Pycnogenol modulates apoptosis by suppressing oxidative stress and inflammation in high glucose-treated renal tubular cells

Procyanidins Ameliorate Acetaminophen-induced Acute Liver Injury via Activating the Nrf-2/SOD-1 Signal Pathway

Background and Objectives

An overdose of acetaminophen (APAP) usually leads to acute liver injury, and oxidative stress is one of the fundamental mechanisms used to characterize it. Procyanidins (PCs) can reduce the oxidative stress in the liver of mice. This study aimed to investigate the potential protective role of PCs against APAP-induced acute liver injury.

Materials and Methods

Experiments were performed on male Kunming mice in six groups: phosphate-buffered saline, PCs, APAP, and PCs pretreated with 10, 50, and 100 mg/kg. The mice were peritoneally injected with PCs 30 min before the administration of APAP. First, survival rates of mice were scored every 12 hr for three days in succession. Furthermore, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (T-Bil), total cholesterol (TC), triglyceride (TG), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-1 (IL-6) were determined. Additionally, histological analysis and hepatic oxidative stress including the levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) were assessed. Finally, the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and SOD-1 was detected by Western blotting.

Results

The data indicated that PCs improved survival rates of APAP-induced liver injury in mice models. Moreover, PCs could reduce the elevated serum levels of ALT, AST, T-Bil, TC, TG, TNF-α, IL-1β, and IL-6 due to APAP exposure with a dose-dependent manner. Besides, PCs pretreatment attenuated hepatic histopathological damage and oxidative stress which manifested the increases of SOD and GSH, whereas the decrease of MDA. Furthermore, PCs enhanced the protein expression of Nrf2 and SOD-1 in the PCs pretreatment groups compared with the APAP group.

Conclusion

PCs ameliorated APAP-induced acute liver injury, and Nrf2 signaling pathway modulating antioxidative stress might be involved in it.

Protective Effect of Pycnogenol against Methotrexate-Induced Hepatic, Renal, and Cardiac Toxicity: An In Vivo Study

Methotrexate (MTX) is one of the most commonly used chemotherapies for various types of cancer, including leukemia, breast cancer, hepatocarcinoma, and gastric cancers. However, the efficacy of MTX is frequently limited by serious side effects. Several studies have reported that the cytotoxic effect of MTX is not limited to cancer cells but can also affect normal tissues, leading to prospective damage to many organs. In the present study, we extensively investigated the molecular and microscopic basis of MTX-induced toxicity in different organs (liver, kidney, and heart) and explored the possible protective effect of pycnogenol, a polyphenolic component extracted from the bark of P. pinaster, to attenuate these effects. Biochemical analysis revealed that administration of MTX significantly reduced the function of the liver, kidney, and heart. Histological and immunohistochemical analysis indicated that MTX treatment caused damage to tissues of different organs. Interestingly, administration of pycnogenol (10, 20, and 30 mg/kg) significantly attenuated the deterioration effects of MTX on different organs in a dose-dependent manner, as demonstrated by biochemical and histological analysis. Our results reveal that pycnogenol successfully ameliorated oxidative damage and reduced toxicity, inflammatory response, and histological markers induced by methotrexate treatment. Taken together, this study provides solid evidence for the pharmacological application of pycnogenol to attenuate damage to different organs induced by MTX treatment.

Effect of French maritime pine bark extract supplementation on metabolic status and serum vascular cell adhesion molecule-1 levels in patients with type 2 diabetes and microalbuminuria

OBJECTIVES

This study investigated the effect of French maritime pine bark extract (PBE) supplementation on metabolic parameters, vascular cell adhesion molecule 1 (VCAM-1), urinary albumin-to-creatinine ratio (UACR), and anthropometric indexes in patients with type 2 diabetes (T2DM) and microalbuminuria.

DESIGN

This randomized, double-blind, placebo-controlled clinical trial was conducted on 46 patients with T2DM and the evidence of microalbuminuria aged 30-65 years.

SETTING

Patients were recruited from the endocrinology clinic of Sina hospital (Tabriz, Iran) from March 2018 to April 2019.

INTERVENTIONS

The subjects were randomly assigned to receive two capsules/day each containing 50mg of PBE or placebo for eight weeks.

MAIN OUTCOME MEASURES

Glycemic parameters, serum VCAM-1 and lipid profile, UACR, and anthropometric indexes were measured for all patients at baseline and the end of the study.

RESULTS

PBE supplementation significantly reduced glycosylated hemoglobin, VCAM-1, total cholesterol, UACR, waist circumference, and waist-to-height ratio compared to the placebo group at the end of the study (all P < 0.05). Changes in fasting blood glucose, insulin, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were not significant between the two groups (all P > 0.05).

CONCLUSIONS

The study findings demonstrated some favorable effects of PBE supplementation on glycemic control, serum VCAM-1 and total cholesterol levels, and microalbuminuria, as well as abdominal obesity in patients with T2DM.

Forsythoside A Alleviates High Glucose-Induced Oxidative Stress and Inflammation in Podocytes by Inactivating MAPK Signaling via MMP12 Inhibition

BACKGROUND

Podocyte injury serves an important role during the progression of diabetic nephropathy (DN). The aim of this study was to investigate the effects of forsythoside A (FA) on high glucose (HG)-induced podocyte injury and to identify the possible mechanisms.

