Effect of luteoin in delaying cataract in STZ-induced diabetic rats

Hypoglycemic Ability of Sericin-Derived Oligopeptides (SDOs) from Bombyx mori Yellow Silk Cocoons and Their Physiological Effects on Streptozotocin (STZ)-Induced Diabetic Rats

Patients with diabetes require daily medication to maintain blood sugar levels. Nevertheless, the long-term use of antidiabetics can lose efficacy and cause degeneration in some patients. For long-term diabetes care, integrating natural dietary foods and medicine is being considered. This study investigated the impact of SDOs on blood sugar levels and their physiological effects on diabetic rats. We induced diabetes in male Wistar rats with STZ (50 mg/kg) and then administered an oral glucose tolerance test to determine the SDO dosage comparable to glibenclamide. The rats were divided into nine groups: normal, diabetic, and diabetic with insulin (10 U/kg), glibenclamide (0.6 mg/kg), bovine serum albumin (BSA; 200 mg/kg), soy protein isolate (200 mg/kg), or SDOs (50, 100, and 200 mg/kg). Diabetic rats administered SDOs had a higher body weight and serum insulin but a lower blood sugar than diabetic control rats. Biochemical assays indicated lower AST/SGOT, ALT/SGPT, BUN, and triglycerides but higher HDL in the SDO groups. Immunohistochemistry showed that SDOs reduced damaged islet cells, increased beta-cell size, and improved insulin levels while decreasing alpha cell size and glucagon. The vascular effects of SDOs were like those of normal control treatment and insulin treatment in diabetic rats. SDOs, a yellow silk protein, show potential for long-term diabetes care.

Dichloroacetate ameliorates apoptosis, EMT and oxidative stress in diabetic cataract via inhibiting the IDO1-dependent p38 MAPK pathway

As an oral antidiabetic agent, dichloroacetate (DCA) has been proven to improve diabetes and related complications. However, its functional role in diabetic cataract (DC) remains to be elucidated. This study was to define the role of DCA and its underlying molecular mechanism in DC in vitro and in vivo. In this study, it was shown that DCA dose-dependently ameliorated DC formation and development in DM rats. In addition, DCA significantly increased cell viability, reduced apoptosis, and inhibited EMT and oxidative stress of high glucose (HG)-treated SRA-01/04 cells in a concentration-dependent manner. Besides, it was revealed that Indoleamine 2,3-dioxygenase 1 (IDO1) expression was upregulated in lenses of DM rats and HG-treated SRA-01/04 cells, which was reversed by DCA. In addition, DCA abrogated the activation of the p38 MAPK signaling in the lenses of DM rats and HG-treated SRA-01/04 cells. Further experiments showed that IDO1 upregulation activated the p38 MAPK signaling in HG-challenged SRA-01/04 cells. Moreover, IDO1 overexpression partially reversed DCA-mediated inactivation of p38 MAPK signaling and suppression of HG-induced damage to SRA-01/04 cells. To sum up, our findings showed that DCA prevented DC-related apoptosis, EMT, and oxidative stress via inactivating IDO1-dependent p38 MAPK signaling.

Review on the potential roles of traditional Chinese medicines in the prevention, treatment, and postoperative recovery of age-related cataract

ETHNIC PHARMACOLOGICAL RELEVANCE

Cataract is the most common cause of blindness worldwide, a visual disorder caused by a clouded lens that seriously affects People's Daily lives. Age-related cataract (ARC) is the most common type of cataract due to long-term combined effects of many factors, and its pathogenesis is varied. At present, the surgery is the main treatment for cataracts, but it is still limited to the prevention, treatment of early cataracts and the postoperative complications care. While, its drug treatments are still in the stage of exploration and research. Traditional Chinese Medicine (TCM), a unique resource in China, is conceived under the guidance of traditional Chinese medicine theory and has little toxicity and side effects, but it has made great progress in the treatment and prevention of ARC.

AIM OF THIS REVIEW

This review presents an overview of the pathogenesis of ARC in both traditional and modern medicines and summarizes the history and therapeutic effect of TCM on ARC including their formula, crude drugs and active components, and also the other auxiliary methods.

METHODS

A number of recognized databases like SciFinder, PubMed, Science Direct, Google Scholar, and China National Knowledge Infrastructure (CNKI) were extensively explored by using keywords and phrases such as "cataract", "age-related cataract", "traditional medicine", "ethnopharmacology", "herbs", "medicinal plants", or other relevant terms, and the plants/phytoconstituents that are evaluated in the models of age-related cataract. As well as the current TCM adjuvant therapy used in the clinical treatment were summarized.

