Methyl 3,4-dihydroxybenzoate protects primary cortical neurons against Aβ25-35-induced neurotoxicity through mitochondria pathway

Methyl 3,4-dihydroxybenzoate alleviates oxidative damage in granulosa cells by activating Nrf2 antioxidant pathway

Oxidative damage induced granulosa cells (GCs) apoptosis was considered as a significant cause of compromised follicle quality, antioxidants therapy has emerged as a potential method for improving endometriosis pregnancy outcomes. Here, we found that GCs from endometriosis patients show increased oxidative stress level. Methyl 3,4-dihydroxybenzoate (MDHB), a small molecule compound that is extracted from natural plants, reversed tert-butyl hydroperoxide (TBHP) induced GCs oxidative damage. Therefore, the aim of this study was to assess the protective effect of MDHB for GCs and its potential mechanisms. TUNEL staining and immunoblotting of cleaved caspase-3/7/9 showed MDHB attenuated TBHP induced GCs apoptosis. Mechanistically, MDHB treatment decreased cellular and mitochondria ROS production, improved the mitochondrial function by rescuing the mitochondrial membrane potential (MMP) and ATP production. Meanwhile, MDHB protein upregulated the expression of vital antioxidant transcriptional factor Nrf2 and antioxidant enzymes SOD1, NQO1 and GCLC to inhibited oxidative stress state, further beneficial to oocytes and embryos quality. Therefore, MDHB may represent a potential drug candidate in protecting granulosa cells in endometriosis, which can improve pregnancy outcomes for endometriosis-associated infertility.

Methyl 3,4-dihydroxybenzoate inhibits RANKL-induced osteoclastogenesis via Nrf2 signaling in vitro and suppresses LPS-induced osteolysis and ovariectomy-induced osteoporosis in vivo

Osteoporosis deteriorates bone mass and biomechanical strength and is life-threatening to the elderly. In this study, we show that methyl 3,4-dihydroxybenzoate (MDHB), an antioxidant small-molecule compound extracted from natural plants, inhibits receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis in vitro. Furthermore, MDHB attenuates the activation of mitogen-activated protein kinase (MAPK) and NF-κB pathways by reducing the levels of reactive oxygen species (ROS), which leads to downregulated protein expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1). We also confirm that MDHB upregulates the protein expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), an important transcription factor involved in ROS regulation, by inhibiting the ubiquitination-mediated proteasomal degradation of Nrf2. Next, animal experiments show that MDHB has an effective therapeutic effect on lipopolysaccharide (LPS)- and ovariectomized (OVX)-induced bone loss in mice. Our study demonstrates that MDHB can upregulate Nrf2 and suppress excessive osteoclast activity in mice to treat osteoporosis.

Gallic Acid Induces Neural Stem Cell Differentiation into Neurons and Proliferation through the MAPK/ERK Pathway

Neural stem cell (NSC) differentiation and proliferation are important biological processes in the cerebral neural network. However, these two abilities of NSCs are limited. Thus, the induction of differentiation and/or proliferation through the administration of plant-derived small-molecule compounds could be used to repair damaged neural networks. The present study reported that gallic acid (GA), an important phenolic acid found in tea, selectively caused NSCs to differentiate into immature neurons and promoted NSC proliferation by activating the mitogen-activated protein kinase/extracellular-regulated kinase (MAPK/ERK) pathway. In addition, it was found that 3,4-dihydroxybenzoic acid was the main active structure exhibiting neurotrophic activity. The substitution of the carboxyl group on the benzene ring with the ester group may promote differentiation based on the structure of 3,4-dihydroxybenzoic acid. Furthermore, the introduction of the 5-hydroxyl group may promote proliferation. The present study identified that GA can promote the differentiation and proliferation of NSCs in vitro and exert pharmacological activity on NSCs.