METHODS

MPC-5 podocytes were cultured under HG conditions. After exposure to different doses of FA, cell viability and apoptosis were respectively evaluated with CCK-8 assay and flow cytometry. Then, the levels of oxidative stress-related markers and inflammatory factors were examined by corresponding kits. Western blot analysis was employed to detect the expression of Nox2, Nox4, COX-2, iNOS and matrix metalloproteinases 12 (MMP12). Subsequently, MMP12 was overexpressed to assess whether the effects of FA on HG-stimulated podocyte injury were mediated by MMP12 and MAPK signaling.

RESULTS

Results indicated that FA dose-dependently elevated cell viability, reduced cell apoptosis in HG-induced MPC-5 cells. Additionally, FA significantly inhibited oxidative stress, which could be certified by decreased content of malondialdehyde (MDA), enhanced activities of superoxide dismutase (SOD) and catalase (CAT), and downregulated expression of Nox2 and Nox4. Moreover, notably reduced levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were observed in FA-treated MPC-5 cells under HG conditions, accompanied by decreased COX-2 and iNOS expression. Remarkably, FA suppressed MMP12 expression in a dose-dependent manner, and the effects of FA on MPC-5 cells exposed to HG were partially counteracted by MMP12 overexpression. Mechanically, FA inactivated the expression of phospho-ERK (p-ERK), p-p38 and p-JNK, which was restored after MMP12 overexpression.

CONCLUSION

These findings demonstrate a protective mechanism of FA by inactivating MAPK signaling via MMP12 inhibition in HG-induced podocyte injury, providing a promising therapeutic candidate for the treatment of DN.

Cyanidin-3-O-glucoside Protects Lens Epithelial Cells against High Glucose-Induced Apoptosis and Prevents Cataract Formation via Suppressing NF-κB Activation and Cox-2 Expression

Diabetic cataract is one of the most important causes of blindness worldwide. Cyanidin-3-O-glucoside (C3G) is found to exert beneficial effects on many diabetic complications. However, its effect on diabetic cataract is not well known. Herein, we investigated the effect of C3G on high glucose-induced lens epithelial cell (SRA01/04) apoptosis and cataract formation as well as the involved mechanisms. We found C3G (20 μM) could preserve cell viability in SRA01/04 cells exposed to high glucose (100 μM). Meanwhile, C3G inhibited SRA01/04 cell apoptosis and regulated the Bcl-2/Bax ratio. Additionally, C3G suppressed NF-κB activation and subsequent cyclooxygenases-2 (Cox-2) expression, which are associated with the protection against apoptosis. Moreover, C3G attenuated lens opacity and protein aggregation in lens culture exposed to high glucose. In conclusion, C3G protected against high glucose-induced SRA01/04 cell apoptosis and cataract formation, which indicated the potential protection of anthocyanins on diabetic cataract.

Effects of Compound Centella on Oxidative Stress and Keap1-Nrf2-ARE Pathway Expression in Diabetic Kidney Disease Rats

The formula of Compound Centella mainly contains 3 traditional Chinese herbs: Centella asiatica (L.) Urb. (JiXueCao), Astragalus Membranaceus Fish. (HuangQi), and Tripterygium wilfordii Hook. f. (LeiGongTeng). Though this formula is effective for treating diabetic kidney disease (DKD) in clinic, the exact mechanism is still unclear. This study aims to investigate the effect and antioxidant mechanism of Compound Centella on DKD rats. High-performance liquid chromatography (HPLC) was applied to analyse 3 herbs in Compound Centella. Sprague-Dawley rats were divided into the normal group (NG), DKD group (DKDG), Compound Centella group (CCG), and losartan group (LG), with 8 rats in each group. On the first day of the experiment, rats in the NG were fed with ordinary –feed, while the other groups were fed with high-fat and high-sugar feed. On the 29^th day, except the NG, the other 3 groups received a single intraperitoneal injection of streptozocin (STZ, 35 mg/kg). Fasting blood glucose (FBG) was measured on the 1^st day, 32^nd day, 46^th day, 56^th day, 84^th day, and 112^th day. Total protein/creatinine ratio of urine was determined by the phenol red assay on the 1^st day and 112^th day. Serum creatinine (Scr) was determined by an automatic biochemical analyser on the 112^th day. Kidneys were collected on the 112^th day for analysis and evaluation. Periodic acid-Schiff (PAS) staining, hematoxylin-eosin (HE) staining, and transmission electron microscopy were used to observe kidney pathological changes. The mRNA and protein expressions of Kelch-like ECH-associated protein 1 (Keap1) and nuclear factor-erythroid 2-related factor 2 (Nrf2) in renal tissues were detected by RT-qPCR, Western blot, and immunohistochemistry. Oxidative stress was evaluated by detecting the levels of malondialdehyde (MDA) and heme oxidase-1 (HO-1). The results showed that the content of asiaticoside, astragaloside, and triptolide in the herb was 5960, 809, and 2.42 μg/g and in the Compound Centella was 340, 64, and 0.1403 μg/mL by HPLC. Compound Centella reduced the urine protein/creatinine ratio and improved renal pathology in the kidneys of DKD rats. In addition, the mRNA and protein expressions of Keap1 and Nrf2 in kidneys were upregulated by Compound Centella. The expressions of MDA were downregulated but HO-1 were upregulated by Compound Centella. Therefore, the protective effect of Compound Centella in the kidney of DKD rats may be related to regulating the Keap1-Nrf2-ARE pathway under oxidative stress, suggesting Compound Centella as a promising treatment against DKD.

