Method Development and Validation for Simultaneous Determination of Six Flavonoids in Rat Eyes after Oral Administration of Diospyros kaki Leaves Extract by UPLC-MS/MS.

A robust ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technique was proven effective for simultaneous characterization of six flavonoids including quercetin-3-O-beta-galactoside (Q3GAL), quercetin-3-O-beta-glucoside (Q3GLU), quercetin-3-(2-galloylglucoside) (Q3GG), kaempferol-3-O-beta-galactoside (K3GAL), kaempferol-3-O-beta-glucoside (K3GLU), and kaempferol-3-(2-galloylglucoside) (K3GG) in rat eyes. By investigation of corresponding validation parameters (linearity, selectivity, precision, accuracy, matrix effect, extraction recovery, and stability), the method was verified to be within current acceptable criteria. Thereafter, the validated method enabled quantification of the six compounds successful in rat eyes after oral administration of ethanol extract Diospyros kaki (EEDK) at 0, 3, 15, 35, 60, 120 min.

Probing the chemoprevention potential of the antidepressant fluoxetine combined with epigallocatechin gallate or kaempferol in rats with induced early stage colon carcinogenesis.

The enhanced chemopreventive action against 1,2 Dimethylhydrazine (DMH)-induced preneoplastic lesion in rats could be achieved via simultaneous administration of the antidepressant fluoxetine (FLX) with two natural polyphenolic compounds viz., kaempferol (KMP) and/or epigallocatechin-gallate (EGCG). The obtained results revealed that single FLX pre-treatment possess a significant apoptotic effect by increasing the activity of serum and colon tissue caspase 3. It also attenuated the DMH driven increase in, colon tissue MDA, NO, PCNA and COX-2 expression as well as serum and colon tissue ß-catenin, with a decrease in the multiplicity of ACF and number of MPLs. The combination of FLX with either KMP or EGCG improved the antioxidant, anti-inflammatory and antiproliferating activities but with higher apoptotic activity in case of KMP. Eventually, histopathological assessment of colon tissues exposed that while sole pre-treatment can improve DMH-induced hyperplasia with only moderate inflammatory infiltration, tissues from the combined pre-treatment regimens groups exhibited almost a normal colonic architecture with slight submucosal edema. The study proved that single FLX administration prior to DMH exerts a chemopreventive effect and that the investigated combined pre-treatment regimens demonstrated more potent chemopreventive and antiproliferative actions.

Astragalin attenuates oxidative stress and acute inflammatory responses in carrageenan-induced paw edema in mice.

Astragalin is a flavonoid existed in several edible and medicinal plants and was recorded to have multiple biological and pharmacological significances. This work aimed to assess the possible protective effect of astragalin administration against oxidative tension, acute inflammation and histopathological deformations in a mouse paw edema model induced following intra sub-plantar injection of carrageenan. Thirty-six male Swiss mice were divided into four groups: control, carrageenan, astragalin (75 mg/kg) + carrageenan, and indomethacin (10 mg/kg) + carrageenan. Astragalin administration for five consecutive days to carrageenan injected mice showed a significant reduction in the development of paw in a time dependent effect, inhibited lipoperoxidation by-product, malondialdehyde and increased superoxide dismutase and catalase activities. Astragalin was found also to suppress the inflammatory signaling in the inflamed tissue as exhibited by the decreased myeloperoxidase activity along with the decreased protein and transcriptional level of pro-inflammatory cytokines including tumor necrosis factor-alpha, interleukin-1 beta and interleukin-6. Moreover, inducible nitric oxide synthase and cyclooxygenase-2 expressions and their products (nitric oxide and prostaglandin E2) were downregulated. Additionally, astragalin decreased monocyte chemoattractant protein-1 and nuclear factor kappa B expression in the inflamed paw tissue. The recorded findings provide evidences for the potential application of astragalin as a plant-derived remedy for the treatment of acute inflammation due to its promising antioxidant and anti-inflammatory activities along with its ameliorative impact against the histopathological changes in the paw tissue.

