Protective Effect Of Syringic Acid Research Articles

Protective Effects of Syringic Acid Against Oxidative Damage, Apoptosis, Autophagy, Inflammation, Testicular Histopathologic Disorders, and Impaired Sperm Quality in the Testicular Tissue of Rats Induced by Mercuric Chloride.

Mercury (Hg) is one of the most toxic heavy metals that damage testicular tissue. Mercury chloride (HgCl2) is one of the most toxic forms of mercury that can easily cross biological membranes. Syringic acid (SA) is a natural flavonoid found in many vegetables and fruits. In this study, the effects of SA against HgCl2-induced testicular damage in rats were determined by biochemical, histopathological, and spermatological analyses. For this study, a total of 35 Spraque Dawley rats were used. Rats were divided into five groups as control, HgCl2, SA 50, HgCl2 + SA 25, and HgCl2 + SA 50. HgCl2 was administered intraperitoneal (IP) at a dose of 1.23 mg/kg/bw, while SA was administered by oral gavage at doses of 25 and 50 mg/kg/bw. The rats were then sacrificed, and testicular tissues were removed. HgCl2 caused an increase in MDA level and a decrease in SOD, CAT, and GPx activity and GSH level in the testicular tissue of rats. HgCl2 is involved in the increase of eIF2-α, PERK, ATF-4, ATF-6, CHOP, NF-κB, TNF-α, IL-1β, Apaf-1, Bax, and Caspase-3 mRNA expression. HgCl2 caused a decrease in sperm motility, an increase in the rate of abnormal sperm and sperm DNA fragmentation in rats. However, SA oral administration dose-dependently inhibited endoplasmic reticulum stress, oxidative stress, inflammation, and apoptosis and preserved epididymal sperm quality and testicular histoarchitectures. In conclusion, SA had protective effects against HgCl2-induced testicular oxidative damage, inflammation, endoplasmic reticulum stress, and apoptosis.

Syringic acid loaded silver nanoparticles protects ovarian ischemia-reperfusion injury in rats by inhibiting endoplasmic reticulum stress-mediated apoptosis

In the present study, we investigated the protective effect of syringic acid (SA) loaded silver nanoparticles (AgNPs) on endoplasmic reticulum stress-mediated apoptosis during ovarian ischemia-reperfusion injury (IR) in rats. Initial UV–Vis and FT-IR analysis revealed the presence of the Ag and SA in the SA-AgNPs, respectively. TEM analysis demonstrated the spherical morphology with 10–50 nm of nanoparticle size. Next, we evaluated the protective effect of SA-AgNPs against IR. 15-weeks-old rats were divided into seven groups, as follows: control, AgNPs, SA, IR, AgNPs + IR, SA + IR, and SA + AgNPs + IR. Induction of IR led to a significant increase in apoptotic markers (caspase-3), pro-inflammatory markers (IL-1β, TNF-α, ATF-6, NF- κB-p65, and P2X7R), and endoplasmic reticulum stress marker (IRE1) in ovary tissue. Additionally, a remarkable increase in serum IL-1β and TNF-α were found. Moreover, an increase in serum MDA and decreased endogenous anti-oxidant enzymes, including GSH and SOD were observed. Interestingly, treatment with either AgNPs or SA significantly reduced apoptosis, inflammation, and ER stress markers in IR-induced rats. Nevertheless, discernible effects were detected in rats upon treatment with SA + AgNPs. These findings strongly suggest that syringic acid-loaded silver nanoparticles have a promising therapeutic application in ovarian ischemia-reperfusion (IR) injury.

The Protective Effects of Syringic Acid on Bisphenol A-Induced Neurotoxicity Possibly Through AMPK/PGC-1α/Fndc5 and CREB/BDNF Signaling Pathways.

