Isolation and structural characterization of 2R, 3R taxifolin 3-O-rhamnoside from ethyl acetate extract of Hydnocarpus alpina and its hypoglycemic effect by attenuating hepatic key enzymes of glucose metabolism in streptozotocin-induced diabetic rats

Modulation of Metabolic Pathways and Protection against Cadmium-Induced Disruptions with Taxifolin-Enriched Extract

Cadmium, a ubiquitous environmental pollutant, has been implicated in the disruption of various metabolic pathways, contributing to the development of insulin resistance, glucose intolerance, and associated metabolic disorders. This study aimed to investigate the cadmium chloride (CdCl2) exposure on metabolic pathways and to assess the potential therapeutic efficacy of the taxifolin-enriched extract in mitigating these disruptions by modulating biochemical pathways. Taxifolin-enriched extract (TEE) was prepared from Pinus roxburghii bark using a green extraction method. About 60 Wistar albino rats were divided into six groups: the control group (n = 10), the CdCl2 group (30 mg/kg) (n = 10), and four groups (each comprises n = 10) treated with 30 mg/kg CdCl2 in combination with metformin (100 mg/kg), ascorbic acid, taxifolin (30 mg/kg), and TEE (30 mg/kg), respectively. After the treatment period of 1 month, a comprehensive assessment of metabolic biomarkers and gene expressions that regulate the metabolism of carbohydrates and lipids was conducted to evaluate the impact of CdCl2 exposure and the potential protective effects of TEE. The results revealed that CdCl2 exposure significantly increased (P < 0.001) serum levels of α-glucosidase, α-amylase, insulin, G6PC, hexokinases, TGs, LDL, HMG-CoA reductase, and pro-inflammatory cytokines such as IL-6 and TNF-α. Conversely, CdCl2 exposure led to a reduction in HDL, antioxidant enzyme levels, phosphofructokinases, and glucose-6-phosphatase dehydrogenase. However, the administration of TEE alongside CdCl2 substantially mitigated (P < 0.001) these fluctuations in metabolic and inflammatory biomarker levels induced by CdCl2 exposure. Both TEE and taxifolin treatment effectively lowered the elevated levels of α-amylase, α-glucosidase, G6PC, insulin, TGs, HMG-CoA reductase, leptin, ALT, AST, blood urea nitrogen, creatinine, and pro-inflammatory cytokines while simultaneously enhancing levels of HDL cholesterol and antioxidant enzymes. Moreover, CdCl2 exposure suppressed mRNA expression of critical metabolic biomarkers such as glucose transporter 2 (GLUT2), insulin-like growth factor 1 (IGF-1), lactate dehydrogenase, and HMG-CoA lyases while upregulating the mRNA expression of angiotensin receptor 2 and vasopressin, key metabolic biomarkers involved in glucose metabolism and insulin regulation. TEE demonstrated the potential to restore normal metabolic functions and reduce the adverse impacts caused by CdCl2 exposure by mitigating disturbances in several metabolic pathways and restoring gene expression of critical metabolic biomarkers related to glucose metabolism and insulin regulation. Nevertheless, further investigation is warranted to comprehensively understand the underlying mechanisms and optimize the appropriate dosage and duration of TEE treatment for achieving the most effective therapeutic outcomes.

Venom Peptides, Polyphenols and Alkaloids: Are They the Next Antidiabetics That Will Preserve β-Cell Mass and Function in Type 2 Diabetes?

Improvement of insulin secretion by pancreatic β-cells and preservation of their mass are the current challenges that future antidiabetic drugs should meet for achieving efficient and long-term glycemic control in patients with type 2 diabetes (T2D). The successful development of glucagon-like peptide 1 (GLP-1) analogues, derived from the saliva of a lizard from the Helodermatidae family, has provided the proof of concept that antidiabetic drugs directly targeting pancreatic β-cells can emerge from venomous animals. The literature reporting on the antidiabetic effects of medicinal plants suggests that they contain some promising active substances such as polyphenols and alkaloids, which could be active as insulin secretagogues and β-cell protectors. In this review, we discuss the potential of several polyphenols, alkaloids and venom peptides from snake, frogs, scorpions and cone snails. These molecules could contribute to the development of new efficient antidiabetic medicines targeting β-cells, which would tackle the progression of the disease.

