The Use of Curcumin for the Treatment of Renal Disorders: A Systematic Review of Randomized Controlled Trials

Sirtuin 3 in renal diseases and aging: From mechanisms to potential therapies

The longevity protein sirtuins (SIRTs) belong to a family of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases. In mammals, SIRTs comprise seven members (SIRT1-7) which are localized to different subcellular compartments. As the most prominent mitochondrial deacetylases, SIRT3 is known to be regulated by various mechanisms and participate in virtually all aspects of mitochondrial homeostasis and metabolism, exerting significant impact on multiple organs. Notably, the kidneys possess an abundance of mitochondria that provide substantial energy for filtration and reabsorption. A growing body of evidence now supports the involvement of SIRT3 in several renal diseases, including acute kidney injury, chronic kidney disease, and diabetic nephropathy; notably, these diseases are all associated with aging. In this review, we summarize the emerging role of SIRT3 in renal diseases and aging, and highlights the intricate mechanisms by which SIRT3 exerts its effects. In addition, we highlight the potential therapeutic significance of modulating SIRT3 and provide valuable insights into the therapeutic role of SIRT3 in renal diseases to facilitate clinical application.

Can curcumin supplementation break the vicious cycle of inflammation, oxidative stress, and uremia in patients undergoing peritoneal dialysis?

BACKGROUND & AIMS

Turmeric (a source of curcumin) is an excellent food to modulate oxidative stress, inflammation, and gut dysbiosis in patients with chronic kidney disease (CKD). However, no studies report the benefits of curcumin in patients undergoing peritoneal dialysis (PD). This study aims to evaluate the effects of curcuminoid supplementation on oxidative stress, inflammatory markers, and uremic toxins originating from gut microbiota in patients with CKD undergoing PD.

METHODS

This longitudinal, randomized, single-blind, placebo-controlled trial evaluated 48 patients who were randomized into two groups: Curcumin (three capsules of 500 mg of Curcuma longa extract, with 98.42 % total curcuminoids) or placebo (three capsules of 500 mg of starch) for twelve weeks. In the peripheral blood mononuclear cells (PBMCs), the transcriptional expression levels of Nrf2, HOX-1 and NF-κB were evaluated by quantitative real-time PCR. Oxidative stress was evaluated by malondialdehyde (MDA) and total Thiol (T-SH). TNF-α and IL-6 plasma levels were measured by ELISA. P-cresyl sulphate plasma level, a uremic toxin, was evaluated by high-performance liquid chromatography (HPLC) with fluorescent detection.

RESULTS

Twenty-four patients finished the study: 10 in the curcumin group (57.5 ± 11.6 years) and 14 in the placebo group (56.5 ± 10.0 years). The plasma levels of MDA were reduced after 12 weeks in the curcumin group (p = 0.01), while the placebo group remained unchanged. However, regarding the difference between the groups at the endpoint, no change was observed in MDA. Still, there was a trend to reduce the p-CS plasma levels in the curcumin group compared to the placebo group (p = 0.07). Likewise, the concentrations of protein thiols, mRNA expression of Nrf2, HOX-1, NF-κB, and cytokines plasma levels did not show significant changes.

CONCLUSION

Curcuminoid supplementation for twelve weeks attenuates lipid peroxidation and might reduce uremic toxin in patients with CKD undergoing PD. This study was registered on Clinicaltrials.gov as NCT04413266.

Oxidative stress and inflammation in diabetic nephropathy: role of polyphenols

Diabetic nephropathy (DN) often leads to end-stage renal disease. Oxidative stress demonstrates a crucial act in the onset and progression of DN, which triggers various pathological processes while promoting the activation of inflammation and forming a vicious oxidative stress-inflammation cycle that induces podocyte injury, extracellular matrix accumulation, glomerulosclerosis, epithelial-mesenchymal transition, renal tubular atrophy, and proteinuria. Conventional treatments for DN have limited efficacy. Polyphenols, as antioxidants, are widely used in DN with multiple targets and fewer adverse effects. This review reveals the oxidative stress and oxidative stress-associated inflammation in DN that led to pathological damage to renal cells, including podocytes, endothelial cells, mesangial cells, and renal tubular epithelial cells. It demonstrates the potent antioxidant and anti-inflammatory properties by targeting Nrf2, SIRT1, HMGB1, NF-κB, and NLRP3 of polyphenols, including quercetin, resveratrol, curcumin, and phenolic acid. However, there remains a long way to a comprehensive understanding of molecular mechanisms and applications for the clinical therapy of polyphenols.