Bisphenol A (BPA), an endocrine disruptor, is commonly used to produce epoxy resins and polycarbonate plastics. Continuous exposure to BPA may contribute to the development of diseases in humans and seriously affect their health. Previous research suggests a significant relationship between the increased incidence of neurological diseases and the level of BPA in the living environment. Syringic acid (SA), a natural derivative of gallic acid, has recently considered much attention due to neuromodulator activity and its anti-oxidant, anti-apoptotic, and anti-inflammatory effects. Therefore, in this study, we aimed to investigate the effects of SA on oxidative stress, apoptosis, memory and locomotor disorders, and mitochondrial function, and to identify the mechanisms related to Alzheimer's disease (AD) in the brain of rats receiving high doses of BPA. For this purpose, male Wistar rats received BPA (50, 100, and 200mg/kg) and SA (50mg/kg) for 21days. The results showed that BPA exposure significantly altered the rats' neurobehavioral responses. Additionally, BPA, by increasing the level of ROS, and MDA level, increased the level of oxidative stress while reducing the level of antioxidant enzymes, such as SOD, CAT, GPx, and mitochondrial GSH. The administration of BPA at 200mg/kg significantly decreased the expression of ERRα, TFAM, irisin, PGC-1α, Bcl-2, and FNDC5, while it increased the expression of TrkB, cytochrome C, caspase 3, and Bax. Moreover, the Western blotting results showed that BPA increased the levels of P-AMPK, GSK3b, p-tau, and Aβ, while it decreased the levels of PKA, P-PKA, Akt, BDNF, CREB, P-CREB, and PI3K. Meanwhile, SA at 50mg/kg reversed the behavioral, biochemical, and molecular changes induced by high doses of BPA. Overall, BPA could lead to the development of AD by affecting the mitochondria-dependent apoptosis pathway, as well as AMPK/PGC-1α/FNDC5 and CREB/BDNF/TrkB signaling pathways, and finally, by increasing the expression of tau and Aβ proteins. In conclusion, SA, as an antioxidant, significantly reduced the toxicity of BPA.

Syringic acid alleviates valproic acid induced autism via activation of p38 mitogen-activated protein kinase: Possible molecular approach.

Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental disorder characterized by restrictive and repetitive behavior followed by impairment in social, verbal, and non-verbal interaction and communication. Valproic acid (VPA) is a well-known anti-epileptic drug, but its prenatal exposure to animals causes social impairment, neurotransmitters imbalance, and neuroinflammation with ASD-like phenotypes. Syringic acid (SA) is a polyphenolic compound with anti-inflammatory, anti-apoptotic, antioxidant, and neuromodulator activity. The purpose of study was to investigate the protective effect of Syringic acid (SA) in prenatal VPA-treated rats through behavioral, neuroinflammation, oxidative stress, neurotransmitters, neuronal integrity, and apoptotic marker. Single dose of VPA was administered 600 mg/kg, i.p. on a gestational day (GD) 12th and SA was administrated from PnD 26th to 54th at the dose of 25, 50, and 100 mg/kg, p.o. On PnD 56th behavioral parameters (Pain sensitivity, open field test, narrow beam walks test and social impairment test) were performed and all animals were sacrificed, and brain tissue was isolated for oxidative stress (GSH, CAT, and LPO), neuroinflammation (TNF-α and IL-6) and neurotransmitters (GABA and Glutamate), histopathology (H&E, Nissl), immunohistochemistry (p38 MAPK) analysis. Rat treated with SA dose-dependently prevented behavioral alteration, restored antioxidant enzymes, neurotransmitters level, decreased neuroinflammatory markers, and improved neuronal integrity. Furthermore, immunohistochemistry confirmed the reduced p38 MAPK marker expression by SA in VPA induced autistic behavior.

Syringic acid ameliorates experimental diabetic nephropathy in rats through its antiinflammatory, anti-oxidant and anti-fibrotic effects by suppressing Toll like receptor-4 pathway