Extensive metabolism of flavonoids relevant to their potential efficacy on Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder, the incidence of which is climbing with ever-growing aged population, but no cure is hitherto available. The epidemiological studies unveiled that chronic intake of flavonoids was negatively associated with AD risk. Flavonoids, a family of natural polyphenols widely distributed in human daily diets, were readily conjugated by phase II drug metabolizing enzymes after absorption in vivo, and glucuronidation could occur in 1 min following intravenous administration. Recently, as many as 191 metabolites were obtained after intragastric administration of a single flavonoid, indicating that other bioactive metabolites, besides conjugates, might be formed and account for the contradiction between efficacy of flavonoids in human or animal models and low systematic exposure of flavonoid glycosides or aglycones. In this review, metabolism of complete 68 flavonoid monomers potential for AD treatment, grouped in flavonoid O-glycosides, flavonoid aglycones, flavonoid C-glycosides, flavonoid dimers, flavonolignans and prenylated flavonoids according to their common structural elements, respectively, has been systematically retrospected, summarized and discussed, including their unequivocally identified metabolites, metabolic interconversions, metabolic locations, metabolic sites (regio- or stereo-selectivity), primarily involved metabolic enzymes or intestinal bacteria, and interspecies correlations or differences in metabolism, and their bioactive metabolites and the underlying mechanism to reverse AD pathology were also reviewed, providing whole perspective about advances on extensive metabolism of diverse potent flavonoids in vivo and in vitro up to date and aiming at elucidation of mechanism of actions of flavonoids on AD or other central nervous system (CNS) disorders.

Excretion, Metabolism and Cytochrome P450 Inhibition of Methyl 3,4-Dihydroxybenzoate (MDHB): A Potential Candidate to Treat Neurodegenerative Diseases

BACKGROUND AND OBJECTIVES

Methyl 3,4-dihydroxybenzoate (MDHB) has the potential to prevent neurodegenerative diseases (NDDs). The present work investigated its excretion, metabolism, and cytochrome P450-based drug-drug interactions (DDIs).

METHODS

After intragastric administration of MDHB, the parent drug was assayed in the urine and faeces of mice. Metabolites of MDHB in the urine, faeces, brain, plasma and liver were detected by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). A cocktail approach was used to evaluate the inhibition of cytochrome P450 isoforms by MDHB.

RESULTS

The cumulative excretion permille of MDHB in the urine and faeces were found to be 0.67 ± 0.31 and 0.49 ± 0.44‰, respectively. A total of 96 metabolites of MDHB were identified, and all IC₅₀ (half-maximal inhibitory concentration) values of MDHB towards cytochrome P450 isoforms were > 100 μM.

CONCLUSIONS

The results suggest that MDHB has a low parent drug cumulative excretion percentage and that MDHB has multiple metabolites and is mainly metabolized through the loss of -CH₂ and -CO₂, the loss of -CH₂O, ester bond hydrolysis, the loss of -O and -CO₂, isomerization, methylation, sulfate conjugation, the loss of -CH₂O and -O and glycine conjugation, glycine conjugation, the loss of two -O groups and alanine conjugation, the loss of -CH₂O and -O and glucose conjugation, glucuronidation, glucose conjugation, etc., in vivo. Finally, MDHB has a low probability of cytochrome P450-based DDIs.

Methyl 3,4-dihydroxybenzoate protects against d-galN/LPS-induced acute liver injury by inhibiting inflammation and apoptosis in mice

Objectives

Aimed to investigate the effect and mechanism of methyl 3,4-dihydroxybenzoate (MDHB) on d-galactosamine/lipopolysaccharide (d-galN/LPS)-induced acute liver failure (ALF).

Methods

Confirmed the hepatoprotective effect and hepatotoxicity of MDHB by histopathological examination (HE) and examination of alanine aminotransferase (ALT) and aspartate aminotransferase (AST); the expression of serum tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) was detected by ELISA; transcription levels of TNF-α, IL-1β, IL-6 and Toll-like receptor 4 (TLR4) were detected by qRT-PCR; and phosphorylation levels of p38 and p65 were analysed by Western blot.

Results

Histopathological examination and examination of ALT and AST confirmed that MDHB is a low toxicity drug that can resist d-galN/LPS-induced ALF; MDHB can effectively reduce high transcription and expression of TNF-α, IL-1β, IL-6 and TLR4 in d-galN/LPS-induced ALF; and Western blot showed that MDHB could down-regulate the expression of bax, up-regulate the expression of bcl-xl and bcl-2, and inhibit the phosphorylation of p38 and p65.

Conclusions

Methyl 3,4-dihydroxybenzoate can effectively resist d-galN/LPS-induced acute liver failure, which is related to the inhibition of inflammation and apoptosis.

