Protective effect of total flavones of Abelmoschus manihot L. Medic against poststroke depression injury in mice and its action mechanism

Comparing the effect of fluoxetine, escitalopram, and sertraline, on the level of BDNF and depression in preclinical and clinical studies: a systematic review

Brain-derived neurotrophic factor (BDNF) dysfunction is one of the most important mechanisms underlying depression. It seems that selective serotonin reuptake inhibitors (SSRIs) improve depression via affecting BDNF level. In this systematic review, for the first time, we aimed to review the effect of three SSRIs including fluoxetine, escitalopram, and sertraline, on both depression and BDNF level in preclinical and clinical studies. PubMed electronic database was searched, and 193 articles were included in this study. After reviewing all manuscripts, only one important difference was found: subjects. We found that SSRIs induce different effects in animals vs. humans. Preclinical studies showed many controversial effects, while human studies showed only two effects: improvement of depression, with or without the improvement of BDNF. However, most studies used chronic SSRIs treatment, while acute SSRIs were not effectively used and evaluated. In conclusion, it seems that SSRIs are reliable antidepressants, and the improvement effect of SSRIs on depression is not dependent to BDNF level (at least in human studies).

Huangkui Capsule Attenuates Lipopolysaccharide-Induced Acute Lung Injury and Macrophage Activation by Suppressing Inflammation and Oxidative Stress in Mice

Background

Huangkui capsule (HKC) comprises the total flavonoid extract of flowers of Abelmoschus manihot (L.) Medicus. This study aimed to explore the effects of HKC on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and LPS-stimulated RAW 264.7 cells.

Methods

Enzyme-linked immunosorbent assay, histopathology, spectrophotometry, and quantitative real-time polymerase chain reaction were used for the assessments. Statistical analysis was performed using a one-way analysis of variance.

Results

LPS significantly increased lung inflammation, neutrophil infiltration, and oxidative stress and downregulated lung miR-451 expression. Treatment with HKC dramatically, reduced the total cell count in the bronchoalveolar lavage fluid (BALF), and inhibited myeloperoxidase activity in the lung tissues 24 h after LPS challenge. Histopathological analysis demonstrated that HKC attenuated LPS-induced tissue oedema and neutrophil infiltration in the lung tissues. Additionally, the concentrations of tumour necrosis factor- (TNF-) α and interleukin- (IL-) 6 in BALF and IL-6 in the plasma reduced after HKC administration. Moreover, HKC could enhance glutathione peroxidase and catalase activities and upregulate the expression of miR-451 in the lung tissues. In vitro experiments revealed that HKC inhibited the production of nitric oxide, TNF-α, and IL-6 in LPS-induced RAW 264.7 cells and mouse primary peritoneal macrophages. Additionally, HKC downregulated LPS-induced transcription of TNF-α and IL-6 in RAW 264.7 cells.

Conclusions

These findings suggest that HKC has anti-inflammatory and antioxidative effects that may protect mice against LPS-induced ALI and macrophage activation.

Effects of Abelmoschus manihot Flower Extract on Enhancing Sexual Arousal and Reproductive Performance in Zebrafish

The flower of Abelmoschus manihot L. is mainly used for the treatment of chronic kidney diseases, and has been reported to have bioactivities such as antioxidant, anti-inflammatory, antiviral, and antidepressant activities. This study used wild-type adult zebrafish as an animal model to elucidate the potential bioactivity of A. manihot flower ethanol extract (AME) in enhancing their sexual and reproductive functions. Zebrafish were fed AME twice a day at doses of 0.2%, 1%, and 10% for 28 days, and were then given the normal feed for an additional 14 days. The hormone 17-β estradiol was used as the positive control. Sexual behavioral parameters such as the number of times males chased female fish, the production of fertilized eggs, and the hatching rate of the fertilized eggs were recorded at days 0.33, 7, 14, 21, 28, and 42. The expression levels of sex-related genes—including lhcgr, ar, cyp19a1a, and cyp19a1b—were also examined. The results showed that the chasing number, fertilized egg production, and hatching rate were all increased with the increase in the AME treatment dose and treatment time. After feeding with 1% and 10% AME for 28 days, the chasing number in the treated group as compared to the control group increased by 1.52 times and 1.64 times, respectively; the yield of fertilized eggs increased by 1.59 times and 2.31 times, respectively; and the hatching rate increased by 1.26 times and 1.69 times, respectively. All three parameters exhibited strong linear correlations with one another (p < 0.001). The expression of all four genes was also upregulated with increasing AME dose and treatment duration. When feeding with 0.2%, 1%, and 10% AME for 28 days, the four sex-related genes were upregulated at ranges of 1.79−2.08-fold, 2.74−3.73-fold, and 3.30−4.66-fold, respectively. Furthermore, the effect of AME was persistent, as the promotion effect continued after the treatment was stopped for at least two weeks. The present findings suggest that AME can enhance the endocrine system and may improve libido and reproductive performance in zebrafish.