Cardioprotective effect of isorhamnetin against myocardial ischemia reperfusion (I/R) injury in isolated rat heart through attenuation of apoptosis

In this study, we investigated the effects of isorhamnetin on myocardial ischaemia reperfusion (I/R) injury in Langendorff‐perfused rat hearts. Isorhamnetin treatment (5, 10 and 20 μg/mL) significantly alleviated cardiac morphological injury, reduced myocardial infarct size, decreased the levels of marker enzymes (LDH and CK) and improved the haemodynamic parameters, reflected by the elevated levels of the left ventricular developed pressure (LVDP), coronary flow (CF) and the maximum up/down velocity of left ventricular pressure (+dp/dt_max). Moreover, isorhamnetin reperfusion inhibited apoptosis of cardiomyocytes in the rats subjected to cardiac I/R in a dose‐dependent manner concomitant with decreased protein expression of Bax and cleaved‐caspase‐3, as well as increased protein expression of Bcl‐2. In addition, I/R‐induced oxidative stress was manifestly mitigated by isorhamnetin treatment, as showed by the decreased malondialdehyde (MDA) level and increased antioxidant enzymes activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH‐Px). These results indicated that isorhamnetin exerts a protective effect against I/R‐induced myocardial injury through the attenuation of apoptosis and oxidative stress.

The Bioprotective Effects of Polyphenols on Metabolic Syndrome against Oxidative Stress: Evidences and Perspectives

Polyphenols are the general designation of various kinds of phytochemicals, mainly classified as flavonoids and nonflavonoids. Polyphenolic compounds have been confirmed to exhibit numerous bioactivities and potential health benefits both in vivo and in vitro. Dietary polyphenols have been shown to significantly alleviate several manifestations of metabolic syndrome, namely, central obesity, hypertension, dyslipidemia, and high blood sugar. This review is aimed at discussing the bioprotective effects and related molecular mechanisms of polyphenols, mainly by increasing antioxidant capacity or oxygen scavenging capacity. Polyphenols can exert their antioxidative activity by balancing the organic oxidoreductase enzyme system, regulating antioxidant responsive signaling pathways, and restoring mitochondrial function. These data are helpful for providing new insights into the potential biological effects of polyphenolic compounds and the development of future antioxidant therapeutics.

Effects of French maritime pine bark extract (Oligopin®) supplementation on bone remodeling markers in postmenopausal osteopenic women: A randomized clinical trial

French maritime pine bark extract (FMPBE; Oligopin®), a dietary supplement, is rich in procyanidin. The objective of this study was to determine the effects of FMPBE on bone remodeling in postmenopausal osteopenic women. This randomized, double-blinded, placebo-controlled clinical trial was conducted on 40 postmenopausal osteopenic women. Individuals were randomly assigned to either FMPBE (250 mg/day, n = 21) or placebo (250-mg starch/day, n = 19) for 12 weeks. Biochemical indices, including bone remodeling marker, were assessed before and after the intervention. After the 12-week intervention, that is, FMPBE supplementation, a significant increase in bone alkaline phosphatase (BAP), procollagen type 1 amino-terminal propeptide (P1NP) levels and a significant decrease in C-terminal telopeptide of type I collagen (CTx1) were observed. Compared with the control group, FMPBE supplementation resulted in a significant increase in P1NP (0.015), BAP levels (0.001), and BAP/CTx1 ratio (p = 0.001) and a significant decrease in CTx1 levels (0.006). FMPBE supplementation for 12 weeks in postmenopausal osteopenic women produced favorable effects on bone markers. Meanwhile, further research is needed to determine whether FMPBE supplements can be used as a preventive strategy for bone loss in postmenopausal osteopenic women.

Silver Fir (Abies alba) Extracts Inhibit Enzymes Involved in Blood Glucose Management and Protect against Oxidative Stress in High Glucose Environment

The diet rich in fruits and vegetables reduces the risk of metabolic syndrome, including diabetes development by various mechanisms of action, mainly due to the presence of polyphenolic compounds. Extracts from different conifer species are known to be a rich source of various polyphenols. In the present study we elucidated the in vitro mechanism of anti-diabetic activity of silver fir (Abies alba) wood and bark extracts and compared their activity to non-coniferous sweet chestnut wood extract and standardized maritime pine bark extract. Extracts and lignans were tested for their inhibitory activity of enzymes involved in the regulation of blood glucose in vitro. The ability of extracts to protect against oxidative stress in high glucose environment was tested on mouse myoblast cell line. Silver fir wood and bark extracts were shown to be effective inhibitors of α-glucosidase, α-amylase and dipeptidyl peptidase 4, three enzymes involved in the regulation of blood glucose levels. Coniferous extracts also showed protection against oxidative stress generated in high glucose environment. Lignans, particularly pinoresinol diglucoside, isolariciresinol and secolariciresinol were shown to be important contributors of antihyperglycemic activity through inhibition of dipeptidyl peptidase 4. This corroborates previously published in vivo results on blood glucose level obtained with silver fir wood extract and supports the use of silver fir wood and bark extracts as food supplements or functional foods in borderline diabetes.