Diabetic nephropathy (DN) is an important healthcare challenge because it occurs in about 40% of diabetic people and is a main cause end-stage renal disease. Toll like receptor-4 (TLR-4) signaling is involved in DN incidence and progression through its activation by hyperglycemia and hyperglycemia-induced alterations besides its crucial roles in initiating inflammation and fibrosis in kidney. Syringic acid is a natural phenolic acid. It is naturally available in many fruits and vegetables, including swiss chards, grapes and olives. In this study, Reno protective effects of syringic acid, as anti-inflammatory, anti-oxidant and anti-fibrotic natural compound, against experimental DN were investigated. Streptozotocin (45mg/kg) was used in inducing rat model of DN pathogenesis. In kidney homogenate, concentrations of TLR-4, interleukin-6 and transforming growth factor β1 (TGFβ1) were estimated by ELISA technique. Moreover, hydroxyproline and relevant collagen content in kidney tissues were evaluated using spectrophotometry. Oral administration of syringic acid (50 mg/kg) for 8 weeks succeeded in keeping kidney function evidenced by significant decrease in serum levels of creatinine, blood urea nitrogen (BUN) and decreased urinary protein content. Besides, it led to significant increase in renal superoxide dismutase (SOD) activity and significant decline in kidney malondialdehyde (MDA) content. Moreover, it showed significant anti-inflammatory and anti-fibrotic effects reflected by significant decrease in levels of TLR-4, interleukin-6, TGFβ1 and collagen in kidney homogenate as compared to DN group. Besides, it significantly attenuated DN-induced histopathological deteriorations. In conclusion, syringic acid can be proposed as an effective natural compound in halting DN progression through inhibiting TLR-4 pathway resulting in ameliorating oxidative stress, inflammation and fibrosis in kidney tissues.

Protective effects of syringic acid on inflammation, apoptosis and intestinal barrier function in Caco-2 cells following oxygen-glucose deprivation/reoxygenation-induced injury.

Syringic acid (SA) is an abundant phenolic acid compound that has been demonstrated to yield therapeutic benefits in myocardial and renal ischemia/reperfusion (I/R). However, the role of SA in intestinal I/R injury is unclear. Thus, the present study aimed to investigate the protective effect of SA against intestinal I/R injury. Caco-2 cells were incubated with different doses of SA before oxygen-glucose deprivation/reoxygenation (OGD/R) induction. The viability of Caco-2 cells, the activity of lactate dehydrogenase (LDH), the production of pro-inflammatory cytokines and the levels of reactive oxygen species, superoxide dismutase and malondialdehyde were measured. Apoptosis was evaluated using a TUNEL assay and western blotting. Transepithelial electrical resistance and western blotting were performed to evaluate intestinal barrier function in Caco-2 cells. The present study revealed that pretreatment with SA significantly increased cell viability and reduced LDH release in Caco-2 cells subjected to OGD/R treatment. In addition, SA suppressed OGD/R-induced inflammatory responses by reducing pro-inflammatory cytokine levels. Furthermore, the levels of oxidative stress and apoptosis were ameliorated by SA. SA also alleviated the intestinal barrier disruption exhibited by Caco-2 cells after OGD/R injury. Overall, the present study revealed that SA may potentially protect Caco-2 cells from OGD/R injury, and that this effect may be attributed to its anti-inflammatory and anti-apoptotic activities, as well as its ability to protect the function of the intestinal barrier.

Protective effect of syringic acid via restoring cells biomechanics and organelle structure in human lens epithelial cells

We have previously reported that syringic acid (SA) extracted from D. aurantiacum var. denneanum (kerr) may be used to prevent diabetic cataract (DC). However, the underlying mechanisms through which SA prevents DC in human lens epithelial cells (HLECs) remained unclear. In the present study, we employed single-molecule optics technologies, including transmission electron microscopy (TEM), atomic force microscopy (AFM), laser scanning confocal microscopy (LSCM) and Raman spectroscopy, to monitor the effect of SA on HLECs biomechanics and organelle structure in real-time. TEM suggested that SA improved the ultrastructure of HLECs with regard to nuclear chromatin condensation and reducing mitochondrial swelling and degeneration, which may aid in the maintenance of HLECs integrity in the presence of glucose. AFM revealed a reduced surface roughness and stiffness following SA treatment, suggesting an improved viscoelasticity of HELCs. Raman spectrometry and LSCM further revealed that these changes were related to a modification of cell liquidity and cytoskeletal structure by SA. Taken together, these results provide insights into the effects of SA on the biomechanics of HLECs and further strengthen the evidence for its potential use as a novel therapeutic strategy for DC prevention.