RESULTS

TCM revealed to plays an active role in treating age-related cataract, via multi-pathway and multi-target, and can treat or delay ARC by inhibiting abnormal glucose metabolism, antioxidant damage, inhibiting LEC apoptosis, and so on, which is in concordance with the good effects of the global use of TCM in clinical application. Concerning the early prevention and treatment of cataract and postoperative complications, TCM and auxiliary methods remain to achieve better clinical effects.

CONCLUSION

ARC belongs to the category of "Yuan Yi Nei Zhang" in TCM theory, showing that there are many causes of ARC including aging, and kidney-yang, spleen, sperm and blood deficiencies. At the same time, the viscera gradually decline, as well as yin or yang progressively become weak, especially in the elder people. So, TCM could be mainly based on liver, kidney, and spleen syndrome differentiation, personalizing diagnosis and treatment, following multiple targets, regulating fundamentally yin and yang, and thus justifying the advantages of Chinese medicine in the prevention and treatment of ARC.

Application of Luteolin in Neoplasms and Nonneoplastic Diseases

Researchers are amazed at the multitude of biological effects of 3',4',5,7-tetrahydroxyflavone, more commonly known as luteolin, as it simultaneously has antioxidant and pro-oxidant, as well as antimicrobial, anti-inflammatory, and cancer-preventive, properties. The anticancer properties of luteolin constitute a mosaic of pathways due to which this flavonoid influences cancer cells. Not only is it able to induce apoptosis and inhibit cancer cell proliferation, but it also suppresses angiogenesis and metastasis. Moreover, luteolin succeeds in cancer cell sensitization to therapeutically induced cytotoxicity. Nevertheless, apart from its promising role in chemoprevention, luteolin exhibits numerous potential utilizations in patients with conditions other than neoplasms, which include inflammatory skin diseases, diabetes mellitus, and COVID-19. This review aims to present the multidimensionality of the luteolin's impact on both neoplastic and nonneoplastic diseases. When it comes to neoplasms, we intend to describe the complexity of the molecular mechanisms that underlay luteolin's anticancer effectiveness, as well as to prove the usefulness of integrating this flavonoid in cancer therapy via the analysis of recent research on breast, colon, and lung cancer. Regarding nonneoplastic diseases, this review aims to emphasize the importance of researching the potential of luteolin in areas such as diabetology, virology, and dermatology as it summarizes the most important discoveries in those fields regarding its application.

Bergenin alleviates Diabetic Retinopathy in STZ-induced rats

Diabetic retinopathy (DR) is the key cause of blindness and visual impairment in diabetes patients around the world. The high levels of oxidative stress in diabetes patients cause diabetic retinopathy. In addition to being an antioxidant, Bergenin also works as an immunosuppressant, an anti-inflammatory, and anticarcinogenic against hepatocarcinoma. This study examined the effects of Bergenin on diabetic retinopathy rats, using Streptozotocin (STZ) intraperitoneally to induce diabetes in rats. The animals were divided into four groups (n = 6), including a normal control (Group I), diabetic control (Group II), Bergenin (25 mg/kg) (Group III), and metformin (350 mg/kg) (Group IV). As previously mentioned, each animal received treatment for 60 days. To induce DR, rats were administered STZ (60 mg/kg) intraperitoneally for 60 days. Standard methods were utilized to measure the body weight of rats, blood glucose levels. We measured lipid profiles (Triglycerides, cholesterol, LDL, and HDL), inflammatory markers, and antioxidant levels with their respective kits. Analysis of retinal tissue morphometry and MMP-9, VEGF, and MCP-1 levels in serum was performed. Our research examined the expression levels of target genes (TNF-α, IL-1β, and IL-6) using RT-PCR analysis. STZ-induced animals that were treated with Bergenin had less food intake, lower blood glucose, and improved body weight. Bergenin significantly suppressed levels of pro-inflammatory cytokines, cholesterol, TG, LDL, AI, MMP-9, VEGF, and MCP-1 and increased the level of HDL and antioxidant enzymes in STZ-induced DR rats. As well as increasing antioxidant levels, reducing retinal thickness, and increasing cell numbers, Bergenin also lessened DR remarkably. The results of this study demonstrated that Bergenin effectively inhibited STZ-induced DR in rats.

A Mediterranean Diet May Be Protective in the Development of Diabetic Retinopathy

