Nephroprotective Effects of Tetramethylpyrazine Nitrone TBN in Diabetic Kidney Disease

Targeting mitochondrial dysfunction: an innovative strategy for treating renal fibrosis

The incidence and hospitalization rate of kidney disease, especially end-stage renal disease, have increased significantly, which seriously endangers the health of patients. Mitochondria are the core organelles of cellular energy metabolism, and their dysfunction can lead to kidney energy supply insufficiency and oxidative stress damage, which has become a global public health problem. Studies have shown that the disturbance of mitochondrial quality control mechanisms, including mitochondrial dynamics, autophagy, oxidative stress regulation and biosynthesis, is closely related to the occurrence and development of renal fibrosis (RF). As a multicellular pathological process, RF involves the injury and shedding of podocytes, the transdifferentiation of renal tubular epithelial cells, the activation of fibroblasts, and the infiltration of macrophages, among which the mitochondrial dysfunction plays an important role. This review systematically elaborates the molecular mechanisms of mitochondrial damage during RF progression, aiming to provide theoretical foundations for developing novel therapeutic strategies to delay RF advancement.

Renal Health Through Medicine-Food Homology: A Comprehensive Review of Botanical Micronutrients and Their Mechanisms

BACKGROUND

As an ancient concept and practice, "food as medicine" or "medicine-food homology" is receiving more and more attention these days. It is a tradition in many regions to intake medicinal herbal food for potential health benefits to various organs and systems including the kidney. Kidney diseases usually lack targeted therapy and face irreversible loss of function, leading to dialysis dependence. As the most important organ for endogenous metabolite and exogenous nutrient excretion, the status of the kidney could be closely related to daily diet. Therefore, medicinal herbal food rich in antioxidative, anti-inflammation micronutrients are ideal supplements for kidney protection. Recent studies have also discovered its impact on the "gut-kidney" axis.

METHODS

Here, we review and highlight the kidney-protective effects of botanicals with medicine-food homology including the most frequently used Astragalus membranaceus and Angelica sinensis (Oliv.) Diels, concerning their micronutrients and mechanism, offering a basis and perspective for utilizing and exploring the key substances in medicinal herbal food to protect the kidney.

RESULTS

The index for medicine-food homology in China contains mostly botanicals while many of them are also consumed by people in other regions. Micronutrients including flavonoids, polysaccharides and others present powerful activities towards renal diseases.

CONCLUSIONS

Botanicals with medicine-food homology are widely speeded over multiple regions and incorporating these natural compounds into dietary habits or as supplements shows promising future for renal health.

Tetramethylpyrazine nitrone delays the aging process of C. elegans by improving mitochondrial function through the AMPK/mTORC1 signaling pathway

Aging is characterized as the process of functional decline in an organism from adulthood, often marked by a progressive loss of cellular function and systemic deterioration of multiple tissues. Among the numerous molecular, cellular, and systemic hallmarks associated with aging, mitochondrial dysfunction is considered one of the pivotal factors that initiates the aging process. During aging, mitochondria undergo varying degrees of damage, resulting in impaired energy production and disruption of the homeostatic regulation of mitochondrial quality control systems, which in turn affects cellular energy metabolism and results in cellular dysfunction, accelerating the aging process. AMP-activated protein kinase (AMPK) and the mechanistic target of rapamycin complex 1 (mTORC1) are two central kinase complexes responsible for sensing intracellular nutrient levels, regulating metabolic homeostasis, modulating aging and play a crucial role in maintaining the homeostatic balance of mitochondria. Our previous studies found that the novel compound tetramethylpyrazine nitrone (TBN) can protect mitochondria via the AMPK/mTOR pathway in many animal models, extending healthy lifespan through the Nrf2 signaling pathway in nematodes. Building upon this foundation, we have posited a reasonable hypothesis, TBN can improve mitochondrial function to delay aging by regulating the AMPK/mTORC1 signaling pathway. This study focuses on the C. elegans, exploring the impact and underlying mechanisms of TBN on aging and mitochondrial function (especially the mitochondrial quality control system) during the aging process. The present studies demonstrated that TBN extends lifespan of wild-type nematodes and is associated with the AMPK/mTORC1 signaling pathway. TBN elevated ATP and NAD+ levels in aging nematodes while orchestrating mitochondrial biogenesis and mitophagy. Moreover, TBN was observed to significantly enhance normal activities during aging in C. elegans, such as mobility and pharyngeal pumping, concurrently impeding lipofuscin accumulation that were closely associated with AMPK and mTORC1. This study not only highlights the delayed effects of TBN on aging but also underscores its potential application in strategies aimed at improving mitochondrial function via the AMPK/mTOR pathway in C. elegans.

