Novel Polysaccharide H-1-2 from Pseudostellaria Heterophylla Alleviates Type 2 Diabetes Mellitus

Exploring histone deacetylases in type 2 diabetes mellitus: pathophysiological insights and therapeutic avenues

Diabetes mellitus is a chronic disease that impairs metabolism, and its prevalence has reached an epidemic proportion globally. Most people affected are with type 2 diabetes mellitus (T2DM), which is caused by a decline in the numbers or functioning of pancreatic endocrine islet cells, specifically the β-cells that release insulin in sufficient quantity to overcome any insulin resistance of the metabolic tissues. Genetic and epigenetic factors have been implicated as the main contributors to the T2DM. Epigenetic modifiers, histone deacetylases (HDACs), are enzymes that remove acetyl groups from histones and play an important role in a variety of molecular processes, including pancreatic cell destiny, insulin release, insulin production, insulin signalling, and glucose metabolism. HDACs also govern other regulatory processes related to diabetes, such as oxidative stress, inflammation, apoptosis, and fibrosis, revealed by network and functional analysis. This review explains the current understanding of the function of HDACs in diabetic pathophysiology, the inhibitory role of various HDAC inhibitors (HDACi), and their functional importance as biomarkers and possible therapeutic targets for T2DM. While their role in T2DM is still emerging, a better understanding of the role of HDACi may be relevant in improving insulin sensitivity, protecting β-cells and reducing T2DM-associated complications, among others.

Pseudostellaria heterophylla polysaccharide mitigates Alzheimer's-like pathology via regulating the microbiota-gut-brain axis in 5 × FAD mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by neuroinflammation, for which gut dysbiosis may be implicated. Our previous study showed that treatment with Pseudostellaria heterophylla aqueous extract and one of its cyclopeptides, heterophyllin B, attenuate memory deficits via immunomodulation and neurite regeneration. However, whether Pseudostellaria heterophylla polysaccharide (PH-PS) exerts neuroprotective effects against AD and its underlying mechanisms remain unclear. The infrared spectrum, molecular weight, and carbohydrate composition of the PH-PS were determined. The results showed that PH-PS (Mw 8.771 kDa) was composed of glucose (57.78 %), galactose (41.52 %), and arabinose (0.70 %). PH-PS treatment ameliorated learning and spatial memory deficits, reduced amyloid β build-up, and suppressed reactive glia and astrocytes in 5 × FAD mice. 16S rRNA sequencing further showed that PH-PS remodelled the intestinal flora composition by promoting probiotic microbiota, such as Lactobacillus, Muribaculum, Monoglobus, and [Eubacterium]_siraeum_group, and suppressing inflammation-related UCG-009 and Blautia. Additionally, PH-PS restored intestinal barrier function; ameliorated peripheral inflammation by reducing the secretion of inflammatory cytokines, thereby converting M1 microglia and A1 astrocyte toward beneficial M2 and A2 phenotypes; and contributed to Aβ plaques clearance by upregulation of insulin degradation enzyme and neprilysin. Collectively, our findings demonstrate that PH-PS may prevent the progression of AD via modulation of the gut microbiota and regulation of glial polarisation, which could provide evidence to design a potential diet therapy for preventing or curing AD.

Acanthopanax trifoliatus (L.) Merr polysaccharides ameliorates hyperglycemia by regulating hepatic glycogen metabolism in type 2 diabetic mice

INTRODUCTION

Drug monotherapy was inadequate in controlling blood glucose levels and other comorbidities. An agent that selectively tunes multiple targets was regarded as a new therapeutic strategy for type 2 diabetes. Acanthopanax trifoliatus (L.) Merr polysaccharide (ATMP) is a bio-macromolecule isolated from Acanthopanax trifoliatus (L.) Merr and has therapeutic potential for diabetes management due to its anti-hyperglycemia activity.

METHODS

Type 2 diabetes mellitus was induced in mice using streptozotocin, and 40 and 80 mg/kg ATMP was administered daily via the intragastric route for 8 weeks. Food intake, water intake, and body weight were recorded. The fasting blood glucose (FBG), fasting insulin (FINS) and an oral glucose tolerance test (OGTT) were performed. Histological changes in the liver and pancreas were analyzed by H&E staining. The mRNA and the protein levels of key factors involved in glycogen synthesis, glycogenolysis, and gluconeogenesis were measured by quantitative real time PCR and Western blotting.

RESULTS

In this study, we found that ATMP could effectively improve glucose tolerance and alleviate insulin resistance by promoting insulin secretion and inhibiting glucagon secretion. In addition, ATMP decreases glycogen synthesis by inhibiting PI3K/Akt/GSK3β signaling, reduces glycogenolysis via suppressing cAMP/PKA signaling, and suppresses liver gluconeogenesis by activating AMPK signaling.

CONCLUSION

Together, ATMP has the potential to be developed as a new multitargets therapeutics for type 2 diabetes.