The Mediterranean diet is recognized as one of the healthiest available dietary patterns. This perception results from its beneficial effects on the cardiovascular system and, also, on hypertension, diabetes, and cancer compared with other diets. Its impact on the course of diabetes is assessed in the available scientific literature; however, little information is available about its impact on diabetic retinopathy. The MD is characterized mainly by the consumption of fish, seafood, foods of plant origin, and fresh fruit and vegetables. It is also recommended to consume legumes, which are a source of folic acid, magnesium, iron, and dietary fiber. High consumption of nuts and unrefined grains is also recommended in the MD. Marine fish provide polyunsaturated acids from the omega-3 group. Olive oil plays a very important role, especially olive oil obtained from mechanical pressing. Additionally, olive oil contains vitamins E, K, and polyphenols. Polyphenols, which are present in a diverse range of vegetables, fruits, and seeds, have the ability to decrease oxidative stress, inflammation, and insulin resistance. Resveratrol is naturally found in grape skins and seeds, as well as in peanuts and berries, and is a constituent of red wine. Resveratrol can inhibit increased vascular leakage and loss of pericytes and regulate the level of VEGF protein in the retina, thus inhibiting the development of DR. Consumption of fruits, vegetables, fish, and olive oil may be correlated with a lower risk of diabetic retinopathy. This paper presents the definition of the Mediterranean diet and its influence on the course of diabetes and diabetic retinopathy.

D-α-tocopherol polyethylene glycol 1000 succinate-based microemulsion delivery system: Stability enhancement of physicochemical properties of luteolin

In the present study, D-α-Tocopherol polyethylene glycol 1000 succinate-based self-microemulsifying drug delivery systems (TPGS-SMEDDS) were introduced to enhance the solubility and stability of luteolin. The ternary phase diagrams were constructed to obtain the maximum area of microemulsion and suitable formulations of TPGS-SMEDDS. The particle size distribution and polydispersity index of selected TPGS-SMEDDS were analyzed to be less than 100 nm and 0.4, respectively. The thermodynamic stability results suggested that the TPGS-SMEDDS was stable during the heat-cool and freeze-thaw cycle. Moreover, the TPGS-SMEDDS exhibited excellent encapsulation capacity (51.21 ± 4.39 to 85.71 ± 2.40%) and loading efficiency (61.46 ± 5.27 to 102.86 ± 2.88 mg/g) to luteolin. In addition, the TPGS-SMEDDS showed an admirable vitro release ability with a ratio of more than 88.40 ± 1.14% for luteolin in 24 h. Therefore, TPGS-based SMEDDS might provide an effective role for the oral administration of luteolin and holds promise as a potential delivery for poorly soluble bioactive compounds.

Enhancement of oral bioavailability and anti-colitis effect of luteolin-loaded polymer micelles with RA (rosmarinic acid)-SS-mPEG as carrier

OBJECTIVE

Polymer micelles were prepared (L-RSPMs) with luteolin and synthetic RA-SS-mPEG polymeric material before evaluation of their anti-inflammatory effect on 2, 4, 6-trinitro-benzene-sulfonic acid (TNBS)-induced ulcerative colitis (UC) model in rats.

METHODS

The synthetic RA-SS-mPEG was characterized with NMR spectroscopy, before preparation of luteolin-coated RA-SS-mPEG polymer micelles. The in vitro characterization and evaluation of the formulation were accomplished, couple with its pharmacokinetic parameters. The levels of PEG2, MDA, CRP and GSH, as well as concentrations of TNF-α, IL1-β, IL-6 and IL-10 in serum and colon tissue were detected via ELISA kit. The degree of colon injury and inflammation was evaluated via histopathologic examination.

RESULTS

L-RSPMs displayed small average droplet size (133.40 ± 4.52 nm), uniformly dispersed (PDI: 0.163 ± 0.011), good stability, slow release and enhanced solubility. We observed 353.28% increase in the relative bioavailability of L-RSPMs compared to free luteolin, while the half-life of the micelle was extended by 6.16h. Compared to model (M) group, luteolin (low and high doses) and L-RSPMs (low and high doses) significantly reduced levels of MDA, PEG2, CRP, TNF-α, IL-6 and IL-1β in colon tissue and serum of colitic rats but dose dependently increased IL-10 and SOD levels (p < 0.01). Histopathologic examination of colon showed that luteolin (low and high doses) and L-RSPMs (low and high doses) improved colonic inflammation in colitic rats to varying degrees compared to M group.

CONCLUSION

L-RSPMs could improve TNBS-induced colon inflammation by enhancing bioavailability, promoting antioxidant effects and regulating cytokine release, which may become a potential agent for UC treatment in clinical settings.

Role of potential bioactive metabolites from traditional Chinese medicine for type 2 diabetes mellitus: An overview