Syringic acid mitigates myocardial ischemia reperfusion injury by activating the PI3K/Akt/GSK-3β signaling pathway

Syringic acid is an abundant phenolic acid compound that possesses anti-oxidant, anti-microbial, anti-inflammatory, and anti-endotoxic properties. However, the research of pretreatment with syringic acid against myocardial ischemia reperfusion is still limited. Thus, our research revealed the protective effect of syringic acid in the rat model with myocardial ischemia reperfusion injury. Histological analysis was performed by hematoxylin and eosin (H&E). The myocardial systolic function was detected by echocardiographic. Myocardial infarct size was measured by Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) double staining. The apoptosis index was recorded by Terminal deoxynucleotidyl transferase dUTP nick end labeling staining (TUNEL). The contents of creatine kinase MB (CK-MB) and lactate dehydrogenase (LDH) in the serum were determined by a commercial kit. The expression of the PI3K/Akt/GSK-3β signaling pathway-related molecules and apoptosis-associated indicators was detected by western blotting or real-time PCR. We found that pretreatment with syringic acid obviously increased the myocardial systolic function (LVEF and LVFS) and decreased the infarct size, the apoptosis index as well as the serum level of CK-MB and LDH. Meanwhile, syringic acid also remarkably augmented the contents of p-PI3K, p-Akt, p-GSK-3β, Bcl-2 and mitochondria cytochrome c. However, the expression of caspase-3, -9 and Bax significantly reduced. Interestingly, co-treatment with PI3K inhibitor of LY294002 counteracted those effects induced by syringic acid. In conclusion, pretreatment with syringic acid can mitigate myocardial ischemia reperfusion injury by inhibiting mitochondria-induced apoptosis which is regulated by the PI3K/Akt/GSK-3β signaling pathway.

Effect of syringic acid and syringaldehyde on oxidative stress and inflammatory status in peripheral blood mononuclear cells from patients of myocardial infarction.

Oxidative stress and inflammation are considered as therapeutic targets in myocardial injury. The aim of the present study was to investigate the protective effect of syringic acid (SA) and syringaldehyde (SYD) on peripheral blood mononuclear cells (PBMCs) of myocardial infarction (MI) patients. PBMCs from MI patients were cultured in the presence and absence of SA and SYD. The level of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and nitric oxide (NO) was estimated. Reactive oxygen species (ROS) formation, oxidation of lipids, proteins, and activity of antioxidant enzymes were also quantified. To further determine biomolecular changes in treated PBMCs, Fourier transform infrared (FTIR) spectroscopic analysis was done. Molecular docking study was also conducted to evaluate the binding interaction of SA and SYD with various target proteins. SA and SYD treated PBMCs of MI patients showed decreased secretion of TNF-α, IL-6, and NO. Moreover, the content of ROS, level of lipid, and protein oxidation showed diminution by treatment with both the compounds. Enhanced antioxidant defense was also observed in treated PBMCs. The FTIR spectra of treated cells revealed safeguarding effect of SA and SYD on biomolecular structure. The molecular docking analysis displayed significant binding affinity of the two compounds towards TNF-α, IL-6, and antioxidant enzymes. Our findings demonstrated potent antioxidant and anti-inflammatory effects of SA and SYD on PBMCs of MI patients. Thus, SA and SYD supplementation might be beneficial in attenuating oxidative stress and inflammation in MI.

Protective effects of syringic acid on neurobehavioral deficits and hippocampal tissue damages induced by sub-chronic deltamethrin exposure

Recent developments in the field of insecticide exposure have led to a renewed interest in alternative antioxidant therapy. The present study was to investigate the neuroprotective role of syringic acid (SA, 25 mg/kg/day) on the neurotoxicity and oxidative damage induced by deltamethrin (DTM, 1.28 mg/kg/day during two months) in CA1/3 pyramidal neurons. Animals were divided into 4 groups (n = 16/group) (250–270 g) for control, DTM, SA and DTM + SA. DTM and SA were administered by oral gavage daily. Rats that were given sub-chronic DTM had revealed a significant increase in caspase-3 levels, impaired recognition memory, reduced antioxidant activity and enhanced free radicals in the hippocampus. The results showed that SA ameliorated neurobehavioral alterations, reduced reactive oxygen/nitrogen species, pyknosis in the CA1/3 and increased antioxidant enzyme activity. In conclusion, SA (25 mg/kg/day) had potential neuroprotective and therapeutic impacts against sub-chronic DTM exposure via its antioxidant and antiapoptotic efficacy. Therefore, it can be used as a neuroprotective natural plant-derived agent against DTM-induced neurotoxicity.

