Antioxidative potential of chrysin, a flavone in streptozotocin–nicotinamide-induced diabetic rats

Inhibitory mechanism of chrysin and diosmetin to α-glucosidase: insights from kinetics, multispectroscopy and molecular docking investigations

Inhibition of α-glucosidase activity is a promising method to prevent postprandial hyperglycemia. The inhibitory effect and interaction of chrysin and diosmetin on α-glucosidase were studied in this study. The results of inhibition kinetics showed that chrysin and diosmetin reversibly inhibited α-glucosidase activity with IC50 value of 26.445 ± 1.406 μmol L-1 and 18.380 ± 1.264 μmol L-1, respectively. Further research revealed that chrysin exhibited a mixed-type inhibitory pattern against α-glucosidase, while diosmetin was noncompetitive inhibitory with Ki value of (2.6 ± 0.04) ×10-4 mol L-1. Fluorescence spectroscopy showed that both chrysin and diosmetin could quench the intrinsic fluorescence of α-glucosidase, the maximum emission wavelength of tyrosine (Tyr) and tryptophan (Trp) were not moved by chrysin, but red shifted by diosmetin. UV-Vis, fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) measurements showed that the secondary structure and microenvironment of α-glucosidase were changed by chrysin and diosmetin. Further analysis of molecular docking showed that chrysin and diosmetin could bind with α-glucosidase and might cause the decrease of α-glucosidase activity. The results of molecular dynamics (MD) simulation showed that the stability of chrysin (or diosmetin)-α-glucosidase complex system was changed during binding process. In conclusion, chrysin and diosmetin are good α-glucosidase inhibitors.Communicated by Ramaswamy H. Sarma.

Chrysin improves diabetic nephropathy by regulating the AMPK-mediated lipid metabolism in HFD/STZ-induced DN mice

Diabetic nephropathy (DN) is a highly prevalent and severe diabetic complication. It is urgent to explore high efficiency and minor side effects therapy for DN. Chrysin is a natural flavonoid with various biological activities found in honey and propolis, and has considerable potential to improve DN. The study was designed to explore the effects and the specific underlying mechanism of chrysin for DN in high-fat-diet (HFD) and streptozotocin (STZ) induced DN mice. Firstly, the study revealed that chrysin effectively improved obesity, insulin resistance (IR), renal function, and pathological injury in DN mice. Secondly, the study found that chrysin improved the key indices and markers of lipid accumulation, oxidative stress, and inflammation which are closely related to the development or progression of DN. Moreover, chrysin markedly modulated lipid metabolism by regulating Adenosine 5' monophosphate-activated protein kinase (AMPK) and essential downstream proteins. Furthermore, AMPK inhibitor (Dorsomorphin) intervention partially suppressed the positive effects of chrysin on all testing indicators, indicating that activated AMPK is crucial for chrysin action on DN. The present study demonstrated that chrysin may improve DN by regulating lipid metabolism, and activated AMPK plays a critical role in the regulation of chrysin. PRACTICAL APPLICATIONS: The study verified the positive effects of chrysin on obesity, insulin resistance, kidney injury, renal function, lipid accumulation, inflammation, and oxidative stress, which are closely related to the development or progression of diabetic nephropathy (DN). Moreover, we explored that chrysin improves DN by regulating AMPK-mediated lipid metabolism. Furthermore, the AMPK inhibitor was used to confirm that activated AMPK plays a critical role in the effects of chrysin. These results could offer a full explanation and a potential option for adjuvant therapy of DN diabetes with chrysin.

Promising Protective Effects of Chrysin in Cardiometabolic Diseases

Cardiometabolic diseases (CMD) have a great burden in terms of morbidity and mortality worldwide. The vicious cycle of CMD consists of type II diabetes, hypertension, dyslipidemia, obesity, and atherosclerosis interacting and feedbacking each other. The natural flavonoid chrysin has been displayed to own a broad spectrum of therapeutic impacts for human health. Herein, we did an in-depth investigation of the novel mechanisms of chrysin's cardioprotection against cardiometabolic disorder. Studies have shown that chrysin protects the cardiovascular system by enhancing the intrinsic antioxidative defense system. This antioxidant boost by chrysin protects against several risk factors of cardiometabolic disorders including atherosclerosis, vascular inflammation and dysfunction, platelet aggregation, hypertension, dyslipidemia, cardiotoxicity, myocardial infarction, injury and remodeling, diabetes-induced injuries, and obesity. Chrysin also exhibited anti-inflammatory mechanisms through inhibiting pro-inflammatory pathways including NF-κB, MAPK, and PI3k/Akt. Furthermore, chrysin modulated NO pathway, RAS system, AGE/RAGE pathway, PPARs pathway which contributed to the risk factors of cardiometabolic disorders. Taken together, the mechanisms in which chrysin protects against cardiometabolic disorder are more than merely antioxidation and anti-inflammation in the cardiovascular system.

