Potential renoprotective effects of piceatannol in ameliorating the early-stage nephropathy associated with obesity in obese Zucker rats

Synergistic Power of Piceatannol and/or Vitamin D in Bleomycin-Induced Pulmonary Fibrosis In Vivo: A Preliminary Study

Oxidative stress and epigenetic alterations, including the overexpression of all class I and II histone deacetylases (HDACs), particularly HDAC2 and HDAC4, have been identified as key molecular mechanisms driving pulmonary fibrosis. Treatment with piceatannol (PIC) or vitamin D (Vit D) has previously exhibited mitigating impacts in pulmonary fibrosis models. The present study investigated the effects of PIC, Vit D, or a combination (PIC-Vit D) on the expression of HDAC2, HDAC4, and transforming growth factor-beta (TGF-β) in the lungs; the phosphatidylinositide-3-kinase (PI3K)/AKT signaling pathway; and the antioxidant status of the lungs. The objective was to determine if the treatments had protective mechanisms against pulmonary fibrosis caused by bleomycin (BLM) in rats. Adult male albino rats were given a single intratracheal dosage of BLM (10 mg/kg) to induce pulmonary fibrosis. PIC (15 mg/kg/day, oral (p.o.)), Vit D (0.5 μg/kg/day, intraperitoneal (i.p.)), or PIC-Vit D (15 mg/kg/day, p.o. plus 0.5 μg/kg/day, i.p.) were given the day following BLM instillation and maintained for 14 days. The results showed that PIC, Vit D, and PIC-Vit D significantly improved the histopathological sections; downregulated the expression of HDAC2, HDAC4, and TGF-β in the lungs; inhibited the PI3K/AKT signaling pathway; decreased extracellular matrix (ECM) deposition including collagen type I and alpha smooth muscle actin (α-SMA); and increased the antioxidant capacity of the lungs by increasing the levels of glutathione (GSH) that had been reduced and decreasing the levels of malondialdehyde (MDA) compared with the BLM group at a p-value less than 0.05. The concomitant administration of PIC and Vit D had a synergistic impact that was greater than the impact of monotherapy with either PIC or Vit D. PIC, Vit D, and PIC-Vit D exhibited a notable protective effect through their antioxidant effects, modulation of the expression of HDAC2, HDAC4, and TGF-β in the lungs, and suppression of the PI3K/AKT signaling pathway.

Potential of Polyphenols to Restore SIRT1 and NAD+ Metabolism in Renal Disease

SIRT1 is an NAD⁺-dependent class III histone deacetylase that is abundantly expressed in the kidney, where it modulates gene expression, apoptosis, energy homeostasis, autophagy, acute stress responses, and mitochondrial biogenesis. Alterations in SIRT1 activity and NAD⁺ metabolism are frequently observed in acute and chronic kidney diseases of diverse origins, including obesity and diabetes. Nevertheless, in vitro and in vivo studies and clinical trials with humans show that the SIRT1-activating compounds derived from natural sources, such as polyphenols found in fruits, vegetables, and plants, including resveratrol, quercetin, and isoflavones, can prevent disease and be part of treatments for a wide variety of diseases. Here, we summarize the roles of SIRT1 and NAD⁺ metabolism in renal pathophysiology and provide an overview of polyphenols that have the potential to restore SIRT1 and NAD⁺ metabolism in renal diseases.

Hepatoprotective effect of piceatannol against carbon tetrachloride-induced liver fibrosis in mice