Toll-Like Receptor-Dependent Immunomodulatory Activity of Pycnogenol®

BACKGROUND

Pycnogenol® (PYC), an extract of French maritime pine bark, is widely used as a dietary supplement. PYC has been shown to exert anti-inflammatory actions via inhibiting the Toll-like receptor 4 (TLR4) pathway. However, the role of the other receptors from the TLR family in the immunomodulatory activity of PYC has not been described so far.

AIM

The aim of this study was to investigate whether PYC might exert its immunomodulatory properties through cell membrane TLRs (TLR1/2, TLR5, and TLR2/6) other than TLR4. Moreover, the effect of gastrointestinal metabolism on the immunomodulatory effects of PYC was investigated.

FINDINGS

We showed that intact non-metabolized PYC dose-dependently acts as an agonist of TLR1/2 and TLR2/6 and as a partial agonist of TLR5. PYC on its own does not agonize or antagonize TLR4. However, after the formation of complexes with lipopolysaccharides (LPS), it is a potent activator of TLR4 signaling. Gastrointestinal metabolism of PYC revealed the immunosuppressive potential of the retentate fraction against TLR1/2 and TLR2/6 when compared to the control fraction containing microbiota and enzymes only. The dialyzed fraction containing PYC metabolites revealed the capacity to induce anti-inflammatory IL-10 secretion. Finally, microbially metabolized PYC affected the colonic microbiota composition during in vitro gastrointestinal digestion.

CONCLUSIONS

This study showed that gastrointestinal metabolism of PYC reveals its biological activity as a potential inhibitor of TLRs signaling. The results suggest that metabolized PYC acts as a partial agonist of TLR1/2 and TLR2/6 in the presence of the microbiota-derived TLR agonists (retentate fraction) and that it possesses anti-inflammatory potential reflected by the induction of IL-10 from THP-1 macrophages (dialysate fraction).

Preventive role of Pycnogenol® against the hyperglycemia-induced oxidative stress and DNA damage in diabetic rats

Diabetes mellitus, a complex progressive metabolic disorder, leads to some oxidative stress related complications. Pycnogenol^® (PYC), a plant extract obtained from Pinus pinaster, has been suggested to be effective in many diseases including diabetes, cancer, inflammatory and immune system disorders. The mechanisms underlying the effects of PYC in diabetes need to be elucidated. The aim of this study was to determine the effects of PYC treatment (50 mg/kg/day, orally, for 28 days) on the DNA damage and biochemical changes in the blood, liver, and kidney tissues of experimental diabetic rats. Changes in the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase enzymes, and the levels of 8-hydroxy-2'-deoxyguanosine, total glutathione, malondialdehyde, insulin, total bilirubin, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, high density lipoprotein, low density lipoprotein, total cholesterol, and triglyceride were evaluated. DNA damage was also determined in the whole blood cells and the liver and renal tissue cells using the alkaline comet assay. PYC treatment significantly ameliorated the oxidative stress, lipid profile, and liver function parameters as well as DNA damage in the hyperglycemic rats. The results show that PYC treatment might improve the hyperglycemia-induced biochemical and physiological changes in diabetes.

Effects of procyanidin on cardiomyocyte apoptosis after myocardial ischemia reperfusion in rats

BACKGROUND

This study is aimed at investigating the effects of procyanidin on cardiomyocyte apoptosis of myocardial ischemia/reperfusion (I/R) injury in rats.

METHODS

Sprague-Dawley rats were randomly assigned into four groups: control group (normal saline), ischemic group (normal saline), procyanidin low-dose group (procyanidin 50 mg/kg/day) and procyanidin high-dose group (procyanidin 100 mg/kg/day) by intragastric administration for 2 weeks. After last administration, myocardial I/R model was induced by ligating left anterior descending artery for 30 min followed by 120 min of perfusion. The activity of serum creatine kinase mb isoenzyme (CK-MB) was detected after experiment. The content of reactive oxygen species (ROS) was determined by ROS fluorescent probe dihydroethidium; the expressions of p53, Caspase-9, Caspase-3, Bcl-2 and Bax were determined by western blotting; myocardial apoptosis was measured by the method of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.

RESULTS

Compared with control group, the contents of serum CK-MB, ROS, the expressions of p53, Caspase-9, Caspase-3 and Bax increased significantly in ischemic group, the Bcl-2 expression, Bcl-2/Bax ratio decreased and the cardiomyocyte apoptosis index increased (p < 0.05); compared with ischemic group, the content of CK-MB, ROS, the expressions of p53, Caspase-9, Caspase-3 and Bax decreased, the Bcl-2 expression, Bcl-2/Bax ratio increased and the cardiomyocyte apoptosis index decreased in procyanidin group (p < 0.05).

