Preventing the onset of diabetes-induced chronic kidney disease during prediabetes: The effects of oleanolic acid on selected markers of chronic kidney disease in a diet-induced prediabetic rat model

Partial Replacement of Soyabean Meal with Defatted Black Soldier Fly (Hermetia illucens L.) Larvae Meal Influences Blood Biochemistry and Modulate Oxidative Stress, but Not Growth Performance of Pigs

The production of soybean meal (SBM) can be linked to various issues related to the environment (e.g., deforestation, water waste, and transportation costs), and reducing its inclusion in pig diets by using alternative protein sources, such as insect meal, is an important challenge for nutritionists. This study aimed to compare the productive performance, dietary digestible energy (DE), nutrient digestibility, and some blood indices of growing Danube White pigs fed graded levels of Black Soldier fly (Hermetia illucens L.) larvae meal (BSFLM) at 0, 30, 60, 90, and 120 g/kg of diets, in replacement of SBM for 38 days, from 119 to 157 d old. Each diet was fed to eight pigs in individual boxes following randomization. Pigs grew according to breeders' recommendations and did not have any clinical health problems. Replacing SBM did not change (p > 0.05) the pigs' growth performance and DE, as only dietary fat digestibility increased in a linear fashion (p < 0.001), possibly due to the high BSFLM, i.e., the high-fat inclusion rate. There was a simultaneous rise in some oxidative damage indicators and an increase in antioxidant status, thus suggesting that further research involving longer feeding periods is needed to identify a potential time sequence of events. Overall, BSFLM is a promising ingredient in pig nutrition.

Oleanolic Acid Alleviates Hyperuricemia via Gut Microbiota Control the Integrity of Gut Barrier and the Expressions of Urate Transporter in Mice

Hyperuricemia (HUA) is a globally prevalent metabolic disorder characterized by an imbalance in uric acid (UA) production and excretion. In this study, we found that oleanolic acid (OA), a natural pentacyclic triterpene, effectively reduced HUA and associated kidney injury in C57BL/6J mice. A 12-week OA treatment significantly and dose-dependently reduced UA and creatinine levels in serum and urine while suppressing hepatic xanthine oxidase activity in HUA mice. Mechanistic analysis revealed that OA modulates the expression of urate transporters including ABCG2, GLUT9, and URAT1 in the kidney and small intestine. Furthermore, OA restored gut microbiota imbalances, increased short-chain fatty acid production, and enhanced the expressions of intestinal tight junction proteins in HUA mice, thereby improving gut barrier integrity in HUA mice. Consequently, fecal microbiota transplantation (FMT) was employed to illustrate the major mediating role of gut microbiota in OA's alleviation of HUA in mice. Recipient HUA mice transplanted with feces from OA-treated HUA mice exhibited significantly lower blood and urinary UA levels, reduced kidney inflammation, and improved gut microbiota balance compared to those receiving feces from untreated HUA mice (p < 0.05). Additionally, FMT normalized urate transporter expression and reinforced intestinal tight junctions in recipient mice. These findings underscore that OA mitigates HUA primarily by modulating gut microbiota, regulating urate transporter expression, and reinforcing gut barrier integrity, offering novel insights into its preventive potential for managing HUA and related complications.

Exploring the therapeutic potential of oleanolic acid and its derivatives in cancer treatment: a comprehensive review

Oleanolic acid (OA) is a triterpenoid that occurs naturally and may be isolated from various plants. Analogs of oleanolic acid can be produced artificially or naturally. The current treatments have limited selectivity and may also impact normal cells. OA and its derivatives provide a promising cancer treatment platform with greater selectivity and less toxic effects. As a result of their enhanced sensitivity, selectivity, and low toxicity, they are great options for focusing on particular biological pathways and reducing the growth of tumor cells. The effects of OA and derivatives of OA on various cancer types have been investigated. However, breast and hepatocellular malignancies are the most studied cancers. In breast cancer, derivatives such as saikosaponin A (SSa), saikosaponin B (SSb), and SZC014 influence key pathways such as the Janus kinase/signal transducer and activator of transcription (JAK/STAT), protein kinase-B (Akt), and nuclear factor-kappa B (NF-κB) pathways, inhibiting metastasis, angiogenesis, and cell migration, respectively. When a para-aminobenzoic acid (PABA)/nitric oxide (NO) derivative of OA is administered to HepG2 cells, the reactive oxygen species (ROS)/mitogen-activated protein kinase (MAPK)-mediated mitochondrial pathway causes apoptosis. Nanoformulations incorporating OA, such as OA-paclitaxel (PTX), show potential for suppressing tumor progression by inhibiting drug efflux mechanisms. Thus, exploring the interactions of OA and a few of its derivatives with various cellular pathways offers a promising approach to combating different types of cancer. This review delves into the potential of oleanolic acid and its derivatives in retarding cancer progression through their interactions with diverse cellular pathways.