Hydroalcoholic extract from Abelmoschus manihot (Linn.) Medicus flower reverses sleep deprivation-evoked learning and memory deficit

Previous researches have indicated that sleep plays a vital role in cognitive functions. Sleep deprivation (SD) causes learning and memory damage, which is associated with oxidative stress. This study was performed to investigate the neuroprotective effects of an extract of Abelmoschus manihot flower (EAM) against memory deficit induced by SD in mice. The SD model was evoked by multiple platform method for 5 days, successively. The learning and memory-improving effects of EAM were assessed by behavioral trials and the underlying mechanism was investigated by measuring the oxidative stress alteration. Our findings indicated that the SD-induced memory deficit and the EAM treatment improved the cognitive functions of mice in the object location recognition test and passive avoidance task. In addition, EAM effectively improved the activities of the antioxidant enzyme, decreased the content of malondialdehyde (MDA), and restored the protein expression of the brain-derived neurotrophic factor (BDNF), tyrosine kinase B (TrkB) and glutamate receptor 1 (GluR1) in brain tissues. In conclusion, EAM could improve the SD-evoked learning and memory impairments. The possible underlying mechanisms of EAM may be related to its antioxidant capacity and enhanced BDNF/TrkB/GluR1 levels in the hippocampal memory.

Total Flavone of Abelmoschus manihot Ameliorates Stress-Induced Microbial Alterations Drive Intestinal Barrier Injury in DSS Colitis

Purpose

Total flavone of Abelmoschus manihot (TFA), the effective constituents extracted from Flos Abelmoschus Manihot, has been reported to inhibit inflammation. However, the effect of TFA on ulcerative colitis (UC) progression in patients with depression is unknown. The purpose of our research was to explore the anti-UC effects of TFA in the context of depression in mice with UC by regulating the gut microbiota to drive the intestinal barrier.

Methods

In this study, chronic stress (CS) and dextran sodium sulfate (DSS) were used to induce depression and UC, respectively, in C57BL/6J mice. Fecal microbiota transplantation (FMT) was used to evaluate how treating mice modeling UC and depression with TFA effected their gut microbiota.

Results

Our results showed that TFA effectively improved UC aggravated by CS. In addition, TFA treatment improved the depression-like phenotype, the disturbed gut microbiota, and the intestinal barrier function in CS mice. It is worth noting that FMT from the CS mice to the receptor group further aggravated the damage of the intestinal barrier and the disturbance of the gut microbiota in the recipient DSS mice, thus further aggravating UC, however, treatment of the intervention of TFA in the CS fecal microbiota transplant with TFA also played its therapeutic outcome.

Conclusion

Taken together, our results show that CS disrupts the gut microbiota, triggers intestinal barrier injury and aggravates DSS colitis, while TFA is a promising drug for the treatment of UC in patients with depression.

A review of the protective effects of quercetin-rich natural compounds for treating ischemia-reperfusion injury

Ischemia-reperfusion (IR) injury causes dysfunction of tissues and organs, and oxidative stress plays an important role. During IR, reactive oxygen species (ROS) are increased. Antioxidants are used to decrease ROS associated with IR. We review the protective effects of quercetin-rich natural antioxidants against IR. We searched PubMed, ScienceDirect, Scopus and Cochrane databases using the keywords: ischemic reperfusion, quercetin, antioxidant and herbal medicine. The effects of quercetin during IR have been reported for animal models in vitro and in vivo. Quercetin-rich plants including Abelmoschus esculentus, coriander, Hypericum perforatum, onion, Psidium guajava, buckwheat and Rosa laevigata Michx have been used to reduce oxidative stress damage to various organs during IR.

Traditional Uses, Chemical Constituents, Biological Properties, Clinical Settings, and Toxicities of Abelmoschus manihot L.: A Comprehensive Review

Abelmoschus manihot, an annual herbal flowering plant, is widely distributed throughout eastern Europe and in temperate and subtropical regions of Asia. Its flowers have been traditionally used for the treatment of chronic kidney disease in China. Currently, more than 128 phytochemical ingredients have been obtained and identified from the flowers, seeds, stems, and leaves of A. manihot. The primary components are flavonoids, amino acids, nucleosides, polysaccharides, organic acids, steroids, and volatile oils. A. manihot and its bioactive constituents possess a plethora of biological properties, including antidiabetic nephropathy, antioxidant, antiadipogenic, anti-inflammatory, analgesic, anticonvulsant, antidepressant, antiviral, antitumor, cardioprotective, antiplatelet, neuroprotective, immunomodulatory, and hepatoprotective activities, and have effects on cerebral infarction, bone loss, etc. However, insufficient utilization and excessive waste have already led to a rapid reduction of resources, meaning that a study on the sustainable use of A. manihot is urgent and necessary. Moreover, the major biologically active constituents and the mechanisms of action of the flowers have yet to be elucidated. The present paper provides an early and comprehensive review of the traditional uses, chemical constituents, pharmacological activities, and pharmaceutical, quality control, toxicological, and clinical settings to emphasize the benefits of this plant and lays a solid foundation for further development of A. manihot.

Neuroplasticity and behavioral effects of fluoxetine after experimental stroke

The brain can undergo self-repair and has the ability to compensate for functions lost after a stroke. The plasticity of the ischemic brain is influenced by several factors including aging and pharmacotherapy. Fluoxetine is an antidepressant which enhances serotonergic neurotransmission through selective inhibition of neuronal reuptake of serotonin. In clinical practice, fluoxetine alleviates the symptoms of post-stroke depression (PSD), helps motor recovery in stroke patients. In animal experiments, chronic administration of fluoxetine induces increased excitability of mature granule cells (GCs), enhancing axonal and dendritic reorganization, as well as promoting neurogenesis or angiogenesis in the dentate gurus (DG), but the effect of fluoxetine in the subventricular zone (SVZ) remains controversial. Meanwhile, chronic treatment with fluoxetine did not reverse age-dependent suppression of proliferation cells in the DG. Interestingly, although fluoxetine has been found to enhance neurogenesis in the DG in stroke rats, this property is not consistent with the behavioral recovery. More studies into this issue will be required to reveal how to translate enhanced neuronal plasticity into behavioral benefits. This review provides an update of the current knowledge about the neurogenesis and the fate of the newly generated cells after the use of fluoxetine, as well as its ability to promote a behavioral recovery after stroke in clinical and experimental results and attempts to define the therapeutic properties of fluoxetine in regenerative neuroscience.