Chrysin Reduces Oxidative Stress but Does Not Affect Polyol Pathway in the Lenses of Type 1 Diabetic Rats

Prolonged hyperglycemia is one of the main causes of reactive oxygen species and free radicals generation in diabetes which may affect various organs, including the eye. Oxidative damage to proteins and lipids in the eye lens could lead to cataract formation. To cope with oxidative stress, the endogenous antioxidative system may be supported by the supplementation of exogenous antioxidants. The aim of this study was to evaluate the effect of chrysin, a natural flavonoid, on oxidative stress and polyol pathway-related markers in the lenses of streptozotocin-induced type 1 male diabetic rats. Chrysin at doses of 50 and 100 mg/kg was administered by gavage for 28 days. This treatment resulted in a decrease in antioxidative enzymes activity and oxidative stress index. Moreover, chrysin administration elevated the reduced glutathione level in the lenses. A decrease in the markers linked to oxidative damage to proteins and lipids in the lenses was noted, especially after treatment with 50 mg/kg of chrysin. Neither of the chrysin doses affected glycemia-related markers in the serum or altered parameters related to the polyol pathway and advanced glycation end-products level in the lenses of diabetic rats. Upon obtaining results, it can be concluded that chrysin reveals antioxidative activity in the lenses but shows no antihyperglycemic or antiglycation properties.

Therapeutic effects of chrysin in a rat model of traumatic brain injury: A behavioral, biochemical, and histological study

AIMS

Oxidative stress and apoptosis have major roles in the progression of traumatic brain injury (TBI)-associated motor and cognitive deficits. The present study was aimed to elucidate the putative effects of chrysin, a natural flavonoid compound, against TBI-induced motor and cognitive dysfunctions and possible involved mechanisms.

MAIN METHODS

Chrysin (25, 50 or 100 mg/kg) was orally administered to rats starting immediately following TBI induction by Marmarou's weight-drop technique and continuously for 3 or 14 days. Neurological functions, motor coordination, learning and memory performances, histological changes, cell apoptosis, expression of pro- and anti-apoptotic proteins, and oxidative status were assayed at scheduled time points after experimental TBI.

KEY FINDINGS

The results indicated that treatment with chrysin improved learning and memory disabilities in passive avoidance task, and ameliorated motor coordination impairment in rotarod test after TBI. These beneficial effects were accompanied by increased the concentrations of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH), decreased malondialdehyde (MDA) content, prevented neuronal loss, diminished apoptotic index, elevated the expression of anti-apoptotic Bcl-2 protein, and reduced the expression of pro-apoptotic Bax protein in the cerebral cortex and hippocampus tissues.

SIGNIFICANCE

Our findings suggest that both anti-oxidative and anti-apoptotic properties of chrysin (especially in the dose of 100 mg/kg) are possible mechanisms that improve cognitive/motor deficits and prevent neuronal cell death after TBI.

The new buzz: Investigating the antimicrobial interactions between bioactive compounds found in South African propolis

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis, a resinous substance produced by the Apis mellifera bee, contains a number of flavonoids sourced from plants found in the surrounding region. Whilst bees use this substance to seal off and protect the beehive, humans have used propolis therapeutically for centuries, making use of its antibacterial, antiseptic, antipyretic and wound healing properties, among others. South African propolis is rich in the flavonoids pinocembrin, galangin, and chrysin and very little previous research has been conducted on the antimicrobial effects of these compounds.

AIM OF THE STUDY

To obtain an understanding of the antimicrobial activity of the compounds pinocembrin, galangin, and chrysin, both independently and in combination.

MATERIALS AND METHODS

The compounds pinocembrin, galangin and chrysin were investigated for interactive antimicrobial activity by determining the minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), anti-quorum sensing activity, biofilm studies, and toxicity studies (brine shrimp lethality assay).

