Protective effects of nobiletin on cisplatin induced neurotoxicity in rats

Nobiletin alleviates cisplatin-induced ototoxicity via activating autophagy and inhibiting NRF2/GPX4-mediated ferroptosis

Nobiletin, a citrus polymethoxy flavonoid with antiapoptotic and antioxidative properties, could safeguard against cisplatin-induced nephrotoxicity and neurotoxicity. Cisplatin, as the pioneer of anti-cancer drug, the severe ototoxicity limits its clinical applications, while the effect of nobiletin on cisplatin-induced ototoxicity has not been identified. The current study investigated the alleviating effect of nobiletin on cisplatin-induced ototoxicity and the underlying mechanisms. Apoptosis and ROS formation were evaluated using the CCK-8 assay, Western blotting, and immunofluorescence, indicating that nobiletin attenuated cisplatin-induced apoptosis and oxidative stress. LC3B and SQSTM1/p62 were determined by Western blotting, qPCR, and immunofluorescence, indicating that nobiletin significantly activated autophagy. Nobiletin promoted the nuclear translocation of NRF2 and the transcription of its target genes, including Hmox1, Nqo1, and ferroptosis markers (Gpx4, Slc7a11, Fth, and Ftl), thereby inhibiting ferroptosis. Furthermore, RNA sequencing analysis verified that autophagy, ferroptosis, and the NRF2 signaling pathway served as crucial points for the protection of nobiletin against ototoxicity caused by cisplatin. Collectively, these results indicated, for the first time, that nobiletin alleviated cisplatin-elicited ototoxicity through suppressing apoptosis and oxidative stress, which were attributed to the activation of autophagy and the inhibition of NRF2/GPX4-mediated ferroptosis. Our study suggested that nobiletin could be a prospective agent for preventing cisplatin-induced hearing loss.

Nobiletin alleviates methotrexate-induced hepatorenal toxicity in rats

We investigated the possible ameliorative effects of nobiletin (NBL) against methotrexate (MTX)-induced hepatorenal toxicity in rats. Twenty-eight Wistar albino rats were randomly divided into four groups, namely: Control; MTX (administered 20 mg/kg MTX); MTX+NBL (administered 20 mg/kg MTX and 10 mg/kg NBL per day); and NBL (administered 10 mg/kg/day NBL). Histopathological, immunohistochemical and biochemical analyses were performed on the kidney and liver tissues of rats at the end of the study. MTX caused renal toxicity, as indicated by increases in malondialdehyde (MDA) and caspase-3, as well as decreases in reduced glutathione (GSH), glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase (GPx), catalase (CAT) and B-cell lymphoma-2 (Bcl-2). MTX also caused hepatotoxicity, as indicated by increases in 8-hydroxy-2'-deoxyguanosine (8-OHdG), tumor necrosis factor alpha (TNF-α), MDA and caspase-3 and decrease in interleukin 10 (IL-10), GSH, total antioxidant capacity, GPx, G6PD, CAT and Bcl-2. MTX caused histopathological changes in kidney and liver tissues indicating tissue and cellular damage. Administration of NBL concurrently with methotrexate reduced oxidative stress, inflammatory and apoptotic signs, and prevented kidney and liver damage caused by methotrexate. We consider NBL has attenuating and ameliorating effects on methotrexate-induced hepatorenal toxicity.

Eucalyptol alleviates cisplatin-induced kidney damage in rats

This study was aimed to explore the therapeutic effect of eucalyptol on cisplatin induced kidney damage in Wistar albino rats. The animals were divided into four groups: sham (S), eucalyptol (E), cisplatin (C), and cisplatin + eucalyptol (CE) randomly, six animals in each group. Groups C and CE were received cisplatin (12 mg/kg, a single dose, intraperitoneally (i.p.)). Groups E and CE were treated with eucalyptol (100 mg/kg, for seven days, orally). The blood samples and kidney tissues were collected following sacrification and analyzed histopathologically and biochemically. Histopathological results revealed tubular degeneration and necrosis, inflammatory cell infiltration, tubular lumen dilatation, enlargement of bowman's space and hyaline cast were significantly irregular in the group C than group S. However, eucalyptol treatment (CE) modulated the alterations in the group C. Serum levels of blood urea nitrogen (BUN) and creatinine (CRE) were considerably higher in the group C compared to the other groups. There was no significant difference among the other groups statistically (except group C) in terms of BUN and CRE values. Eucalyptol treatment (at 100 mg/kg, for seven days) decreased the cisplatin induced increase in serum BUN and CRE levels and restored the reduced Vit C level and CAT activity of kidneys caused by cisplatin. Thus, eucalyptol's antioxidative, nephroprotective, and curative effects indicated the potential for future drug development.