Tetramethylpyrazine Nitrone (TBN) Reduces Amyloid β Deposition in Alzheimer's Disease Models by Modulating APP Expression, BACE1 Activity, and Autophagy Pathways

Alzheimer's disease (AD) is a neurodegenerative disorder associated with age. A wealth of evidence indicates that the amyloid β (Aβ) aggregates result from dyshomeostasis between Aβ production and clearance, which plays a pivotal role in the pathogenesis of AD. Consequently, therapies targeting Aβ reduction represent a promising strategy for AD intervention. Tetramethylpyrazine nitrone (TBN) is a novel tetramethylpyrazine derivative with potential for the treatment of AD. Previously, we demonstrated that TBN markedly enhanced cognitive functions and decreased the levels of Aβ, APP, BACE 1, and hyperphosphorylated tau in 3×Tg-AD mice. However, the mechanism by which TBN inhibits Aβ deposition is still unclear. In this study, we employed APP/PS1 mice treated with TBN (60 mg/kg, ig, bid) for six months, and N2a/APP695swe cells treated with TBN (300 μM) to explore the mechanism of TBN in Aβ reduction. Our results indicate that TBN significantly alleviated cognitive impairment and reduced Aβ deposition in APP/PS1 mice. Further investigation of the underlying mechanisms revealed that TBN decreased the expression of APP and BACE1, activated the AMPK/mTOR/ULK1 autophagy pathway, inhibited the PI3K/AKT/mTOR/ULK1 autophagy pathway, and decreased the phosphorylation levels of JNK and ERK in APP/PS1 mice. Moreover, TBN was found to significantly reduce the mRNA levels of APP and BACE1, as well as those of SP1, CTCF, TGF-β, and NF-κB, transcription factors involved in regulating gene expression. Additionally, TBN was observed to decrease the level of miR-346 and increase the levels of miR-147 and miR-106a in the N2a/APP695swe cells. These findings indicate that TBN may reduce Aβ levels likely by reducing APP expression by regulating APP gene transcriptional factors and miRNAs, reducing BACE1 expression, and promoting autophagy activities.

Palladium-Catalyzed Synthesis of Nitrones Via Redox Cross-Coupling of Nitro Compounds and Alcohols

A novel methodology for the synthesis of nitrones via palladium-catalyzed redox cross-coupling of nitro compounds and alcohols is established. The protocol is a mild, convenient, ligand-free, and scalable synthesis method that can be compatible with various nitro compounds and alcohols. Nitrone is a significant multifunctional platform synthon which can be synthesized directly and efficiently via this tactic from commercially available and cheap raw materials.

Bitter yet beneficial: The dual role of dietary alkaloids in managing diabetes and enhancing cognitive function

With the rising prevalence of diabetes and its association with cognitive impairment, interest in the use of dietary alkaloids and other natural products has grown significantly. Understanding how these compounds manage diabetic cognitive dysfunction (DCD) is crucial. This comprehensive review explores the etiology of DCD and the effects of alkaloids in foods and dietary supplements that have been investigated as DCD therapies. Data on how dietary alkaloids like berberine, trigonelline, caffeine, capsaicin, 1-deoxynojirimycin, nuciferine, neferine, aegeline, tetramethylpyrazine, piperine, and others regulate cognition in diabetic disorders were collected from PubMed, Research Gate, Web of Science, Science Direct, and other relevant databases. Dietary alkaloids could improve memory in behavioral models and modulate the mechanisms underlying the cognitive benefits of these compounds, including their effects on glucose metabolism, gut microbiota, vasculopathy, neuroinflammation, and oxidative stress. Evidence suggests that dietary alkaloids hold promise for improving cognition in diabetic patients and could open exciting avenues for future research in diabetes management.