Total Flavones of Abelmoschus manihot Exhibits Pro-Angiogenic Activity by Activating the VEGF-A/VEGFR2-PI3K/Akt Signaling Axis

Angiogenesis is a process of new blood vessel formation from pre-existing vessels. Vascular endothelial growth factor-A (VEGF-A) binds to VEGF receptor-2 (VEGFR2) and thus activation of phosphatidylinositol 3-kinase (PI3K)/Akt pathway play a central role in angiogenesis. Total flavones of Abelmoschus manihot (TFA), the major active component of the traditional Chinese herb Abelmoschus manihot, display novel pro-angiogenic activity. However, little information concerning its underlying mechanism is available. Here we investigate the pro-angiogenesis of TFA with the aim of understanding its mechanism of action. Human umbilical vein endothelial cells (HUVECs) and the chick chorioallantoic membrane (CAM) model were used to evaluate pro-angiogenesis of TFA using cell viability, wounding healing, transwell invasion, tube formation, RT-qPCR and Western blot methods. LY294002, a PI3K inhibitor, was used to interfere with PI3K/Akt pathway signal for assessing the underlying mechanism. Results in vitro indicated TFA obviously promoted HUVECs proliferation, migration, invasion and tube formation. Furthermore, TFA markedly augmented PI3K and Akt phosphorylation and up-regulated VEGF-A and VEGFR2 expression in HUVECs. However, pre-treatment with LY294002 not only markedly attenuated TFA-induced cells proliferation, migration, invasion and tube formation, but also significantly abolished TFA-induced VEGF-A and VEGFR2 over-expression as well as PI3K and Akt phosphorylation. Experiments in CAM model showed TFA significantly promoted the formation of branched blood vessels and was dramatically suppressed by LY294002. Taken together, TFA promoted angiogenesis both in vitro and in vivo which, however, were counteracted by LY294002, suggesting at least in part, TFA exhibits pro-angiogenic activity by activating the VEGF-A/VEGFR2-PI3K/Akt signaling axis.

Total flavones of Abelmoschus manihot improve diabetic nephropathy by inhibiting the iRhom2/TACE signalling pathway activity in rats

CONTEXT

Total flavones extracted from Abelmoschus manihot L. (Malvaceae) medic (TFA) have been proven clinically effective at improving renal inflammation and glomerular injury in chronic kidney disease (CKD).

OBJECTIVE

This study evaluated the function of TFA as an inhibitor of iRhom2/TACE (tumour necrosis factor-α converting enzyme) signalling and investigated its anti-DN (diabetic nephropathy) effects in a DN rat model.

MATERIALS AND METHODS

In vitro, cells were treated with 200 μg/mL advanced glycation end products (AGEs), and then co-cultured with 20 μg/mL TFA for 24 h. Real time PCR, western blotting and co-immunoprecipitation assays were performed. In vivo, DN was induced in 8 week old male Sprague-Dawley rats via unilateral nephrectomy and intraperitoneal injection of streptozotocin, then TFA were administered to rats by gavage for 12 weeks at three different doses (300, 135 and 75 mg/kg/d). 4-Phenylbutanoic acid (2.5 mg/kg/d) was used as a positive control.

RESULTS

IC₅₀ of TFA is 35.6 μM in HK2 and 39.6 μM in HRMC. TFA treatment (20 μM) inhibited the activation of iRhom2/TACE signalling in cultured cells induced by AGEs. LD₅₀>26 g/kg and ED₅₀=67 mg/kg of TFA in rat by gavage, TFA dose-dependently downregulated the expression of proinflammatory cytokines and exerted anti-inflammatory effects significantly though inhibiting the activation of iRhom2/TACE signalling.

DISCUSSION AND CONCLUSIONS

Our results show that TFA could dose-dependently ameliorate renal inflammation by inhibiting the activation of iRhom2/TACE signalling and attenuating ER stress. These results suggest that TFA has potential therapeutic value for the treatment of DN in humans.

Total flavones of abelmoschus manihot enhances angiogenic ability both in vitro and in vivo

Angiogenesis is a process of new blood vessel formation from pre-existing vessels. It is a normal and vital process in growth and development, as well as in wound healing and in the formation of granulation tissue. Total flavones of Abelmoschus manihot (TFA) are the major constituents of the traditional Chinese herb Abelmoschus manihot L. Medic. The aim of this study is to investigate the effect of TFA on angiogenic ability using human umbilical vein endothelial cells (HUVECs) in vitro and chick chorioallantoic membrane (CAM) in vivo. HUVECs were treated with TFA at different concentrations. Cell viability, cell cycle progression, cell apoptosis, cell migration and tubular formation were investigated. The expression of vascular endothelial growth factor (VEGF) and kinase insert domain receptor (KDR, VEGFR-2) was examined by immunohistochemistry to identify mechanism of action of TFA. CAM model was used to evaluate the effect of TFA on angiogenesis in vivo. Our results showed that TFA promoted HUVECs proliferation in a dose- and time-dependent manner. It increased HUVECs migratory ability and the number of tubular structure, promoted vessel formation in HUVECs culture and CAM model. Furthermore, TFA treatment resulted in a decrease in cell apoptosis and enhanced the expression of VEGF and KDR. Taken together, TFA, as the major active component isolated from the traditional Chinese herb Abelmoschus manihot L. Medic, could enhance angiogenic ability of HUVECs in vitro and CAM in vivo. TFA may be used in the treatment of wound healing and ischemic/reperfusion injuries.