Type 2 diabetes mellitus (T2DM) is a metabolic disease with persistent hyperglycemia primarily caused by insulin resistance (IR). The number of diabetic patients globally has been rising over the past decades. Although significant progress has been made in treating diabetes mellitus (DM), existing clinical drugs for diabetes can no longer fully meet patients when they face complex and huge clinical treatment needs. As a traditional and effective medical system, traditional Chinese medicine (TCM) has a unique understanding of diabetes treatment and has developed many classic and practical prescriptions targeting DM. With modern medicine and pharmacy advancements, researchers have discovered that various bioactive metabolites isolated from TCM show therapeutic on DM. Compared with existing clinical drugs, these bioactive metabolites demonstrate promising prospects for treating DM due to their excellent biocompatibility and fewer adverse reactions. Accordingly, these valuable metabolites have attracted the interest of researchers worldwide. Despite the abundance of research works and specialized-topic reviews published over the past years, there is a lack of updated and systematic reviews concerning this fast-growing field. Therefore, in this review, we summarized the bioactive metabolites derived from TCM with the potential treatment of T2DM by searching several authoritative databases such as PubMed, Web of Science, Wiley Online Library, and Springer Link. For the convenience of readers, the content is divided into four parts according to the structural characteristics of these valuable compounds (flavonoids, terpenoids, alkaloids, and others). Meanwhile, the detailed mechanism and future directions of these promising compounds curing DM are also summarized in the related sections. We hope this review inspires increasingly valuable and significant research focusing on potential bioactive metabolites from TCM to treat DM in the future.

Luteolin reduces fear, anxiety, and depression in rats with post-traumatic stress disorder

Exposure to severe stress can lead to the development of neuropsychiatric disorders, including post-traumatic stress disorder (PTSD). The cause of PTSD is dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis and an imbalance of monoamines. Fruits and vegetables contain large amounts of luteolin (LU; 3′,4′,5,7-tetrahydroxylflavone), which has various pharmacological activities such as anti-inflammatory, antioxidant, and anti-allergic effects. We investigated the effects of LU on fear, depression, and anxiety following monoamine imbalance and hyperactivation of the HPA axis in rats exposed to single prolonged stress (SPS). Male rats were dosed with LU (10 and 20 mg/kg) once daily for 14 days after exposure to SPS. Administration of LU reduced fear freezing responses to extinction recall and depression- and anxiety-like behaviors, and suppressed increases in plasma corticosterone and adrenocorticotropic hormone levels. Also, administration of LU restored the increased norepinephrine and decreased serotonin levels in the structures within the fear circuit, medial prefrontal cortex, and hippocampus. Our results showed that administration of LU improved freezing behavior according in a situation-dependent manner, and showed anti-depressant and anxiolytic effects. Thus, LU may be a useful therapeutic agent to prevent traumatic stress such as PTSD.

Effects of a Mediterranean diet on the development of diabetic complications: A longitudinal study from the nationwide diabetes report of the National Program for Prevention and Control of Diabetes (NPPCD 2016-2020)

OBJECTIVE

To evaluate the effectiveness of a Mediterranean dietary pattern on the incidence of macrovascular and microvascular complications of diabetes, namely cardiovascular disease (CVD), diabetic foot disorders, diabetic retinopathy, nephropathy, and neuropathy.

METHODS

This longitudinal study was conducted among 71392 adults with diabetes who attended academic tertiary-care outpatient clinics from February 2016 to March 2020 across Iran using the National Program for Prevention and Control of Diabetes database. Among them, 22187 patients with diabetes (type 1 and type 2) completed 2-11 follow-up visits after baseline registration. The association between adherence to a Mediterranean diet and diabetic complications was assessed using pooled logistic regression models. This association was adjusted for potential confounders. The effect of time was assessed using fractional polynomials.

RESULTS

A total of 22187 participants were included in the analysis (30.22% men and 69.78% women) with either type 1 (mean age 50.7 years) or type 2 (mean age 59.9 years) diabetes. After adjustment for confounding variables, there was a negative correlation between adherence to a Mediterranean diet and the incidence of CVD among patients with type 1 diabetes (T1D) and 2 diabetes (T2D) (OR= 0.53, 95% CI: 0.37 - 0.75, p-value <0.001 and OR= 0.61, 95% CI: 0.57 - 0.89, p-value <0.001, respectively). Also, the diet had a statistically significant protective effect against incident symptomatic neuropathy (OR= 0.32, 95% CI: 0.23 - 0.43, p-value <0.001, and OR= 0.68, 95% CI: 0.64 - 0.72, p-value <0.001, respectively), nephropathy (OR= 0.42, 95% CI: 0.30 - 0.58, p-value <0.001, and OR= 0.88, 95% CI: 0.80 - 0.96, p-value= 0.007, respectively), and retinopathy (OR= 0.32, 95% CI: 0.24 - 0.44, p-value <0.001, and OR= 0.68, 95% CI: 0.61 - 0.71, p-value <0.001, respectively) in T1D and T2D.

CONCLUSION

The Mediterranean dietary pattern is associated with a lower incidence of CVD and microvascular complications (i.e. diabetic retinopathy, nephropathy, and neuropathy) among a cohort of patients with T1D and T2D in Iran.