Piceatannol (3,5,3',4'-trans-tetrahydroxystilbene) is a natural analog and a metabolite of resveratrol present in grapes and red wine. Previous studies have reported that piceatannol exerts a broad spectrum of health benefits including antioxidant, anti-inflammatory, chemopreventive, and neuroprotective effects. However, little is known about the hepatoprotective effect of piceatannol against toxin-induced liver fibrosis. Therefore, the objective of this study is to evaluate the protective effect of piceatannol in a mouse model of CCl₄-induced hepatic fibrosis. Oral administration of piceatannol significantly improved the hepatic functions of CCl₄-treated mice in both therapeutic and preventive models. Additionally, the immunohistochemical staining results revealed that collagen deposition in CCl₄-injected mice was significantly reduced by treatment with piceatannol. Moreover, piceatannol remarkably suppressed the expressions of collagen I, α-smooth muscle protein (α-SMA), and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) induced by CCl₄. The anti-fibrotic mechanism of piceatannol was associated with the regulation of the transforming growth factor-β (TGF-β)/Smad signaling pathway. Finally, piceatannol also profoundly alleviated CCl₄-induced hepatic oxidative damage by elevating the level of glutathione and catalase activity. Altogether, our current findings suggest that piceatannol may serve as a bioactive agent that inhibits or alleviates toxic-induced fibroproliferative diseases, especially in the prevention of liver fibrosis.

Plaque control alleviated renal damage that was aggravated by experimental periodontitis in obese rats

OBJECTIVE

This study aimed to evaluate the influence of experimental periodontitis on renal damage in obese rats.

MATERIALS AND METHODS

Thirty-two male Sprague Dawley rats were randomly allocated into 4 groups with 8 animals each: obese rats (obese group), obese rats with periodontitis (periodontitis obese group), obese rats with periodontitis that underwent plaque control (plaque-control obese group), and healthy rats (healthy group). Rats were fed a high-fat diet to establish an obesity model. Experimental periodontitis was induced by local ligation with silk around the bilateral maxillary second molars. The plaque control was accomplished by removing ligations and local wiping with an antiseptic rinse. Histology was used to observe the gingival inflammation and clinical attachment level (CAL) to further assess bone loss and to also observe renal structure. Serum creatinine, urea nitrogen, and kidney injury molecule-1 (KIM-1) levels were measured to evaluate renal function. Renal Toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB), serum C-reactive protein (CRP), lipopolysaccharides (LPS), and interleukin-1β (IL-1β) were measured to evaluate renal and systemic inflammation.

RESULTS

Periodontal histology showed that in the periodontitis obese group, the epithelial barrier was considerably eroded by inflammatory cells, which infiltrated into the subepithelial connective tissue and lamina propria. A periodontal pocket was forming accompanied by the loss of attachment. The extent of infiltration of inflammatory cells and the CAL were significantly higher than those of the obese group (p < .001). In the plaque-control obese group, although the inflammatory condition was significantly improved than in the periodontitis obese group, the clinical attachment level with the presence of fiber hyperplasia could not be restored. Renal histology showed that renal tubular structural damage was aggravated in the periodontitis obese group, including vacuolar degeneration, exfoliation of the proximal tubular epithelial cell lining, multifocal loss of the brush border, and movement of several nuclei from the basement membrane to the lumen. These alterations were improved in the plaque-control obese group. Kidney TLR4 and NF-κB mRNA levels increased significantly in the periodontitis obese group compared to the obese group (p = .015 and p = .015, respectively) and decreased significantly in the plaque-control obese group (p = .028 and p = .021, respectively). Kidney TLR4 and NF-κB protein expression in the plaque-control obese group were significantly lower than those in the periodontitis obese group (p < .001 and p = .043, respectively). Serum creatinine and KIM-1 levels significantly decreased in the plaque-control obese group compared to the periodontitis obese group (p = .001 and p = .002, respectively). At 21 weeks (1 week after periodontal ligation), serum CRP levels in the periodontitis obese group were significantly higher than that in the healthy group (p = .017). Other serum inflammatory markers (LPS and IL-1β) did not change significantly.

CONCLUSION

Experimental periodontitis induced dysfunction and structural destruction of the kidney in obese rats. Plaque control relieved renal damage.

Lesser Investigated Natural Ingredients for the Management of Obesity

Obesity, an epidemiological disorder, is related to various complications in both the developed and developing world. It epitomizes a crucial risk factor for health, decreasing productivity and life expectancy while increasing health care costs worldwide. Conventional therapies with synthetic drugs or bariatric surgery, associated with numerous side effects, recurrence, and surgical complexity, have been restricted in their use. Lifestyle changes and dietary restrictions are the proven methods for successful weight loss, although maintaining a strict lifestyle is a challenge. Multiple natural products have been explored for weight management with varied efficacy. The current review explores less explored natural herbs, their active constituents, and their mechanisms of action against obesity.