Advances in biochemistry and the biotechnological production of taxifolin and its derivatives

Taxifolin (dihydroquercetin) and its derivatives are medicinally important flavanonols with a wide distribution in plants. These compounds have been isolated from various plants, such as milk thistle, onions, french maritime, and tamarind. In general, they are commercially generated in semisynthetic forms. Taxifolin and related compounds are biosynthesized via the phenylpropanoid pathway, and most of the biosynthetic steps have been functionally characterized. The knowledge gained through the detailed investigation of their biosynthesis has provided the foundation for the reconstruction of biosynthetic pathways. Plant- and microbial-based platforms are utilized for the expression of such pathways for generating taxifolin-related compounds, either by whole-cell biotransformation or through reconfiguration of the genetic circuits. In this review, we summarize recent advances in the biotechnological production of taxifolin and its derivatives.

Chemical Constituents and Pharmacological Activities of Family Flacourtiaceae: A Class of Important Phytomedicine

Flacourtiaceae plants are widely used as folk medicines in traditional medicine systems for its chemical diversity and pharmacological activities. In many different areas, Flacourtiaceae plants are used as traditional medicines for the treatment of ulcers, malaria, rheumatism. The Flacourtiaceae plants contain a very plentiful chemical composition, and phytochemical studies show that the Flacourtiaceae plants contained terpenoids, aromatic glycosides, flavnoids, phenylpropanoids, alkaloids, fatty hydrocarbon, and other compounds. In pharmacological studies, various extract and isolated individual compounds exhibited antitumor, anti-oxidation, and anti-inflammatory activities. In this review, the literature data on the chemical constituents and pharmacological investigations of the Flacourtiaceae plants are summarized, to provide information about a more comprehensive chemical composition and detailed pharmacological activities of Flacourtiaceae plants, with a view of further development of clinical medication. However, research on quantitative analysis, toxicity, and drug safety in vitro and in vivo is still insufficient, and further research is required.

Anil Kumar N, Sharopov F, Ramírez-Alarcón K, Ruiz-Ortega A, Abdulmajid Ayatollahi S, Valere Tsouh Fokou P, Kobarfard F, Amiruddin Zakaria Z, Iriti M, Taheri Y, Martorell M, Sureda A, N. Setzer W, Durazzo A, Lucarini M, Santini A, Capasso R, Adrian Ostrander E, -ur-Rahman A, Iqbal Choudhary M, C. Cho W, Sharifi-Rad J. Antidiabetic Potential of Medicinal Plants and Their Active Components

Diabetes mellitus is one of the major health problems in the world, the incidence and associated mortality are increasing. Inadequate regulation of the blood sugar imposes serious consequences for health. Conventional antidiabetic drugs are effective, however, also with unavoidable side effects. On the other hand, medicinal plants may act as an alternative source of antidiabetic agents. Examples of medicinal plants with antidiabetic potential are described, with focuses on preclinical and clinical studies. The beneficial potential of each plant matrix is given by the combined and concerted action of their profile of biologically active compounds.

Influence of Flavonoids on Mechanism of Modulation of Insulin Secretion

BACKGROUND

The development of alternatives for insulin secretion control in vivo or in vitro represents an important aspect to be investigated. In this direction, natural products have been progressively explored with this aim. In particular, flavonoids are potential candidates to act as insulin secretagogue.

OBJECTIVE

To study the influence of flavonoid on overall modulation mechanisms of insulin secretion.

METHODS

The research was conducted in the following databases and platforms: PubMed, Scopus, ISI Web of Knowledge, SciELO, LILACS, and ScienceDirect, and the MeSH terms used for the search were flavonoids, flavones, islets of Langerhans, and insulin-secreting cells.