Metformin attenuated histopathological ocular deteriorations in a streptozotocin-induced hyperglycemic rat model

Diabetes mellitus (DM) often causes ocular disorders leading to vision loss. Metformin is commonly prescribed for type 2 diabetes. This study assessed the effect of metformin on hyperglycemic histopathological eye abnormalities and some possible pathways involved. Male rats were divided into 3 groups (N = 6), namely, healthy control, hyperglycemic non-treated control, and hyperglycemic rats treated with 200 mg/kg metformin. Two weeks after diabetes induction by an intraperitoneal streptozotocin (60 mg streptozotocin (STZ)/kg) injection, the rats develop ocular abnormalities, and metformin (200 mg/kg) treatment was administered daily. Rats underwent dilated retinal digital ophthalmoscope examination and graded for diabetic retinopathy. Rats were sacrificed at 12 weeks, and the cornea, lens, sclera, ciliary body, iris, conjunctiva, retinal, and optic nerve were examined histologically. Rats' fasting blood glucose and body weight were monitored. Serum tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), claudin-1, and glutathione/malondialdehyde ratios were analyzed. Metformin significantly attenuated diabetes-related histopathological ocular deteriorations in the cornea, lens, sclera, ciliary body, iris, conjunctiva, retina, and optic nerve partly by restoring serum TNF-α, VEGF, claudin-1, and glutathione/malondialdehyde ratios without significantly affecting the fasting blood glucose levels or body weight in these hyperglycemic rats. Metformin attenuated hyperglycemia-associated histopathological eye deteriorations, possibly partly by ameliorating vascular leakage, oxidative stress, inflammation, and neovascularization, without affecting the fasting blood glucose levels or body weights in these STZ-induced diabetic rats.

Expression of α-Klotho Is Downregulated and Associated with Oxidative Stress in the Lens in Streptozotocin-induced Diabetic Rats

Purpose: Oxidative stress, an imbalance between the production of reactive oxygen species and antioxidant defenses, plays an important role in the pathogenesis of diabetic cataract. The lens in diabetes mellitus (DM) has been shown to exhibit impaired antioxidant defenses, but the underlying mechanisms remain poorly understood. Accumulating evidence reveals that Klotho family genes can regulate antioxidant defenses and prevent oxidative stress in multiple tissues. Here, we examined whether DM alters Klotho expression in the lens and if so, whether altered Klotho expression is associated with oxidative stress in the lens in DM.

Methods: Male Wistar rats were divided into DM and control groups. DM was induced by injection of streptozotocin (STZ, 60 mg/kg ip) and control rats were injected with vehicle. Twelve weeks after DM induction, levels of α-Klotho in plasma, expression of α- and γ-Klotho, and nuclear factor erythroid 2-related factor 2 (Nrf2), and levels of antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione (GSH) and oxidative stress marker malondialdehyde (MDA) in the lens were measured.

Results: Diabetic rats had markedly higher blood glucose concentrations and lower plasma α-Klotho levels than control rats. Both α- and γ-Klotho were expressed in the lens in diabetic and control rats. The expression of α-Klotho but not γ-Klotho in the lens was downregulated in diabetic rats, which was accompanied by reduced expression of nuclear Nrf2 and levels of all antioxidants and increased levels of MDA. Moreover, expression of α-Klotho in the lens was positively correlated with expression of nuclear Nrf2 and levels of all antioxidants, but negatively correlated with levels of MDA.

Conclusions: These findings suggest that DM selectively reduces α-Klotho levels in the circulation and lens, which may attenuate transcriptional activity of Nrf2 and impair antioxidant defenses in response to oxidative insults, contributing to oxidative stress and cataract formation in DM.

Flavones as a Privileged Scaffold in Drug Discovery: Current Developments

BACKGROUND

Flavones are one of the main subclasses of flavonoids with diverse pharmacological properties. They have been reported to possess antimalarial, antimicrobial, anti-tuberculosis, anti-allergic, antioxidant, anti-inflammatory activities, among others.

OBJECTIVE

The present review summarizes the recent information on the pharmacological properties of naturally occurring and synthetic flavones.

METHODS

Scientific publications referring to natural and synthetic flavones in relation to their biological activities were hand-searched in databases such as SciFinder, PubMed (National Library of Medicine), Science Direct, Wiley, ACS, SciELO, Springer, among others.

RESULTS

As per the literature, seventy-five natural flavones were predicted as active compounds with reference to their IC50 (<20 µg/mL) in in vitro studies. Also, synthetic flavones were found active against several diseases.

CONCLUSION

As per the literature, flavones are important sources for the potential treatment of multifactorial diseases. However, efforts toward the development of flavone-based therapeutic agents are still needed. The appearance of new catalysts and chemical transformations is expected to provide avenues for the synthesis of unexplored flavones, leading to the discovery of flavones with new properties and biological activities.

