Silymarin reduces retinal microvascular damage in streptozotocin-induced diabetic rats

Beta-carotene ameliorates diabetic nephropathy in rats: involvement of AMPK/SIRT1/autophagy pathway

OBJECTIVE

This study aimed to demonstrate the protective effect of beta-carotene against STZ-induced DN in rats and explore the possible underlying mechanisms that may have mediated such condition.

MATERIAL AND METHODS

Wistar rats were allocated into four groups. Normal group received distilled water for 3 weeks. The other three groups were rendered diabetic by an intraperitoneal dose of STZ (50 mg/kg), 48 h later, group 2: received the vehicle and served as control, groups (3 &4) received orally beta-carotene in doses of 10 and 20 mg/kg, respectively for 3 weeks. Then serum and renal tissue were collected for biochemical, molecular, immunohistopathological, and histopathological examination.

RESULTS

Beta-carotene ameliorated the reduction in body weight, reduced blood glucose, elevated serum insulin, reduced blood urea nitrogen, and serum creatinine levels. Beta-carotene elevated phosphorylated 5' adenosine monophosphate-activated protein kinase (p-AMPK)/AMPK, alleviated phosphorylated mammalian target of rapamycin (p-mTOR)/mTOR, reduced interleukin 1 beta (IL-1β), increased Beclin 1, LC3II/LC3I, and reduced p62 renal contents. Moreover, it elevated renal SIRT1 gene expression and reduced renal tumor necrosis factor-alpha (TNF-α) and caspase-3 protein expressions.

CONCLUSION

Beta-carotene exerted renoprotective effect against STZ-induced DN and histopathological alterations through alleviating hyperglycemia, attenuating inflammation, activating AMPK/SIRT1/autophagy pathway, and combating apoptosis.

Silymarin prevents endothelial dysfunction by upregulating Erk-5 in oxidized LDL exposed endothelial cells

Extracellular signal-regulated kinase (Erk)-5 is a key mediator of endothelial cell homeostasis, and its inhibition causes loss of critical endothelial markers leading to endothelial dysfunction (ED). Circulating oxidized low-density lipoprotein (oxLDL) has been identified as an underlying cause of ED and atherosclerosis in metabolic disorders. Silymarin (Sym), a flavonolignan, possesses various pharmacological activities however its preventive mechanism in ED warrants further investigation. Here, we have examined the effects of Sym in regulating the expression of Erk-5 and ameliorating ED using in vitro and in vivo models. Primary human umbilical vein endothelial cells (pHUVECs) viability was measured by MTT assay; mRNA and protein expression by RT-qPCR and Western blotting; tube-formation assay was performed to examine endothelialness. In in-vivo experiments, normal chow-fed mice (control) or high-fat diet (HFD)-fed mice were administered Sym or Erk-5 inhibitor (BIX02189) and body weight, blood glucose, plasma-LDL, oxLDL levels, and expression of EC markers in the aorta were examined. Sym (5 μg/ml) maintained the viability and tube-formation ability of oxLDL exposed pHUVECs. Sym increased the expression of Erk-5, vWF, and eNOS and decreased ICAM-1 at transcription and translation levels in oxLDL-exposed pHUVECs. In HFD-fed mice, Sym reduced the body weight, blood glucose, LDL-cholesterol, and oxLDL levels, and increased the levels of vWF and eNOS along with Erk-5 and decreased the level of ICAM-1 in the aorta. These data suggest that Sym could be a potent anti-atherosclerotic agent that could elevate Erk-5 level in the ECs and prevent ED caused by oxidized LDL during HFD-induced obesity in mice.

