Ameliorative potential of phloridzin in type 2 diabetes-induced memory deficits in rats

Ethyl gallate ameliorates diabetes-induced Alzheimer's disease-like phenotype in rats via activation of α7 nicotinic receptors and mitigation of oxidative stress

Cognitive decline, an important comorbidity of type 2 diabetes (T2D), is attributed to oxidative stress and impaired cholinergic signaling in the brain. The α7 nicotinic acetylcholine receptor (α7nAChR) is densely distributed in the hippocampus and cortex, and exerts neuroprotective and procognitive actions. Ethyl gallate (EG), a natural phenolic antioxidant compound, showed high in-silico binding affinity towards α7nAChR and brain penetrability. Therefore, the present study aimed to evaluate the involvement of α7nAChR in the potential of EG to ameliorate T2D-induced Alzheimer's disease-like condition. T2D was induced by intraperitoneal (i.p.) injection of streptozotocin (35 mg/kg) in rats on high-fat diet. Diabetic animals were treated with EG (10 and 20 mg/kg, i.p.) for four weeks, and their learning and memory performance was evaluated by the Morris water maze (MWM). Further, the brains were subjected to biochemical analysis of antioxidants like glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT), and oxidative stress marker malonaldehyde (MDA). While diabetic rats showed a significant decline in cognitive performance in the MWM, a substantial improvement was noticed following EG treatment. Further, the diabetes-associated reductions in GSH, SOD, and CAT levels, along with increased MDA contents in the brain, were effectively restored by EG. Interestingly, pre-treatment with α7nAChR antagonist methyllycaconitine (1 mg/kg, i.p.) attenuated the effects of EG on behavioral and biochemical parameters. The results suggest that EG may augment cholinergic signaling in the brain via α7nAChR to mitigate oxidative stress, consequently alleviating T2D-associated dementia. Therefore, EG could be a potential candidate for addressing cognitive impairment comorbid with T2D.

An extract of Hibiscus sabdariffa improves short-term memory in rats with experimental diabetic hyperglycemia

BACKGROUND

Calyxes of Hibiscus sabdariffa (Hs) contain anthocyanins, that normalize blood glucose levels (BGL) in diabetic patients. Diabetes also causes memory alterations, which could hypothetically decrease with the consumption of Hs.

OBJECTIVES

To investigate the effect of dietary supplementation with a Hs extract on working memory and BGL in rats.

METHODS

Diabetic hyperglycemia (DHG) was induced with streptozotocin (STZ, 55 mg/kg i.p.) in Wistar rats. After 72 h DHG was confirmed, and the consumption of Hs extract began (50 mg/Kg/day). BGL and body weight (BW) were measured at 10, 20 and 30 days after DHG induction in controls and treated animals. Learning and short-term memory were evaluated after 30 days with Novel Object Recognition Test (NOR) and Barnes Maze (BM). The gross hippocampal structure was histologically analyzed.

RESULTS

STZ-treated animals presented low BW and persistent DHG (BGL <300 mg/dL). Diabetic animals consuming the Hs extract had a dual response: some showed BGL comparable to controls, while others had levels comparable to diabetic animals not consuming extract. Diabetic animals that consumed the Hs extract had a better performance in NOR and BM than the diabetic animals not consuming the extract. At the histological level, hippocampal morphological differences were observed between diabetic animals that consumed the extract and those that did not.

DISCUSSION

The Hs extract used here could be a good co-adjuvant in the treatment of DHG, aimed at mitigating memory deficits and high BGL. These beneficial effects could be attributed to the anthocyanin content in the extract.