Shikonin blocks CAF-induced TNBC metastasis by suppressing mitochondrial biogenesis through GSK-3β/NEDD4-1 mediated phosphorylation-dependent degradation of PGC-1α

BACKGROUND

Triple-negative breast cancer (TNBC) is characterized by its high metastatic potential, which results in poor patient survival. Cancer-associated fibroblasts (CAFs) are crucial in facilitating TNBC metastasis via induction of mitochondrial biogenesis. However, how to inhibit CAF-conferred mitochondrial biogenesis is still needed to explore.

METHODS

We investigated metastasis using wound healing and cell invasion assays, 3D-culture, anoikis detection, and NOD/SCID mice. Mitochondrial biogenesis was detected by MitoTracker green FM staining, quantification of mitochondrial DNA levels, and blue-native polyacrylamide gel electrophoresis. The expression, transcription, and phosphorylation of peroxisome-proliferator activated receptor coactivator 1α (PGC-1α) were detected by western blotting, chromatin immunoprecipitation, dual-luciferase reporter assay, quantitative polymerase chain reaction, immunoprecipitation, and liquid chromatography-tandem mass spectrometry. The prognostic role of PGC-1α in TNBC was evaluated using the Kaplan-Meier plotter database and clinical breast cancer tissue samples.

RESULTS

We demonstrated that PGC-1α indicated lymph node metastasis, tumor thrombus formation, and poor survival in TNBC patients, and it was induced by CAFs, which functioned as an inducer of mitochondrial biogenesis and metastasis in TNBC. Shikonin impeded the CAF-induced PGC-1α expression, nuclear localization, and interaction with estrogen-related receptor alpha (ERRα), thereby inhibiting PGC-1α/ERRα-targeted mitochondrial genes. Mechanistically, the downregulation of PGC-1α was mediated by synthase kinase 3β-induced phosphorylation of PGC-1α at Thr295, which associated with neural precursor cell expressed developmentally downregulated 4e1 recognition and subsequent degradation by ubiquitin proteolysis. Mutation of PGC-1α at Thr295 negated the suppressive effects of shikonin on CAF-stimulated TNBC mitochondrial biogenesis and metastasis in vitro and in vivo.

CONCLUSIONS

Our findings indicate that PGC-1α is a viable target for blocking TNBC metastasis by disrupting mitochondrial biogenesis, and that shikonin merits potential for treatment of TNBC metastasis as an inhibitor of mitochondrial biogenesis through targeting PGC-1α.

CircACTR2 attenuated the effects of tetramethylpyrazine on human kidney cell injury

Tetramethylpyrazine (TMP) is one of the active ingredients of Chuan Xiong that has been reported to have effects on numerous diseases, including diabetic nephropathy (DN). Whereas, related molecular mechanisms are not fully elucidated. We aimed to explore circACTR2's role in TMP-mediated protective effects on DN. In vitro DN condition was established in human kidney cells (HK-2) by treating high glucose (HG). CCK-8 assay and flow cytometry assay were used to observe cell viability and survival. Oxidative stress was determined by the associated markers using kits. The release of inflammatory factors was detected using ELISA kits. Quantitative real-time PCR (qPCR) and western blot were utilized for expression analysis of cricACTR2, miR-140-5p, and GLI pathogenesis-related 2 (GLIPR2). The binding between miR-140-5p and circACTR2 or GLIPR2 was confirmed by dual-luciferase, RIP, and pull-down studies. HG largely induced HK-2 cell apoptosis, oxidative stress, and inflammation, which were alleviated by TMP. CircACTR2's expression was enhanced in HG-treated HK-2 cells but attenuated in HG + TMP-treated HK-2 cells. CircACTR2 overexpression attenuated the functional effects of TMP and thus restored HG-induced cell apoptosis, oxidative stress, and inflammation. CircACTR2 bound to miR-140-5p to enhance the expression of GLIPR2. MiR-140-5p restoration or GLIPR2 inhibition reversed the role of circACTR2 overexpression. CircACTR2 attenuated the protective effects of TMP on HG-induced HK-2 cell damages by regulating the miR-140-5p/GLIPR2 network, indicating that circACTR2 was involved in the functional network of TMP in DN.