CONCLUSIONS

Procyanidin can reduce cardiomyocyte apoptosis after I/R. This beneficial effect is partially dependant on decreased ROS, p53, Caspase-9, Caspase-3 and Bax, as well as increased Bcl-2 and Bcl-2/Bax ratio.

Pycnogenol Cytotoxicity in Pancreatic INS-1E β cells Induced by Calcium Dysregulation

Natural standardized flavonoid extract from the bark of Pinus pinaster, Pycnogenol (Pyc), was recently found to decrease intensively the activity of sarcoplasmic reticulum Ca²⁺ -ATPase of rabbit skeletal muscle (SERCA1). On the basis of this inhibitory effect in a cell-free system and similarities of SERCA1 to its other isoforms, proapoptotic properties of Pyc may be expected in cellular systems. Pycnogenol (40-100 μg/mL) induced a concentration-dependent decrease of the viability of pancreatic INS-1E β cells associated with induction of apoptosis. In addition, intracellular Ca²⁺ level increase was found along with reduction of protein expression level of SERCA2b and impairment of insulin secretion by β cells. These facts indicate that Pyc may induce apoptosis by impairment of calcium homeostasis. Copyright © 2017 John Wiley & Sons, Ltd.

Procyanidins Mitigate Osteoarthritis Pathogenesis by, at Least in Part, Suppressing Vascular Endothelial Growth Factor Signaling

Procyanidins are a family of plant metabolites that have been suggested to mitigate osteoarthritis pathogenesis in mice. However, the underlying mechanism is largely unknown. This study aimed to determine whether procyanidins mitigate traumatic injury-induced osteoarthritis (OA) disease progression, and whether procyanidins exert a chondroprotective effect by, at least in part, suppressing vascular endothelial growth factor signaling. Procyanidins (extracts from pine bark), orally administered to mice subjected to surgery for destabilization of the medial meniscus, significantly slowed OA disease progression. Real-time polymerase chain reaction revealed that procyanidin treatment reduced expression of vascular endothelial growth factor and effectors in OA pathogenesis that are regulated by vascular endothelial growth factor. Procyanidin-suppressed vascular endothelial growth factor expression was correlated with reduced phosphorylation of vascular endothelial growth factor receptor 2 in human OA primary chondrocytes. Moreover, components of procyanidins, procyanidin B2 and procyanidin B3 exerted effects similar to those of total procyanidins in mitigating the OA-related gene expression profile in the primary culture of human OA chondrocytes in the presence of vascular endothelial growth factor. Together, these findings suggest procyanidins mitigate OA pathogenesis, which is mediated, at least in part, by suppressing vascular endothelial growth factor signaling.

Supplementing Conventional Treatment with Pycnogenol® May Improve Hepatitis C Virus-Associated Type 2 Diabetes: A Mini Review

Hepatitis C virus (HCV) infection and type 2 diabetes mellitus (T2DM) present a significant health burden, with increasing complications and mortality rates worldwide. Pycnogenol® (PYC), a natural product, possesses antidiabetic and antiviral properties that may improve HCV-associated T2DM. In this review, we present previously published data on the effectiveness of PYC against HCV replication and T2DM. We believe that supplementing conventional treatment with PYC may improve the current HCV therapy, attenuate HCV-associated T2DM, and reduce the risk of complications such as cirrhosis or hepatocellular carcinoma and cardiovascular disease.

Thymoquinone Alleviates the Experimental Diabetic Peripheral Neuropathy by Modulation of Inflammation

Thymoquinone has been reported to exhibit antioxidant and anti-inflammatory effects. Inflammation plays an important role in pathogenesis of diabetic peripheral neuropathy. This study investigated the effects of TQ on proliferation and apoptosis of Schwann cells exposed to high glucose conditions and electrophysiological and morphological changes of the sciatic nerve in a DPN rat model as well as relevant inflammatory mechanism. Cell proliferation and apoptosis of Schwann cells were measured using the Cell Counting Kit-8 and flow cytometry. DPN model was established in streptozotocin-induced diabetic rats. Nerve conduction velocity was measured before and after treatment. Morphologic changes were observed by H&E staining and transmission electron microscopy. COX-2, IL-1β, IL-6, and Caspase-3 expression was investigated by western blotting and Bio-Plex Pro^TM Assays. Finally, TQ alleviated the inhibition of Schwann cell proliferation and protected against Schwann cell apoptosis. It improved nerve conduction velocity, and alleviated the DPN-induced morphological changes and demyelination of the sciatic nerve. COX-2, IL-1β, IL-6 and Caspase-3 expression in sciatic nerve or isolated cultured Schwann cells, were also decreased by TQ. These results indicate TQ has a protective effect on peripheral nerves in a DPN rat model. The mechanism may be mediated partly by the modulation of the inflammatory reaction.