Lycopene alleviates BCG-induced depressive phenotypes in mice by disrupting 5-HT3 receptor - IDO1 interplay in the brain

The 5-HT3 receptor and indoleamine 2,3-dioxygenase 1 (IDO1) enzyme play a crucial role in the pathogenesis of depression as their activation reduces serotonin contents in the brain. Since molecular docking analysis revealed lycopene as a potent 5-HT3 receptor antagonist and IDO1 inhibitor, we hypothesized that lycopene might disrupt the interplay between the 5-HT3 receptor and IDO1 to mitigate depression. In mice, the depression-like phenotypes were induced by inoculating Bacillus Calmette-Guerin (BCG). Lycopene (intraperitoneal; i.p.) was administered alone or in combination with 5-HT3 receptor antagonist ondansetron (i.p.) or IDO1 inhibitor minocycline (i.p.), and the behavioral screening was performed by the sucrose preference test, open field test, tail suspension test, and splash test which are based on the different principles. Further, the brains were subjected to the biochemical analysis of serotonin and its precursor tryptophan by the HPLC. The results showed depression-like behavior in BCG-inoculated mice, which was reversed by lycopene administration. Moreover, prior treatment with ondansetron or minocycline potentiated the antidepressant action of lycopene. Minocycline pretreatment also enhanced the antidepressant effect of ondansetron indicating the regulation of IDO1 activity by 5-HT3 receptor-triggered signaling. Biochemical analysis of brain samples revealed a drastic reduction in the levels of tryptophan and serotonin in depressed animals, which were restored following treatment with lycopene and its combination with ondansetron or minocycline. Taken together, the data from molecular docking, behavioral experiments, and biochemical estimation suggest that lycopene might block the 5-HT3 receptor and consequently inhibit the activity of IDO1 to ameliorate BCG-induced depression in mice.

Discovery of Loureirin analogues with colorectal cancer suppressive activity via regulating cell cycle and Fas death receptor

Chalcones and dihydrochalcones (DHCs) are important bioactive natural products (BNPs) isolated from traditional Chinese medicine. In this study, 13 chalcones were designed with the inspiration of Loureirin, a DHC extracted from Resina Draconis, and synthesized by classical Claisen-Schmidt reactions. Afterwards the reduction reactions were carried out to obtain the corresponding DHCs. Cytotoxicity assay indicated chalcones and DHCs possessed selective cytotoxicity against colorectal cancer (CRC) cells. The preliminary structure-activity relationships (SAR) of these compounds suggested the α, β-unsaturated ketone of the chalcones were crucial for the anticancer activity. Interestingly, compounds 3d and 4c exhibited selective anticancer activity against CRC cell line HCT116 with IC50s of 8.4 and 17.9 μM but not normal cell. Moreover, 4c could also inhibit the migration and invasion of CRC cells. Mechanism investigations showed 4c could induce cell cycle G2/M arrest by regulating cell cycle-associated proteins and could also up-regulate Fas cell surface death receptor. The virtual docking further pointed out that compounds 3d and 4c could nicely bind to the Fas/FADD death domain complex (ID: 3EZQ). Furthermore, silencing of Fas significantly enhanced the proliferation of CRC cells and attenuated the cytotoxicity induced by 4c. These results suggested 4c exerted its anticancer activity possibly regulating cell cycle and Fas death receptor. In summary, this study investigated the anticancer activity and mechanism of Loureirin analogues in CRC, suggesting these compounds may warrant further investigation as promising anticancer drug candidates for the treatment of CRC.

The protective role of phlorizin against lipopolysaccharide-induced acute orchitis in mice associated with changes in gut microbiota composition

Objective

Orchitis is a common reproductive disease of male animals, which has serious implications to human and animal reproduction. Additionally, phlorizin (PHN), a common polyphenol in apples and strawberries, has a variety of biological activities, including antioxidant, anti-inflammatory, anti-diabetic, and anti-aging activities. We aimed to determine the protective effects and potential mechanisms of PHN in lipopolysaccharide (LPS)-induced acute orchitis in mice.

Method

After 21 days of PHN pretreatment, mice were injected with LPS to induce testicular inflammation, and then the changes of testicular tissue structure, expression of inflammatory factors, testosterone level, expression of testosterone-related genes, adhesion gene and protein expression were detected, and the structural changes in the intestinal flora after PHN treatment were further detected by 16SRNA.