Methyl 3,4-dihydroxybenzoate protects retina in a mouse model of acute ocular hypertension through multiple pathways

Methyl 3,4 dihydroxybenzoate (MDHB) is a small molecule that shows neuroprotective effects in vitro and in a photoreceptor-degenerative mouse model. Here we investigated whether MDHB protects retina in a mouse model of acute ocular hypertension (AOH) and explores the underlying mechanisms. AOH was induced in mice by increasing intraocular pressure to approximately 90 mmHg for 60 min, then MDHB or vehicle was intraperitoneally injected daily up to 7 days. Immunostaining and multi-electrode array recordings were performed to examine the structure and function of retinas receiving the treatments. Western-blotting was applied to test the expression of several proteins related to oxidative stress and brain-derived neurotrophic factor (BDNF)-initiated signaling. Results showed that AOH injury reduced the number of Brn3a-stained retinal ganglion cells (RGCs) and ChAT-amacrine cells; thinned the inner retinal layers and induced apoptosis. Physiologically, AOH decreased the response of OFF and ON-OFF RGCs. All of these changes were reversed by MDHB-treatment. Mechanistically, MDHB appeared to work on three parallel pathways: (1) MDHB decreased the production of reactive oxygen species, the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and cytosol heme oxygenase 1 (HO-1); (2) It upregulated the expression of BDNF and its receptor tropomyosin-related kinase B (TrkB), and activated the downstream AKT pathways; (3) It inhibited reactive gliosis by reducing GFAP and Iba-1 expression. Thus our results suggest that MDHB protects retina against AOH injury by inhibiting oxidative stress, activating the BDNF/AKT signaling and inhibiting inflammatory pathways. Therefore, MDHB may serve as a promising candidate to treat retinal ischemia.

Methyl 3,4-Dihydroxybenzoate Induces Neural Stem Cells to Differentiate Into Cholinergic Neurons in vitro

Neural stem cells (NSCs) have been shown as a potential source for replacing degenerated neurons in neurodegenerative diseases. However, the therapeutic potential of these cells is limited by the lack of effective methodologies for controlling their differentiation. Inducing endogenous pools of NSCs by small molecule can be considered as a potential approach of generating the desired cell types in large numbers. Here, we reported the characterization of a small molecule (Methyl 3,4-dihydroxybenzoate; MDHB) that selectively induces hippocampal NSCs to differentiate into cholinergic motor neurons which expressed synapsin 1 (SYN1) and postsynaptic density protein 95 (PSD-95). Studies on the mechanisms revealed that MDHB induced the hippocampal NSCs differentiation into cholinergic motor neurons by inhibiting AKT phosphorylation and activating autophosphorylation of GSK3β at tyrosine 216. Furthermore, we found that MDHB enhanced β-catenin degradation and abolished its entering into the nucleus. Collectively, this report provides the strong evidence that MDHB promotes NSCs differentiation into cholinergic motor neurons by enhancing gene Isl1 expression and inhibiting cell cycle progression. It may provide a basis for pharmacological effects of MDHB directed on NSCs.

Determination of the Pharmacokinetics and Tissue Distribution of Methyl 3,4-Dihydroxybenzoate (MDHB) in Mice Using Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND AND OBJECTIVES

Methyl 3,4-dihydroxybenzoate (MDHB) has the potential to prevent neurodegenerative diseases (NDDs). The present work aims to reveal the pharmacokinetics and tissue distribution characteristics of MDHB.

METHODS

The pharmacokinetics and tissue distribution of MDHB were analyzed using LC-MS/MS after a single intragastric administration (50 to 450 mg/kg) in mice, and samples were collected from five animals at specific time points.

RESULTS

Pharmacokinetic parameters of MDHB following intragastric administrations were: the time to peak concentration (T_max) ranged from 0.033 to 0.07 h, the peak concentration (C_max) ranged from 12,379.158 to 109798.712 μg/l, the elimination half-life (t_1/2z) ranged from 0.153 to 1.291 h, the area under the curve (AUC_0-∞) ranged from 640.654 to 20,241.081 μg/l × h, the mean residence time (MRT_0-∞) ranged from 0.071 to 0.206 h, the apparent volume of distribution (V_z/F) ranged from 17.538 to 45.244 l/kg, and the systemic clearance (Cl_z/F) ranged from 22.541 to 80.807 l/h/kg. The oral bioavailability of MDHB was 23%. The maximum MDHB content was detected in the stomach, and the minimum content was observed in the testes; the peak content in the brain was 15,666.93 ng/g.