Protective effects of syringic acid, resveratrol and their combination against isoprenaline administered cardiotoxicity in wistar rats.

To evaluate the cardio-protection of syringic acid (SA) in combination with resveratrol (RV) in isoproterenol (ISO) induced myocardial infarcted (MI) rats. Groups of all rats were subjected oral pre-treatment at the beginning of the study with SA (50 mg/kg), RV (50 mg/kg) and combination (COMB) of SA (25 mg/kg) and RV (25 mg/kg) along with gallic acid (GA) (50 mg/kg) for 30 days. After sacrification, homogenate of heart tissue along with serum were utilized for further biochemical investigations. The effects on creatine kinase (CK), aspartate transaminase (AST), alanine transaminase (ALT) and gamma glutamyl transferase (GGT) were studied in serum and heart tissues. Glutathione-s-transferase (GST), glutathione peroxidase (GPX) and reduced glutathione (GSH), membrane bound enzymes and electrolytes were tested in heart tissues. Body weights and heart weights were also observed along with high sensitivity C-reactive protein (hs-CRP), uric acid and total protein content (TPC) in serum. CK, AST, ALT and GGT levels in serum were augmented significantly while these enzymes are decreased in cardiac tissue samples of ISO-treated rats. GST, GPX, GSH, Na+/K+, Mg2+, Ca2+ ATPases, K+ ions were significantly decreased while Na+ and Ca2+ ions were increased in the heart tissues of ISO-injected rats. Loss and gain of body and heart weights were noticed significantly in rats having ISO administration. ISO group showed significant increase in hs-CRP and Uric acid while significant decrease in TPC. All of actions of ISO were ameliorated by COMB. COMB suppressed ISO induced MI in rats and exhibited cardio-protection.

The protective effect of syringic acid on dextran sulfate sodium-induced experimental colitis in BALB/c mice.

Inflammatory bowel diseases involve chronic intestinal inflammation which is mostly caused by Crohn's disease and ulcerative colitis (UC) conditions. Patients having UC are prone to colorectal cancer and dysplastic polyps, and also have sporadic adenomas. Syringic acid (SA) possesses many health benefits including antioxidant, anti-bacterial, and anti-cancer. This study was aimed to identify the effects of SA on UC, using a murine experimental model. Clinical symptoms and weight loss were significantly reduced in mice induced with dextran sulfate sodium (DSS) and treated with SA, compared to untreated mice. The effects of SA exhibited in DSS-induced mice were associated with significant decrease in the expressions levels of inflammatory mediators such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), pro-inflammatory cytokines (tumor necrosis factor [TNF-α], interleukin [IL-1β and IL-6]), remarkable amelioration of colonic architectural disruption, and a significant reduction in the activity of colonic myeloperoxidase. To further confirm the anti-inflammatory property of SA, RAW 264.7 cells were stimulated with lipopolysaccharides. SA dose-dependently inhibited the cytokines TNF-α, IL-1β, and IL-6. It also decreased the expressions of p65-NF-κB and IκB, thus reducing the activation and nuclear accumulation of p-STAT-3Y705 . This prohibited the degradation of inhibitory protein, IκB, as well as inhibited the nuclear translocation of p65-NF-κB in colonic tissue. It was concluded that SA has a potential to limit inflammation via inhibiting the p65-NF-κB and STAT3 signaling; hence it can be used for therapeutic purposes.