Result

Our results demonstrated that PHN treatment reduced LPS-induced testicular injury and body and testicular weight losses. The mRNA expression levels of pro-inflammatory cytokines-related genes and antioxidant enzyme activity were also decreased and elevated, respectively, by PHN administration; however, PHN treatment also reduced the LPS-induced decrease in testosterone levels in the testes. Additionally, further studies found that PHN increased the expression of marker proteins zonula occludens-1 (ZO-1) and occludin associated with the blood testosterone barrier compared with that in LPS treatment groups. To further examine the potential mechanisms of the protective effect of PHN on LPS-induced testicular injury, we compared the differences of gut microbiota compositions between the 100 mg/kg PHN treatment group and the control group using 16SRNA. Metagenomic analyses indicated that the abundances of Bacteroidetes, Muribaculaceae, Lactobacillaceae, uncultured bacterium f Muribaculaceae, and Lactobacillus in the PHN treatment group improved, while potential microbes that can induce intestinal diseases, including Verrucomicrobia, Epsilonbacteraeota, Akkermansiaceae, and Akkermansia decreased in the PHN treatment group.

Conclusion

Our results indicate that PHN pretreatment might alleviate orchitis by altering the composition of gut microflora, which may provide a reference for reducing the occurrence of acute orchitis in male animals.

Pathophysiological and therapeutic implications of neuropeptide S system in neurological disorders

Neuropeptide S (NPS) is a 20 amino acids-containing neuroactive molecule discovered by the reverse pharmacology method. NPS is detected in specific brain regions like the brainstem, amygdala, and hypothalamus, while its receptor (NPSR) is ubiquitously expressed in the central nervous system (CNS). Besides CNS, NPS and NPSR are also expressed in the peripheral nervous system. NPSR is a G-protein coupled receptor that primarily uses Gq and Gs signaling pathways to mediate the actions of NPS. In animal models of Parkinsonism and Alzheimer's disease, NPS exerts neuroprotective effects. NPS suppresses oxidative stress, anxiety, food intake, and pain, and promotes arousal. NPSR facilitates reward, reinforcement, and addiction-related behaviors. Genetic variation and single nucleotide polymorphism in NPSR are associated with depression, schizophrenia, rheumatoid arthritis, and asthma. NPS interacts with several neurotransmitters including glutamate, noradrenaline, serotonin, corticotropin-releasing factor, and gamma-aminobutyric acid. It also modulates the immune system via augmenting pro-inflammatory cytokines and plays an important role in the pathogenesis of rheumatoid arthritis and asthma. In the present review, we discussed the distribution profile of NPS and NPSR, signaling pathways, and their importance in the pathophysiology of various neurological disorders. We have also proposed the areas where further investigations on the NPS system are warranted.

CB2 Cannabinoid Receptor as a Potential Target in Myocardial Infarction: Exploration of Molecular Pathogenesis and Therapeutic Strategies

The lipid endocannabinoid system has recently emerged as a novel therapeutic target for several inflammatory and tissue-damaging diseases, including those affecting the cardiovascular system. The primary targets of cannabinoids are cannabinoid type 1 (CB1) and 2 (CB2) receptors. The CB2 receptor is expressed in the cardiomyocytes. While the pathological changes in the myocardium upregulate the CB2 receptor, genetic deletion of the receptor aggravates the changes. The CB2 receptor plays a crucial role in attenuating the advancement of myocardial infarction (MI)-associated pathological changes in the myocardium. Activation of CB2 receptors exerts cardioprotection in MI via numerous molecular pathways. For instance, delta-9-tetrahydrocannabinol attenuated the progression of MI via modulation of the CB2 receptor-dependent anti-inflammatory mechanisms, including suppression of pro-inflammatory cytokines like IL-6, TNF-α, and IL-1β. Through similar mechanisms, natural and synthetic CB2 receptor ligands repair myocardial tissue damage. This review aims to offer an in-depth discussion on the ameliorative potential of CB2 receptors in myocardial injuries induced by a variety of pathogenic mechanisms. Further, the modulation of autophagy, TGF-β/Smad3 signaling, MPTP opening, and ROS production are discussed. The molecular correlation of CB2 receptors with cardiac injury markers, such as troponin I, LDH1, and CK-MB, is explored. Special attention has been paid to novel insights into the potential therapeutic implications of CB2 receptor activation in MI.

