A study on the role of cholinergic and gamma amino butyric acid systems in the anti-nociceptive effect of gossypin

In Vivo and In Vitro Cardioprotective Effect of Gossypin Against Isoproterenol-Induced Myocardial Infarction Injury

The aim of the study was to examine the protective effects and possible mechanism of gossypin against isoproterenol (ISO)-mediated myocardial damage in vivo and H9c2 cell damage in vitro. H9c2 cells were categorized into five groups. Viability was evaluated with MTT and LDH release in H9c2 cells. Apoptotic parameter analysis was performed with cytochrome c (Cyt-c), caspase-3 (CASP-3), and BCL2/Bax mRNA expression levels. In vivo, gossypin was administered orally to mice at doses of 5, 10, and 20 mg/kg for 7 days. ISO groups were injected with isoproterenol (150 mg/kg) subcutaneously (on 8th and 9th) for 2 days. Afterward, lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB) levels and Troponin-I (Tn-I) amount from their serum, oxidative stress parameters superoxide dismutase (SOD) activity, glutathione (GSH) and malondialdehyde (MDA) levels, and tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1 β), and NF-kB mRNA expression levels with inflammatory markers from heart tissue were evaluated. In addition, IL-1B, BCL-2, and cas-3 immunohistochemical staining was performed from heart tissue and TNF-a level was measured by ELISA method. Administration of Gossypin protected the cells by dose-dependent, eliminating the reduced cell viability and increased LDH release of ISO in H9c2 cells. In mice serum analyses, increased LDH, CK-MB levels, and Tn-I levels were normalized by gossypin. ISO administration in heart tissue is regulated by gossypin with increased SOD activity, GSH amount, TNF-α, IL-6, IL-1β, and NF-kB mRNA expression levels and decreased MDA amount. Overall, the present results demonstrated that gossypin has a potential cardioprotective treatment for ischemic heart disease on in vivo and in vitro.

Antinociceptive effect of flavonol and a few structurally related dimethoxy flavonols in mice

Previous reports suggest flavonoids as potent analgesic compounds. Based on these observations, the present study investigated the antinociceptive action of flavonol, 3', 4'-dimethoxy flavonol, 6, 3'-dimethoxy flavonol, 7, 2'-dimethoxy flavonol, and 7, 3'-dimethoxy flavonol and the possible mechanisms involved in these effects. The antinociceptive effect of the investigated compounds in doses of 25, 50, 100, and 200 mg/kg was evaluated in male Swiss albino mice using the acetic acid test, formalin-induced nociception, and hot water tail immersion test. The role of opioid, tryptaminergic, adrenergic, dopaminergic, GABAergic, and K⁺_ATP channels in producing the antinociceptive effect was also studied using appropriate interacting agents. Treatment with flavonol and dimethoxy flavonols resulted in a significant reduction in the number of abdominal constrictions in the acetic acid test, a significant inhibition of the paw-licking/biting response time in both the phases of formalin nociception and also a significant increase in mean reaction time in the hot water tail immersion test. These observations revealed the antinociceptive effect of dimethoxy flavonols. The role of opioid, serotonergic (5HT₃), and dopaminergic system was identified in the antinociceptive effect of flavonol and all dimethoxy derivatives investigated. In addition, the role of GABAergic, K⁺_ATP channel, and α-2 adrenergic mechanisms were also observed in the antinociceptive action of some of the investigated compounds. The present study identified the antinociceptive effect of flavonol and dimethoxy flavonols in mice acting through different neuronal pathways.

Anti-nociceptive activity of a few structurally related trimethoxy flavones and possible mechanisms involved

BACKGROUND

The present study was designed to investigate the anti-nociceptive activity of a few structurally related trimethoxy flavones (7,2',3'-TMF, 7,2',4'-TMF, 7,3',4'-TMF and 7,5,4'-TMF) and the possible mechanisms involved.

METHODS

Anti-nociceptive activity was evaluated in mice by employing acetic acid-induced writhing, formalin-induced nociception and hot water tail immersion methods. The involvement of opioid, GABAergic, tryptaminergic, adrenergic and dopaminergic mechanisms and K+ATP channels in the anti-nociceptive activity of trimethoxy flavones was investigated using suitable interacting chemicals.