Syringic acid protects from isoproterenol induced cardiotoxicity in rats

Identification of pharmacologically potent antioxidant compounds for their use in preventive medicine is thrust area of current research. This study was undertaken with the aim of determining the protective role of syringic acid (SA) on isoproterenol (ISO) induced myocardial infarction (MI) in rats. SA was orally given to rats for 21 days at three different concentrations (12.5, 25 and 50 mg/kg). At 20th and 21st day, rats were subcutaneously injected with ISO and at the end of experimental period, rats were killed. ISO induced myocardial damage was averted by pre-co-treatment of SA, as decrease was found in serum level of marker enzymes (CKMB, LDH, AST, ALT), lipid peroxidation, protein carbonyl (PC) and proinflammatory cytokines (TNFα, IL 6). Furthermore, content of glutathione (GSH) and activities of antioxidant enzymes in heart tissue were significantly raised. Improvement in infarct size and erythrocyte (RBCs) morphology was also observed. The biochemical findings were supported by histopathological outcome and protective effect of SA was found to be dose dependent. The results of our study demonstrated that the cardioprotective potential of SA in rat model of ISO induced MI might be due to anti-lipid peroxidative and endogenous antioxidant system enhancement effects.

Research into the protective effect of syringic acid in rats with induced experimental pancreatitis

Research into the protective effect of syringic acid in rats with induced experimental pancreatitis

Protective effect of syringic acid on kidney ischemia-reperfusion injury

The objective of the present study was to determine whether preischemic administration of syringic acid (SA) would attenuate renal ischemia-reperfusion injury (IRI). Rats were divided into three groups: Sham group; IR group; and IR + SA group. The effects of SA were examined using biochemical parameters including serum ischemia-modified albumin (IMA), total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), tissue superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and malondialdehyde (MDA). The apoptosis status and histopathological changes were evaluated. After calculating the score for each histopathological change, the total score was obtained by summing all the scores. In the SA group, MDA, IMA, TOS, and OSI decreased significantly compared to the IR group. After SA administration, the increase in GPx activity was found to be significant. Apoptosis decreased significantly in the SA group compared with the IR group. The total score significantly decreased after administration of SA. Taken together, our findings suggest that SA preconditioning is effective in reducing tissue damage induced in kidney IRI. Renal histology also showed convincing evidence regarding the protective nature of SA.

The Axon Protective Effects of Syringic Acid on Ischemia/Reperfusion Injury in a Rat Sciatic Nerve Model.

In the relevant literature, there is no experimental study that investigated the axon protective effects of syringic acid- a polyphenol compound- with an anti-oxidant capacity on ischemia/reperfusion injury. The rats were randomly divided into four groups: Control group (no medication or surgical procedure), Sham group, Syringic acid group, and Methyprednisolone (MP) Group. Ischemia was achieved by abdominal aorta clamping and all animals were sacrificed 24 hours after ischemia. Harvested sciatic nerve segments were investigated histopathologically and for tissue biochemistry. Ischemic fiber degeneration scores were found significantly lower in syringic acid and MP groups than sham group. Additionally, apoptosis-related cysteine peptidase caspase-3 immunostaining scores were lower in syringic acid and MP groups. Biochemically, superoxide dismutase and nuclear respiratory factor 1 values were significantly higher in syringic acid group compared to those of control and sham groups while malondialdehyde levels were significantly lower in the syringic acid group. Syringic acid reduces oxidative stress and axonal degeneration in rat sciatic nerve after ischemia/reperfusion injury. Therefore, syringic acid may play a role in the treatment of peripheral nerve injuries due to ischemia/reperfusion.

The protective effect of syringic acid on ischemia injury in rat brain.

Brain ischemia and treatment are important topics in neurological science. Free oxygen radicals and inflammation formed after ischemia are accepted as the most significant causes of damage. Currently there are studies on many chemopreventive agents to prevent cerebral ischemia damage. Our aim is to research the preventive effect of the active ingredient in syringic acid, previously unstudied, on oxidative damage in cerebral ischemia. The rats were randomly divided into 4 groups: control group (no medication or surgical procedure), sham group (artery occlusion), artery occlusion + syringic acid group sacrificed at 6 h, and artery occlusion + syringic acid group sacrificed at 24 h. Obtained brain tissue from the right hemisphere was investigated histopathologically and for tissue biochemistry. Superoxide dismutase and nuclear respiratory factor 1 values decreased after ischemia and they increased after syringic acid treatment, while increased malondialdehyde levels after ischemia were reduced after treatment. Caspase-3 and caspase-9 values increased after ischemia and decreased after treatment; this reduction was more pronounced at 24 h. Our study revealed that syringic acid treatment in cerebral ischemia reduced oxidative stress and neuronal degeneration. In the light of the biochemical and histopathologic results of the present study, we think that syringic acid treatment may be an alternative treatment method.