Physical activity in a swimming pool attenuates memory impairment by reducing glutamate and inflammatory cytokines and increasing BDNF in the brain of mice with type 2 diabetes

Type 2 diabetes is a risk factor for the development of cognitive impairment. Increasing evidence suggests that regular exercise is beneficial for the treatment of clinical symptoms in diabetic patients. The current study aimed to evaluate whether increasing physical activity through swimming training can reduce memory impairment in an animal model of type 2 diabetes. Diabetes and non-diabetes mice underwent swimming training for four weeks, and then working, spatial, and recognition memory were evaluated using three behavioral tests. Body weight, glucose, and insulin resistance were monitored. We also measured inflammatory cytokines (interleukin (IL)- 6, IL-1β, and tumor-necrosis-factor (TNF)-α), an anti-inflammatory cytokine (IL-10), and brain-derived-neurotrophic-factor (BDNF), and glutamate levels in the hippocampus or prefrontal cortex of mice. The findings showed that diabetes increased body weight, glucose, and insulin resistance, impaired working, spatial and recognition memory, increased levels of IL-6, IL-1β, TNF-α, and glutamate levels, and decreased BDNF in the hippocampus of diabetic mice. While higher physical activity was associated with reduced body weight, glucose, and insulin resistance, attenuated memory impairment, IL-6, IL-1β, TNF-α, and glutamate, and increased BDNF levels in the hippocampus and prefrontal cortex of diabetic mice. This study shows that swimming training can normalize body weight and glucose-insulin axis and reduce inflammation and glutamate in the hippocampus and enhance the neurotrophic system in both the hippocampus and prefrontal cortex of diabetic mice. This study also suggests that higher physical activity through swimming training can improve cognitive impairment in a mouse model of type 2 diabetes.

Rosa canina L. improves learning and memory-associated cognitive impairment by regulating glucose levels and reducing hippocampal insulin resistance in high-fat diet/streptozotocin-induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Recent studies claim that Type-2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) overlap in several common pathological pathways which from neuronal damage to impaired memory performance. It is known that the use of Rosa canina L. (R. canina) as medicine in folk medicine dates back to ancient times and is used in the treatment of nervous diseases in Persian medicine. However, the effect of R. canina on diabetes-related cognitive decline and memory impairment has not yet been studied.

AIM OF THE STUDY

We evaluated the impact of T2DM on AD-like alterations and examined the molecular mechanism of a possible effect of R. canina on cognitive alterations in diabetic rats.

MATERIALS&METHODS

R. canina ethanol extract was obtained by maceration method. This study was performed with male Spraque-Dawley rats fed with a high-fat diet (HFD) for 8 weeks, low-dose streptozotocin (STZ; 35 mg/kg IP) injection for 4 weeks, and R. canina (250 mg/kg; per oral) and metformin (400 mg/kg; per oral) administration for 4 weeks. The weight and blood glucose of rats were measured weekly. To evaluate glucose tolerance area under the curve (AUC) was calculated by performing an oral glucose tolerance test. Then the rats were subjected to behavioural tests, and their hippocampus and cortex tissues were obtained for biochemical and morphological analyses.

RESULTS

R. canina could manage glucose responsiveness by reducing post-prandial blood glucose levels, preventing weight loss, and raising serum insulin levels in T2DM-induced rats. Behavioural tests showed that R. canina significantly improves diabetes-related cognitive decline in recall and long-term memory. Treatment with R. canina significantly reversed HFD/STZ-induced increases in insulin, amyloid-β, amyloid precursor protein levels, and acetylcholinesterase activity in the prefrontal cortex and hippocampus. Furthermore, histological analyzes revealed the protection of R. canina against neuronal disruption in the cortical and hippocampal CA3 region caused by chronic hyperglycemia.

CONCLUSION

Analyzed collectively, these results suggest that R. canina can correct T2DM-related cognitive decline may be attributed to insulin pathway modulation, prevention of amyloid deposition, and increased cholinergic transmission.