Piceatannol protects against cerebral ischemia/reperfusion‑induced apoptosis and oxidative stress via the Sirt1/FoxO1 signaling pathway

Reperfusion is a critical therapeutic intervention used following acute ischemic stroke; however, it may cause cerebral ischemia/reperfusion injury (CIRI) and aggravate brain damage. Piceatannol (Pic), a hydroxylated analog of resveratrol, has been reported to exhibit anti‑inflammatory effects. However, the detailed molecular mechanisms and its effects on CIRI have not been sufficiently assessed, and, to the best of our knowledge, current methods of prevention of CIRI are limited. The aim of the present study was to investigate the effects of Pic on improving neurological function in a mouse model of CIRI. For the animal experiments, 8‑week‑old C57BL/6 mice were raised and randomly grouped, and an in vivo model of CIRI was established. Mice were administered a low (10 mg/kg/day) or high‑dose (20 mg/kg/d) of Pic 1 h after CIRI orally and once daily for the next 6 days. Neurological dysfunction was assessed using a modified neurological severity score and a rotarod test 1 week after CIRI establishment, and the cognitive status of the mice was assessed using a Morris water maze. Hematoxylin and eosin staining was used to evaluate the histopathological changes. The expression levels of sirtuin 1 (Sirt1), FoxO1, cleaved caspase‑3 (CC‑3), Bax and Bcl‑2 were measured using western blotting. Intracellular reactive oxygen species (ROS) generation, antioxidant enzymes [superoxide dismutase, glutathione (GSH) peroxidase and catalase] and non‑enzymatic antioxidants (GSH) were also detected using spectrophotometry. After inhibition of the Sirt1/FoxO1 pathway, a TUNEL assay was used for the detection of apoptotic cells in vitro and in vivo. The co‑localization of neuron‑specific nuclear protein and CC‑3 was assessing using immunofluorescent staining. Pic improved neurological functions and ameliorated hippocampal neuronal pathology following CIRI. In addition, the expression levels of CC‑3 and Bax and intracellular ROS levels were increased, while levels of antioxidant and non‑enzymatic enzymes were decreased in the mouse model of CIRI. Low and high doses of Pic significantly decreased ROS production and the expression levels of apoptosis‑related proteins, but increased antioxidant enzyme levels. However, a high‑dose of Pic did not result in increased levels of non‑enzymatic enzymes. Furthermore, low and high doses of Pic treatment significantly activated the Sirt1/FoxO1 pathway. Following inhibition of the Sirt1/FoxO1 pathway, the percentage of TUNEL‑positive cells and expression of CC‑3 were increased, and CC‑3 was enriched in neurons. The antioxidant effects of Pic were blocked by inhibition of Sirt1 in vitro and in vivo. In conclusion, these results suggested that Pic may exert a neuroprotective effect against in hippocampal neurons via the Sirt1/FoxO1 pathway.

Biological Activities of Stilbenoids

Stilbenoids are a group of naturally occurring phenolic compounds found in various plant species. They share a common backbone structure known as stilbene, but differ in the nature and position of substituents. Stilbenoids are classified as phytoalexins, which are antimicrobial compounds produced de novo in plants to protect against fungal infection and toxins. In this review, the biological effects of stilbenoids such as resveratrol, pterostilbene, gnetol and piceatannol are discussed. Stilbenoids exert various biological activities ranging from cardioprotection, neuroprotection, anti-diabetic properties, depigmentation, anti-inflammation, cancer prevention and treatment. The results presented cover a myriad of models, from cell culture to animal studies as well as clinical human trials. Although positive results were obtained in most cell culture and animal studies, further human studies are needed to substantiate beneficial effects of stilbenoids. Resveratrol remains the most widely studied stilbenoid. However, there is limited information regarding the potential of less common stilbenoids. Therefore, further research is warranted to evaluate the salutary effects of various stilbenoids.