Total Flavonoid Extract from Abelmoschus manihot (L.) Medic Flowers Attenuates d-Galactose-Induced Oxidative Stress in Mouse Liver Through the Nrf2 Pathway

Abelmoschus manihot (L.) Medic is an edible hibiscus that is rich in flavonoids, and its use as Chinese herbal medicine for the treatment of diseases and health maintenance dates back to ancient times. The chemical compositions of total flavonoid of A. manihot (L.) Medic flower extract (TFAE) were identified and determined by high performance liquid chromatography (HPLC). The effects of TFAE on antioxidative activities in a d-galactose (d-gal)-induced mouse model and Nrf2-mediated antioxidant responses were evaluated. Male Kunming mice were randomly divided into normal control group, d-gal aging model group, d-gal+ascorbic acid group that served as a positive control, and d-gal+TFAE (40, 80, and 160 mg TFAE/kg) group. After 42 days, the antioxidant effects of these treatments were determined by biochemical studies, Western blotting, quantitative real-time polymerase chain reaction, and histological analysis. The results showed that the groups administered TFAE exhibited significant elevation in liver activities of antioxidant enzymes, including catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC), and decreased malondialdehyde (MDA) production in a dose-dependent manner compared with the d-gal-induced model group. Expression of Nrf2 and its target antioxidants (HO-1 and NQO1) was manifestly increased by TFAE treatment. TFAE also increased mRNA expression of GPx, SOD, and CAT and decreased tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). Furthermore, the microstructure of livers in TFAE-administered mice was obviously improved as compared with the d-gal model group. These results suggest that TFAE protects mice against d-gal-induced oxidative stress, and the effect is related to the activation of Nrf2 signaling.

Effect of food deprivation or short-term Western diet feeding on BDNF protein expression in the hypothalamic arcuate, paraventricular, and ventromedial nuclei

Mutations in the brain-derived neurotrophic factor (BDNF) gene are associated with human obesity, and BDNF has potent inhibitory effects on eating and body weight. Little is known about the effects of energy balance manipulations on BDNF protein in the hypothalamus, though this brain region is critical for regulation of feeding and body weight and has high levels of BDNF. Here we investigated the effects of negative and positive energy status on BDNF protein levels in the arcuate (ARC), paraventricular, and ventromedial (VMH) hypothalamic nuclei and the ectorhinal cortex. To achieve this, mice were food deprived for 48 h or fed a Western diet (WD), a restricted amount of WD, or chow for 6 h, 48 h, 1 wk, or 3 wk. BDNF protein levels were estimated as the number of neurons in each brain region that exhibited BDNF-like immunoreactivity. Food deprivation decreased BDNF protein (and mRNA) expression in the ARC compared with fed mice (32%). In contrast, 1 wk of WD consumption increased BDNF protein expression in the VMH compared with chow or restricted WD feeding (40%) and, unexpectedly, increased BDNF protein in the ectorhinal cortex (20%). Furthermore, of the diet conditions and durations tested, only 1 wk of WD consumption was associated with both hyperphagia and excess weight, suggesting that effects of one or both contributed to the changes in BDNF levels. The decrease in ARC BDNF may support increased feeding in food-deprived mice, whereas the increase in the VMH may moderate overeating in WD-fed mice.

Investigations of the total flavonoids extracted from flowers of Abelmoschus manihot (L.) Medic against α-naphthylisothiocyanate-induced cholestatic liver injury in rats

ETHNOPHARMACOLOGY RELEVANCE

The decoction of the flowers of Abelmoschus manihot (L.) Medic was traditionally used for the treatment of jaundice and various types of chronic and acute hepatitis in Anhui and Jiangsu Provinces of China for hundreds of years. Phytochemical studies have indicated that total flavonoids extracted from flowers of A. manihot (L.) Medic (TFA) were the major constituents of the flowers. Our previous studies have investigated the hepatoprotective effects of the TFA against carbon tetrachloride (CCl4) induced hepatocyte damage in vitro and liver injury in vivo. This study aimed to investigate the protective effects and mechanisms of TFA on α-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury in rats.

MATERIAL AND METHODS

The hepatoprotective activities of TFA (125, 250 and 500mg/kg) were investigated on ANIT-induced cholestatic liver injury in rats. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were used as indices of hepatic cell damage and measured. Meanwhile, the serum levels of alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), total bilirubin (TBIL), direct bilirubin (DBIL), and total bile acid (TBA) were used as indices of biliary cell damage and cholestasis and evaluated. Hepatic malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione transferase (GST), tumor necrosis factor-α (TNF-α) and nitric oxide (NO) were measured in the liver homogenates. The bile flow in 4h was estimated and the histopathology of the liver tissue was evaluated. Furthermore, the expression of transporters, bile salt export pump (BSEP), multidrug resistance-associated protein 2 (MRP2), and Na(+)-taurocholate cotransporting polypeptide (NTCP) were studied by western blot and reverse transcription-quantitative real-time polymerase chain reaction (RT-PCR) to elucidate the protective mechanisms of TFA against ANIT-induced cholestasis.