Sambucus nigra-Lyophilized Fruit Extract Attenuated Acute Redox-Homeostatic Imbalance via Mutagenic and Oxidative Stress Modulation in Mice Model on Gentamicin-Induced Nephrotoxicity

Background: Gentamicin (GM) administration is associated with decreased metabolism, increased oxidative stress, and induction of nephrotoxicity. Sambucus nigra L., containing flavonoids, anthocyanins, and phytosterols, possesses antioxidant and anti-inflammatory potential. Objectives: The present study aimed to investigate the nephroprotective and anti-inflammatory potential of lyophilized Sambucus nigra fruit extract (S. nigra extract) to reduce acute oxidative stress and residual toxicity of GM in a 7-day experimental model in Balb/c rodents. Methods: The S. nigra extract was lyophilized (300 rpm; 10 min; -45 °C) to improve pharmacological properties. Balb/c mice were divided into four (n = 6) groups: controls; S. nigra extract per os (120 mg kg-1 day-1 bw); GM (200 mg kg-1 day-1 bw) (4); and GM + S. nigra therapy. The activities of antioxidant and renal enzymes, cytokines, and levels of oxidative stress biomarkers-Hydroxiproline, CysC, GST, KIM-1, PGC-1α, MDA, GSPx-were analyzed by ELISA tests. The ROS and RNS levels, as well as 5-MSL-protein oxidation, were measured by EPR spectroscopy. Results: The antioxidant-protective effect of S. nigra extract (120 mg kg-1) was demonstrated by reduced MDA, ROS, and RNS and increased activation of endogenous enzymes. Furthermore, S. nigra extract significantly reduced the expression of IL-1β, IL-6, IL-10, TNF-α, IFN-γ, and KIM-1 and regulated collagen/protein (PGC-1α and albumin) deposition in renal tissues. Conclusions: Histological evaluation confirmed that S. nigra (120 mg kg-1) attenuated renal dysfunction and structural damage by modulating oxidative stress and acute inflammation and could be used as an anti-fibrotic alternative in GM nephrotoxicity.

Integrated gut microbiota and serum metabolomics reveal the protective effect of oleanolic acid on liver and kidney-injured rats induced by Euphorbia pekinensis

Euphorbia pekinensis (EP) is a commonly used Chinese medicine treating edema with potential hepatorenal toxicity. However, its toxic mechanism and prevention are remained to be explored. Oleanolic acid (OA) is a triterpene acid with potential hepatorenal protective activities. We investigated the protective effect and potential mechanism of OA on EP-induced hepatorenal toxicity. In this study, rats were given total diterpenes from EP (TDEP, 16 mg/kg) combined with OA (10, 20, 40 mg/kg) by gavage for 4 weeks. The results showed that TDEP administration could lead to a 3-4-fold increasement in hepatorenal biochemical parameters with histopathological injuries, while OA treatment could ameliorate them in a dose-dependent manner. At microbial and metabolic levels, intestinal flora and host metabolism were perturbed after TDEP administration. The disturbance of bile acid metabolism was the most significant metabolic pathway, with secondary bile acids increasing while conjugated bile acids decreased. OA treatment can improve the disorder of intestinal flora and metabolic bile acid spectrum. Further correlation analysis screened out that Escherichia-Shigella, Phascolarctobacterium, Acetatifactor, and Akkermansia were closely related to the bile acid metabolic disorder. In conclusion, oleanolic acid could prevent hepatorenal toxicity induced by EP by regulating bile acids metabolic disorder via intestinal flora improvement.