CONCLUSIONS

The pharmacokinetic characteristics of MDHB include fast absorption, high systemic clearance, a short half-life and an oral bioavailability of 23%. Additionally, MDHB permeates the blood-brain barrier (BBB) and is rapidly distributed to all organs. The identification of the pharmacokinetics of MDHB following its oral administration will contribute to further preclinical and clinical studies of its effects.

Neuroprotective Effects of Methyl 3,4-Dihydroxybenzoate against TBHP-Induced Oxidative Damage in SH-SY5Y Cells

This study investigated the neuroprotective effects of methyl 3,4-dihydroxybenzoate (MDHB) against t-butyl hydroperoxide (TBHP) induced oxidative damage in SH-SY5Y (human neuroblastoma cells) and the underlying mechanisms. SH-SY5Y were cultured in DMEM + 10% FBS for 24 h and pretreated with different concentrations of MDHB or N-acetyl-l-cysteine (NAC) for 4 h prior to the addition of 40 μM TBHP for 24 h. Cell viability was analyzed using the methylthiazolyltetrazolium (MTT) and lactate dehydrogenase (LDH) assays. An annexin V-FITC assay was used to detect cell apoptosis rates. The 2',7'-dichlorofluorescin diacetate (DCFH-DA) assay was used to determine intracellular ROS levels. The activities of antioxidative enzymes (GSH-Px and SOD) were measured using commercially available kits. The oxidative DNA damage marker 8-OHdG was detected using ELISA. Western blotting was used to determine the expression of Bcl-2, Bax, caspase 3, p-Akt and Akt proteins in treated SH-SY5Y cells. Our results showed that MDHB is an effective neuroprotective compound that can mitigate oxidative stress and inhibit apoptosis in SH-SY5Y cells.

Methyl 3,4-dihydroxybenzoate promote rat cortical neurons survival and neurite outgrowth through the adenosine A2a receptor/PI3K/Akt signaling pathway

Methyl 3,4-dihydroxybenzoate (MDHB), a kind of phenolic acid compounds, has been reported to have antioxidant effects. Moreover, our previous study found that it could promote neurite outgrowth and brain-derived neurotrophic factor expression in cortical neurons of neonatal rats. In the present study, we focused on the mechanism of its neurotrophic effect; the results showed that MDHB-induced upregulation of neuronal survival and neurite outgrowth in cultured primary cortical neurons could be blocked by the adenosine A2a receptor inhibitor (ZM241385) and the phosphoinositide 3-kinase (PI3K) inhibitor (LY294002). Subsequently, we found that the upregulation of Akt phosphorylation by MDHB could be suppressed by A2a-R and PI3K-specific inhibitor, but not the Trk-R inhibitor. Furthermore, MDHB could activate Akt in a concentration-dependent manner. These results suggested that activation of the PI3K/Akt signaling pathway may be involved in the MDHB-induced neurotrophic effects and MDHB could be a candidate compound to develop drugs for neurodegenerative disease.

Oncostatin M-dependent Mcl-1 induction mediated by JAK1/2-STAT1/3 and CREB contributes to bioenergetic improvements and protective effects against mitochondrial dysfunction in cortical neurons

Oncostatin M (OSM), a cytokine in the interleukin-6 (IL-6) family, has been proposed to play a protective role in the central nervous system, such as attenuation of excitotoxicity induced by N-methyl-D-aspartate (NMDA) and glutamate. However, the potential neuroprotective effects of OSM against mitochondrial dysfunction have never been reported. In the present study, we tested the hypothesis that OSM may confer neuronal resistance against 3-nitropropionic acid (3-NP), a plant toxin that irreversibly inhibits the complex II of the mitochondrial electron transport chain, and characterized the underlying molecular mechanisms. We found that OSM preconditioning dose- and time-dependently protected cortical neurons against 3-NP toxicity. OSM stimulated expression of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic Bcl-2 family member expressed in differentiating myeloid cells, that required prior phosphorylation of Janus kinase-1 (JAK1), JAK2, extracellular signal-regulated kinase-1/2 (ERK1/2), signal transducer and activator of transcription-3 (STAT3), STAT1, and cAMP-response element-binding protein (CREB). Pharmacological inhibitors of JAK1, JAK2, ERK1/2, STAT3, STAT1, and CREB as well as the siRNA targeting at STAT3 and Mcl-1 all abolished OSM-dependent 3-NP resistance. Finally, OSM-dependent Mcl-1 induction contributed to the enhancements of mitochondrial bioenergetics including increases in spare respiratory capacity and ATP production. In conclusion, our findings indicated that OSM induces Mcl-1 expression via activation of ERK1/2, JAK1/2, STAT1/3, and CREB; furthermore, OSM-mediated Mcl-1 induction contributes to bioenergetic improvements and neuroprotective effects against 3-NP toxicity in cortical neurons. OSM may thus serve as a novel neuroprotective agent against mitochondrial dysfunction commonly associated with pathogenic mechanisms underlying neurodegeneration.