A review on recent advances on nobiletin in central and peripheral nervous system diseases

In recent years, the role of nobiletin in neuronal disorders has received extensive attention. However, the study of nobiletin in the peripheral nervous system is limited. Nobiletin, as a compound with high fat solubility, high bioavailability and low toxicity, has been extensively studied. Accumulating scientific evidence has shown that nobiletin has a variety of biological functions in the nervous system, such as inhibiting the expression of inflammatory factors, reducing the neurotoxic response, improving the antioxidant capacity, promoting the survival of nerve cells, promoting axon growth, reducing blood‒brain barrier permeability, reducing brain oedema, promoting cAMP response element binding protein expression, improving memory, and promoting mild depolarization of nerve cell mitochondria to improve antioxidative stress capacity. Accumulating studies have shown that nobiletin also protects enteric nervous system, spinal cord and sciatic nerve. To explore the new therapeutic potential of nobiletin in the nervous system, recent and relevant research progress is reviewed in this article. This will provide a new research idea for nobiletin in the nervous system.

Neuroprotective Potential of Intranasally Delivered Sulforaphane-Loaded Iron Oxide Nanoparticles Against Cisplatin-Induced Neurotoxicity

Cisplatin (CIS) is a platinum-based chemotherapeutic drug that is widely used to treat cancer. However, its therapeutic efficiency is limited due to its potential to provoke neurotoxicity. Sulforaphane (SF) is a natural phytochemical that demonstrated several protective activities. Iron oxide nanoparticles (Fe₃O₄-NPs) could be used as drug carriers. This study aimed to explore the nanotoxic influence of SF-loaded within Fe₃O₄-NPs (N.SF), and to compare the neuroprotective potential of both N.SF and SF against CIS-induced neurotoxicity. N.SF or SF was administrated intranasally for 5 days before and 3 days after a single dose of CIS (12 mg/kg/week, i.p.) on the 6^th day. Neuromuscular coordination was assessed using hanging wire and tail-flick tests. Acetylcholinesterase (AChE) activities and markers of oxidative stress were measured in the brain. In addition, the brain iron (Fe) content was estimated. CIS significantly induced a significant increase in AChE activities and lipid peroxides, and a significant decrement in glutathione (GSH) and nitric oxide (NO) contents. CIS elicited impaired neuromuscular function and thermal hyperalgesia. CIS-induced brains displayed a significant reduction in Fe content. Histopathological examination of different brain regions supported the biochemical and behavioral results. Contradict, treatment of CIS-rats with either N.SF or SF significantly decreased AChE activity, mitigated oxidative stress, and ameliorated the behavioral outcome. The histopathological features supported our results. Collectively, N.SF demonstrated superior neuroprotective activities on the behavioral, biochemical, and histopathological (striatum and cerebral cortex) aspects. N.SF could be regarded as a promising “pre-clinical” neuroprotective agent. Furthermore, this study confirmed the safe toxicological profile of Fe₃O₄-NPs.

Nobiletin prevents amyloid β1-40-induced cognitive impairment via inhibition of neuroinflammation and oxidative/nitrosative stress

Alzheimer's disease (AD) is presented as an age-related neurodegenerative disease with multiple cognitive deficits and amyloid β (Aβ) accumulation is the most important involved factor in its development. Nobiletin is a bioflavonoid isolated from citrus fruits peels with anti-inflammatory and anti-oxidative activity as well as anti-dementia property that has shown potency to ameliorate intracellular and extracellular Ab. The aim of the present study was to assess protective effect of nobiletin against Aβ_1-40-induced cognitive impairment as a consistent model of AD. After bilateral intrahippocampal (CA1 subfield) injection of Aβ_1-40, rats were treated with nobiletin (10 mg/kg/day; p.o.) from stereotaxic surgery day (day 0) till day + 7. Cognition function was evaluated in a battery of behavioral tasks at week 3 with final assessment of hippocampal oxidative stress and inflammation besides Nissl staining and 3-nitrotyrosine (3-NT) immunohistochemistry. Analysis of behavioral data showed notable and significant improvement of alternation in Y maze test, discrimination ratio in novel object recognition task, and step through latency in passive avoidance test in nobiletin-treated Aβ group. Additionally, nobiletin treatment was associated with lower hippocampal levels of MDA and ROS and partial reversal of SOD activity and also improvement of Nrf2 with no significant effect on GSH and catalase. Furthermore, nobiletin attenuated hippocampal neuroinflammation in Aβ group as shown by lower tissue levels of TLR4, NF-kB, and TNFa. Histochemical findings showed that nobiletin prevents CA1 neuronal loss in Nissl staining in addition to its alleviation of 3-nitrotyrosine (3-NT) immunoreactivity as a marker of nitrosative stress. Collectively, these findings indicated neuroprotective and anti-dementia potential of nobiletin that is partly attributed to its anti-oxidative, anti-nitrosative, and anti-inflammatory property associated with proper modulation of TLR4/NF-kB/Nrf2 pathways.