Neuroprotective effects of silymarin in 3-nitropropionic acid-induced neurotoxicity in male mice: improving behavioral deficits by attenuating oxidative stress and neuroinflammation

3-Nitropropionic acid (3-NP) is strongly believed to be an irreversible inhibitor of mitochondrial complex II, leading to neural damage. This study aimed to investigate the neuroprotective effects of silymarin against 3-NP-induced neurotoxicity in male mice. Six-week-old mice received subacute doses of 3-NP intraperitoneally for 17 days. Mice were given silymarin (70 mg/kg/day, P.O.) for 2 weeks before 3-NP administration or for 4 weeks after 3-NP administration. At the end of the treatment schedule, animals were evaluated for behavioral alterations. Subsequently, neuronal damage in the hippocampus region of the brain tissues, oxidative stress-related parameters (lipid peroxidation, nitric oxide, superoxide dismutase, glutathione, and total antioxidant capacity), and pro-inflammatory cytokine (TNF-α, IL-17, and IL-1β) levels were evaluated. Our results indicated that 3-NP treatment significantly (p < 0.05) tended to reduce motor coordination, memory, and neuronal antioxidant status while increasing pro-inflammatory cytokine levels. However, silymarin in both treatment and pretreatment protocols markedly (p < 0.05) attenuated the behavioral deficits, oxidative stress status, and neuroinflammation. The results of the current study suggest that the neuroprotective effect of silymarin against 3-NP-induced neurotoxicity might be due to the mitigation of oxidative stress status and provide insight into the therapeutic potential of silymarin.

Impacts of Supplementation with Silymarin on Cardiovascular Risk Factors: A Systematic Review and Dose-Response Meta-Analysis

It has been suggested that silymarin (SIL) supplementation has positive effects on cardiovascular health and reduces the risk of cardiometabolic syndrome (CMS). This systematic review and dose-response meta-analysis assessed the impacts of SIL administration on cardiovascular risk factors. A systematic search of multiple databases was performed to identify eligible controlled trials published up to January 2023. The analysis used a random-effects model and included 33 trials with 1943 participants. It was revealed that SIL supplementation led to a notable reduction in serum levels of fasting blood glucose (FBG) (weighted mean difference (WMD): -21.68 mg/dL, 95% CI: -31.37, -11.99; p < 0.001), diastolic blood pressure (DBP) (WMD: -1.25 mmHg; 95% CI: -2.25, -0.26; p = 0.013), total cholesterol (TC) (WMD: -13.97 mg/dL, 95% CI: -23.09, -4.85; p = 0.003), triglycerides (TG) (WMD: -26.22 mg/dL, 95% CI: -40.32, -12.12; p < 0.001), fasting insulin (WMD: -3.76 mU/mL, 95% CI: -4.80, -2.72; p < 0.001), low-density lipoprotein (LDL) (WMD: -17.13 mg/dL, 95% CI: -25.63, -8.63; p < 0.001), and hemoglobin A1C (HbA1c) (WMD: -0.85%, 95% CI: -1.27, -0.43; p < 0.001) in the SIL-treated groups compared to their untreated counterparts. In addition, there were no substantial differences in body mass index (BMI), systolic blood pressure (SBP), C-reactive protein (CRP), body weight, and high-density lipoprotein (HDL) between the two groups. These outcomes suggest that SIL consumption reduces certain CMS risk factors and has favorable impacts on lipid and glycemic profiles with potential hypotensive effects. These findings should be supported by additional trials with larger sample sizes and longer durations.

Mechanistic Insights into the N-Hydroxylations Catalyzed by the Binuclear Iron Domain of SznF Enzyme: Key Piece in the Synthesis of Streptozotocin

SznF, a member of the emerging family of heme-oxygenase-like (HO-like) di-iron oxidases and oxygenases, employs two distinct domains to catalyze the conversion of Nω-methyl-L-arginine (L-NMA) into N-nitroso-containing product, which can subsequently be transformed into streptozotocin. Using unrestricted density functional theory (UDFT) with the hybrid functional B3LYP, we have mechanistically investigated the two sequential hydroxylations of L-NMA catalyzed by SznF's binuclear iron central domain. Mechanism B primarily involves the O-O bond dissociation, forming Fe(IV)=O, induced by the H+/e- introduction to the FeA side of μ-1,2-peroxo-Fe2(III/III), the substrate hydrogen abstraction by Fe(IV)=O, and the hydroxyl rebound to the substrate N radical. The stochastic addition of H+/e- to the FeB side (mechanism C) can transition to mechanism B, thereby preventing enzyme deactivation. Two other competing mechanisms, involving the direct O-O bond dissociation (mechanism A) and the addition of H2O as a co-substrate (mechanism D), have been ruled out.