Activation of Sirtuin1 by lyceum barbarum polysaccharides in protection against diabetic cataract

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum polysaccharide (LBP) extracted from the Lycium barbarum L. has been widely used to improve diabetes and its relative complications. However, the mechanisms have not fully understood. A recent study has demonstrated that LBP upregulates suituin 1 (SIRT1).

OBJECTIVE

This study was to define the role of Sirt1 and its downstream signaling pathways in diabetic cataract using in vitro and in vivo models.

MATERIALS AND METHODS

Human lens epithelial cell line SRA01/04 cells were cultured under high glucose (HG) medium with treatment of LBP or vehicle. Cell viability, apoptosis, protein and/or mRNA levels of Sirt1, BAX, Bcl-2, active-caspase-3, FOXO1, p27 and acetylated p53 were measured. SIRT1 upregulated- and knocked-down cells were generated and tested in high glucose culture. Diabetes mellitus was induced in rats by streptozotocin injection. Body weight, blood glucose levels, lens transparency and retinal function were assessed and SIRT1, as well as the aforementioned biomarkers were measured using Western blotting and qPCR in the animal lens samples.

RESULTS

The results showed that HG decreased cell viability and LBP prevented the decrease. The reduced viability in HG cultured SRA01/04 cells was associated with increased levels of BAX, active caspase 3, FOXO1, p27, and p53 and decreased levels of SIRT1 and Bcl-2. Further experiments using sirt1 gene modulated cells showed that upregulation of Sirt1 improved viability, increase cell division as reflected by an increased proportion of S phase in the cell cycle, reduced the number of apoptotic cell death and suppressed p53 acetylation and caspase 3 activation. Opposite results were observed in SIRT1 knock-down cells. Treating diabetic animals with LBP reduced body weight loss and blood glucose content in diabetic animals. Similarly, LBP hindered the development of cataract in lenses and improved retinal function. The beneficial effect of LBP on diabetic cataract was associated with the supression of p53, caspase 3, FOXO1, BAX, p27 and elevation of SIRT1 and Bcl-2, which were consistent with the in vitro findings.

CONCLUSION

Our findings showed that diabetes caused cataract is associated with suppression of SIRT1 and Bcl-2 and activation of other cell death related genes. LBP prevented diabetic cataract in animals by upregulating Sirt1 and Bcl-2 and suppressing cell death related genes.

Biochemical Evidence Indicates the Preventive Effect of Resveratrol and Nicotinamide in the Treatment of STZ-induced Diabetic Cataract

PURPOSE

High glucose level is a strong initiator of both oxidative stress and DNA damage to various cellular proteins. This activates the poly ADP-ribose polymerase (PARP) enzyme, which is responsible for disturbing physiological energy metabolic homeostasis. The present study aimed to elucidate the association between stress and the PARP pathway by using resveratrol (RSV) and nicotinamide (NAM, PARP inhibitor) to treat diabetic cataract.

METHOD

Albino rats were used for the experimental study. A single streptozotocin administration (55 mg/kg, i.p.) prompted diabetes in the animals. The experimental groups were the normal group (non-diabetic) and the diabetic groups: the diabetic control animals (group D), the diabetic animals treated with RSV at 40 mg/kg/day, i.p. (D+ RSV group), NAM at 100 and 300 mg/kg/day, i.p. (D+ NAM100, D+ NAM300 groups, respectively), and a combination of RSV and NAM i.p. (D+ RSV+NAM100 = Combi 1 group, D+ RSV+NAM300 = Combi 2 group). Glucose levels and the eyes were examined biweekly; various cataractogenic parameters in the lenses were examined after completion of the eight-week experimental protocol.

RESULTS

Compared to diabetic control, RSV monotherapy significantly decreased hyperglycemia and other lenticular alterations. NAM at the high dose only showed beneficial effects without altering the blood glucose level, lenticular aldose reductase (AR) activity, and sorbitol content, primarily restored the lenticular NAD level and decreased oxidative stress in diabetic rats. These findings regarding NAM treatment indicate that a pathway other than the antioxidant defense system and the polyol pathway, which might be due to PARP inhibition, is involved in diabetic cataracts. Moreover, compared to RSV monotherapy, combination treatments were effective.

CONCLUSION

These results indicate that hyperglycemia and oxidative-osmotic-nitrosative stress play central roles in the pathophysiology of diabetic cataracts. Moreover, our study also revealed that concurrent treatment with the RSV and NAM may prove useful in the pharmacotherapy of diabetes and its secondary complications such as cataract.