RESULTS

Minimum inhibitory concentration results demonstrated that combinations of compounds showed better inhibitory activity than single compounds. When the flavonoids were tested in combination using the MIC assay, synergy was noted for 22% of the 1:1 ratio combinations and for 66% of the triple 1:1:1 ratio combinations. Similarly, MBC results showed bactericidal activity from selected combinations, while the compounds on their own demonstrated no cidal activity. Quorum sensing studies showed that compound combinations are more effective at inhibiting bacterial communication than the individual compounds. Biofilm assays showed that the highest percentage inhibition was observed for the triple combination against E. coli at 24 h. Finally, brine shrimp lethality studies revealed that combinations of the three compounds had reduced cytotoxicity when compared to the individual compounds.

CONCLUSION

The results obtained in this study demonstrate that the compounds found in South African propolis work synergistically to achieve an optimal antimicrobial effect, whilst simultaneously minimizing cytotoxicity.

The crystal structure of benzenaminium 5,7-dihydroxy-4-oxo-2-phenyl-4H-chromene-8-sulfonate hydrate, C21H19NO8S

C21H19NO8S, triclinic, P1̄ (no. 2), a = 7.2884(9) Å, b = 11.9469(15) Å, c = 12.2002(16) Å, α = 95.862(2)°, β = 106.659(2)°, γ = 93.189(2)°, V = 1008.4(2) Å3, Z = 2, R gt(F) = 0.0659, wR ref(F 2) = 0.1831, T = 296(2) K.

Baicalin and chrysin mixture imparts cyto-protection against methylglyoxal induced cytotoxicity and diabetic tubular injury by modulating RAGE, oxidative stress and inflammation

Protective effect of mixture of flavonoids baicalin and chrysin (BCH) was studied against methylglyoxal (MG, a precursor of AGEs) induced cytotoxicity in NRK 52E kidney epithelial cells. Flow cytometry and microscopic analysis showed increased ROS generation, compromised antioxidant status, depolarization of mitochondria and apoptosis in MG stressed cells which were significantly transformed (p≤0.01) during BCH co-treatment. In vivo studies in streptozotocin induced diabetic rats increased protein levels of iNOS, protein kinase C (PKC) and decreased IκB which was modulated by oral BCH treatment (75mg baicalin and 10mg chrysin/kg b.wt.). Increased levels of AGEs and their receptor proteins (RAGE) in diabetic rats were reduced significantly (p≤0.01) in BCH treated group. Renal tubular injuries and deranged kidney function were significantly improved in BCH treated animals. The results indicate that the protection accorded by BCH through its antioxidant and anti-inflammatory effects can be explored for management of diabetic nephropathy.

Chrysin Protects Rat Kidney from Paracetamol-Induced Oxidative Stress, Inflammation, Apoptosis, and Autophagy: A Multi-Biomarker Approach

Paracetamol (PC) is a safe analgesic and antipyretic drug at therapeutic doses, and it is widely used in clinics. However, at high doses, it can induce hepatotoxicity and nephrotoxicity. Chrysin (CR) is a natural flavonoid that has biological activities that include being an antioxidant, an anti-inflammatory, and an anti-cancer agent. The main objective of this study was to investigate the efficacy of CR against PC-induced nephrotoxicity in rats. CR was given orally via feeding needle to male Sprague Dawley rats as a single daily dose of 25 or 50 mg/kg for six days. PC was administered orally via feeding needle as a single dose on the sixth day. PC caused significant glutathione depletion, lipid peroxidation, increased serum toxicity markers (serum urea and creatinine), and reductions in activities of antioxidant enzymes (superoxide dismutase — SOD, catalase — CAT, and glutathione peroxidase — GPx). The renal protective effect of CR was associated with decreasing the regulation of serum renal toxicity markers and increasing the regulation of antioxidant enzyme activities. Additionally, PC led to significant increases in the levels of inflammatory markers including tumour necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-33 (IL-33). Furthermore, PC induced apoptotic tissue damage by increasing cysteine aspartate-specific protease-3 (caspase-3) activity and autophagic tissue damage by increasing the expression of light chain 3B (LC3B). CR therapy significantly decreased these values in rats. This study demonstrated that CR has antioxidant, anti-apoptotic, anti-inflammatory and anti-autophagic effects on PC-induced kidney toxicity in rats.