Bridging Type 2 Diabetes and Alzheimer's Disease: Assembling the Puzzle Pieces in the Quest for the Molecules With Therapeutic and Preventive Potential

Type 2 diabetes (T2D) and Alzheimer's disease (AD) are two age-related amyloid diseases that affect millions of people worldwide. Broadly supported by epidemiological data, the higher incidence of AD among type 2 diabetic patients led to the recognition of T2D as a tangible risk factor for the development of AD. Indeed, there is now growing evidence on brain structural and functional abnormalities arising from brain insulin resistance and deficiency, ultimately highlighting the need for new approaches capable of preventing the development of AD in type 2 diabetic patients. This review provides an update on overlapping pathophysiological mechanisms and pathways in T2D and AD, such as amyloidogenic events, oxidative stress, endothelial dysfunction, aberrant enzymatic activity, and even shared genetic background. These events will be presented as puzzle pieces put together, thus establishing potential therapeutic targets for drug discovery and development against T2D and diabetes-induced cognitive decline-a heavyweight contributor to the increasing incidence of dementia in developed countries. Hoping to pave the way in this direction, we will present some of the most promising and well-studied drug leads with potential against both pathologies, including their respective bioactivity reports, mechanisms of action, and structure-activity relationships.

The Therapeutic Potential of Piceatannol, a Natural Stilbene, in Metabolic Diseases: A Review

Metabolic disease comprises a set of risk factors highly associated with obesity and insulin resistance and is a consequence of central adiposity, hyperglycemia, and dyslipidemia. Furthermore, obesity increases the risk of the development of metabolic disease due to ectopic fat deposition, low-grade inflammation, and systemic energy disorders caused by dysregulated adipose tissue function. Piceatannol is a naturally occurring polyphenolic stilbene found in various fruits and vegetables and has been reported to exhibit anticancer and anti-inflammatory properties. In addition, recently reported beneficial effects of piceatannol on hypercholesterolemia, atherosclerosis, and angiogenesis underscore its therapeutic potential in cardiovascular disease. However, investigation of its role in metabolic disease is still in its infancy. This review intensively summarizes in vitro and in vivo studies supporting the potential therapeutic effects of piceatannol in metabolic disease, including inhibition of adipogenesis and lipid metabolism in adipocytes, and regulation of hyperlipidemia, hyperglycemia, insulin resistance, and fatty acid-induced inflammation and oxidative stress.

Piceatannol Attenuates Renal Fibrosis Induced by Unilateral Ureteral Obstruction via Downregulation of Histone Deacetylase 4/5 or p38-MAPK Signaling

Piceatannol, a resveratrol metabolite, is a phenolic compound found in red wine and grapes. We investigated the effect of piceatannol on renal fibrosis and histone deacetylase (HDAC) expression in a mouse model of unilateral ureteral obstruction (UUO). Fibrosis was established by UUO and piceatannol was intraperitoneally injected for 2 weeks. Piceatannol suppressed extracellular matrix (ECM) protein deposition including collagen type I and fibronectin as well as connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA) in UUO kidneys. However, the expressions of epithelial-mesenchymal transition (EMT) marker genes, such as N-cadherin and E-cadherin, were not changed in the kidneys after UUO. Masson’s trichrome staining and fluorescence immunostaining showed that piceatannol administration attenuated collagen deposition in UUO kidneys. HDAC1, HDAC4, HDAC5, HDAC6, and HDAC10 protein expression was upregulated in UUO kidneys, whereas that of HDAC8 was downregulated. Piceatannol treatment significantly reduced HDAC4 and HDAC5 protein expression. Further, piceatannol attenuated phosphorylation of p38 mitogen-activated protein kinase (p38-MAPK) in UUO kidneys, but not that of transforming growth factor beta1-Smad2/3. These results suggest that class I HDACs and class IIa/b HDACs are involved in renal fibrosis development. Piceatannol may be a beneficial therapeutic agent for treating renal fibrosis via reduction of HDAC4 and HDAC5 protein expression or suppression of the p38-MAPK signaling pathway.