Citrus flavone tangeretin is a potential insulin sensitizer targeting hepatocytes through suppressing MEK-ERK1/2 pathway

The roles of dietary polyphenols at crosstalk between type 2 diabetes and Alzheimer's disease in ameliorating oxidative stress and mitochondrial dysfunction via PI3K/Akt signaling pathways

Alzheimer's disease (AD) is a fatal neurodegenerative disease in which senile plaques and neurofibrillary tangles are crucially involved in its physiological and pathophysiological processes. Growing animal and clinical studies have suggested that AD is also comorbid with some metabolic diseases, including type 2 diabetes mellitus (T2DM), and therefore, it is often considered brain diabetes. AD and T2DM share multiple molecular and biochemical mechanisms, including impaired insulin signaling, oxidative stress, gut microbiota dysbiosis, and mitochondrial dysfunction. In this review article, we mainly introduce oxidative stress and mitochondrial dysfunction and explain their role and the underlying molecular mechanism in T2DM and AD pathogenesis; then, according to the current literature, we comprehensively evaluate the possibility of regulating oxidative homeostasis and mitochondrial function as therapeutics against AD. Furthermore, considering dietary polyphenols' antioxidative and antidiabetic properties, the strategies for applying them as potential therapeutical interventions in patients with AD symptoms are assessed.

Plant-Derived Coumarins: A Narrative Review of Their Structural and Biomedical Diversity

Plant-derived coumarin (PDC) is a naturally occurring heterocyclic backbone that belongs to the benzopyrone family. PDC and its based products are characterized by low toxicity and high distribution in a variety of herbal treatments that have numerous therapeutic potentials. These include anticoagulants, antibacterials, anti-inflammatory agents, anticancer agents, antioxidants, and others. So, it may be appropriate to investigate the qualities and potential bioactivities of PDCs. This article provides an overview of the biomedical potentials, availability, and clinical use possibilities of PDCs, with a focus on their important modes of action, using information on various pharmacological qualities discovered. The data used in this study came from published research between 2015 and 2023. We reviewed a selection of databases, including PubMed, Scopus, Web of Science, and Google Scholar, during that period. In conclusion, because of their abundance in medicinal plants, the clinical biochemistry attributes of PDCs are currently of interest. In a variety of medical specialties, PDCs serve a useful role as therapeutic agents.

Traditional Chinese medicine formulae: A complementary method for the treatment of polycystic ovary syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Polycystic ovary syndrome (PCOS) is a prevalent female endocrine condition that significantly affects women of all age groups and is characterized by metabolic dysfunction. The efficacy of existing pharmaceutical interventions for the treatment of PCOS remains inadequate. With a rich history and cultural significance spanning thousands of years, Traditional Chinese Medicine (TCM) is extensively employed for treating a variety of ailments and can serve as a supplementary therapy for managing PCOS. Multiple clinical observations and laboratory tests have unequivocally demonstrated the substantial effectiveness and safety of TCM formulae in treating PCOS, and further investigations are currently in progress.

AIM OF THE STUDY

To summarize the TCM formulae commonly employed in the clinical management of PCOS, examine their therapeutic benefits, investigate their mechanism of action, active constituents, and establish the correlation between efficacy, mechanism of action, and active constituents.

MATERIALS AND METHODS

We conducted a comprehensive search on PubMed, Web of Science, and China national knowledge infrastructure (CNKI) using the following keywords: "Polycystic Ovary Syndrome", "Traditional Chinese Medicine Decoctions", "Traditional Chinese Medicine formulae", "Traditional Chinese Medicine", "Clinical Observation", "Mechanism", "Treatment", "Pharmacology", and various combinations of these terms. From January 1, 2006 until October 7, 2023, (inclusive).

RESULTS

This paper summarized the clinical effectiveness, mechanism of action, and active components of 8 TCM formulae for the treatment of PCOS. Our research indicates that TCM formulae can potentially treat PCOS by enhancing the levels of hyperandrogenism and other endocrine hormones, decreasing insulin resistance and hyperinsulinemia, and controlling chronic low-grade inflammation, among other modes of action. In addition, we found an association between epigenetics and TCM formulae for the treatment of PCOS.

CONCLUSION

TCM formulae have specific advantages in the treatment of Polycystic Ovary Syndrome (PCOS). They achieve therapeutic benefits by targeting several pathways and connections, attracting considerable interest and playing a vital role in the treatment of PCOS. TCM formulae can be used as an adjunctive therapy for the treatment of PCOS.