Evaluation of the mosquito larvicidal potential and comparative assessment of the juice of Lantana camara Linn and Ocimum gratissimum Linn

In the present study, the larvicidal efficacy of the juices of the weeds Lantana camara Linn (L. camara) and Ocimum gratissimum Linn (O. gratissimum) was evaluated against the larvae of the malaria vectors Aedes aegypti, Anopheles subpictus and Culex quinquefasciatus. The freshly prepared juices of leaves were prepared by grinding them and diluting them at concentrations of 25, 50, 75, and 100 ppm. Twenty larvae of each species were introduced in different sterile Petri dishes in aqueous media under a controlled environment for the assessment of biological activity. The larvicidal activity of both juices was evaluated at 6, 12 and 24 hr post-exposure time points by observing the movement of each larva. The obtained data were subjected to probit analysis to determine the lethal concentrations that kill 50% and 90% (LC50 and LC90) of the treated larvae. The results revealed a noticeable larvicidal activity following 24 h of exposure. The juice of L. camara leaves exhibited an LC50 range of 47.47-52.06 ppm and an LC90 range of 104.33-106.70 ppm. Moreover, for the juice of O. gratissimum leaves, the LC50 range was 42.94-44.91 ppm and the LC90 range was 105.11-108.66 ppm. Taken together, the results indicate that the juices of L. camara and O. gratissimum leaves may be useful as effective, economical and eco-friendly larvicidal agents. However, additional studies are needed to explore the bioactive components of the weeds that exhibit larvicidal activity along with their mode of action.

The Effect of the Sodium-Glucose Cotransporter Inhibitor on Cognition and Metabolic Parameters in a Rat Model of Sporadic Alzheimer's Disease

Type 2 diabetes mellitus increases the risk of sporadic Alzheimer's disease (sAD), and antidiabetic drugs, including the sodium-glucose cotransporter inhibitors (SGLTI), are being studied as possible sAD therapy. We have explored whether the SGLTI phloridzin may influence metabolic and cognitive parameters in a rat model of sAD. Adult male Wistar rats were randomized to a control (CTR), an sAD-model group induced by intracerebroventricular streptozotocin (STZ-icv; 3 mg/kg), a CTR+SGLTI, or an STZ-icv+SGLTI group. Two-month-long oral (gavage) SGLTI treatment (10 mg/kg) was initiated 1 month after STZ-icv and cognitive performance tested prior to sacrifice. SGLTI treatment significantly decreased plasma glucose levels only in the CTR group and failed to correct STZ-icv-induced cognitive deficit. In both the CTR and STZ-icv groups, SGLTI treatment diminished weight gain, decreased amyloid beta (Aβ) 1-42 in duodenum, and decreased the plasma levels of total glucagon-like peptide 1 (GLP-1), while the levels of active GLP-1, as well as both total and active glucose-dependent insulinotropic polypeptide, remained unchanged, compared to their respective controls. The increment in GLP-1 levels in the cerebrospinal fluid and its effect on Aβ 1-42 in duodenum could be one of the molecular mechanisms by which SGLTIs indirectly induce pleiotropic beneficial effects.

Bioactive Substances and Biological Functions in Malus hupehensis: A Review

Malus hupehensis (MH), as a natural resource, contains various active ingredients such as polyphenols, polysaccharides, proteins, amino acids, volatile substances, and other components. Increasingly, studies have indicated that MH showed a variety of biological activities, including antioxidant, hypoglycemic, hypolipidemic, anti-cancer, anti-inflammatory activities, and other activities. Hence, MH has attracted wide interest because of its high medical and nutritional value. It is necessary to review the active components and biological activities of MH. This paper systematically reviewed the chemical substances, biological activities, and potential problems of MH to further promote the related research of MH and provide an important reference for its application and development in medicine and food.