The Effect and Mechanism of Oleanolic Acid in the Treatment of Metabolic Syndrome and Related Cardiovascular Diseases

Metabolic syndromes (MetS) and related cardiovascular diseases (CVDs) pose a serious threat to human health. MetS are metabolic disorders characterized by obesity, dyslipidemia, and hypertension, which increase the risk of CVDs' initiation and development. Although there are many availabile drugs for treating MetS and related CVDs, some side effects also occur. Considering the low-level side effects, many natural products have been tried to treat MetS and CVDs. A five-cyclic triterpenoid natural product, oleanolic acid (OA), has been reported to have many pharmacologic actions such as anti-hypertension, anti-hyperlipidemia, and liver protection. OA has specific advantages in the treatment of MetS and CVDs. OA achieves therapeutic effects through a variety of pathways, attracting great interest and playing a vital role in the treatment of MetS and CVDs. Consequently, in this article, we aim to review the pharmacological actions and potential mechanisms of OA in treating MetS and related CVDs.

The role of fibrinolysis in the development of prediabetes-associated coronary heart disease: a focus on the plasminogen activator inhibitor -1 and its potential use as a predictive marker in diet-induced prediabetes

Introduction

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of cardiovascular diseases (CVD). However, the onset of T2DM is preceded by prediabetes, which is associated with sedentary lifestyles and consumption of high-calorie diets. Studies have shown that impaired glucose homeostasis creates an environment for developing T2DM-related complications. Using a high-fat-high-carbohydrate diet-induced prediabetes animal model, this study sought to assess the risk factors of coronary heart disease (CHD) in diet-induced prediabetes and identify biomarkers that can be used for early detection of prediabetes-associated CHD.

Methods

Male Sprague Dawley rats were randomly grouped into two groups and were kept on different diets for 20 weeks (n = 6 in each group). One group was fed standard rat chow to serve as a non-prediabetes (NPD) control, while the other group consumed a high-fat-high-carbohydrate diet to induce prediabetes (PD). Post induction, the homeostasis model assessment- insulin resistance (HOMA-IR) and glycated haemoglobin (HbA1c) was used to test for insulin resistance. Body weight, mean arterial pressure (MAP), resting heart rate (HR), inflammatory cytokines (C-reactive protein (CRP), tumor necrosis factor (TNF-α), interleukin-6 (IL-6)), lipids (total cholesterol (TC), triglyceride (TG), lipoproteins (HDL, LDL, VLDL)), endothelial function (endothelial nitric oxide (eNOS), endothelin -1 (ET-1)), fibrinolysis (plasminogen activator inhibitor-1 (PAI-1)) were all measured to assess the risk of CHD. All data were expressed as means ± S.E.M. Statistical comparisons were performed with Graph Pad. Instat Software using Student's two-sided t-test. The Pearson correlation coefficient and linear regression were calculated to assess the association. The value of p < 0.05 was considered statistically significant.

Results

There was significant insulin resistance accompanied by significantly increased HbA1c and body weight in PD compared to NPD. Simultaneously, there was a significant increase in inflammatory cytokines in PD compared to NPD. This was accompanied by significantly increased TG and VLDL and endothelial dysfunction in PD. The association between HOMA-IR and PAI-1 was insignificantly positive in NPD, whereas a significantly strong positive association was observed in PD.

Conclusion

There is a positive correlation between insulin resistance and PAI-1 during prediabetes; therefore, suggesting that prediabetes increases the risk of developing vascular thrombosis. The current therefore study warrants further investigation on PAI-1 and other markers of fibrinolysis for the early detection of thrombosis and risk of CHD in prediabetes.

A cellulose-based intelligent temperature-sensitive molecularly imprinted aerogel reactor for specific recognition and enrichment of ursolic acid

In this article, thermosensitive molecularly imprinted polymer and composite aerogel were combined for the first time to create an intelligent temperature-responsive aerogel reactor to effectively enrich ursolic acid (UA). Because aerogel carrier had a higher specific surface area and higher porosity compared to other carriers, the ursolic acid molecularly imprinted intelligent temperature responsive aerogel reactor (ITR&AR(G570)&UA-MIP) demonstrated a higher adsorption capacity for UA. More notably, ITR&AR(G570)&UA-MIP have the extraordinary capacity to spontaneously adsorb-desorb target molecule UA by regulating the reaction temperature. The ratio of the target molecule UA to the functional monomer and crosslinker in the grafting process and external influences had a major impact on how ITR&AR(G570)&UA-MIP were prepared overall. When the molar ratio of UA to 4-VP was 1:8, the weight ratio between ITR&AR(G570)&UA-MIP and EGDMA/DVB was 1:2:10, the reaction temperature was 60 °C, and the ambient pH = 6, the material showed the best adsorption capacity, reaching a peak of about 70 mg g-1. After researching the appropriate synthesis conditions, ITR&AR(G570)&UA-MIP were applied to lingonberry (Vaccinium Vitis-Idaea L.) berry extracts in this work. The outcomes show that this technique provides a new, intelligent, temperature-controlled adsorption material for the solid-phase extraction of triterpenoid acids in natural products, with good specific adsorption performance for the target molecule UA.