Citrus hystrix leaf extract attenuated diabetic-cataract in STZ-rats

Diabetic cataract causes severe vision loss. This study evaluated the effects of hesperidin-standardized Citrus hystrix leaf flavonoids-rich extract (CLE) on diabetic-cataract development. Streptozotocin-induced diabetic rats were orally given 150 and 300 mg CLE/kg body-weight. These were compared with non-treated diabetic or healthy rats as controls, over 8 weeks. The CLE gradually attenuated fasting blood glucose (FBG), biomarkers for inflammation (Tumor necrosis factor alpha TNF-α; prostaglandin E2 PGE2); vascular permeability, (Vascular endothelial growth factor VEGF); and oxidative stress, (malondialdehyde MDA). The diabetic cataract was significantly mitigated by the 150 mg CLE/kg dose. Good correlations were found between cataract incidence with FBG (r²  = 0.90), serum PGE2 (r²  = 0.91), MDA (r²  = 0.99), VEGF (r²  = 0.71), but not with TNF-α levels (r²  = 0.49) suggesting the serum FBG, PGE2, MDA, and possibly the VEGF levels may help to predict the cataract risks. The CLE mitigated cataract probably by attenuating hyperglycaemia, inflammation, lens fluid influx, vascular leakage, lens osmotic-imbalance, and fibers over-hydration. PRACTICAL APPLICATIONS: The study shows the flavonoids-rich Citrus hystrix leaf consumption, effectively attenuated diabetes (fasting blood glucose) and mitigated diabetic cataract. It help reduce diabetes-related hyperglycaemia, oxidative stress, inflammation, and vascular leakage. The evidences were the CLE consumptions reduced the serum biomarkers tumor necrosis factor-alpha TNF-α; prostaglandin E2 PGE2, vascular endothelial growth factor (VEGF), and malondialdehyde (MDA). The C. hystrix leaf contains hesperidin, apiin, diosmin, saponarin, apigetrin, rutin and xanthotoxol, and other flavonoid glucosides. The study also showed good correlations between cataract incidence with fasting blood glucose FBG (r²  = 0.90), serum PGE2 (r²  = 0.91), and MDA (r²  = 0.99), and less closely with VEGF (r²  = 0.71) suggesting these serum biomarkers may help predict cataract risks. The CLE indicated cataract mitigation properties probably by attenuating FBG, inflammation, lens fluid influx, lens osmotic-imbalance, and fibers over-hydration.

Klotho ameliorates the onset and progression of cataract via suppressing oxidative stress and inflammation in the lens in streptozotocin-induced diabetic rats

Increased oxidative stress and inflammation play an important role in the pathogenesis of diabetic cataract. Klotho, known as an anti-ageing protein, has antioxidative and anti-inflammatory properties. Klotho is expressed in limited tissues including the lens. Here we examined whether klotho expression is decreased in diabetic lens and, if so, whether klotho treatment can prevent diabetic cataract formation. Streptozotocin (STZ)-induced diabetic rats and age-matched control rats were treated with vehicle or klotho protein, starting at 1 week after STZ injection. Twelve weeks after treatment, cataract formation was observed in diabetic rats but not control rats. Cataract formation and scores were significantly less in klotho-treated diabetic rats than vehicle-treated diabetic rats. Levels of klotho in plasma, aqueous humor and lens were significantly decreased in vehicle-treated diabetic rats, compared with control rats, but were restored in klotho-treated diabetic rats. Additionally, vehicle-treated diabetic rats had increased oxidative stress and inflammation in the lens, which were associated with decreased antioxidant transcriptional master regulator Nrf2 activity and increased transcription factor NF-κB activity. All of these findings were ameliorated in klotho-treated diabetic rats. Notably, klotho treatment did not alter blood glucose in diabetic rats. These results indicate that klotho reduction may increase susceptibility of the lens to oxidative and inflammatory insults, promoting cataract formation under diabetic conditions. Klotho treatment can ameliorate the onset and progression of diabetic cataract via enhancing Nrf2-mediated antioxidant defense and suppressing NF-κB-mediated inflammatory responses. Klotho in the lens may be a novel therapeutic target for prevention of cataract formation in diabetes.

Porcine models for studying complications and organ crosstalk in diabetes mellitus

The worldwide prevalence of diabetes mellitus and obesity is rapidly increasing not only in adults but also in children and adolescents. Diabetes is associated with macrovascular complications increasing the risk for cardiovascular disease and stroke, as well as microvascular complications leading to diabetic nephropathy, retinopathy and neuropathy. Animal models are essential for studying disease mechanisms and for developing and testing diagnostic procedures and therapeutic strategies. Rodent models are most widely used but have limitations in translational research. Porcine models have the potential to bridge the gap between basic studies and clinical trials in human patients. This article provides an overview of concepts for the development of porcine models for diabetes and obesity research, with a focus on genetically engineered models. Diabetes-associated ocular, cardiovascular and renal alterations observed in diabetic pig models are summarized and their similarities with complications in diabetic patients are discussed. Systematic multi-organ biobanking of porcine models of diabetes and obesity and molecular profiling of representative tissue samples on different levels, e.g., on the transcriptome, proteome, or metabolome level, is proposed as a strategy for discovering tissue-specific pathomechanisms and their molecular key drivers using systems biology tools. This is exemplified by a recent study providing multi-omics insights into functional changes of the liver in a transgenic pig model for insulin-deficient diabetes mellitus. Collectively, these approaches will provide a better understanding of organ crosstalk in diabetes mellitus and eventually reveal new molecular targets for the prevention, early diagnosis and treatment of diabetes mellitus and its associated complications.