Nobiletin Ameliorates Cellular Damage and Stress Response and Restores Neuronal Identity Altered by Sodium Arsenate Exposure in Human iPSCs-Derived hNPCs

Environmental exposure to arsenic has been profoundly associated with chronic systemic disorders, such as neurodegeneration, in both experimental models and clinical studies. The neuronal cells of the brain and the nervous system have a limited regeneration capacity, thus making them more vulnerable to exposure to xenobiotics, leading to long-lasting disabilities. The functional and anatomical complexity of these cells hinders the complete understanding of the mechanisms of neurodegeneration and neuroprotection. The present investigations aimed to evaluate the neuroprotective efficacy of a herbal formulation of Nobiletin (NOB) against the toxic insult induced by sodium arsenate (NA) in human neural progenitor cells (hNPCs) derived from human induced pluripotent stem cells (hiPSCs). Prior to the neuroprotective experiments, biologically safe doses of both NOB and NA were ascertained using standard endpoints of cytotoxicity. Thereafter, the hNPCs were exposed to either NOB (50 μM) or NA (50 μM) and co-exposed to biologically safe concentrations of NA (50 μM) with NOB (50 μM) for a period of up to 48 h. NOB treatment restored the morphological damage (neurite damage), the levels of stress granule G3BP1 (Ras-GTPase-activating protein (SH3 domain)-binding protein) and TIA1 (T cell-restricted intracellular antigen), and the expression of neuronal markers (Tuj1, Nestin, MAP2, and PAX6) when compared to NA-exposed cells. A substantial restoration of reactive oxygen species and mitochondrial membrane potential was also witnessed in the co-exposure group (NA + NOB) in comparison to the NA-exposed group. The findings suggest that NOB possesses a significant restorative/protective potential against the NA challenge in hNPCs under experimental conditions and imply that nobiletin may impart a potential therapeutic impact if studied adequately using in vivo studies.

The pharmacokinetic study on the interaction between nobiletin and anemarsaponin BII in vivo and in vitro

CONTEXT

The interaction between nobiletin and anemarsaponin BII could affect the pharmacological activity of these two drugs during their combination.

OBJECTIVE

The co-administration of nobiletin and anemarsaponin BII was investigated to explore the interaction and the potential mechanism.

MATERIALS AND METHODS

Male Sprague-Dawley rats were only orally administrated with 50 mg/kg nobiletin as the control and another six rats were pre-treated with 100 mg/kg anemarsaponin BII for 7 d followed by the administration of nobiletin. The transport and metabolic stability of nobiletin were evaluated in vitro, and the effect of anemarsaponin BII on the activity of CYP3A4 was also assessed to explore the potential mechanism underlying the interaction.

RESULTS

The increasing C_max (2309.67 ± 68.06 μg/L vs. 1767.67 ± 68.86 μg/L), AUC (28.84 ± 1.34 mg/L × h vs. 19.57 ± 2.76 mg/L × h), prolonged t_1/2 (9.80 ± 2.33 h vs. 6.24 ± 1.53 h), and decreased clearance rate (1.46 ± 0.26 vs. 2.42 ± 0.40) of nobilein was observed in rats. Anemarsaponin BII significantly enhanced the metabolic stability of nobiletin in rat liver microsomes (half-life increased from 31.56 min to 39.44 min) and suppressed the transport of nobiletin in Caco-2 cells (efflux rate decreased from 1.57 ± 0.04 to 1.30 ± 0.03). The inhibitory effect of anemarsaponin BII on CYP3A4 was also found with an IC₅₀ value of 10.23 μM.

DISCUSSION AND CONCLUSIONS

The interaction between anemarsaponin BII and nobiletin was induced by the inhibition of CYP3A4, which should draw special attention in their clinical co-administration.

Nobiletin Attenuates Pathological Cardiac Remodeling after Myocardial Infarction via Activating PPARγ and PGC1α

Materials and Methods

C57BL/6 mice were treated with coronary artery ligation to generate an MI model, followed by treatment for 3 weeks with NOB (50 mg/kg/d) or vehicle (50 mg/kg/d), with or without the peroxisome proliferator-activated receptor gamma (PPARγ) inhibitor T0070907 (1 mg/kg/d). Cardiac function (echocardiography, survival rate, Evans blue, and triphenyl tetrazolium chloride staining), fibrosis (Masson's trichrome staining, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot (WB)), hypertrophy (haematoxylin-eosin staining, wheat germ agglutinin staining, and qRT-PCR), and apoptosis (WB and terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining) were evaluated. Hypoxia-induced apoptosis (TUNEL, WB) and phenylephrine- (PE-) induced pathological hypertrophy (immunofluorescence staining, qRT-PCR) models were established in primary neonatal rat ventricular myocytes (NRVMs). The effects of NOB with or without T0070907 were examined for the expression of PPARγ and PPARγ coactivator 1α (PGC1α) by WB in mice and NRVMs. The potential downstream effectors of PPARγ were further analyzed by WB in mice.

Results

Following MI in mice, NOB intervention enhanced cardiac function across three predominant dimensions of pathological cardiac remodeling, which reflected in decreasing cardiac fibrosis, apoptosis, and hypertrophy decompensation. NOB intervention also alleviated apoptosis and hypertrophy in NRVMs. NOB intervention upregulated PPARγ and PGC1α in vivo and in vitro. Furthermore, the PPARγ inhibitor abolished the protective effects of NOB against pathological cardiac remodeling during the progression from MI to CHF. The potential downstream effectors of PPARγ were nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase 1 (HO-1).

Conclusions

Our findings suggested that NOB alleviates pathological cardiac remodeling after MI via PPARγ and PGC1α upregulation.