Asiatic acid attenuates tubular injury in diabetic kidney disease by regulating mitochondrial dynamics via the Nrf-2 pathway

BACKGROUND

Mitochondrial dynamics plays a crucial role in tubular injury in diabetic kidney disease (DKD). Asiatic acid (AA) has demonstrated renal protective effects in DKD; however, its therapeutic effect on tubular injury in DKD remains unclear.

PURPOSE

This study aimed to verify the effects of AA on tubular injury in DKD and underlying mechanisms.

STUDY DESIGN

In the present study, the effects of AA on tubular injury were assessed in rats with streptozotocin-induced diabetes and advanced glycation end products (AGEs)-stimulated HK-2 cells models.

METHODS

After oral administration with or without AA for ten weeks, body weight and levels of fast blood glucose, serum creatinine (sCr), blood urea nitrogen (BUN), urinary albumin, and kidney injury molecule-1 (KIM-1) were detected. Histological analysis was performed to evaluate the renal function of rats. Moreover, the expression of proteins associated with the Nrf-2 pathway and mitochondrial dynamics was analyzed. AGEs-stimulated HK-2 cells were examined to evaluate the tubular protection and the mechanism of AA in vitro.

RESULTS

AA remarkably decreased albumin levels, KIM-1 levels in urine, and serum Cr, and BUN levels. In addition, AA prevented tubular injury and mitochondrial injury by regulating the Nrf-2 pathway and mitochondrial dynamics. Furthermore, the effects of AA on mitochondrial dynamics and tubular protection were eliminated after treatment with ML385 (Nrf2 inhibitor).

CONCLUSION

These findings suggested that AA might be developed as a potential candidate for the treatment of tubular injury in DKD, and its effects are potentially mediated via the regulation of the Nrf-2 pathway and mitochondrial dynamics.

Recent advances in medicinal chemistry of oleanolic acid derivatives

Oleanolic acid (OA), a ubiquitous pentacyclic oleanane-type triterpene isolated from edible and medicinal plants, exhibits a wide spectrum of pharmacological activities and tremendous therapeutic potential. However, the undesirable pharmacokinetic properties limit its application and development. Numerous researches on structural modifications of OA have been carried out to overcome this limitation and improve its pharmacokinetic and therapeutic properties. This review aims to compile and summarize the recent progresses in the medicinal chemistry of OA derivatives, especially on structure-activity relationship in the last few years (2010-2021). It gives insights into the rational design of bioactive derivatives from OA scaffold as promising therapeutic agents.

Assessing the risk factors for myocardial infarction in diet-induced prediabetes: myocardial tissue changes

Background

Hyperglycaemia is known to result in oxidative stress tissue injury and dysfunction. Interestingly, studies have reported hepatic and renal oxidative stress injury during prediabetes; however, any injury to the myocardium during prediabetes has not been investigated. Hence this study aims to assess changes in the myocardial tissue in an HFHC diet-induced model of prediabetes.

Methods

Male Sprague Dawley rats were randomly grouped into non-prediabetes and prediabetes (n = 6 in each group) and consumed a standard rat chow or fed a high-fat-high-carbohydrate diet respectively for a 20-week prediabetes induction period. Post induction, prediabetes was confirmed using the ADA criteria. Aldose reductase, NADH oxidase 1, superoxide dismutase, glutathione peroxide, cardiac troponins were analysed in cardiac tissue homogenate using specific ELISA kits. Lipid peroxidation was estimated by determining the concentration of malondialdehyde in the heart tissue homogenate according to the previously described protocol. Myocardial tissue sections were stained with H&E stain and analysed using Leica microsystem. All data were expressed as means ± SEM. Statistical comparisons were performed with Graph Pad instat Software using the Student's two-sided t-test. Pearson correlation coefficient was calculated to assess the association. Value of p < 0.05 was considered statistically significant.