The caspase 3-dependent apoptotic effect of pycnogenol in human oral squamous cell carcinoma HSC-3 cells

In the present study, the apoptotic effect of pycnogenol and its molecular mechanism in human oral squamous cell carcinoma HSC-3 cells were investigated. Pycnogenol significantly inhibited the viability of HSC-3 cells and suppressed neoplastic cell transformation in HSC-3 cells and TPA-treated JB6 cells. It caused caspase-dependent apoptosis evidenced by the increase in cleaved poly (ADP-ribose) polymerase and caspase 3 in a dose-dependent manner. Pycnogenol increased Bak protein by enhancing its protein stability whereas other Bcl-2 family members were not altered. In addition, the treatment with pycnogenol led to the production of reactive oxygen species and N-acetyl-l-cysteine almost blocked pycnogenol-induced reactive oxygen species generation. Taken together, these findings suggest that pycnogenol may be a potential candidate for the chemoprevention or chemotherapy of human oral cancer.

Inhibitory Effect of a French Maritime Pine Bark Extract-Based Nutritional Supplement on TNF-α-Induced Inflammation and Oxidative Stress in Human Coronary Artery Endothelial Cells

Oxidative stress and inflammation, leading to endothelial dysfunction, contribute to the pathogenesis of atherosclerosis. The popularity of natural product supplements has increased in recent years, especially those with purported anti-inflammatory and/or antioxidant effects. The efficacy and mechanism of many of these products are not yet well understood. In this study, we tested the antioxidant and anti-inflammatory effects of a supplement, HIPER Health Supplement (HIPER), on cytokine-induced inflammation and oxidative stress in human coronary artery endothelial cells (HCAECs). HIPER is a mixture of French maritime pine bark extract (PBE), honey, aloe vera, and papaya extract. Treatment for 24 hours with HIPER reduced TNF-α-induced reactive oxygen species (ROS) generation that was associated with decreased NADPH oxidase 4 and increased superoxide dismutase-1 expression. HIPER inhibited TNF-α induced monocyte adhesion to HCAECs that was in keeping with decreased expression of vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1 and decreased nuclear factor-kappa B (NF-κB) activation. Further investigation of mechanism showed HIPER reduced TNF-α induced IκBα and p38 and MEK1/2 MAP kinases phosphorylation. Our findings show that HIPER has potent inhibitory effects on HCAECs inflammatory and oxidative stress responses that may protect against endothelial dysfunction that underlies early atherosclerotic lesion formation.

Pycnogenol Protects Against Rotenone-Induced Neurotoxicity in PC12 Cells Through Regulating NF-κB-iNOS Signaling Pathway

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by dopaminergic neurons degeneration and oxidative damage may underlie this process. However, there are still no efficient drugs to cure the disease. Pycnogenol (PYC) isolated from the procyanidin-rich French maritime pine (Pinus maritime) bark has shown various antioxidant activities in previous studies. In this study, we explored its effect against rotenone (Rot)-induced neurotoxicity and the underlying mechanisms in PC12 cells. Using Rot-induced cell model of PD, we found that PYC treatment significantly increased cell viability and decreased cell apoptosis in Rot-treated PC12 cells in a dose-dependent manner. Furthermore, data showed that PYC markedly reduced inducible nitric oxide synthase (iNOS)-nitric oxide (NO) signaling in Rot-treated PC12 cells. Pretreatment with the iNOS-specific inhibitor significantly attenuated Rot-induced neurotoxicity. Moreover, PYC was found to be capable of reducing Rot-induced NF-κB activation. Blocking NF-κB signaling with its inhibitor mimicked the biological effect of PYC on Rot-induced iNOS and NO expression levels, as well as neurotoxicity in PC12 cells, suggesting that the NF-κB-iNOS signaling pathway was likely to participate in the PYC-mediated protective progress. Our results suggest that PYC protects against Rot-induced neurotoxicity in PC12 cells, and the mechanism may be associated with the downregulation of NF-κB-iNOS signaling pathway.

Effects of kolaviron on hepatic oxidative stress in streptozotocin induced diabetes

Background

Alteration in antioxidant defence and increase in oxidative stress that results in tissue injury is characteristic of diabetes. We evaluated the protective effects of kolaviron (a flavonoid complex extracted from the seeds of Garcinia kola) on hepatic antioxidants, lipid peroxidation and apoptosis in diabetic rats.

Methods

To induce diabetes, rats were injected with streptozotocin intraperitoneally at a single dose of 50 mg/kg. Kolaviron (100 mg/kg) was administered orally for 6 weeks (5 times weekly). Activities of liver antioxidant enzymes was analysed with Multiskan Spectrum plate reader. High performance liquid chromatography (HPLC) was used in the analysis of MDA (malondialdehyde), a product of lipid peroxidation. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

Result

Diabetic rats exhibited a significant increase in the peroxidation of hepatic lipids as observed from the elevated level of malondialdehyde (MDA). In addition, Oxygen Radical Absorbance Capacity (ORAC), level of reduced glutathione (GSH), ratio of reduced to oxidized glutathione (GSH: GSSG) and catalase (CAT) activity were decreased in the liver of diabetic rats. The activities of GPX (glutathione peroxidase) and SOD (superoxide dismutase) were unaltered in diabetic rats. TUNEL assay revealed increased apoptotic cell death in the liver. Kolaviron attenuated lipid peroxidation and apoptosis, increased CAT activity, GSH levels and GSH: GSSG ratio. The ORAC of kolaviron-treated diabetic liver was restored to near-normal values.