Tetramethylpyrazine Nitrone alleviates D-galactose-induced murine skeletal muscle aging and motor deficits by activating the AMPK signaling pathway

Tetramethylpyrazine nitrone (TBN), a novel derivative of tetramethylpyrazine (TMP) designed and synthesized by our group, possesses multi-functional mechanisms of action and displays broad protective effects in vitro and in animal models of age-related brain disorders such as stroke, Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis (ALS) and Parkinson's disease (PD). In the present report, we investigated the effects of TBN on aging, specifically on muscle aging and the associated decline of motor functions. Using a D-galactose-induced aging mouse model, we found that TBN could reverse the levels of several senescence and aging markers including p16, p21, ceramides, and telomere length and increase the wet-weight ratio of gastrocnemius muscle tissue, demonstrating its efficacy in ameliorating muscle aging. Additionally, the pharmacological effects of TBN on motor deficits (gait analysis, pole-climbing test and grip strength test), muscle fibrosis (hematoxylin & eosin (HE), Masson staining, and αSMA staining), inflammatory response (IL-1β, IL-6, and TNF-α), and mitochondrial function (ATP, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were also confirmed in the D-galactose-induced aging models. Further experiments demonstrated that TBN alleviated muscle aging and improved the decline of age-related motor deficits through an AMPK-dependent mechanism. These findings highlight the significance of TBN as a potential anti-aging agent to combat the occurrence and development of aging and age-related diseases.

Pharmacokinetics, Safety Profile, and Tolerability of Tetramethylpyrazine Nitrone Tablets After Single and Multiple Ascending Doses in Healthy Chinese Volunteers

BACKGROUND AND OBJECTIVES

Tetramethylpyrazine nitrone (TBN) is a novel tetramethylpyrazine derivative armed with a strong free radical scavenging nitrone moiety. This study aims to evaluate the pharmacokinetics, safety profile, and tolerability of TBN tablets after a single ascending dose (SAD) and multiple ascending doses (MAD) in healthy Chinese volunteers.

METHODS

This phase I, single-center, open-label study was conducted in China. The SAD portion consisted of four cohorts with dose levels of 400-1800 mg. The MAD portion included three cohorts in which subjects received doses of 600-1800 mg twice daily for 7 days (13 consecutive doses). The third portion was a randomized, two-period, crossover design to assess the influence of food with a single dose of TBN tablets (1200 mg). The safety profile was evaluated by monitoring adverse events (AEs), vital signs, electrocardiograms, physical examinations, and laboratory test results.

RESULTS

Fifty-two healthy subjects aged 18 to 45 years with a body mass index between 19.0 and 26.0 kg/m2 were enrolled. After a single dose of TBN, the median time to maximum plasma concentration (Tmax) was 2.48-3.24 h and the mean half-life (t1/2) was 1.28 to 2.10 h across all doses. In the MAD study, the median Tmax was 2.48 to 3.48 h. In the 400-1800 mg dose range, there was a tendency for less than proportional increases in the maximum plasma concentration (Cmax), the area under the concentration-time curve from 0 to time of last measurable concentration (AUC0-t), and the area under the concentration-time curve from 0 to infinity (AUC0-inf) in both single- and multiple-dose periods. A significantly higher TBN exposure was observed in females than males in both a single and multiple doses of the 600 mg and 1200 mg groups, with a geometric mean female-to-male ratio of 138.69-203.18%. Food decreased the Cmax and AUC0-t of TBN to 45.19% and 59.73%, respectively. Each dose group reached a steady state after 4 days. No drug accumulation was observed. Two subjects had drug-related AEs. A decreased neutrophil count and drug eruption in the SAD portion (1200 mg group) and an increased alanine aminotransferase level in the food effect group were found. All AEs were mild and tolerable (CTCAE grade 1) and resolved without any medical intervention.

CONCLUSION

TBN tablets had a good safety profile and were well tolerated in healthy Chinese volunteers. Steady-state concentrations were reached after 4 consecutive days of oral administration. The results of this phase I study will provide guidance for the design of future TBN clinical studies.

CHINESE CLINICAL TRIAL REGISTRY

ChiCTR1900022092.