Results

The prediabetes group showed a markedly high oxidative stress as indicated by significantly increased NADH oxidase 1 and malondialdehyde while superoxide dismutase and glutathione peroxide were decreased compared to non-prediabetes group. There was no statistical difference between cardiac troponin I and T in the non-prediabetes and prediabetes groups. Cardiac troponins had a weak positive association with glycated haemoglobin.

Conclusion

The findings of this study demonstrate that prediabetes is associated with myocardial injury through oxidative stress. Future studies are to investigate cardiac contractile function and include more cardiac biomarkers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02758-8.

Recent Advances Regarding the Molecular Mechanisms of Triterpenic Acids: A Review (Part I)

Triterpenic acids are phytocompounds with a widespread range of biological activities that have been the subject of numerous in vitro and in vivo studies. However, their underlying mechanisms of action in various pathologies are not completely elucidated. The current review aims to summarize the most recent literature, published in the last five years, regarding the mechanism of action of three triterpenic acids (asiatic acid, oleanolic acid, and ursolic acid), corelated with different biological activities such as anticancer, anti-inflammatory, antidiabetic, cardioprotective, neuroprotective, hepatoprotective, and antimicrobial. All three discussed compounds share several mechanisms of action, such as the targeted modulation of the PI3K/AKT, Nrf2, NF-kB, EMT, and JAK/STAT3 signaling pathways, while other mechanisms that proved to only be specific for a part of the triterpenic acids discussed, such as the modulation of Notch, Hippo, and MALAT1/miR-206/PTGS1 signaling pathway, were highlighted as well. This paper stands as the first part in our literature study on the topic, which will be followed by a second part focusing on other triterpenic acids of therapeutic value.

Regulation of reactive oxygen species by phytochemicals for the management of cancer and diabetes

Cancer and diabetes mellitus are served as typical life-threatening diseases with common risk factors. Developing therapeutic measures in cancers and diabetes have aroused attention for a long time. However, the problems with conventional treatments are in challenge, including side effects, economic burdens, and patient compliance. It is essential to secure safe and efficient therapeutic methods to overcome these issues. As an alternative method, antioxidant and pro-oxidant properties of phytochemicals from edible plants have come to the fore. Phytochemicals are naturally occurring compounds, considered promising agent applicable in treatment of various diseases with beneficial effects. Either antioxidative or pro-oxidative activity of various phytochemicals were found to contribute to regulation of cell proliferation, differentiation, cell cycle arrest, and apoptosis, which can exert preventive and therapeutic effects against cancer and diabetes. In this article, the antioxidant or pro-oxidant effects and underlying mechanisms of flavonoids, alkaloids, and saponins in cancer or diabetic models demonstrated by the recent studies are summarized.

Diet-induced prediabetes: Effects on the activity of the renin-angiotensin-aldosterone system (RAAS) in selected organs

Derangements often observed with type 2 diabetes (T2D) are associated with disturbances in renin-angiotensin-aldosterone system (RAAS) activity. A positive correlation between local RAAS activity and the complications observed in T2D has been noted. However, the detrimental ramifications due to moderate hyperglycemia noted in prediabetes and the affected organ system and mechanistic pathways are not elucidated. Hence, this study investigated the effects of diet-induced prediabetes on RAAS in various organs.

MATERIALS AND METHODS

Male Sprague-Dawley rats were separated into two groups: non-pre-diabetic (NPD) through exposure to standard rat chow and diet-induced prediabetic (PD) group by exposure to a high-fat high carbohydrate diet for 32 weeks. RAAS activity in the skeletal muscle, adipose tissue, liver, pancreas and heart was determined through the analysis of RAAS components such as; renin, angiotensinogen, angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT1R) via PCR as well as the quantification of angiotensin II and aldosterone concentration. Furthermore, NADPH oxidase, SOD and GPx1 concentrations were determined in the skeletal muscle, pancreas and heart in addition to the hepatic triglycerides.

RESULTS

The RAAS components were elevated in the PD group when compared to the NPD. This was further accompanied by increased NADPH oxidase and reduced SOD and GPx1 concentrations in the selected organs, in addition to the elevated hepatic triglycerides concentration in the PD by comparison to NPD.

CONCLUSION

Due to these observed changes, we suggest that local RAAS activity in the prediabetic state in selected organs elicits the derangements noted in T2D.