Flavonoids, Isoflavonoids and others Bioactives for Insulin Sensitizations

Diabetes is a chronic condition that has an impact on a huge part of the world. Both animals and humans have been demonstrated to benefit from natural goods, and organisms (animals, or microbes). In 2021, approximately 537 million adults (20-79 years) are living with diabetes, making it the one of the biggest cause of death worldwide. Various phytoconstituent preserved β- cells activity helps to prevent the formation of diabetes problems. As a result, β-cells mass and function are key pharmaceutical targets. The purpose of this review is to provide an overview of flavonoids' effects on pancreatic β-cells. Flavonoids have been demonstrated to improve insulin release in cell lines of isolated pancreatic islets and diabetic animal models. Flavonoids are thought to protect β-cells by inhibiting nuclear factor-κB (NF-κB) signaling, activating the phosphatidylinositol 3-kinase (PI3K) pathway, inhibiting nitric oxide production, and lowering reactive oxygen species levels. Flavonoids boost β-cells secretory capacity by improving mitochondrial bioenergetic function and increasing insulin secretion pathways. Some of the bioactive phytoconstituents such as S-methyl cysteine sulfoxides stimulate insulin synthesis in the body and increase pancreatic output. The berberine increased insulin secretion in the HIT-T15 and Insulinoma 6 (MIN6) mouse cell line. Epigallocatechin-3-Gallate protects against toxicity accrued by cytokines, reactive oxygen species (ROS), and hyperglycemia. Quercetin has been proven to boost insulin production by Insulinoma 1 (INS-1) cells and also protect cell apoptosis. Overall flavonoids have beneficial effects on β-cells by prevented their malfunctioning or degradation and improving synthesis or release of insulin from β-cells.

Fruit waste: a current perspective for the sustainable production of pharmacological, nutraceutical, and bioactive resources

Fruits are crucial components of a balanced diet and a good source of natural antioxidants, that have proven efficacy in various chronic illnesses. Various kinds of waste generated from fruit industries are considered a global concern. By utilizing this fruit waste, the international goal of "zero waste" can be achieved by sustainable utilization of these waste materials as a rich source of secondary metabolites. Moreover, to overcome this waste burden, research have focused on recovering the bioactive compounds from fruit industries and obtaining a new strategy to combat certain chronic diseases. The separation of high-value substances from fruit waste, including phytochemicals, dietary fibers, and polysaccharides which can then be used as functional ingredients for long-term health benefits. Several novel extraction technologies like ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) could provide an alternative approach for successful extraction of the valuable bioactives from the fruit waste for their utilization as nutraceuticals, therapeutics, and value-added products. Most of these waste-derived secondary metabolites comprise polyphenols, which have been reported to have anti-inflammatory, insulin resistance-treating, cardiovascular disease-maintaining, probiotics-enhancing, or even anti-microbial and anti-viral capabilities. This review summarizes the current knowledge of fruit waste by-products in pharmacological, biological, and probiotic applications and highlights several methods for identifying efficacious bioactive compounds from fruit wastes.

An Ethnopharmaceutical Study on the Hypolipidemic Formulae in Taiwan Issued by Traditional Chinese Medicine Pharmacies

Globally, approximately one-third of ischemic heart diseases are due to hyperlipidemia, which has been shown to cause various metabolic disorders. This study was aimed to disassemble and analyze hypolipidemic formulae sold by traditional Chinese medicine (TCM) pharmacies. Using commonly used statistical parameters in ethnopharmacology, we identified the core drug combination of the hypolipidemic formulae, thereby exploring the strategy by which the Taiwanese people select hypolipidemic drugs. Most important of all, we preserved the inherited knowledge of TCM. We visited 116 TCM pharmacies in Taiwan and collected 91 TCM formulae. The formulae were mainly disassembled by macroscopical identification, and the medicinal materials with a relative frequency of citation (RFC) >0.2 were defined as commonly used medicinal materials. Subsequently, we sorted the information of medicinal materials recorded in the Pharmacopeia, searched for modern pharmacological research on commonly used medicinal materials using PubMed database, and visualized data based on the statistical results. Finally, the core hypolipidemic medicinal materials used in folk medicine were obtained. Of the 91 TCM formulae collected in this study, 80 traditional Chinese medicinal materials were used, belonging to 43 families, predominantly Lamiaceae. Roots were the most commonly used part as a medicinal material. There were 17 commonly used medicinal materials. Based on medicinal records in Pharmacopeia, most flavors and properties were warm and pungent, the majority traditional effects were “tonifying and replenishing” and “blood-regulating.” Besides, the targeted diseases searching from modern pharmacological studies were diabetes mellitus and dyslipidemia. The core medicinal materials consisted of Astragalus mongholicus Bunge and Crataegus pinnatifida Bunge, and the core formulae were Bu-Yang-Huan-Wu-Tang and Xie-Fu-Zhu-Yu-Tang. In addition, 7 groups of folk misused medicinal materials were found. Although these TCMs have been used for a long period of time, their hypolipidemic mechanisms remain unclear, and further studies are needed to validate their safety and efficacy.