RESULTS

The oral administration of TFA to ANIT-treated rats could reduce the increases in serum levels of ALT, AST, LDH, ALP, GGT, TBIL, DBIL and TBA. Decreased bile flow by ANIT was restored with TFA treatment. Concurrent administration of TFA reduced the severity of polymorphonuclear neutrophil infiltration and other histological damages, which were consistent with the serological tests. Hepatic MDA and GSH contents in liver tissue were reduced, while SOD and GST activities, which had been suppressed by ANIT, were elevated in the groups pretreated with TFA. With TFA intervention, levels of TNF-α and NO in liver were decreased. Additionally, TFA was found to increase the expression of liver BSEP, MRP2, and NTCP in both protein and mRNA levels in ANIT-induced liver injury with cholestasis.

CONCLUSION

TFA exerted protective effects against ANIT-induced liver injury. The possible mechanisms could be related to anti-oxidative damage, anti-inflammation and regulating the expression of hepatic transporters. It layed the foundation for the further research on the mechanisms of cholestasis as well as the therapeutic effects of A. manihot (L.) Medic for the treatment of jaundice.

Conjugated metabolites represent the major circulating forms of Abelmoschus manihot in vivo and show an altered pharmacokinetic profile in renal pathology

CONTEXT

The nephron-protective efficacy of Abelmoschus manihot (Linn.) Medicus (Malvaceae) has been proved by randomized controlled clinical trial.

OBJECTIVE

Flavonoids are main active components of A. manihot, which can be transformed into glucuronide/sulfate conjugates in vivo. Exploring the pharmacokinetic profile of these conjugates is necessary to further elucidate the mechanism of action.

MATERIAL AND METHOD

Flavonoid fraction of A. manihot (FFA) was extracted from A. manihot flower with ethanol. FFA (400 mg/kg) was orally given to normal rats and chronic kidney disease (CKD) model rats. Blood samples were collected at 5, 15, 30, 45, 60, 90, 120, 240, 360, and 720 min after administration. The plasma concentrations of quercetin and isorhamnetin glucuronide/sulfate conjugates were analyzed by UPLC-MS/MS.

RESULTS

In normal rats, AUC of quercetin-glucuronide conjugates, isorhamnetin-glucuronide conjugates, quercetin-sulfate conjugates, and isorhamnetin-sulfate conjugates was 459.45 ± 192.70, 1153.01 ± 697.04, 417.81 ± 220.31, and 2475.19 ± 1085.22 μmol h/L, respectively. While AUC of quercetin and isorhamnetin was 5.47 ± 2.54 and 30.73 ± 25.95 μmol h/L. AUC of the glucuronide-sulfate conjugates of quercetin and isorhamnetin is 125-times higher than that of aglycone (quercetin and isorhamnetin), showing that glucuronide/sulfate conjugates represent the major circulating forms of A. manihot flavonoid in vivo. AUC of isorhamnetin-glucuronide conjugates and quercetin-sulfate conjugates was 719.65 ± 619.22 and 275.49 ± 1 60.95 μmol h/L, indicating that less conjugated metabolites were formed in CKD rats compared with normal rats. The ratio of AUCglucuronide/sulfate/AUCaglycone decreased from 125 to 104, which implied the impaired phase II metabolism ability in CKD rat.

DISCUSSION AND CONCLUSION

Glucuronide-sulfate conjugates provide an important clue for further elucidating the activity of conjugated metabolites and their relationship with the nephroprotective efficacy of A. manihot. It is necessary to take caution when extrapolating pharmacokinetics parameters from healthy animals in designing pharmacological studies.

Pectin from Abelmoschus esculentus: optimization of extraction and rheological properties

Response surface methodology (RSM) was applied to optimize the parameters of pectin extraction from okra pods. The extracted okra pectin was then investigated by steady-shear and oscillatory rheological measurements. Statistical analysis showed that the linear term of the liquid-solid ratio, the quadratic term of the pH, and the linear term of the extraction time showed highly significant effects on pectin yield. The optimal extraction conditions that maximized the pectin yield within the experimental range of the variables researched were a pH of 3.9, an extraction time of 64 min, an extraction temperature of 60°C, and a liquid-solid ratio of 42:1. Under these conditions, the pectin yield was predicted to be 2.71%. At a liquid-solid ratio less than 2.5% w/w in aqueous solution, the pectin extracted from okra presented non-Newtonian shear-thinning behavior and could be well described by the Cross model. The okra pectin showed predominantly viscous responses (G'<G″) over a wide range of frequencies (10(-1)-10 Hz) at 20% strain.

Abelmoschi Corolla non-flavonoid components altered the pharmacokinetic profile of its flavonoids in rat

AIM

Abelmoschi Corolla is a well-known herbal medicine used for the treatment of chronic renal disease. Flavonoids are the major bioactive ingredients of Abelmoschi Corolla, but some non-flavonoid components also exist in this herb. In order to clarify the influences of non-flavonoid components on the pharmacokinetics profile of the flavonoid fraction from Abelmoschi Corolla (FFA), an investigation was carried out to compare the pharmacokinetic parameters of seven flavonoid components after administration of FFA and after administration of FFA combined with different non-flavonoid fractions.