Research progress of natural active compounds on improving podocyte function to reduce proteinuria in diabetic kidney disease

Diabetic kidney disease (DKD) is a primary cause of end-stage renal disease. Proteinuria is a clinical indicator of the different stages of DKD, and podocyte injury is a major cause of proteinuria. Podocyte-specific proteins (PSPs) play important roles in the normal filtration of podocytes. Studies have shown that natural active compounds (NACs) can ameliorate proteinuria; however, the mechanism related to PSPs needs to be explored. In this study, the five stages of DKD related to proteinuria and the functions of PSPs are displayed separately. Mechanisms for ameliorating proteinuria and improving the PSPs of the 15 NACs are summarized. The in vitro and in vivo mechanistic research showed that five compounds, astragaloside IV, ligustrazine, berberine, emodin and resveratrol, exerted renal protective effects via AMPK signaling, icariin and berberine via TLR4 signaling, hirudin and baicalin via MAPK signaling, curcumin and baicalin via NF-κB signaling, and emodin via protein kinase RNA-like endoplasmic reticulum kinase signaling. The 13 PSPs were divided into five categories: actin cytoskeleton, basal domain, apical domain, slit diaphragm, and others. In conclusion, anti-inflammatory effects, anti-oxidative stress, and enhanced autophagy are the main mechanisms underlying the ameliorative effects of NACs. Podocyte apoptosis is mainly related to nephrin and podocin, which are the most studied slit diaphragm PSPs.

Tetramethylpyrazine nitrone activates hypoxia-inducible factor and regulates iron homeostasis to improve renal anemia

Renal anemia is one of the most common complications of chronic kidney disease and diabetic kidney disease. Despite the progress made in recent years, there is still an urgent unmet clinical need for renal anemia treatment. In this research, we investigated the efficacy and mechanism of action of the novel tetramethylpyrazine nitrone (TBN). Animal models of anemia including the streptozotocin (STZ)-induced spontaneously hypertensive rats (SHR) and the cisplatin (CDDP)-induced C57BL/6J mice are established to study the TBN's effects on expression of hypoxia-inducible factor and erythropoietin. To explore the mechanism of TBN's therapeutic effect on renal anemia, cobalt chloride (CoCl2) is used in Hep3B/HepG2 cells to simulate a hypoxic environment. TBN is found to increase the expression of hypoxia-inducible factor HIF-1α and HIF-2α under hypoxic conditions and reverse the reduction of HIFs expression caused by saccharate ferric oxide (SFO). TBN also positively regulates the AMPK pathway. TBN stimulates nuclear transcription and translation of erythropoietin by enhancing the stability of HIF-1α expression. TBN has a significant regulatory effect on several major biomarkers of iron homeostasis, including ferritin, ferroportin (FPN), and divalent metal transporter-1 (DMT1). In conclusion, TBN regulates the AMPK/mTOR/4E-BP1/HIFs pathway, and activates the hypoxia-inducible factor and regulates iron homeostasis to improve renal anemia.

Tetramethylpyrazine nitrone TBN extends the lifespan of C. elegans by activating the Nrf2/SKN-1 signaling pathway

SKN-1, the ortholog of mammalian Nrf2 proteins, is a transcription factor that plays an important role in oxidative stress resistance and longevity. Similar to other defense systems, the Nrf2-mediated stress response is compromised in aging and neurodegenerative diseases. Our previous studies demonstrated that tetramethylpyrazine nitrone (TBN), a derivative of tetramethylpyrazine armed with a potent free radical-scavenging nitrone moiety, exerted multifunctional neuroprotection in neurological and other diseases. However, the ability of TBN to extend a healthy lifespan and its underlying mechanisms of action are not yet clear. C. elegans have become a popular animal model in aging research. Herein, we demonstrate that TBN can extend the lifespan, promote age-associated health indicators, and restore mitochondrial function in C. elegans. TBN also significantly reduced ROS levels and superoxide accumulation in C. elegans. We show that TBN-mediated lifespan extension is SKN-1dependent. The present study provides valuable insights into the mechanisms by which TBN inhibits aging via the Nrf2/SKN-1 pathway in C. elegans.