Silymarin and Inflammation: Food for Thoughts

Inflammation is a vital defense mechanism, creating hostile conditions for pathogens, preventing the spread of tissue infection and repairing damaged tissues in humans and animals. However, when inflammation resolution is delayed or compromised as a result of its misregulation, the process proceeds from the acute phase to chronic inflammation, leading to the development of various chronic illnesses. It is proven that redox balance disturbances and oxidative stress are among major factors inducing NF-κB and leading to over-inflammation. Therefore, the anti-inflammatory properties of various natural antioxidants have been widely tested in various in vitro and in vivo systems. Accumulating evidence indicates that silymarin (SM) and its main constituent silibinin/silybin (SB) have great potential as an anti-inflammation agent. The main anti-inflammatory mechanism of SM/SB action is attributed to the inhibition of TLR4/NF-κB-mediated signaling pathways and the downregulated expression of pro-inflammatory mediators, including TNF-α, IL-1β, IL-6, IL-12, IL-23, CCL4, CXCL10, etc. Of note, in the same model systems, SM/SB was able to upregulate anti-inflammatory cytokines (IL-4, IL-10, IL-13, TGF-β, etc.) and lipid mediators involved in the resolution of inflammation. The inflammatory properties of SM/SB were clearly demonstrated in model systems based on immune (macrophages and monocytes) and non-immune (epithelial, skin, bone, connective tissue and cancer) cells. At the same time, the anti-inflammatory action of SM/SB was confirmed in a number of in vivo models, including toxicity models, nonalcoholic fatty liver disease, ischemia/reperfusion models, stress-induced injuries, ageing and exercising models, wound healing and many other relevant model systems. It seems likely that the anti-inflammatory activities of SM/SB are key elements on the health-promoting properties of these phytochemicals.

Effect of silymarin on the relative gene expressions of some inflammatory cytokines in the liver of CCl4-intoxicated male rats

The intensive exposure of the liver cells to any type of noxae, such as viruses, drugs, alcohols, and xenobiotics could induce hepatic inflammation through the upregulation of gene expression of several fibrotic and inflammatory mediators. So, our study assessed the role of silymarin on the inflammatory response induced by carbon tetrachloride (CCl4) as an example of xenobiotics on liver tissues in male rats. Forty-eight Wister male rats (weight: 130 ± 10) were housed for 14 days and then divided randomly into six groups: control, SLY: rats received only silymarin orally for 12 weeks (daily), CO: rats were injected with corn oil for 8 weeks (3 times weekly), CCl4: rats were injected with CCl4 solubilized in corn oil for 8 weeks (day by day), Treated: rats received silymarin for 4 weeks after CCl4 injection, Protected: rats received silymarin for 4 weeks before and 8 weeks during CCl4 injection. When the treatment period for the rats was over, they underwent scarification after anesthesia. Then, the sera were extracted from the collected blood for the determination of irisin levels, liver functions, and lipid profiles. Liver tissues were separated for the histopathological examinations, the determination of oxidative stress (OS) parameters content, and the relative gene expression of inflammatory cytokines; nuclear factor kappa (NF)-κB, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, cyclooxygenase (COX)-2, and transforming growth factor beta (TGF-β). The findings showed that silymarin reduced liver inflammation by overcoming the OS process and inflammatory cytokines production which was stimulated by CCl4. These results were confirmed by histopathology of liver tissues.