MATERIALS AND METHODS

A selective and sensitive UPLC-MS/MS method was established to determine the plasma concentrations of the seven compounds. Sprague-Dawley rats were allocated to four groups which orally administered FFA, FFA combined with macromolecular fraction (FFA-MF), FFA combined with small molecule fraction (FFA-SF) and FFA combined with MF-SF (FFA-MF-SF) with approximately the same dose of FFA. At different time points, the concentration of rutin (1), hyperoside (2), isoquercitrin (3), hibifolin (4), myricetin (5), quercetin-3'-O-glucose (6), quercetin (7) in rat plasma were determined and main pharmacokinetic parameters including T(1/2), T(max), AUC and C(max) were calculated using the DAS 2.0 software package. The statistical analysis was performed using the Student's t-test with P<0.05 as the level of significance.

RESULTS

Flavonoids almost had similar pharmacokinetics profile that were rapidly absorbed, reached the peak concentration at 30-60 min in group A, but the pharmacokinetic profiles and parameters of these flavonoids changed when co-administered with non-flavonoid components. It was found that AUC of five flavonoids but not hibifolin and quercetin in group FFA-SF and group FFA-MF-SF increased (P<0.05) in comparison with group FFA while the tendency was not observed in group FFA-MF. Moreover, seven flavonoids had varying degrees of differences in the pharmacokinetics parameters such as C(max), T(max) and T(1/2) (P<0.05) in group FFA-MF, FFA-SF and FFA-MF-SF by comparison with group FFA.

CONCLUSION

These results indicate that non-flavonoid components could improve the bioavailability and delay the elimination of some flavonoids in rat.

Hepatoprotective evaluation of the total flavonoids extracted from flowers of Abelmoschus manihot (L.) Medic: In vitro and in vivo studies

ETHNOPHARMACOLOGICAL RELEVANCE

The decoction of the flowers of Abelmoschus manihot (L.) Medic is traditionally used for the treatment of jaundice and various types of chronic and acute hepatitis in Anhui and Jiangsu Provinces of China. Phytochemical studies have indicated that total flavonoids extracted from flowers of Abelmoschus manihot (L.) Medic (TFA) were the major constituents of the flowers. The present study was designed to investigate the hepatoprotective effect of the plant extracts against carbon tetrachloride (CCl4) induced hepatocyte damage in vitro and liver injury in vivo.

MATERIAL AND METHODS

In the in vitro studies, freshly isolated rat hepatocytes were exposed to CCl4 (1%) along with/without various concentrations of TFA (4.5-72mg/L). Cell damage was assessed by the trypan blue exclusion method and alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in the medium were analyzed. In the in vivo studies, the hepatoprotective activity of TFA (125, 250 and 500mg/kg) were investigated on CCl4-induced liver damages in mice. The levels of ALT, AST and ALP, gamma glutamyltransferase (γ-GT), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and nitric oxide (NO) were determined in serum. Hepatic malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione transferase (GST) were measured in the liver homogenates. Cytokine transcript levels of TNF-α, IL-1β and inducible nitric oxide synthase (iNOS) in the liver tissues of mice were measured using reverse transcription-polymerase chain reaction (RT-PCR). Livers were dissected out and evaluated for histomorphological changes.

RESULTS

A concentration-dependent increase in the percentage viability was observed when CCl4-exposed hepatocytes were treated with different concentrations of TFA. Levels of ALT, AST and ALP in the medium were significantly decreased. In the animal studies, TFA showed significant protection with the depletion of ALT, AST, ALP and γ-GT in serum as was raised by the induction of CCl4. Moreover, TFA decreased the MDA level and elevated the content of GSH in the liver as compared to those in the CCl4 group. Furthermore, activities of antioxidative enzymes, including SOD, GPx, CAT and GST, were enhanced dose dependently with TFA. Meanwhile, the inflammatory mediators (e.g., TNF-α, IL-1β and NO) were inhibited by TFA treatment both at the serum and mRNA levels. Additionally, histological analyses also showed that TFA reduced the extent of liver lesions induced by CCl4.

CONCLUSION

These results suggested that TFA protected mice against CCl4-induced liver injury through antioxidant stress and antiinflammatory effects. This finding justified the use of this plant in traditional medicine for the treatment of liver disease.

Neuroprotective and anti-inflammatory effects of the flavonoid-enriched fraction AF4 in a mouse model of hypoxic-ischemic brain injury

We report here neuroprotective and anti-inflammatory effects of a flavonoid-enriched fraction isolated from the peel of Northern Spy apples (AF4) in a mouse of model of hypoxic-ischemic (HI) brain damage. Oral administration of AF4 (50 mg/kg, once daily for 3 days) prior to 50 min of HI completely prevented motor performance deficits assessed 14 days later that were associated with marked reductions in neuronal cell loss in the dorsal hippocampus and striatum. Pre-treatment with AF4 (5, 10, 25 or 50 mg/kg, p.o.; once daily for 3 days) produced a dose-dependent reduction in HI-induced hippocampal and striatal neuron cell loss, with 25 mg/kg being the lowest dose that achieved maximal neuroprotection. Comparison of the effects of 1, 3 or 7 doses of AF4 (25 mg/kg; p.o.) prior to HI revealed that at least 3 doses of AF4 were required before HI to reduce neuronal cell loss in both the dorsal hippocampus and striatum. Quantitative RT-PCR measurements revealed that the neuroprotective effects of AF4 (25 mg/kg; p.o.; once daily for 3 days) in the dorsal hippocampus were associated with a suppression of HI-induced increases in the expression of IL-1β, TNF-α and IL-6. AF4 pre-treatment enhanced mRNA levels for pro-survival proteins such as X-linked inhibitor of apoptosis and erythropoietin following HI in the dorsal hippocampus and striatum, respectively. Primary cultures of mouse cortical neurons incubated with AF4 (1 µg/ml), but not the same concentrations of either quercetin or quercetin-3-O-glucose or its metabolites, were resistant to cell death induced by oxygen glucose deprivation. These findings suggest that the inhibition of HI-induced brain injury produced by AF4 likely involves a transcriptional mechanism resulting from the co-operative actions of various phenolics in this fraction which not only reduce the expression of pro-inflammatory mediators but also enhance pro-survival gene signalling.

