidone and tectorigenin, respectively, by intestinal microflora in the intestines, and which may be subsequently absorbed into the blood where they can express their estrogenic effect.

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.

Passive Cutaneous Anaphylaxis-Inhibitory Action of Tectorigenin, a Metabolite of Tectoridin by Intestinal Microflora

Tectoridin isolated from the flowers of Pueraria thunbergiana (Leguminosae) are metabolized to tectorigenin by human intestinal microflora. When tectoridin was orally administered to rats, tectorigenin, but not tectoridin, was detected in urine after beta-glucuronidase hydrolysis. The main metabolite tectorigenin potently inhibited the passive cutaneous anaphylaxis reaction and inhibited in vitro the release of beta-hexosaminidase from RBL-2H3 cells induced by IgE. These results suggest that tectoridin is a prodrug, which can be transformed into the active agent tectorigenin by human intestinal bacteria and can be a candidate for antiallergic agent.