Evaluation of antibacterial and enhancement of antibiotic action by the flavonoid kaempferol 7-O-ß-D-(6″-O-cumaroyl)-glucopyranoside isolated from Croton piauhiensis müll.

There has been a rapid increase in the incidence and prevalence of opportunistic bacterial infections. Inappropriate use of current antibiotics has continuously contributed to the emergence of resistance to conventional antibiotic therapy. Therefore, the search for natural molecules that are able to combat infections is of great public interest, and many of these compounds with antimicrobial properties can be obtained from phytochemical studies of medicinal plants. In this context, this study reports the isolation and characterization of the flavonoid, kaempferol 7-O-ß-D-(6″-O-cumaroyl)-glucopyranoside, from Croton piauhiensis leaves. Additionally, the intrinsic antimicrobial action of the compound and its enhancement against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus strains were assessed. The minimum inhibitory concentration (MIC) of the compound was determined using broth microdilution assays. To evaluate the modulatory effect of the flavonoid, the MIC of antibiotics amikacin and gentamicin, belonging to the class aminoglycosides was assessed, with and without the compound in sterile microplates. The results of intrinsic antibacterial activity tests revealed that the compound had no antibacterial activity against strains tested at concentrations <1024 µg/mL. The combination of the flavonoid at a concentration of 128 µg/mL with gentamicin presented synergistic effects against S. aureus 10 and E. coli 06, and also reduced the MIC from 16 µg/mL to 4 µg/mL and 8 µg/mL, respectively. Amikacin also showed synergistic effects against S. aureus 10 and E. coli 06. We also observed reduced MIC for both, from 128 µg/mL to 32 µg/mL; however, antagonism for P. aeruginosa increased the MIC from 16 µg/mL to 64 µg/mL. The combination of the flavonoid with the aminoglycosides may be an alternative to potentiate the expected results in treatment against S. aureus and E. coli, since their association leads to a synergistic effect, reducing the MIC of these drugs and decreasing the dose necessary for therapeutic success.

Intracerebroventricular microinjection of kaempferol on memory retention of passive avoidance learning in rats: involvement of cholinergic mechanism(s).

Purpose of the study: Kaempferol (KM) is a flavonoid found in plant-derived foods and medicinal plants. Recently, it is well established that KM plays a protective role to develop Alzheimer's disease. The current study aimed at evaluating the effect of intracerebroventricular micro-injection of KM on memory retention of passive avoidance learning (MRPAM) and identifying the potentially related cholinergic mechanisms (ChMs) in rats. Materials and methods: In the current study, male Wistar rats randomly divided into control, vehicle and KM (10, 20 and 40 µg/rat) groups. Moreover, MRPAM was evaluated by shuttle box test. The role of ChM was studied using non-selective and selective acetylcholine antagonists (scopolamine [SCN], 4-DAMP and methoctramine [MN], respectively) as well as pirenzepine (PZ) in combination with KM. Results: The employment of KM (40 µg/rat) improved the SCN-induced memory impairment in MRPAM. Co-treatment with KM (40 µg/rat) plus 4-DAMP significantly increased the step-through latency (STL, P < 0.05; 167 ± 28 s) and decreased the total dark chamber (TDC, P < 0.05; 121 ± 31 s) compared with those of the 4-DAMP group (STL: 75 ± 13 s; TDC: 178 ± 46 s). Co-treatment with KM (40 µg/rat) plus PZ attenuated STL, and also increased TDC (P < 0.01; 220 ± 28 s) compared with those of the PZ group. Co-treatment with KM (10 and 20 µg/rat) and MN increased STL (P < 0.05), and deceased TDC compared with those of the MN group (P < 0.01). Conclusions: Totally, the results of the present study showed that cholinergic system may be involved in improving effect of KM on SCN-induced memory impairment.

Cudrania Tricuspidata Extract and Its Major Constituents Inhibit Oxidative Stress-Induced Liver Injury.