Conclusion

Kolaviron protects the liver against oxidative and apoptotic damage induced by hyperglycemia.

Pycnogenol attenuates the symptoms of immune dysfunction through restoring a cellular antioxidant status in low micronutrient-induced immune deficient mice

BACKGROUND/OBJECTIVES

We investigated the effect of Pycnogenol (Pyc) on survival and immune dysfunction of C57BL/6 mice induced by low micronutrient supplementation.

MATERIALS/METHODS

Female C57/BL/6 mice were fed a diet containing 7.5% of the recommended amount of micronutrients for a period of 12 wks (immunological assay) and 18 wks (survival test). For immunological assay, lymphocyte proliferation, cytokine regulation, and hepatic oxidative status were determined.

RESLUTS

Pyc supplementation with 50 and 100 mg·kg^-1·bw·d^-1 resulted in partial extension of the median survival time. Pyc supplementation led to increased T and B cell response against mitogens and recovery of an abnormal shift of cytokine pattern designated by the decreased secretion of Th1 cytokine and increased secretion of Th2 cytokine. Hepatic vitamin E level was significantly decreased by micronutrient deficiency, in accordance with increased hepatic lipid peroxidation level. However, Pyc supplementation resulted in a dose-dependent reduction of hepatic lipid peroxidation, which may result from restoration of hepatic vitamin E level.

CONCLUSION

Findings of this study suggest that Pyc supplementation ameliorates premature death by restoring immune dysfunction, such as increasing lymphocyte proliferation and regulation of cytokine release from helper T cells, which may result from the antioxidative ability of Pyc.

Modulating effects of pycnogenol® on oxidative stress and DNA damage induced by sepsis in rats

The aim of this study was to evaluate the protective effects of Pycnogenol® (Pyc), a complex plant extract from the bark of French maritime pine, on oxidative stress parameters (superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities and total glutathione (GSH) and malondialdehyde (MDA) levels), an inflammatory cytokine (tumor necrosis factor alpha (TNF-α) level) and also DNA damage in Wistar albino rats. Rats were treated with 100 mg/kg intraperitonally Pyc following the induction of sepsis by cecal ligation and puncture. The decreases in MDA levels and increases in GSH levels, and SOD and GPx activities were observed in the livers and kidneys of Pyc-treated septic rats. Plasma TNF-α level was found to be decreased in the Pyc-treated septic rats. In the lymphocytes, kidney, and liver tissue cells of the sepsis-induced rats, Pyc treatment significantly decreased the DNA damage and oxidative base damage using standard alkaline assay and formamidopyrimidine DNA glycosylase-modified comet assay, respectively. In conclusion, Pyc treatment might have a role in the prevention of sepsis-induced oxidative damage not only by decreasing DNA damage but also increasing the antioxidant status and DNA repair capacity in rats.

Zinc modulates high glucose-induced apoptosis by suppressing oxidative stress in renal tubular epithelial cells

Hyperglycemia is a characteristic of diabetic nephropathy, inducing renal tubular cell apoptosis by eliciting oxidative stress and inflammation. Zinc (Zn) is known as an essential trace element in many enzymes and proteins involved in antioxidant defenses, electron transport, and exerting antiapoptotic or cytoprotective effects. In this study, the underlying mechanisms involved in the protective effects of Zn on high glucose-induced cytotoxicity were explored using cultured renal tubular epithelial cells (NRK-52E). The authors discovered that Zn supplementation inhibited high glucose (HG)-induced NRK-52E cell apoptosis by attenuating reactive oxygen species production, inhibiting HG-induced caspase-3 and caspase-9 activation, and inhibiting the release of cytochrome c from mitochondria to the cytosol. Further analysis revealed that Zn supplementation facilitated cell survival through increasing nuclear translocation of NF-E2-related factor 2 (Nrf2), leading to increased regulation of levels of two antioxidant enzymes, hemeoxygenase-1 and glutamate cysteine ligase, which provided an adaptive survival response against the HG-induced oxidative cytotoxicity. Moreover, the Zn-mediated increases in Nrf2 activity were suppressed by the pharmacological inhibition of Akt or extracellular signal-regulated kinase 1/2. Taken together, these findings suggest that Zn antiapoptosis capacity through the activation of Akt and ERK signal pathways leads to Nrf2 activation and, subsequently, Nrf2 target gene induction, thereby protecting the NRK-52E cells from HG-induced apoptosis.