RESULTS

Trimethoxy flavones exhibited a significant and dose-dependent inhibition of acetic acid writhing. The paw-licking response time was reduced both in the early and late phases of formalin nociception in a dose-dependent manner by trimethoxy flavones. A significant increase in tail withdrawal latency time was also observed after trimethoxy flavones treatment. These observations revealed the potential anti-nociceptive action of the investigated trimethoxy flavones. Pretreatment with naloxone and bicuculline significantly attenuated the reduction of abdominal constrictions produced by all the tested trimethoxy flavones indicating a definite role of opioid and GABAergic mechanisms in the anti-nociceptive effect of trimethoxy flavones. The anti-nociceptive action elicited by various trimethoxy flavones was differently modulated by glibenclamide, ondansetron, yohimbine and sulpiride.

CONCLUSIONS

The investigated trimethoxy flavones exhibited promising anti-nociceptive activity in various nociceptive models, and multiple mechanisms are involved in the anti-nociceptive activity of these compounds.

Antinociceptive effect of certain dimethoxy flavones in mice

The aim of the present study was to evaluate the antinociceptive action of certain dimethoxy flavones (DMF, (7,2׳-dimethoxy flavone, 7,3׳-dimethoxy flavone, 7,4׳-dimethoxy flavone and 7,8,-dimethoxy flavone) and the possible mechanisms involved. The antinociceptive effect of dimethoxy flavones was investigated in mice employing acetic acid-induced abdominal writhings, formalin-induced nociception and hot water tail immersion assay procedures. To identify the possible mechanisms involved in the antinociceptive action of these compounds, acetic acid-induced abdominal constriction assay alone was employed. Mice were pretreated with naloxone, yohimbine, ondansetron, haloperidol, bicuculline or glibenclamide before dimethoxy flavone treatment to identify the role of opioid, adrenergic, 5HT3-serotonergic, dopaminergic, gamma-amino butyric acid (GABA) receptor or potassium channels, respectively. The investigated dimethoxy flavones produced a significant reduction in the number of abdominal constrictions in acetic acid assay. A dose dependent decrease in paw-licking response time was evident in both the early and late phases of formalin induced nociception. A significant increase in reaction time was also evident after treatment with various dimethoxy flavones in hot water tail immersion assay. Pretreatment with naloxone, ondansetron or glibenclamide significantly attenuated the antinociceptive effect of all the four dimethoxy flavones. Yohimbine pretreatment attenuated the antinociceptive response of 7,3׳-dimethoxy flavone, 7,4׳-dimethoxy flavone and 7,8-dimethoxy flavone. Pretreatment with haloperidol potentiated the antinociceptive response of all the tested dimethoxy flavones. The antinociceptive effect of 7,2׳-dimethoxy flavone and 7,3׳-dimethoxy flavone was annulled by bicuculline pretreatment. The results of the present study reveal the antinociceptive effect of dimethoxy flavones involving multiple pathways.

Gossypin up-regulates LDL receptor through activation of ERK pathway: a signaling mechanism for the hypocholesterolemic effect

Hypercholesterolemia is one of the major risk factors for the development of cardiovascular disease. This study aims to elucidate the effect of gossypin on cholesterol metabolism in HepG2 cells. Results indicated that gossypin significantly reduced the total cholesterol concentration in a dose-dependent manner. There was a time- and dose-dependent increase in the expression of low-density lipoprotein receptor (LDLR) protein. However, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis, was not affected by gossypin. Moreover, gossypin had no effect on nuclear sterol regulatory element binding proteins (SREBP)-2 abundance. The activity of gossypin on LDLR expression was inhibited by the extracellular signal-regulated kinase (ERK) inhibitor PD98059. Western blotting analysis revealed that gossypin treatment dose- and time-dependently increased ERK activation and preceded the up-regulation of LDLR expression. Collectively, these new findings identify gossypin as a new hypocholesterolemic agent that up-regulates LDLR expression independent of SREBP-2 but is dependent on ERK activation.

Comparative evaluation of some flavonoids and tocopherol acetate against the systemic toxicity induced by sulphur mustard

OBJECTIVE

To evaluate the protective value of quercetin, gossypin, Hippophae rhamnoides (HR) flavone and tocopherol acetate against the systemic toxicity of percutaneously administered sulphur mustard (SM) in mice.

MATERIALS AND METHODS

Quercetin, gossypin, HR flavone or tocopherol acetate (200 mg/kg, i.p.) were administered just before percutaneous administration of SM and protection against the SM lethality was evaluated. In another experiment quercetin, gossypin, HR flavone or tocopherol acetate were administered against 2 LD(50) SM. The animals were sacrificed seven days post SM administration and various biochemical parameters were estimated.