Tangeretin protects mice from diet-induced metabolic inflammation via activating adipose lactate accumulation and macrophage M2 polarization

Infiltration by adipose tissue macrophages (ATMs) and subsequent metabolic inflammation are the key causes of obesity-induced insulin resistance and metabolic disorders. In this study, we analyzed the potential protective effect of tangeretin, a key flavonoid found extensively in citrus peels, against diet-induced metabolic inflammation. Daily gavages of tangeretin at 20 mg/kg protected the mice from high fat diet (HFD) feeding-induced insulin resistance, ATMs activation, and M1 macrophage polarization. Interestingly, in vitro assays using bone marrow-derived macrophages (BMDMs) showed that tangeretin had only a minimal effect on macrophage polarization. Assays of central carbon metabolism (CCM) in adipose tissue showed that tangeretin treatment rerouted the carbon metabolism and caused lactate accumulation in the microenvironment. Co-culture assays further suggested that tangeretin enhanced M2 polarization of BMDMs when adipocytes were present, whereas blocking the lactate uptake in macrophages reversed the effect of tangeretin on polarization. Taken together, these findings indicated that tangeretin provided indirect protection from diet-induced ATMs activation by reprogramming glucose metabolism and promoting lactate accumulation that subsequently promoted macrophage M2 polarization and reduced inflammation.

Tangeretin Protects Mice from Alcohol-Induced Fatty Liver by Activating Mitophagy through the AMPK-ULK1 Pathway

Alcoholic beverages are widely consumed all over the world, but continuous ethanol exposure leads to hepatic steatosis that, without proper treatment, will later develop into severe liver disorders. In this study, we investigated the potential protective effect of tangeretin, a flavonoid derived from citrus peel, against alcoholic fatty liver. The in vivo effects of tangeretin were analyzed by oral intake in a chronic-binge alcohol feeding C57BL/6j mouse model, while the underlying mechanism was explored by in vitro studies performed on ethanol-treated hepatic AML-12 cells. Ethanol feeding increased the serum alanine aminotransferase and aspartate aminotransferase levels, the liver weight, and the serum and liver triacylglycerol contents, whereas 20 and 40 mg/kg tangeretin treatment promoted a dose-dependent suppression of these effects. Interestingly, tangeretin prevented increases in the liver oxidative stress level and protected the hepatocyte mitochondria from ethanol-induced morphologic abnormalities. A mechanistic study showed that 20 μM tangeretin treatment activated mitophagy through an AMP-activated protein kinase (AMPK)-uncoordinated 51-like kinase 1 (Ulk1) pathway, thereby restoring mitochondria respiratory function and suppressing steatosis. By contrast, blocking the AMPK-Ulk1 pathway with compound C reversed the hepatoprotective effect of tangeretin. Overall, tangeretin activated mitophagy and protected against ethanol-induced hepatic steatosis through an AMPK-Ulk1-dependent mechanism.

Research progress of coumarins and their derivatives in the treatment of diabetes

Diabetes is a group of metabolic diseases characterised by chronic hyperglycaemia caused by multiple causes, which is caused by insulin secretion and/or utilisation defects. It is characterised by increased fasting and postprandial blood glucose levels due to insulin deficiency or insulin resistance. It is reported that the harm of diabetes mainly comes from its complications, and the cardiovascular disease caused by diabetes is the primary cause of its harm. China has the largest number of diabetic patients in the world, and the prevention and control of diabetes are facing great challenges. In recent years, many kinds of literature have been published abroad, which have proved that coumarin and its derivatives are effective in the treatment of diabetic complications such as nephropathy and cardiovascular disease. In this paper, the types of antidiabetic drugs and the anti-diabetic mechanism of coumarins were reviewed.

Omnifarious fruit polyphenols: an omnipotent strategy to prevent and intervene diabetes and related complication?