The fruits, leaves, and roots of Cudrania tricuspidata have been reported to contain large amounts of vitamin B, vitamin C, and flavonoids. They exhibit various physiological activities such as antitumor and anti-inflammatory effects. However, the hepatoprotective effects of C. tricuspidata extracts against oxidative stress-mediated liver injury have not yet been investigated. We thus examined whether C. tricuspidata leaf extracts (CTEs) protect against oxidative stress-mediated liver injury in vitro and in vivo and elucidated the underlying mechanism. The cytoprotective effects of CTE through the NF-E2-related factor 2 (Nrf2)/antioxidant response element (ARE) activation were presented and measured by biochemical analysis in HepG2 cells. To assess the protective effects of CTE in vivo, mice were administered with CTE (250 and 500 mg/kg; 5 days; p.o.) before a single dose of acetaminophen (APAP) (300 mg/kg; 24 h; i.p.). CTE increased ARE luciferase activity when compared with extracts of other parts of C. tricuspidata. CTE upregulated nuclear translocation of Nrf2 and its target gene expression. In addition, CTE inhibited the generation of reactive oxygen species (ROS) and cell death induced by arachidonic acid (AA) and iron (Fe) treatment in primary hepatocytes or HepG2 cells. The cytoprotective effects of CTE against oxidative stress might be due to kaempferol, the major flavonoid present in CTE. Kaempferol pretreatment blocked AA+Fe-induced ROS production and reversed glutathione depletion, which in turn led to decreased cell death. Furthermore, the protective effects of CTE against liver injury induced by excess APAP in mice or primary hepatocytes were observed. CTE could be a promising therapeutic candidate against oxidative stress-induced liver injury.

The Flavonoid Kaempferol Ameliorates Streptozotocin-Induced Diabetes by Suppressing Hepatic Glucose Production.

In diabetes mellitus, the excessive rate of glucose production from the liver is considered a primary contributor for the development of hyperglycemia, in particular, fasting hyperglycemia. In this study, we investigated whether kaempferol, a flavonol present in several medicinal herbs and foods, can be used to ameliorate diabetes in an animal model of insulin deficiency and further explored the mechanism underlying the anti-diabetic effect of this flavonol. We demonstrate that oral administration of kaempferol (50 mg/kg/day) to streptozotocin-induced diabetic mice significantly improved hyperglycemia and reduced the incidence of overt diabetes from 100% to 77.8%. This outcome was accompanied by a reduction in hepatic glucose production and an increase in glucose oxidation in the muscle of the diabetic mice, whereas body weight, calorie intake, body composition, and plasma insulin and glucagon levels were not altered. Consistently, treatment with kaempferol restored hexokinase activity in the liver and skeletal muscle of diabetic mice while suppressed hepatic pyruvate carboxylase activity and gluconeogenesis. These results suggest that kaempferol may exert antidiabetic action via promoting glucose metabolism in skeletal muscle and inhibiting gluconeogenesis in the liver.

Antidiabetic Effect of Cyclocarya paliurus Leaves Depends on the Contents of Antihyperglycemic Flavonoids and Antihyperlipidemic Triterpenoids.

Cyclocarya paliurus has been used commonly to treat diabetes in China. However, the effective components and the effect of plant origin remain unclear. In this study, C. paliurus leaves with different chemical compositions were selected from five geographical locations, and their effects on streptozotocin (STZ)-induced diabetic mice were evaluated with both ethanol and aqueous extracts. Glucose levels, lipid levels, and biomarkers of liver and kidney function were measured. The principal components of both C. paliurus ethanol and aqueous extracts from different geographical locations differed quantitatively and qualitatively. Results showed that C. paliurus extracts with better antihyperglycemic effects were characterized by higher contents of total flavonoids, especially quercetin-3-O-glucuronide and kaempferol-3-O-glucuronide. Furthermore, significantly negative correlations were found between triterpenoids contents and lipid levels. These results revealed the potential antihyperglycemic capacity of C. paliurus flavonoids and the antihyperlipidemic effect of C. paliurus triterpenoids. Thus, we suggest that the composition of C. paliurus compounds might help to design therapeutic alternatives for the treatment of diabetes mellitus. However, geographic origins and the extraction solvents can also affect the effectiveness of the treatment as these factors influence the chemical compositions and thereby the biological activities.