RESULTS

The protection against the lethality of SM was very good with the flavonoids (quercetin = 4.7 folds; gossypin = 6.7 folds and HR flavone = 5.6 folds), compared to no protection with tocopherol acetate (0.7 fold). SM (2 LD(50)) showed decrease in reduced and oxidised glutathione (GSH and GSSG) levels, and an increase in malondialdehyde level (MDA). Oxidative stress enzymes like glutathione peroxidase, glutathione reductase and superoxide dismutase were significantly decreased. The total antioxidant status was also significantly decreased. Additionally, there was a significant increase in red blood corpuscles and hemoglobin content. All the flavonoids significantly protected the GSH, GSSG and MDA, and also the hematological variables. Tocopherol acetate failed to offer any protection in those parameters. Gossypin protected glutathione peroxidase, while HR flavone protected both glutathione reductase and glutathione peroxidase significantly. The decrease in body weight induced by SM and the histological lesions in liver and spleen were also significantly protected by the flavonoids but not by tocopherol acetate.

CONCLUSION

The present study supports that SM induces oxidative stress and flavonoids are promising cytoprotectants against this toxic effect.

Gossypin, a pentahydroxy glucosyl flavone, inhibits the transforming growth factor beta-activated kinase-1-mediated NF-kappaB activation pathway, leading to potentiation of apoptosis, suppression of invasion, and abrogation of osteoclastogenesis

Gossypin, a flavone originally isolated from Hibiscus vitifolius, has been shown to suppress angiogenesis, inflammation, and carcinogenesis. The mechanisms of these activities, however, are unknown. Because nuclear factor-kappaB (NF-kappaB) is associated with inflammation, carcinogenesis, hyperproliferation, invasion, and angiogenesis, we hypothesized that gossypin mediates its effects through modulation of NF-kappaB activation. In the present study, we demonstrate that gossypin (and not gossypetin, an aglycone analog) inhibited NF-kappaB activation induced by inflammatory stimuli and carcinogens. Constitutive NF-kappaB activation in tumor cells was also inhibited by this flavone. Inhibition of I kappa B alpha kinase by gossypin led to the suppression of I kappa B alpha phosphorylation and degradation, p65 nuclear translocation, and NF-kappaB-regulated gene expression. This, in turn, led to the down-regulation of gene products involved in cell survival (IAP2, XIAP, Bcl-2, Bcl-xL, survivin, and antiFas-associated death domain-like interleukin-1 beta-converting enzyme-inhibitory protein), proliferation (c-myc, cyclin D1, and cyclooxygenase-2), angiogenesis (vascular endothelial growth factor), and invasion (matrix metalloprotease-9). Suppression of these gene products by gossypin enhanced apoptosis induced by tumor necrosis factor and chemotherapeutic agents, suppressed tumor necrosis factor-induced cellular invasion, abrogated receptor activator of NF-kappaB ligand-induced osteoclastogenesis, and vascular endothelial growth factor-induced migration of human umbilical vein endothelial cells. Overall, our results demonstrate that gossypin inhibits the NF-kappaB activation pathway, which may explain its role in the suppression of inflammation, carcinogenesis, and angiogenesis.

Gossypin protects primary cultured rat cortical cells from oxidative stress- and β-amyloid-lnduced toxicity

The present study investigated the effects of gossypin, 3,3',4',5,7,8-hexahydroxyflavone 8-glucoside, on the toxicity induced by oxidative stress or beta-amyloid (Abeta) in primary cultured rat cortical cells. The antioxidant properties of gossypin were also evaluated by cell-free assays. Gossypin was found to inhibit the oxidative neuronal damage induced by xanthine/xanthine oxidase or by a glutathione depleting agent, D,L-buthionine (S,R)-sulfoximine. In addition, gossypin significantly attenuated the neurotoxicity induced by Abeta(25-35). Furthermore, gossypin dramatically inhibited lipid peroxidation initiated by Fe2+ and ascorbic acid in rat brain homogenates. It also exhibited potent radical scavenging activity generated from 1,1-diphenyl-2-picrylhydrazyl. These results indicate that gossypin exerts neuroprotective effects in the cultured cortical cells by inhibiting oxidative stress- and Abeta-induced toxicity, and that the antioxidant properties of gossypin may contribute to its neuroprotective actions.