Polysaccharides from Pseudostellaria heterophylla modulate gut microbiota and alleviate syndrome of spleen deficiency in rats

Pseudostellaria heterophylla, also called Tai-zi-shen (TZS) in Traditional Chinese Medicine (TCM), is always used clinically to treat spleen deficiency symptoms. Polysaccharides in TZS have various pharmacological activities, including anti-diabetic, immune regulation, and myocardial protection. However, the relationship between the spleen-invigorating effects of TZS or its polysaccharides and intestinal flora are not clear. This study investigated the effects of TZS decoction (PHD) and polysaccharide (PHP) on immune function and intestinal flora in a rat model of spleen deficiency syndrome (SDS) induced by a decoction of raw rhubarb (RRD). PHD and PHP increased immune organ index, alleviated inflammatory cell filtration, and reduced the levels of pro-inflammatory cytokines in rats with spleen deficiency syndrome. In addition, the production of butyric acid was promoted in PHD and PHP groups. Moreover, 16S rRNA gene sequencing showed that PHD and PHP reduced the relative abundance of Firmicutes while increasing the one of Bacteroidetes; significantly increased the abundance of Lactobacillus and decreased the abundance of Rombutsia; and PHP significantly increased the abundance of Alloprevotella. And there was a significant positive correlation between the alleviation of SDS and short-chain fatty acids (SCFAs)-producing bacteria. These findings suggested PHD and PHP, especially PHP, has a potential to relieve spleen deficiency by reducing intestinal inflammation, modulating structure and composition of gut microbiota, and promoting the production of butyric acid.

Pseudosterins A-C, Three 1-Ethyl-3-formyl-β-carbolines from Pseudostellaria heterophylla and Their Cardioprotective Effects

Pseudostellaria heterophylla is used in China not only as a functional food but also as an herb to tonify the spleen, enhance immunity, and treat palpitation. Our previous investigation showed that a fraction enriched in glycosides obtained from the roots of P. heterophylla possessed pronounced protective effects on H9c2 cells against CoCl₂-induced hypoxic injury. However, the active compounds responsible for the observed effects were still unknown. In the current investigation, pseudosterins A–C (1–3), three new alkaloids with a 1-ethyl-3-formyl-β-carboline skeleton, together with polydatin, have been isolated from the active fraction. Their structures were elucidated on the basis of spectroscopic analysis and quantum chemical calculations. The four compounds showed cardioprotective effects against sodium hydrosulfite-induced hypoxia-reoxygenation injury in H9c2 cells, with the three alkaloids being more potent. This is also the first report of alkaloids with a β-carboline skeleton isolated from P. heterophylla as cardioprotective agents.

Heterophyllin B, a cyclopeptide from Pseudostellaria heterophylla, enhances cognitive function via neurite outgrowth and synaptic plasticity

Neurite outgrowth-induced construction of neural circuits and networks is responsible for memory generalization, consolidation, and retrieval. In this study, we found that the traditional Chinese medicine Pseudostellaria heterophylla promoted neurite regrowth and enhanced cognitive function in normal mice. Further, we orally administered Pseudostellaria heterophylla water extracts (PHE) to ICR mice, and detected heterophyllin B (HET-B), an important cyclopeptide, in the plasma and cerebral cortex. We demonstrated that neurites were significantly elongated after coculturing with HET-B for 4 days. Next, the intraperitoneal injection of HET-B on seven consecutive days in 3-month-old ICR mice significantly enhanced the object recognition memory and object location memory than that in control. Immunohistochemical analysis indicated significantly increased β3-tubulin-positive neurite density, synaptophysin, and postsynaptic density 95 in the perirhinal cortex and hippocampus after administering HET-B. Furthermore, the concentration of neurotransmitters was measured using HPLC analysis; HET-B significantly increased five-levels of HT in the hippocampus, and decreased metabolites of dopamine, dihydroxyphenylacetic acid, and homovanillic acid, in the prefrontal cortex and hippocampus. Taken together, HET-B induces neurite elongation and neurotransmitter regulation and possibly enhances cognitive memory.

Pseudostellaria heterophylla Extract Polysaccharide H-1-2 Suppresses Pancreatic Cancer by Inhibiting Hypoxia-Induced AG2

We aimed to examine the therapeutic potential of polysaccharide H-1-2, a bioactive component of Pseudostellaria heterophylla, against pancreatic cancer, as well as to demonstrate the underlying molecular mechanisms. Invasion and migration of pancreatic cells treated with H-1-2 were evaluated. A xenograft tumor mouse model was established to assess the effect of H-1-2 on tumor growth. Expression levels of hypoxic inducible factor-1α (HIF1α) and anterior gradient 2 (AGR2) were measured in pancreatic cells after H-1-2 treatment. Luciferase report and chromatin immunoprecipitation assays were conducted to investigate HIF1α regulation on AGR2. AGR2 expression was re-introduced into pancreatic cells to assess the role of AGR2 as a downstream effector of hypoxia after H-1-2 treatment. H-1-2 inhibited invasion and migration of pancreatic cancer cells, repressed xenograft pancreatic tumor growth, and increased survival of mice. H-1-2 repressed AGR2 expression in pancreatic cancer cells through the hypoxia response element (HRE) in its promoter region. Ectopic AGR2 expression partially negated the H-1-2 inhibitory effect on invasion and migration of pancreatic cells and on xenograft pancreatic tumors growth, and it also compromised the H-1-2 promotional effect on survival of mice. We conclude that H-1-2 suppresses pancreatic cancer by inhibiting hypoxia-induced AGR2 expression, supporting further investigation into its efficacy against pancreatic cancer in clinical settings.