Hypoglycemic Effects in Alloxan-Induced Diabetic Rats of the Phenolic Extract from Mongolian Oak Cups Enriched in Ellagic Acid, Kaempferol and Their Derivatives.

Our previous reports showed that crude extract prepared with 50% ethanol (ethanol crude extract, ECE) from Mongolian oak cups possessed excellent in vitro antioxidant capacities as well as inhibitory activities against α-glucosidase, α-amylase and protein glycation caused by its enrichment in phenolics, including mainly ellagic acid, kaempferol and their derivatives. Nevertheless, few in vivo studies on antidiabetic activities of these phenolics were conducted. The present study investigated hypoglycemic effects with normal and diabetic rats being administrated orally without or with ECE at 200 and 800 mg/kg for 15 days. In normal rats, no significant differences were exhibited after ECE administration in body weight, fasting blood glucose level, levels of cholesterol, triglyceride, LDL and AST in serum, organ indexes, and levels of GSH and MDA in organs. In diabetic rats, the fasting blood glucose level, indexes of heart and liver, and levels of cholesterol and triglyceride in serum and MDA in heart tissue were significantly decreased. Moreover, HDL levels in serum and SOD activities in the four organs of diabetic rats were significantly improved after ECE administration at 800 mg/kg. Thus, in addition to inhibiting α-glucosidase, α-amylase and protein glycation reported previously, oak cups might contain novel dietary phytonutrients in preventing abnormal changes in blood glucose and lipid profile and attenuating oxidant stress in vivo. The results also implied that it is ellagic acid, kaempferol and their derivatives enriched in ECE that might play vital roles in managing type 1 as well as type 2 diabetes.

Effect of Kaempferol isolated from seeds of Eruca sativa on changes of pain sensitivity in Streptozotocin-induced diabetic neuropathy.

Generation of excessive reactive oxygen species (ROS) and advanced glycation end products (AGEs), and cellular apoptosis are implicated in the pathogenesis of diabetic neuropathy. Present study was aimed to explore the effect of Eruca sativa and Kaempferol (KP) on hyperalgesia (thermal and mechanical); tactile allodynia, motor nerve conduction velocity (MNCV) and oxidative-nitrosative stress in streptozotocin (STZ) induced experimental diabetes. Neuropathy developed in diabetic rats was evident from a marked hyperalgesia and allodynia; reduced MNCV associated with excess formation of AGEs and ROS. Chronic treatment with E. sativa hydroalcoholic extract (EHA; 100, 200 and 400 mg/kg) and KP (5 and 10 mg/kg) for 30 days starting from the 60th day of STZ administration significantly ameliorated behavioral and biochemical changes linked to diabetic neuropathy. Present study suggested that EHA and KP corrected hyperglycemia and reversed the pain response partially in diabetic rats along via modulating oxidative and nitrosative stress along with reduction of AGEs formation in diabetic rats. Thus E. sativa might be beneficial in chronic diabetes, ameliorate the progression of diabetic neuropathy and may also find application in diabetic neuropathic pain.

Hepatoprotective Effects of Kaempferol-3-O-α-l-Arabinopyranosyl-7-O-α-l-Rhamnopyranoside on d-Galactosamine and Lipopolysaccharide Caused Hepatic Failure in Mice.