Syringic acid ameliorates l-NAME-induced hypertension by reducing oxidative stress

The objective of the present study was to investigate the effects of syringic acid (SA), a phenolic acid, on N(ω)-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats. Hypertension was induced in adult male albino rats by oral administration of L-NAME (40 mg/kg/day) dissolved in drinking water daily for 4 weeks. Rats were treated with different doses of SA (25, 50, and 100 mg/kg body weight (b.w.)). Systolic blood pressure of control and experimental rats was recorded. Plasma nitric oxide metabolites (NOx), lipid peroxidative products such as thiobarbituric acid reactive substances, lipid hydroperoxides, conjugated dienes, and antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, vitamin C, vitamin E, and reduced glutathione were estimated in erythrocytes, plasma, and tissues of experimental rats. Hepatic marker enzymes such as aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase and renal functional markers such as urea, uric acid, and creatinine were also estimated in serum. The increased levels of blood pressure, lipid peroxidation products, hepatic and renal function markers, and the decreased level of NOx and antioxidants in L-NAME-induced hypertensive rats were reversed upon SA treatment. The protective effect at the dose of the three tested doses (25, 50, and 100 mg/kg) of SA at a dose of 50 mg/kg b.w. exerts optimum protection. Biochemical findings are substantiated by the histological observation. The protective effects of SA are mediated by reducing oxidative stress and retaining the bioavailability of NO in the cardiovascular system.

Attenuation of oxidative stress by syringic acid on acetaminophen-induced nephrotoxic rats

This study was aimed to evaluate the preventive efficacy of syringic acid (SA) on acetaminophen (APAP)-induced nephrotoxicity. Nephrotoxicity was induced in male Wistar albino rats by the administration of a single dose of 750 mg/kg APAP intraperitoneally. In this study, we evaluated the levels of renal markers, lipid peroxidation markers (thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH)), enzymatic and nonenzymatic antioxidant status, and histopathological changes of kidney. Our results show significant (P < 0.05) increased levels of serum urea, uric acid, creatinine, and TBARS, LOOH in the kidney tissue. In addition, the activities of superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione levels significantly (P < 0.05) decreased in the kidney of APAP nephrotoxic rats. Moreover, histopathological observations also correlated with the biochemical findings to improved morphological changes including tubular epithelial degeneration, vacuolization, cell desquamation, and necrosis. Oral administration of SA (50 mg/kg body weight) to APAP rats for 6 days prevented the above biochemical and renal morphology changes and improved towards normalcy. These findings suggested that the protective effects of SA against APAP-induced kidney injuries might result from the amelioration of APAP-induced oxidative stress.

Protective Effects of Syringic Acid against Acetaminophen-Induced Hepatic Damage in Albino Rats

The protective effect of the phenolic compound syringic acid, one of the major benzoic acid derivatives from edible plants and fruits, was evaluated against acetaminophen (APAP)-induced hepatotoxicity in rats. Toxicity was induced in adult male albino Wistar rats by the administration of APAP (750 mg/kg body weight) intraperitoneally. Rats were treated with syringic acid (25, 50, and 100 mg/kg body weight) by the oral route. We assessed the activity of hepatic markers aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase, and bilirubin. Lipid peroxidative markers thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, and a decrease in enzymatic antioxidants superoxide dismutase, catalase, glutathione peroxidase, and non-enzymatic antioxidants vitamin C, vitamin E and reduced glutathione levels. Liver histology also showed convincing evidence regarding their protective nature against fatty changes induced during APAP intoxication. Syringic acid administered at a dose of 50 mg/kg body weight significantly decreased the activities of hepatic and renal function markers to near normal values when compared with the other two doses. The results suggest that syringic acid could afford a significant protective effect against APAP induced hepatic damage in rats.