Hepatoprotective effects of moderate-intensity interval training along with ginger juice in an old male rat model

Aging is a natural process coupled with oxidative stress and chronic inflammation, gradually associated with losing organ function over time. Therefore, the objective of the current work was to peruse the protective effects of 8-week moderate-intensity interval training (MIIT) and ginger extract supplementation on some biomarkers of oxidative stress, inflammation, and lipid metabolism in the liver of elderly males Wistar rats (animal study with ethical code IR.BMSU.REC.1401.015). A total of thirty-two 22-month-aged male Wistar rats were randomly assigned to four groups: (1) control, (2) MIIT, (3) ginger, and (4) MIIT + ginger. After 8 weeks of treadmill training and ginger extract supplementation, the biochemical parameters (liver enzyme and lipid profile), inflammatory mediators (leucine-rich α-2 glycoprotein 1 (LRG1), tumor necrosis factor-alpha, and interleukin-6), pro-oxidant (malondialdehyde), antioxidant biomarkers (catalase, superoxide dismutase, total antioxidant capacity), some lipid metabolism regulators (carnitine palmitoyltransferase 1, adipose triglyceride lipase, acetyl-CoA carboxylase, CD36, and AMP-activated protein kinase), and liver histopathological changes were appraised. The acquired findings pointed out that MIIT combined with ginger extract appreciably diminished the serum levels of LRG1, liver enzymes, and lipid profile relative to the other groups after 8 weeks of intervention. Furthermore, ginger + MIIT caused a great improvement in the liver levels of antioxidant biomarkers, pro-oxidant, pro-inflammatory biomarkers, lipid metabolism regulators, and liver tissue impairment compared to the other groups. The findings suggested that MIIT + ginger was more effective in improving examined indices relative to the other groups.

Ginger's Antiapoptotic and Antioxidant Effects on Ovaries of Cyclophosphamide-therapied Rats

BACKGROUND

In the recent decade, there has been increasing interest in preventing ovarian toxicity after chemotherapy exposure. It has been documented that ginger (Zingiber officinale) might normalize the hormonal balance and control the menstrual cycle..

OBJECTIVE

This study has analyzed whether ginger extract protects against cyclophosphamide (CP)-induced ovarian failure in rats.

METHODS

Rats were distributed into four groups consisting of vehicle, CP, ginger, and CP + ginger. At the end of the treatment, all rats were killed under anesthesia to obtain ovarian tissues and blood samples for histological, molecular, and biochemical experiments.

RESULTS

Our results indicated that ginger improves CP-caused histological changes in ovarian tissues and significantly restores serum hormonal abnormalities. Ginger also showed unique antioxidant, anti-inflammatory, and antiapoptotic properties in the ovarian tissues of CP-induced rats. Further, our findings indicated that ginger might activate the Nrf2 and SIRT and inhibit the PI3K/AKT pathway in the ovaries of CP-treated rats. In conclusion, ginger was found to protect against CP-caused ovarian toxicity in rats.

CONCLUSION

The protective impacts of ginger may mediate, at least partly, by alleviating the oxidant state, inhibiting pro-inflammatory conditions, and exhibiting antiapoptotic activities.

Current Treatments and Innovations in Diabetic Retinopathy and Diabetic Macular Edema

Diabetic retinopathy (DR) is one of the leading causes of blindness worldwide. Multiple treatment options have been used over time to attempt to modify the natural progression of the disease in both proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME). These two retinal complications are the result of microvascular occlusions and vascular hyperpermeability and are considered one of the leading causes of irreversible blindness in patients of working age. It is now well demonstrated that PDR and DME are associated with increased levels of inflammatory and pro-angiogenic factors in the ocular compartment. To date, laser photocoagulation, vascular endothelial growth factor (VEGF) inhibitors, and corticosteroids have demonstrated efficacy in their treatment in large randomized controlled trials and in real-life observational studies. This manuscript aims to provide a comprehensive review of current treatments, including the main drugs used in diabetic pathologic manifestations, as well as new therapeutic alternatives, such as extended-release intraocular devices.