Fulminant hepatic failure (FHF), associated with high mortality, is characterized by extensive death of hepatocytes and hepatic dysfunction. There is no effective treatment for FHF. Several studies have indicated that flavonoids can protect the liver from different factor-induced injury. Previously, we found that the extracts of Elaeagnus mollis leaves had favorable protective effects on acute liver injury. However, the role and mechanisms behind that was elusive. This study examined the hepatoprotective mechanisms of kaempferol-3-O-α-l-arabinopyranosyl-7-O-α-l-rhamnopyra-noside (KAR), a major flavonol glycoside of E. mollis, against d-galactosamine (GalN) and lipopolysaccharide (LPS)-induced hepatic failure. KAR reduces the mouse mortality, protects the normal liver structure, inhibits the serum aspartate aminotransferase (AST) and alamine aminotransferase (ALT) activity and decreases the production of malondialdehyde (MDA) and reactive oxygen species (ROS) and inflammatory cytokines, TNF-α, IL-6, and IL-1ß. Furthermore, KAR inhibits the apoptosis of hepatocytes and reduces the expression of TLR4 and NF-κB signaling pathway-related proteins induced by GalN/LPS treatment. These findings suggest that the anti-oxidative, anti-inflammatory, and anti-apoptotic effects of KAR on GalN/LPS-induced acute liver injury were performed through down-regulating the activity of the TLR4 and NF-κB signaling pathways.

Astragalin Reduces Hexokinase 2 through Increasing miR-125b to Inhibit the Proliferation of Hepatocellular Carcinoma Cells in Vitro and in Vivo.

Astragalin (ASG) can be found in a variety of food components. ASG exhibits cytotoxic effects on several different types of malignant cells. However, its effects on hepatocellular carcinoma (HCC) cells and the underlying molecular mechanisms have remained to be fully elucidated. Here, we revealed that ASG remarkably suppressed the proliferation of HCC cells. In HCC cells, ASG inhibited glucose glycolysis and promoted oxidative phosphorylation, resulting in a surge of reactive oxygen species (ROS). Mechanistically, ASG suppressed the expression of hexokinase 2 (HK2). This event was indispensible for ASG-mediated metabolic reprogramming, ROS accumulation, and subsequent growth arrest. Our further investigations unveiled that ASG repressed HK2 expression via increasing miR-125b. In vivo experiments showed that gavage of ASG decreased the proliferation of Huh-7 HCC xenografts in nude mice and inhibited the growth of transplanted H22 HCC cells in Kunming mice. Declined HCC tumor growth in vivo was associated with boosted miR-125b and reduced expression of HK2 in tumor tissues. Collectively, our results demonstrated that ASG is able to suppress the proliferation of HCC cells both in vitro and in vivo. Inhibition of HK2 through upregulating miR-125b and subsequent metabolic reprogramming is implicated in the antiproliferative effects of ASG on HCC cells.

Justicia spicigera Schltdl. and kaempferitrin as potential anticonvulsant natural products.

Justicia spicigera Schltdl. is a vegetal species traditionally used to control epilepsy, but scientific evidence is required to reinforce this activity. The aim of the study was to evaluate the anticonvulsant-like activity of J. spicigera aqueous extract (JsAE) and a bioactive compound. JsAE was assessed in a dose-response manner (30, 100 and 1000mg/kg, i.p.) using the pentylenetetrazol (PTZ)-induced seizures and maximal electroshock seizure (MES) test in mice in comparison to ethosuximide (ETX, reference drug 100mg/kg, i.p.) or phenytoin (25mg/kg, i.p.), respectively. Then a significant dosage (1000mg/kg, i.p.) was chosen to examine electrographic activity (EEG) in rats. Treatment groups were compared to the vehicle and ETX in the convulsive behavior alone or simultaneous to EEG after PTZ-induced seizures (80 or 35mg/kg, i.p., mice or rats). Kaempferitrin (a flavonoid of JsAE) and ETX were administered via intracerebroventricular (i.c.v, 4th ventricle, 1µg/µL) and tested in the presence of PTZ in rats. Results confirmed that JsAE delayed the onset of seizures and reduced frequency of tonic convulsion and mortality in mice. JsAE or kaempferitrin also decreased the EEG spikes frequency and amplitude in a similar manner than EXT in rats. In conclusion, these preliminary data give evidence of the potential of J. spicigera as possible anticonvulsant as recommended in folk medicine for treating epilepsy, where kaempferitrin is suggested as a partial responsible bioactive compound.