Natural Polyphenol Recovery from Apple-, Cereal-, and Tomato-Processing By-Products and Related Health-Promoting Properties

Polyphenols of plant origin are a broad family of secondary metabolites that range from basic phenolic acids to more complex compounds such as stilbenes, flavonoids, and tannins, all of which have several phenol units in their structure. Considerable health benefits, such as having prebiotic potential and cardio-protective and weight control effects, have been linked to diets based on polyphenol-enriched foods and plant-based products, indicating the potential role of these substances in the prevention or treatment of numerous pathologies. The most representative phenolic compounds in apple pomace are phloridzin, chlorogenic acid, and epicatechin, with major health implications in diabetes, cancer, and cardiovascular and neurocognitive diseases. The cereal byproducts are rich in flavonoids (cyanidin 3-glucoside) and phenolic acids (ferulic acid), all with significant results in reducing the incidence of noncommunicable diseases. Quercetin, naringenin, and rutin are the predominant phenolic molecules in tomato by-products, having important antioxidant and antimicrobial activities. The present understanding of the functionality of polyphenols in health outcomes, specifically, noncommunicable illnesses, is summarized in this review, focusing on the applicability of this evidence in three extensive agrifood industries (apple, cereal, and tomato processing). Moreover, the reintegration of by-products into the food chain via functional food products and personalized nutrition (e.g., 3D food printing) is detailed, supporting a novel direction to be explored within the circular economy concept.

Therapeutic Potential and Pharmaceutical Development of a Multitargeted Flavonoid Phloretin

Phloretin is a flavonoid of the dihydrogen chalcone class, present abundantly in apples and strawberries. The beneficial effects of phloretin are mainly associated with its potent antioxidant properties. Phloretin modulates several signaling pathways and molecular mechanisms to exhibit therapeutic benefits against various diseases including cancers, diabetes, liver injury, kidney injury, encephalomyelitis, ulcerative colitis, asthma, arthritis, and cognitive impairment. It ameliorates the complications associated with diabetes such as cardiomyopathy, hypertension, depression, memory impairment, delayed wound healing, and peripheral neuropathy. It is effective against various microbial infections including Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Escherichia coli, Candida albicans and methicillin-resistant Staphylococcus aureus. Considering the therapeutic benefits, it generated interest for the pharmaceutical development. However, poor oral bioavailability is the major drawback. Therefore, efforts have been undertaken to enhance its bioavailability by modifying physicochemical properties and molecular structure, and developing nanoformulations. In the present review, we discussed the pharmacological actions, underlying mechanisms and molecular targets of phloretin. Moreover, the review provides insights into physicochemical and pharmacokinetic characteristics, and approaches to promote the pharmaceutical development of phloretin for its therapeutic applications in the future. Although convincing experimental data are reported, human studies are not available. In order to ascertain its safety, further preclinical studies are needed to encourage its pharmaceutical and clinical development.

Curcumin Protects Diabetic Mice against Isoproterenol-Induced Myocardial Infarction by Modulating CB2 Cannabinoid Receptors

Molecular docking revealed curcumin as a potent CB2 cannabinoid receptor (CB2R) agonist. Since CB2R is involved in cardioprotective functions, we explored its role in ameliorative actions of curcumin against myocardial damage triggered by isoproterenol in diabetic animals. Mice were kept on a high-fat diet (HFD) throughout the experiment (30 days). Following 7 days of HFD feeding, streptozotocin was administered (150 mg/kg, intraperitoneal) to induce diabetes. From day 11 to 30, diabetic mice received either curcumin (100 or 200 mg/kg/day, oral), CB2R antagonist AM630 (1 mg/kg/day, intraperitoneal) or both, with concurrent isoproterenol (150 mg/kg, subcutaneous) administration on day 28 and 29. Diabetic mice with myocardial infarction showed an altered hemodynamic pattern and lipid profile, reduced injury markers, antioxidants with increased lipid peroxidation in the myocardium, and elevated glucose and liver enzymes in the blood. Moreover, an increased pro-inflammatory markers, histological severity, myonecrosis, and edema were observed. Curcumin compensated for hemodynamic fluctuations, restored biochemical markers, preserved antioxidant capacity, decreased cytokines levels, and restored cardiac functionality. However, the AM630 pre-treatment attenuated the effects of curcumin. The data suggest the involvement of CB2R in the actions of curcumin such as in the prevention of myocardial stress and in the improvement of the normal status of the myocardial membrane associated with diabetes.