Pretreatment with the total flavone glycosides of Flos Abelmoschus manihot and hyperoside prevents glomerular podocyte apoptosis in streptozotocin-induced diabetic nephropathy

Diabetic nephropathy (DN) is an important diabetic complication, and podocyte apoptosis plays a critical role in the development of DN. In the present study, we examined the preventive effect of the total flavone glycosides of Flos Abelmoschus manihot (TFA) on urinary microalbumin and glomerular podocyte apoptosis in experimental DN rats. The preliminary oral administration of TFA (200 mg/kg/day) for 24 weeks significantly decreased the urinary microalbumin to creatinine ratio and 24-h urinary total protein in streptozotocin-induced DN rats. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay indicated glomerular cell apoptosis in DN rats was significantly improved by pretreatment with TFA. Furthermore, fluorescence-activated cell sorting and Hoechst 33342 staining suggested preincubation with hyperoside (50 and 200 μg/mL), the major active constituent of TFA, could significantly mitigate cultured podocyte apoptosis induced by the advanced glycation end-products (AGEs). Western blot analysis showed that increased caspase-3 and caspase-8 expressions induced by AGEs were also inhibited by pretreatment with hyperoside at both doses. Our results demonstrate that TFA pretreatment can decrease urinary albumin excretion in early-stage DN, which might be accomplished by preventing renal damage and podocyte apoptosis.

Postnatal exposure to trichloroethylene alters glutathione redox homeostasis, methylation potential, and neurotrophin expression in the mouse hippocampus

Previous studies have shown that continuous exposure throughout gestation until the juvenile period to environmentally relevant doses of trichloroethylene (TCE) in the drinking water of MRL+/+ mice promoted adverse behavior associated with glutathione depletion in the cerebellum indicating increased sensitivity to oxidative stress. The purpose of this study was to extend our findings and further characterize the impact of TCE exposure on redox homeostasis and biomarkers of oxidative stress in the hippocampus, a brain region prone to oxidative stress. Instead of a continuous exposure, the mice were exposed to water only or two environmentally relevant doses of TCE in the drinking water postnatally from birth until 6 weeks of age. Biomarkers of plasma metabolites in the transsulfuration pathway and the transmethylation pathway of the methionine cycle were also examined. Gene expression of neurotrophins was examined to investigate a possible relationship between oxidative stress, redox imbalance and neurotrophic factor expression with TCE exposure. Our results show that hippocampi isolated from male mice exposed to TCE showed altered glutathione redox homeostasis indicating a more oxidized state. Also observed was a significant, dose dependent increase in glutathione precursors. Plasma from the TCE treated mice showed alterations in metabolites in the transsulfuration and transmethylation pathways indicating redox imbalance and altered methylation capacity. 3-Nitrotyrosine, a biomarker of protein oxidative stress, was also significantly higher in plasma and hippocampus of TCE-exposed mice compared to controls. In contrast, expression of key neurotrophic factors in the hippocampus (BDNF, NGF, and NT-3) was significantly reduced compared to controls. Our results demonstrate that low-level postnatal and early life TCE exposure modulates neurotrophin gene expression in the mouse hippocampus and may provide a mechanism for TCE-mediated neurotoxicity.

Anticonvulsant, antidepressant-like activity of Abelmoschus manihot ethanol extract and its potential active components in vivo

Depression is the most common psychiatric comorbidity in patients with epilepsy. Searching for antiepileptic (anticonvulsant) and antidepressant-like medicines from natural products is very important for the treatment of this disease. The flower of Abelmoschus manihot (Linn.) Medicus has been reported to have neuroprotective effect against cerebral ischemia injury. In order to further explore the activity of Abelmoschus manihot on the central nervous system, the anticonvulsant and antidepressant-like effects of Abelmoschus manihot ethanol extract (AMEE) as well as its potential active components in vivo was investigated in the present study. It was found that AMEE could protect mice against PTZ-induced clonic convulsions and mortality. AMEE could also decrease immobility time in the FST in mice. Furthermore, the potential active components of AMEE in rat brain were identified by ultra performance liquid chromatography-mass spectrometer (UPLC-MS). Five parent components including isoquercitrin, hyperoside, hibifolin, quercetin-3'-O-glucoside, quercetin and three metabolites were detected in rat brain after administration of AMEE. In conclusion, eight flavonoids were identified in rat brain after administration of AMEE; meanwhile, these flavonoids might represent the potential bioactive components of AMEE and contribute to its anticonvulsant and antidepressant-like activity in vivo.