Evaluation of the sedative and hypnotic effects of astragalin isolated from Eucommia ulmoides leaves in mice.

The purpose of this study was to evaluate the effects of astragalin on the central nervous system. Astragalin is a monomeric compound found in the leaves of Eucommia ulmoides using a system solvent method. In the experiments, astragalin showed significant effects on mice, including reduced spontaneous activity, increased sleep ratio, shortened sleep latency and lengthened sleep time with a subthreshold or superthreshold dose of pentobarbital sodium. In addition, astragalin effectively reduced the convulsion rate and prolonged convulsion latency. These findings confirmed that astragalin had excellent sedative and hypnotic effects and has potential to be commercialised as a novel nutraceutical agent to promote calming and improve central nervous system-associated pathologies.

Astragalin, a Flavonoid from Morus alba (Mulberry) Increases Endogenous Estrogen and Progesterone by Inhibiting Ovarian Granulosa Cell Apoptosis in an Aged Rat Model of Menopause.

BACKGROUND: To determine the mechanism by which the flavonoid glycoside astragalin (AST) reduces ovarian failure in an aged rat model of menopause. METHODS: The in vivo effect of AST on granulosa cell (GC) apoptosis in aged female rats was determined using flow cytometry. In vitro, the effects of AST on cultured GCs were investigated using the MTT proliferation assay and western blot assays. RESULTS: Aged rats had significantly higher GC apoptosis as compared with young female rats. Treatment of aged rats with AST (all three doses; p < 0.01) or Progynova (p < 0.01) significantly reduced GC apoptosis as compared with the aged controls. The proportions of total apoptotic GCs was 25.70%, 86.65%, 47.04%, 27.02%, 42.09% and 56.42% in the normal, aged, 17ß-estradiol (E2), high dose AST, medium dose AST, and low dose AST-treated groups, respectively. Significant increases of serum E2 and P4 levels, as well as altered levels of serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels. In cultured rat GCs, AST stimulated GC proliferation, E2 and progesterone (P4) secretion, reduced apoptosis, reduced the level of the pro-apoptotic protein Bcl-2 (p < 0.01), but had no effect on BAX. CONCLUSIONS: AST enhanced ovarian function in aged female rats by increasing E2 and P4 levels, and reducing ovarian GC apoptosis via a mechanism involving Bcl-2. These data demonstrate a new pharmacological activity for AST, as well as a novel mechanism of action, and further suggest that AST may be a new therapeutic agent for the management of menopausal symptoms.

Inhibition of human GLUT1 and GLUT5 by plant carbohydrate products; insights into transport specificity.

Glucose transporters GLUT1 (transports glucose) and GLUT5 (transports fructose), in addition to their functions in normal metabolism, have been implicated in several diseases including cancer and diabetes. While GLUT1 has several inhibitors, none have been described for GLUT5. By transport activity assays we found two plant products, rubusoside (from Rubus suavissimus) and astragalin-6-glucoside (a glycosylated derivative of astragalin, from Phytolacca americana) that inhibited human GLUT5. These plants are utilized in traditional medicine: R. suavissimus for weight loss and P. americana for cancer treatment, but the molecular interactions of these products are unknown. Rubusoside also inhibited human GLUT1, but astragalin-6-glucoside did not. In silico analysis of rubusoside:protein interactions pinpointed a major difference in substrate cavity between these transporters, a residue that is a tryptophan in GLUT1 but an alanine in GLUT5. Investigation of mutant proteins supported the importance of this position in ligand specificity. GLUT1W388A became susceptible to inhibition by astragalin-6-glucoside and resistant to rubusoside. GLUT5A396W transported fructose and also glucose, and maintained inhibition by rubusoside and astragalin-6-glucoside. Astragalin-6-glucoside can serve as a starting point in the design of specific inhibitors for GLUT5. The application of these studies to understanding glucose transporters and their interaction with substrates and ligands is discussed.