Diabetes mellitus is a metabolic syndrome which cannot be cured. Recently, considerable interest has been focused on food ingredients to prevent and intervene in complications of diabetes. Polyphenolic compounds are one of the bioactive phytochemical constituents with various biological activities, which have drawn increasing interest in human health. Fruits are part of the polyphenol sources in daily food consumption. Fruit-derived polyphenols possess the anti-diabetic activity that has already been proved either from in vitro studies or in vivo studies. The mechanisms of fruit polyphenols in treating diabetes and related complications are under discussion. This is a comprehensive review on polyphenols from the edible parts of fruits, including those from citrus, berries, apples, cherries, mangoes, mangosteens, pomegranates, and other fruits regarding their potential benefits in preventing and treating diabetes mellitus. The signal pathways of characteristic polyphenols derived from fruits in reducing high blood glucose and intervening hyperglycemia-induced diabetic complications were summarized.

Plants Secondary Metabolites as Blood Glucose-Lowering Molecules

Recently, significant advances in modern medicine and therapeutic agents have been achieved. However, the search for effective antidiabetic drugs is continuous and challenging. Over the past decades, there has been an increasing body of literature related to the effects of secondary metabolites from botanical sources on diabetes. Plants-derived metabolites including alkaloids, phenols, anthocyanins, flavonoids, stilbenoids, saponins, tannins, polysaccharides, coumarins, and terpenes can target cellular and molecular mechanisms involved in carbohydrate metabolism. In addition, they can grant protection to pancreatic beta cells from damage, repairing abnormal insulin signaling, minimizing oxidative stress and inflammation, activating AMP-activated protein kinase (AMPK), and inhibiting carbohydrate digestion and absorption. Studies have highlighted many bioactive naturally occurring plants' secondary metabolites as candidates against diabetes. This review summarizes the current knowledge compiled from the latest studies published during the past decade on the mechanism-based action of plants-derived secondary metabolites that can target various metabolic pathways in humans against diabetes. It is worth mentioning that the compiled data in this review will provide a guide for researchers in the field, to develop candidates into environment-friendly effective, yet safe antidiabetics.

Dietary Flavonoids and Insulin Signaling in Diabetes and Obesity

Type 2 diabetes (T2D) and obesity are relevant worldwide chronic diseases. A common complication in both pathologies is the dysregulation of the insulin-signaling pathway that is crucial to maintain an accurate glucose homeostasis. Flavonoids are naturally occurring phenolic compounds abundant in fruits, vegetables and seeds. Rising evidence supports a role for the flavonoids against T2D and obesity, and at present, these compounds are considered as important potential chemopreventive agents. This review summarizes in vitro and in vivo studies providing data related to the effects of flavonoids and flavonoid-rich foods on the modulation of the insulin route during T2D and obesity. Notably, few human studies have evaluated the regulatory effect of these phenolic compounds at molecular level on the insulin pathway. In this context, it is also important to note that the mechanism of action for the flavonoids is not fully characterized and that a proper dosage to obtain a beneficial effect on health has not been defined yet. Further investigations will contribute to solve all these critical challenges and will enable the use of flavonoids to prevent, delay or support the treatment of T2D and obesity.

Physiological effects of tangeretin and heptamethoxyflavone on obese C57BL/6J mice fed a high-fat diet and analyses of the metabolites originating from these two polymethoxylated flavones

Two compounds from citrus peel, tangeretin (TAN) and 3',4',3,5,6,7,8-heptamethoxyflavone (HMF), were investigated for their abilities to repair metabolic damages caused by an high-fat diet (HFD) in C57BL/6J mice. In the first 4 weeks, mice were fed either a standard diet (11% kcal from fat) for the control group, or a HFD (45% kcal from fat) to establish obesity in three experimental groups. In the following 4 weeks, two groups receiving the HFD were supplemented with either TAN or HMF at daily doses of 100 mg/kg body weight, while the two remaining groups continued to receive the standard healthy diet or the nonsupplemented HFD. Four weeks of supplementation with TAN and HMF resulted in intermediate levels of blood serum glucose, leptin, resistin, and insulin resistance compared with the healthy control and the nonsupplemented HFD groups. Blood serum peroxidation (TBARS) levels were significantly lower in the TAN and HMF groups compared with the nonsupplemented HFD group. Several differences occurred in the physiological effects of HMF versus TAN. TAN, but not HMF, reduced adipocyte size in the mice with pre-existent obesity, while HMF, but not TAN, decreased fat accumulation in the liver and also significantly increased the levels of an anti-inflammatory cytokine, IL-10. In an analysis of the metabolites of TAN and HMF, several main classes occurred, including a new set of methylglucuronide conjugates. It is suggested that contrasts between the observed physiological effects of TAN and HMF may be attributable to the differences in numbers and chemical structures of TAN and HMF metabolites.