Inhibitory effects of Pycnogenol® (French maritime pine bark extract) on airway inflammation in ovalbumin-induced allergic asthma

Pycnogenol® (PYC) is a standardized extracts from the bark of the French maritime pine (Pinus maritime) and used as a herbal remedy for various diseases. In this study, we evaluated the effects of PYC on airway inflammation using a model of ovalbumin (OVA)-induced allergic asthma and RAW264.7 cells. PYC decreased nitric oxide production and reduced the interleukine (IL)-1β and IL-6 levels in LPS-stimulated RAW264.7 cells. PYC also reduced the expression of inducible nitric oxide synthase (iNOS) and matrix metalloproteinase (MMP)-9 and enhanced the expression of hemeoxygenase (HO)-1. In the in vivo experiment, PYC decreased the inflammatory cell count and the levels of IL-4, IL-5, IL-13, and immunoglobulin (Ig) E in BALF or serum. These results are consistent with the histological analysis findings, which showed that PYC attenuated the airway inflammation and mucus hypersecretion induced by OVA challenge. In addition, PYC enhanced the expression of HO-1. In contrast, PYC inhibited the elevated expression of iNOS and MMP-9 proteins induced by OVA challenge. In conclusion, PYC exhibits protective effects against OVA-induced asthma and LPS-stimulated RAW264.7 cells. These results suggest that PYC has potential as a therapeutic agent for the treatment of allergic asthma.

Modulation of oxidative stress by proanthocyanidin in H2O2-exposed human diploid fibroblast cells

Proanthocyanidin (a persimmon-peel extract) is known to have potent antioxidative effects, but its protective action specifically against cellular damage has not been fully explored. In this work, we investigated the protective property of proanthocyanidin against cellular oxidative stress with an experimental model, H2O2-exposed human diploid fibroblasts (HDFs). To investigate the proposed underlying beneficial actions of proanthocyanidin as to cellular injury induced by H2O2, several major biochemical parameters were determined, including estimation of total reactive species (RS) generation, antioxidant enzyme activities, reduced glutathione (GSH)/oxidized glulathione (GSSG) ratio, and mitochondrial membrane potential. The results indicate that proanthocyanidin reduced total RS generation while enhancing the activities of catalase and glutathione reductase and the GSH/GSSG ratio. Additionally, proanthocyanidin was found to protect against mitochondrial membrane damage in HDFs treated H2O2. Based on these results, we conclude that proanthocyanidin has strong protective effects against cellular damage to several key cellular functions by suppressing oxidative stress in H2O2-treated HDFs.

Protection of MPTP-induced neuroinflammation and neurodegeneration by Pycnogenol

Oxidative stress and inflammation play a crucial role in Parkinson's disease (PD) pathogenesis and may represent a target for treatment. Current PD drugs provide only symptomatic relief and have limitations in terms of adverse effects and inability to prevent neurodegeneration. Flavonoids have been suggested to exert human health benefits by its anti-oxidant and anti-inflammatory properties. Therefore, in the present study, using 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine (MPTP)-induced mouse model of Parkinsonism, we investigated the neuroprotective potential of bioflavonoid compound Pycnogenol® (PYC), an extract of Pinus maritime bark. MPTP injected mice developed significantly severe oxidative stress and impaired motor coordination at day 1 and day 7 postinjection. This was associated with significantly increased inflammatory responses of astrocyte and microglia as assessed by ionized calcium binding adaptor molecule 1 (Iba 1) and glial fibrillary acidic protein (GFAP) immunohistochemistry, and nuclear transcription factor-κB (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in the striata by Western blot. Additionally, there was significant upregulation of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) expression in the striata of MPTP injected mice compared to saline controls. The MPTP-induced neuroinflammation, neurodegeneration and behavioral impairments were markedly repudiated by treatment with PYC. These results suggest that PYC protects dopaminergic neurons from MPTP-induced toxicity in the mouse model of PD. Thus, the present finding of PYC-induced adaptation to oxidative stress and inflammation could suggest a novel avenue for clinical intervention in neurodegenerative diseases including PD.

Facilitated cellular uptake and suppression of inducible nitric oxide synthase by a metabolite of maritime pine bark extract (Pycnogenol)

Many natural products exhibit anti-inflammatory activity by suppressing excessive nitric oxide (NO) production by inducible NO synthase (iNOS). The maritime pine bark extract Pycnogenol has been formerly shown to decrease nitrite generation, taken as an index for NO, but so far it was not clear which constituent of the complex flavonoid mixture mediated this effect. The purpose of this study was to elucidate whether the in vivo generated Pycnogenol metabolite M1 (δ-(3,4-dihydroxyphenyl)-γ-valerolactone) displayed any activity in the context of induction of iNOS expression and excessive NO production. For the first time we show that M1 inhibited nitrite production (IC(50) 1.3 μg/ml, 95% CI 0.96-1.70) and iNOS expression (IC(50) 3.8 μg/ml, 95% CI 0.99-14.35) in a concentration-dependent fashion. This exemplifies bioactivation by metabolism because the M1 precursor molecule catechin is only weakly active. However, these effects required application of M1 in the low-micromolar range, which was not consistent with concentrations previously detected in human plasma samples after ingestion of maritime pine bark extract. Thus, we investigated a possible accumulation of M1 in cells and indeed observed high-capacity binding of this flavonoid metabolite to macrophages, monocytes, and endothelial cells. This binding was distinctly decreased in the presence of the influx inhibitor phloretin, suggesting the contribution of a facilitated M1 transport into cells. In fact, intracellular accumulation of M1 could explain why in vivo bioactivity can be observed with nanomolar plasma concentrations that typically fail to exhibit measurable activity in vitro.