Soy Leaf Extract Containing Kaempferol Glycosides and Pheophorbides Improves Glucose Homeostasis by Enhancing Pancreatic ß-Cell Function and Suppressing Hepatic Lipid Accumulation in db/db Mice.

This study investigated the molecular mechanisms underlying the antidiabetic effect of an ethanol extract of soy leaves (ESL) in db/db mice. Control groups (db/+ and db/db) were fed a normal diet (ND), whereas the db/db-ESL group was fed ND with 1% ESL for 8 weeks. Dietary ESL improved glucose tolerance and lowered plasma glucose, glycated hemoglobin, HOMA-IR, and triglyceride levels. The pancreatic insulin content of the db/db-ESL group was significantly greater than that of the db/db group. ESL supplementation altered pancreatic IRS1, IRS2, Pdx1, Ngn3, Pax4, Ins1, Ins2, and FoxO1 expression. Furthermore, ESL suppressed lipid accumulation and increased glucokinase activity in the liver. ESL primarily contained kaempferol glycosides and pheophorbides. Kaempferol, an aglycone of kaempferol glycosides, improved ß-cell proliferation through IRS2-related FoxO1 signaling, whereas pheophorbide a, a product of chlorophyll breakdown, improved insulin secretion and ß-cell proliferation through IRS1-related signaling with protein kinase A in MIN6 cells. ESL effectively regulates glucose homeostasis by enhancing IRS-mediated ß-cell insulin signaling and suppressing SREBP-1-mediated hepatic lipid accumulation in db/db mice.

Influence of kaempferol, a flavonoid compound, on membrane-bound ATPases in streptozotocin-induced diabetic rats.

CONTEXT: Kaempferol is a flavonoid found in many edible plants (e.g. tea, cabbage, beans, tomato, strawberries, and grapes) and in plants or botanical products commonly used in traditional medicine. Numerous preclinical studies have shown that kaempferol have a wide range of pharmacological activities, including antioxidant, anti-inflammatory, anticancer, cardioprotective, neuroprotective, and antidiabetic activities. OBJECTIVE: The present study investigates the effect of kaempferol on membrane-bound ATPases in erythrocytes and in liver, kidney, and heart of streptozotocin (STZ)-induced diabetic rats. MATERIALS AND METHODS: Diabetes was induced into adult male albino rats of the Wistar strain, by intraperitoneal administration of STZ (40 mg/kg body weight (BW)). Kaempferol (100 mg/kg BW) or glibenclamide (600 µg/kg BW) was administered orally once daily for 45 d to normal and STZ-induced diabetic rats. The effects of kaempferol on membrane-bound ATPases (total ATPase, Na(+)/K(+)-ATPase, Ca(2+)-ATPase, and Mg(2+)-ATPase) activity in erythrocytes and in liver, kidney, and heart were determined. RESULTS: In our study, diabetic rats had significantly (p < 0.05) decreased activities of total ATPases, Na(+)/K(+)-ATPase, Ca(2+)-ATPase, and Mg(2+)-ATPase in erythrocytes and tissues. Oral administration of kaempferol (100 mg/kg BW) or glibenclamide (600 µg/kg BW) for a period of 45 d resulted in significant (p < 0.05) reversal of these enzymes' activities to near normal in erythrocytes and tissues when compared with diabetic control rats. DISCUSSION AND CONCLUSION: Thus, obtained results indicate that administration of kaempferol has the potential to restore deranged activity of membrane-bound ATPases in STZ-induced diabetic rats. Further detailed investigation is necessary to discover kaempferol's action mechanism.

Hepatoprotective effect of kaempferol against alcoholic liver injury in mice.