Methyl 3,4-dihydroxybenzoate extends the lifespan of Caenorhabditis elegans, partly via W06A7.4 gene

To identify and analyze the compounds that delay aging and extend the lifespan is an important aspect of the gerontology research. A number of compounds, including the ones with the antioxidant properties, have been shown to extend the lifespan of Caenorhabditis elegans. Here, we report that methyl 3,4-dihydroxybenzoate (MDHB), a small antioxidant molecule, prolongs the C. elegans' lifespan under normal as well as stress conditions, delays the age-associated decline in the pharyngeal pumping rate, and obviously enhances the abilities of scavenging intracellular reactive oxygen species (ROS). To further investigate the mechanism underlying the anti-aging action of MDHB, microarray analyses were performed, which demonstrated that 13 genes were differentially expressed in worms treated with MDHB for 48 and 144 h in common. RNA interference of W06A7.4 (NM_001269697.1), the most significantly up-regulated gene, shortened the lifespan of worms by 14%, compared with the L4440 control. Our findings demonstrate that W06A7.4 is a potentially positive determinant of the MDHB induced C. elegans' lifespan extension effect.

Degradation of cyanidin-3-rutinoside and formation of protocatechuic acid methyl ester in methanol solution by gamma irradiation

Anthocyanins are naturally occurring phenolic compounds having broad biological activities including anti-mutagenesis and anti-carcinogenesis. We studied the effects and the degradation mechanisms of the most common type of anthocyanins, cyanidin-3-rutinoside (cya-3-rut), by using gamma ray. Cya-3-rut in methanol (1mg/ml) was exposed to gamma-rays from 1 to 10kGy. We found that the reddish colour of cya-3-rut in methanol disappeared gradually in a dose-dependent manner and effectively disappeared (>97%) at 10kGy of gamma ray. Concomitantly, a new phenolic compound was generated and identified as a protocatechuic acid methyl ester by liquid chromatography, (1)H, and (13)C NMR. The formation of protocatechuic acid methyl ester increased with increasing irradiation and the amount of protocatechuic acid methyl ester formed by decomposition of cya-3-rut (20μg) at 10kGy of gamma ray was 1.95μg. In addition, the radical-scavenging activities were not affected by gamma irradiation.

Pharmacogenomics of Alzheimer's disease: novel therapeutic strategies for drug development

Alzheimer's disease (AD) is a major problem of health and disability, with a relevant economic impact on our society. Despite important advances in pathogenesis, diagnosis, and treatment, its primary causes still remain elusive, accurate biomarkers are not well characterized, and the available pharmacological treatments are not cost-effective. As a complex disorder, AD is a polygenic and multifactorial clinical entity in which hundreds of defective genes distributed across the human genome may contribute to its pathogenesis. Diverse environmental factors, cerebrovascular dysfunction, and epigenetic phenomena, together with structural and functional genomic dysfunctions, lead to amyloid deposition, neurofibrillary tangle formation, and premature neuronal death, the major neuropathological hallmarks of AD. Future perspectives for the global management of AD predict that genomics and proteomics may help in the search for reliable biomarkers. In practical terms, the therapeutic response to conventional drugs (cholinesterase inhibitors, multifactorial strategies) is genotype-specific. Genomic factors potentially involved in AD pharmacogenomics include at least five categories of gene clusters: (1) genes associated with disease pathogenesis; (2) genes associated with the mechanism of action of drugs; (3) genes associated with drug metabolism (phase I and II reactions); (4) genes associated with drug transporters; and (5) pleiotropic genes involved in multifaceted cascades and metabolic reactions. The implementation of pharmacogenomic strategies will contribute to optimize drug development and therapeutics in AD and related disorders.