RESULTS

Twelve articles were included and represent the basis of discussion on mechanisms of insulin secretion of flavonoids. Papers in ISI Web of Knowledge were in number of 1, Scopus 44, PubMed 264, ScienceDirect 511, and no papers from LILACS and SciELO databases.

CONCLUSION

According to the literature, the majority of flavonoid subclasses can modulate insulin secretion through several pathways, in an indication that corresponding molecule is a potential candidate for active materials to be applied in the treatment of diabetes.

SUMMARY

The action of natural products on insulin secretion represents an important investigation topic due to their importance in the diabetes controlIn addition to their typical antioxidant properties, flavonoids contribute to the insulin secretionThe modulation of insulin secretion is induced by flavonoids according to different mechanisms. Abbreviations used: KATP channels: ATP-sensitive K+ channels, GLUT4: Glucose transporter 4, ERK1/2: Extracellular signal-regulated protein kinases 1 and 2, L-VDCCs: L-type voltage-dependent Ca+2 channels, GLUT1: Glucose transporter 1, AMPK: Adenosine monophosphate-activated protein kinase, PTP1B: Protein tyrosine phosphatase 1B, GLUT2: Glucose transporter 2, cAMP: Cyclic adenosine monophosphate, PKA: Protein kinase A, PTK: Protein tyrosine kinase, CaMK II: Ca2+/calmodulin-dependent protein kinase II, GSIS: Glucose-stimulated insulin secretion, Insig-1: Insulin-induced gene 1, IRS-2: Insulin receptor substrate 2, PDX-1: Pancreatic and duodenal homeobox 1, SREBP-1c: Sterol regulatory element binding protein-1c, DMC: Dihydroxy-6'-methoxy-3',5'-dimethylchalcone, GLP-1: Glucagon-like peptide-1, GLP-1R: Glucagon-like peptide 1 receptor.

New Cyclopentyl Fatty Acid and Cyanohydrin Glycosides from Fruits of Hydnocarpus hainanensis

Three new compounds, hydnohainanic acid (1), and hydnohainanin A (2) and B (3) were isolated from the fruits of Hydnocarpus hainanensis (Achariaceae). Their structures were determined by spectroscopic analysis, including 2D NMR, and MS. Compounds 1-3 were evaluated for their cytotoxic activity against the KB cell line. Compound 1 had a moderate cytotoxicity with an IC50 value of 32.5 μg/mL, while the two remaining compounds did not exhibit inhibition, even at a concentration of 128 μg/mL.

The Hypoglycemic, Hypolipidemic, and Anti-Diabetic Nephritic Activities of Zeaxanthin in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats

Zeaxanthin (ZA), an important compound found in Lycium barbarum, shows various pharmacodynamic effects. In our present study, a high-fat, high-sucrose diet and streptozotocin (STZ)-induced diabetic rat model was used to investigate the antidiabetic activities of ZA. After a 4-week administration of 200 and 400 mg/kg of ZA and 100 mg/kg of metformin hydrochloride, various blood biochemical indexes were detected. ZA strongly normalized the reduced bodyweight and enhanced fasting blood glucose in diabetic rats. The positive data obtained from the oral glucose tolerance test further confirmed its antidiabetic effects. ZA displayed significant hypolipidemic activities indicated by its modulation of serum levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and total cholesterol. The antidiabetic nephropathy of ZA was confirmed by its regulation of pathological kidney structures, urine levels of n-acetyl-β-d-glucosaminidase and albuminuria, and serum levels of urea nitrogen. ZA inhibited the serum levels of inflammatory factors including interleukin-2 (IL-2), IL-6, tumor necrosis factor-α, and nuclear factor kappa B, further confirming its renal protection. Moreover, the serum imbalances in superoxide dismutase, glutathione peroxidase, methane dicarboxylic aldehyde, and catalase were normalized by ZA, suggesting its antioxidant properties. Altogether, ZA produced hypoglycemic, hypolipidemic, and antidiabetic nephritic effects in a diet-STZ-induced diabetic rat model.