Kaempferol is a biologically active component present in various plants. The hepatoprotective effect of kaempferol in drug-induced liver injury has been proven, while its effect against alcoholic liver injury (ALI) remains unclear. Hence, the present study aimed to evaluate the effect of kaempferol against ALI in mice. The experimental ALI mice model was developed and the mice were treated with different doses of kaempferol for 4 weeks. The liver functions were observed by monitoring the following parameters: Aspartate aminotransferase (AST/GOT) and alanine aminotransferase (ALT/GPT) levels in serum; histopathological studies of liver tissue; oxidative stress by hydrogen peroxide (H2O2), superoxide dismutase (SOD) and glutathione (GSH); the lipid peroxidation status by malondialdehyde (MDA) and lipid accumulation by triglyceride (TG) level in serum; and the expression levels and activities of a key microsomal enzyme cytochrome 2E1 (CYP2E1), by both in vitro and in vivo methods. The ALI mice (untreated) showed clear symptoms of liver injury, such as significantly increased levels of oxidative stress, lipid peroxidation and excessive CYP2E1 expression and activity. The mice treated with different kaempferol dosages exhibited a significant decrease in the oxidative stress as well as lipid peroxidation, and increased anti-oxidative defense activity. The kaempferol treatment has significantly reduced the expression level and activity of hepatic CYP2E1, thus indicating that kaempferol could down regulate CYP2E1. These findings show the hepatoprotective properties of kaempferol against alcohol-induced liver injury by attenuating the activity and expression of CYP2E1 and by enhancing the protective role of anti-oxidative defense system.

Improved blood-brain barrier distribution: effect of borneol on the brain pharmacokinetics of kaempferol in rats by in vivo microdialysis sampling.

ETHNOPHARMACOLOGICAL RELEVANCE: Kaempferol (KA) exists in a variety of herbal medicines. In vitro and in vivo studies have focused on the anti-Alzheimer effect of KA. However, little is known about its brain pharmacokinetic profile. The accumulated amount of KA in brain is very low because of the protection of blood-brain barrier (BBB). Borneol (BO) is a classical aromatic refreshing traditional Chinese medicine and commonly used as an adjuvant component of traditional Chinese medicines (e.g. compound Danshen dropping pills) in the treatment of cardiovascular and cerebrovascular diseases. According to the basic theories of traditional Chinese medicine, BO is called an "upper guiding drug", which can guide other components to the targeting tissues or organs in the upper part of the body, especially in the brain. MATERIALS AND METHODS: The probes for blood and brain sampling were implanted within the jugular vein/right atrium and right hippocampus of SD rats, respectively. Rats were intravenous administered of KA (25 mg/kg) alone or combined with BO (15, 30 mg/kg) via caudal vein. The blood and brain microdialysates were collected every 15 min for 180 min and every 30 min for 180-300 min. A selective and sensitive high performance liquid chromatography-chemiluminescence method was developed for the determination of unbound KA in rat blood and brain microdialysates, which can be converted to their actual free-form concentrations based on the in vivo relative recoveries of KA across microdialysis probes. RESULTS: KA quickly crossed the BBB to enter the extracellular fluid of hippocampus and reached the maximum concentration of 0.11 µg/mL within 30 min. The brain bioavailability and brain delivery of KA evidently increased with the co-administration of 15 and 30 mg/kg of BO. The AUC0-inf of KA in brain increased 1.84 and 2.19 times, and the Cmax of KA in brain increased 2.09 and 3.18 times than that without BO, respectively. In addition, the brain-to-blood distribution ratio of KA increased by 48.68% and 57.97% compared with that without BO. However, no significant difference in the T1/2 of unbound KA in blood aserved between three groups. CONCLUSIONS: BO can enhance the BBB permeability and improve the transportation of KA to brain. The dose-dependent effect of BO on the brain pharmacokinetic parameters of KA was observed. This co-administration strategy can be designed to enhance the brain accumulation of other neuropsychiatric medications.