Autoregenerative redox nanoparticles as an antioxidant and glycation inhibitor for palliation of diabetic cataracts

Diabetic cataracts (DCs) are one of the most common ocular complications of diabetes, and easily causes blindness among diabetics. However, there are limited drugs to delay and prevent DCs. Research studies indicate that oxidative damage of the crystalline lens and nonenzymatic glycosylation of the lens protein play a key role in the pathogenesis of DCs. Hence, we developed a kind of autoregenerative redox nanoparticle, which was CeO2 NPs coated with PEG-PLGA (PCNPs). We first found that PCNPs could work not only as an antioxidant to protect lens epithelial cells from oxidative stress based on the repetitive elimination of reactive oxygen species (ROS), but also as a glycation inhibitor effectively restraining α-crystallin glycation and crosslinking, thereby keeping the lens transparent and alleviating DCs. Experimental results successfully validated the fact that the PCNPs were able to operate in eyes for a long time to attenuate lens opacity. We expect that this strategy will provide promising potential for the treatment of DCs.

Effect of Moringa oleifera stem extract on hydrogen peroxide-induced opacity of cultured mouse lens

BACKGROUND

Moringa oleifera, also known as horseradish tree or drumstick tree, has strong antioxidant properties. In the present study, we investigated the potential effect of Moringa oleifera stem extract (MOSE) on cataract formation induced by oxidative stress in cultured mouse lenses.

METHODS

Mouse lenses cultured in vitro were pretreated with MOSE (0.5 and 1 mg/mL) for 24 h. Then, 1 mM hydrogen peroxide was added, and mouse lenses were cultured for a further 24 h. The medium was then changed to normal culture medium. After 48 h, lens opacification, reactive oxygen species (ROS) generation, reduced glutathione (GSH) content, and activities of superoxide dismutase (SOD) and catalase (CAT) were measured in lens tissues. In addition, the protein expression of peroxisome proliferator-activated receptor alpha (PPARα), a nuclear receptor with potential benefits to improve vision-threatening eye diseases, was assayed.

RESULTS

MOSE (1 mg/mL) alleviated lens opacification, reduced ROS generation, increased GSH content, and elevated SOD and CAT activities in cultured lenses. Moreover, MOSE upregulated the expressions of SOD, CAT, and PPARα.

CONCLUSIONS

This study showed that MOSE alleviates oxidative stress-induced cataract formation, and the mechanism of the effect is mainly related to its improvement of the endogenous antioxidant system in the lens.

Luteolin-mediated Kim-1/NF-kB/Nrf2 signaling pathways protects sodium fluoride-induced hypertension and cardiovascular complications

The use of sodium fluoride (NaF) as a major ingredient for tooth paste, mouth wash, and mouth rinse has become inevitable in our day-to-day life. However, flavonoids such as Luteolin might be of great value in the prevention of toxicity associated with accidental or inevitable ingestion of NaF. In the study, 40 male Wistar albino rats were randomly divided into four groups with 10 rats in a group. Group A was the control group and received normal saline, Group B was exposed to NaF at 300 ppm (300 mg/L) in drinking water daily for a week, Groups C and D were exposed to 300 ppm (300 mg/L) of NaF and coadministered with Luteolin orally daily at a dosage of 100 mg/kg and 200 mg/kg for the same time point. Our results indicated that NaF caused significant increases in systolic blood pressure, diastolic blood pressure, mean arterial pressure, malondialdehyde, protein carbonyl, myeloperoxidase, advanced oxidative protein products, together with significant reductions in glutathione peroxidase, superoxide dismutase, catalase, glutathione reductase, reduced glutathione, and nitric oxide (NO) bioavailability. The electrocardiogram results showed that NaF alone caused significant prolongation of QT and QTc intervals. Immunohistochemistry revealed that NaF caused increase expressions of Kidney injury marker 1 (Kim-1), nuclear factor kappa bet (NF-κB), nuclear factor erythroid 2-related factors 2 (Nrf2), and cardiac troponin I (CTnI). Together, Luteolin coadministration with NaF improved NO bioavailability, reduced high blood pressure, markers of oxidative stress, reversed prolongation of QT and QTc intervals, and lowered the expressions of Kim-1, NF-κB, and CTnI. © 2018 BioFactors, 44(6):518-531, 2018.