Studies on the Antidiabetic and Antinephritic Activities of Paecilomyces hepiali Water Extract in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats

Paecilomyces hepiali is a fungus widely used in Asian countries for various potential pharmacological activities. The present study aims to evaluate the antidiabetic and antinephritic effects of the Paecilomyces hepiali mycelium water extract (PHC) in diabetic rat, which is established by eight-week high-fat diet administration followed by one-week tail intravenous injection of 25 mg/kg streptozotocin (STZ). After four-week 0.12 g/kg metformin and PHC at doses of 0.08, 0.4, and 2.0 g/kg treatment, an increment of body weight, a decrement of plasma glucose, low levels of total cholesterol, and low density lipoprotein cholesterol in diabetic rats were observed. PHC promotes glucose metabolism by enhancing insulin, pyruvate kinase activity, and increasing the synthesis of glycogen. PHC normalized the disturbed levels of superoxide dismutase, methane dicarboxylic aldehyde, and glutathione peroxidase in kidney. The inhibitory effects on the levels of interleukin-2, interleukin-6, interleukin-10, and tumor necrosis factor-α in serum and kidney revealed the protection of PHC against diabetic nephropathy. Compared with nontreated diabetic rats, four-week PHC treatment resulted in a decrement on nuclear factor kappa B expression in kidney. These results show that Paecilomyces hepiali possesses antidiabetic and antinephritic effects which are related to the modulation of nuclear factor kappa B activity.

Intake of Total Polyphenols and Some Classes of Polyphenols Is Inversely Associated with Diabetes in Elderly People at High Cardiovascular Disease Risk

BACKGROUND

Higher consumption of some polyphenols has been associated with a reduced risk of diabetes. However, no studies have evaluated the relation between all polyphenol subclasses and the incidence of diabetes.

OBJECTIVE

We aimed to prospectively examine the associations between the intake of total polyphenols and different groups of polyphenols (flavonoids, phenolic acids, stilbenes, lignans, and others) on the risk of incident diabetes in the PREDIMED (Prevención con Dieta Mediterránea) trial.

METHODS

This was an observational cohort analysis of the nondiabetic participants in the PREDIMED trial. This study was a multicenter, controlled, randomized, parallel-group feeding trial to assess the effects of either a Mediterranean diet that was supplemented with extra-virgin olive oil or nuts or advice to adhere to a low-fat control diet on cardiovascular outcomes in elderly men and women at high cardiovascular disease risk. From the 7447 randomly assigned participants, 3430 were selected because they were free of diabetes at baseline and filled out the food-frequency questionnaires (FFQs). Polyphenol intake was calculated by matching food consumption data from repeated FFQs with the Phenol-Explorer database on the polyphenol content of each reported food. HRs and 95% CIs for diabetes according to tertiles of polyphenol intake were estimated with the use of time-dependent Cox proportional hazards models.

RESULTS

Over a mean of 5.51 y of follow-up (18,900 person-years), there were 314 new cases of diabetes. After multivariable adjustment, we observed a 28% reduction in new-onset diabetes in the highest compared with the lowest tertile of total polyphenol intake (HR: 0.72; 95% CI: 0.52, 0.99; P-trend = 0.05). The intake of subclasses of polyphenols also was inversely associated with diabetes risk, including for total flavonoids (HR: 0.67; 95% CI: 0.48, 0.93; P-trend = 0.02), stilbenes (HR: 0.57; 95% CI: 0.38, 0.84; P-trend = 0.003), dihydroflavonols (HR: 0.59; 95% CI: 0.40, 0.88; P-trend = 0.003), and flavanones (HR: 0.69; 95% CI: 0.49, 0.97; P-trend = 0.03).

CONCLUSIONS

A high intake of total polyphenols, total flavonoids (specifically flavanones and dihydroflavonols), and stilbenes is associated with a reduced risk of diabetes in elderly persons at high risk of cardiovascular disease. This trial was registered at http://www.controlled-trials.com as ISRCTN35739639.