Curcumin-piperine co-supplementation and human health: A comprehensive review of preclinical and clinical studies

Curcumin is extracted from the rhizomes Curcuma longa L. It is known for its anti-inflammatory and anti-oxidant activities. Despite its safety and potential for use against various diseases, curcumin's utility is restricted due to its low oral bioavailability. Co-administration of curcumin along with piperine could potentially improve the bioavailability of curcumin. The present review aimed to provide an overview of the efficacy and safety of curcumin-piperine co-supplementation in human health. The findings of this comprehensive review show the beneficial effects of curcumin-piperine in improving glycemic indices, lipid profile and antioxidant status in diabetes, improving the inflammatory status caused by obesity and metabolic syndrome, reducing oxidative stress and depression in chronic stress and neurological disorders, also improving chronic respiratory diseases, asthma and COVID-19. Further high-quality clinical trial studies are needed to firmly establish the clinical efficacy of the curcumin-piperine supplement.

Spices and Biomarkers of COVID-19: A Mechanistic and Therapeutic Perspective

In the face of the COVID-19 pandemic, many people around the world have increased their healthy behaviors to prevent transmission of the virus and potentially improve their immune systems. Therefore, the role of diet and food compounds such as spices with bioactive and antiviral properties may be important in these efforts. In this chapter, we review the efficacy of spices such as turmeric (curcumin), cinnamon, ginger, black pepper, saffron, capsaicin, and cumin by investigating the effects of these compounds of COVID-19 disease severity biomarkers.

Bisacurone attenuates diabetic nephropathy by ameliorating oxidative stress, inflammation and apoptosis in rats

BACKGROUND

Diabetes nephropathy (DN) is a serious diabetic problem that may progress to renal failure. The root of Curcuma longa L., often known as turmeric, provides various health benefits. Bisacurone is a bioactive terpenoid found in small amounts in turmeric that possesses anti-inflammatory and antioxidant properties. The present study focuses on the potential protective effects of bisacurone against DN via reducing renal inflammation, oxidative stress, and apoptosis.

METHODS

Type 2 diabetes was created in rats by feeding them a high-fat/high-sugar diet for 8 weeks, followed by a low dose of streptozotocin and Bisacurone (50 and 100 μg/kg bisacurone) given for 4 weeks.

RESULTS

In diabetic rats, bisacurone reduced hyperglycemia, protected against body weight (BW) loss, lowered renal markers, reduced lipid profile alterations and avoided histological abnormalities. Bisacurone treatment reduced oxidative stress by decreasing malondialdehyde (MDA) levels while enhancing antioxidant defenses through superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Furthermore, bisacurone treatment activated the renal Nrf2/Keap1 signaling pathway but attenuated the high levels of NFκB p65, TNF-α, IL-1β, IL-6, Cox2, and iNOS. Bisacurone also reduced Bax, caspase-3, caspase-9 and cytochrome c but increased Bcl-2 in the kidneys of diabetic rats.

CONCLUSION

In the present study, bisacurone reduces DN by reducing hyperglycemia, oxidative stress, inflammation, and apoptosis, while also increasing Nrf2/HO-1 signaling.

Effect of Curcumin on Diabetic Kidney Disease: A Systematic Review and Meta-Analysis of Randomized, Double-Blind, Placebo-Controlled Clinical Trials

Background

Curcumin, a polyphenolic constituent from Curcuma longa, possesses antioxidant, hypolipidemic, and antidiabetic properties and has been reported to protect against diabetic kidney disease (DKD); however, the effect is inconsistent.

Objective

This systematic review and meta-analysis aimed to investigate the effect of curcumin supplementation on renal function, lipid profile, blood pressure, and glycemic control in DKD.

Methods

A systematic and comprehensive literature search of interrelated randomized controlled trials (RCTs) was conducted in PubMed, Embase, Cochrane Library, Web of Science, Scopus, and ClinicalTrials.gov from inception to July 30, 2021. Two investigators independently extracted data and assessed the risk of bias. Weighted mean differences (WMDs) with 95% confidence intervals (CIs) were calculated to describe the effect sizes using a fixed-effect model. Statistical analysis was performed using STATA 14.0 and RevMan 5.3.

Results

Five RCTs involving 290 participants with DKD were included. Curcumin supplementation significantly improved the serum creatinine (WMD: −0.16 mg/dL, 95% CI: −0.3 to −0.02, P = 0.029, I² = 0%, moderate certainty), total cholesterol (WMD: −10.13 mg/dL, 95% CI: −17.84 to −2.14, P = 0.01, I² = 0%, moderate certainty), systolic blood pressure (WMD: 3.94 mmHg, 95% CI: 1.86 to 6.01, P < 0.01, I² = 33.5%, moderate certainty), and fasting blood glucose (WMD: −8.29 mg/dL, 95% CI: −15.19 to −1.39, P = 0.019, I² = 43.7%, moderate certainty) levels; however, it had no significant effects on blood urea nitrogen, proteinuria, triglyceride, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and diastolic blood pressure levels.

Conclusions

Curcumin may provide great potential effects against DKD. More large-scale and high-quality RCTs are required to confirm these findings.