Vitexin protects against myocardial ischemia/reperfusion injury in Langendorff-perfused rat hearts by attenuating inflammatory response and apoptosis

The aim of the present study is to investigate the effects and its possible underlying mechanisms of vitexin on myocardial ischemia/reperfusion (I/R) injury in isolated rat hearts. Isolated rat hearts were perfused with Langendorff apparatus, which subjected to 30 min ischemia and then followed by 60 min reperfusion. In the isolated rat heart subjected to I/R injury, treatment of vitexin (50, 100, 200 μmol/L) significantly enhanced coronary flow, and decreased the pathological scores of myocardium. 50, 100, 200 μmol/L vitexin significantly attenuated I/R-induced increases of myocardial TNF-α and IL-1β, and 25, 50, 100, 200 μmol/L vitexin significantly reduced apoptosis index of cardiac muscle cell of rat isolated heart subjected to I/R injury. Vitexin significantly inhibited I/R-induced increase of myocardial Bax protein expression; however, 100, 200 μmol/L vitexin markedly increased myocardial Bcl-2 protein expression. Furthermore, vitexin at concentrations of 50, 100, 200 μmol/L significantly reduced expression of myocardial NF-κBp65 protein. Therefore, these results demonstrate that vitexin exhibits significant protective effect against myocardial I/R injury in isolated rat heart, which is related to inhibition of the release of inflammatory cytokines and the apoptosis of cardiac muscle cell via up-regulating protein expression of Bcl-2 as well as down-regulating Bax and NF-κBp65.

Protective effect of extract of Astragalus on learning and memory impairments and neurons' apoptosis induced by glucocorticoids in 12-month-old male mice

Alzheimer's disease (AD) is a chronic neurodegenerative disorder marked by a progressive loss of memory and cognitive function. Stress-level glucocorticoids are correlated with dementia progression in patients with AD. In this study, 12-month male mice were chronically treated with stress-level dexamethasone (DEX, 5 mg/kg) and extract of Astragalus (EA, 10, 20, and 40 mg/kg) or Ginsenoside Rg1 (Rg1, 6.5 mg/kg) for 21 days. We investigated the protective effect of EA against DEX injury in mice and its action mechanism. Our results indicate that DEX can induce learning and memory impairments and neuronal cell apoptosis. The mRNA levels of caspase-3 are selectively increased after DEX administration. The results of immunohistochemistry demonstrate that caspase-3 and cytochrome c in hippocampus (CA1, CA3) and neocortex are significantly increased. Furthermore, DEX treatment increased the activity of caspase-9 and caspase-3. Treatment groups with EA (20 and 40 mg/kg) or Rg1 (6.5 mg/kg) significantly improve learning and memory, downregulate the mRNA level of caspase-3, decrease expression of caspase-3 and cytochrome c in hippocampus (CA1, CA3) and neocortex, and inhibit activity of caspase-9 and caspase-3. The present findings highlight a possible mechanism by which stress level of DEX accelerates learning and memory impairments and increases neuronal apoptosis and the potential neuronal protection of EA.

Seed oil and fatty acid content in okra (Abelmoschus esculentus) and related species

Approximately 1100 genebank accessions of okra (Abelmoschus esculentus) and 540 additional accessions that included six of its related species-A. caillei, A. crinitis, A. esculentus, A. ficulneus, A. manihot, A. moschatus and A. tuberculatus-were evaluated for seed oil content using time domain NMR (TD-NMR). Oil content in seed of A. caillei, A. esculentus, A. ficulneus, A. manihot, A. moschatus and A. tuberculatus was in the ranges 2.51-13.61%, 12.36-21.56%, 6.62-16.7%, 16.1-22.0%, 10.3-19.8% and 10.8-23.2%, respectively. Accession PI639680 (A. tuberculatus) had the highest seed oil content (∼23%). Accessions of A. esculentus with high seed oil content included PI nos. PI274350 (21.5%), PI538082 (20.9%) and PI538097 (20.9%). Values for the three accessions of A. manihot with the highest seed oil content were PI nos. PI639673 (20.4%), PI639674 (20.9%) and PI639675 (21.9%), all representing var. tetraphyllus. Average percent seed oil in materials of A. esculentus from Turkey and Sudan (17.35% and 17.36%, respectively) exceeded the averages of materials from other locations. Ninety-eight accessions (total of six species) were also examined for fatty acid composition. Values of linoleic acid ranged from 23.6-50.65% in A. esculentus. However, mean linoleic acid concentrations were highest in A. tuberculatus and A. ficulneus. Concentrations of palmitic acid were significantly higher in A. esculentus (range of 10.3-36.35%) when compared to that of other species, and reached a maximum in PI489800 Concentrations of palmitic acid were also high in A. caillei (mean = ∼30%). Levels of oleic acid were highest in A. manihot, A. manihot var. tetraphyllus and A. moschatus.

Inhibitory effects of flavonoids from Abelmoschus manihot flowers on triglyceride accumulation in 3T3-L1 adipocytes

The 95% EtOH extract from the flowers of Abelmoschus manihot (L.) Medic showed inhibitory activity on TG accumulation in 3T3-L1 preadipocyte. Chemical studies on the active fraction led to the isolation of 14 flavonoids (1-14). To clarify the multi-mechanism of the isolates on preadipocyte differentiation, the levels of TG and FFA and the related role transcription factors (PPARγ, CEBP/α, and ap2) expression were evaluated. At the concentration of 30 μM, compounds 1-6 and 10-14 showed inhibitory activity on TG accumulation significantly in mature 3T3-L1 cells. 1, 2, 4-7, 9, 10, 13, and 14 reduced the level of FFA. At the molecular level, the mRNA expressions of PPARγ, CEBP/α, and ap2 were down-regulated by compounds 1, 5, 9, 12, 13; 1-8, 10-14; and 1-4, 6, 8-12, 14, respectively. The structure-activity relationships of the 14 flavonoids were also discussed.