Olive leaf extract decreases age-induced oxidative stress in major organs of aged rats

The impact of dioctyl phthalate exposure on multiple organ systems and gut microbiota in mice

Dioctyl phthalate, commonly known as bis(2-ethylhexyl) phthalate (DEHP), is a widely used plasticizer in various industries and has been shown to directly or indirectly impact human health. However, there is a lack of comprehensive studies evaluating the potential health risks associated with DEHP accumulation in different organs across various age groups. This study aimed to assess the effects of low (50 mg/kg·bw) and high (500 mg/kg·bw) doses of DEHP on five different organs in mice at young (4-week-old) and aged (76-week-old) life stages. Our findings revealed that both low and high doses of DEHP exposure led to significant dose-dependent inflammation in the liver, spleen, and kidney. Furthermore, regardless of age, DEHP exposure resulted in elevated activity of alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in the liver, as well as increased levels of creatinine (Cr) and urea in the kidney. Moreover, analysis of the fecal microbiota using 16S rRNA sequencing demonstrated that DEHP exposure disrupted the homeostasis of the gut microbiota, characterized by an increased abundance of pathogenic bacteria such as Desulfovibrio and Muribaculum, and a decreased abundance of beneficial bacteria like Lactobacillus. This study provides compelling evidence that DEHP at different concentrations can induce damage to multiple organs and disrupt gut microbiota composition. These findings lay the groundwork for further investigations into DEHP toxicity in various human organs, contributing to a better understanding of the potential health risks associated with DEHP exposure.

Olea europaea L. Leaf Extract Alleviates Fibrosis Progression and Oxidative Stress Induced by Bleomycin on a Murine Model of Lung Fibrosis

In this study, we aim to investigate the effect of industrial Olea europaea L. leaf extract (OLE) against bleomycin (BLM)-induced pulmonary fibrosis (PF) in rats. Male Wistar rats were treated with a single intratracheal injection of BLM (4 mg/kg) and a daily intraperitoneal injection of OLE (10, 20, and 40 mg/kg) for 4 weeks. Results of HPLC and LC-MS analysis revealed a large amount of oleuropein (15.43%/DW) in OLE. BLM induced apparent damage of lung architecture with condensed collagen bundles, increased lipid peroxidation which has been deduced from malondialdehyde (MDA) levels: (.9 ± .13 vs .25 ± .12 nmol/mg protein) and hydroxyproline content (.601 ± .22 vs .154 ± .139 mg/g of lung tissue) and decreased catalase (CAT) (5.93.10-5 ± 4.23.10-5 vs 6.41.10-4 ± 2.33.10-4 μmol/min/mg protein) and superoxide dismutase (SOD) (28.73 ± 3.34 vs 50.13 ± 2.1 USOD/min/mg protein) levels compared to the control. OLE treatment (40 mg/kg) stabilized MDA content (.32 ± .15 and .27 ± .13 vs .9 ± .13 nmol/mg protein), normalized SOD (61.27 ± 13.37 vs 28.73 ± 3.34 USOD/min/mg protein), and CAT (5.2.10-4 ±1.8.10-4 vs 5.93.10-5 ± 4.23.10-5 μmol/min/mg protein) activities and counteracted collagen accumulation and hydroxyproline content (.222 ± .07 vs .601 ± .22 mg/g of lung tissue) in the lung parenchyma. Finally, OLE might have a potent protective effect against PF by regulating oxidative parameters and attenuating collagen deposition, due to the existence of large amount of bioactive phenolic molecules.

Molecular Mechanisms of the Protective Effects of Olive Leaf Polyphenols against Alzheimer's Disease

Alzheimer's Disease (AD) is the cause of around 60-70% of global cases of dementia and approximately 50 million people have been reported to suffer this disease worldwide. The leaves of olive trees (Olea europaea) are the most abundant by-products of the olive grove industry. These by-products have been highlighted due to the wide variety of bioactive compounds such as oleuropein (OLE) and hydroxytyrosol (HT) with demonstrated medicinal properties to fight AD. In particular, the olive leaf (OL), OLE, and HT reduced not only amyloid-β formation but also neurofibrillary tangles formation through amyloid protein precursor processing modulation. Although the isolated olive phytochemicals exerted lower cholinesterase inhibitory activity, OL demonstrated high inhibitory activity in the cholinergic tests evaluated. The mechanisms underlying these protective effects may be associated with decreased neuroinflammation and oxidative stress via NF-κB and Nrf2 modulation, respectively. Despite the limited research, evidence indicates that OL consumption promotes autophagy and restores loss of proteostasis, which was reflected in lower toxic protein aggregation in AD models. Therefore, olive phytochemicals may be a promising tool as an adjuvant in the treatment of AD.

Evaluation of Chitosan-Oleuropein Nanoparticles on the Durability of Dentin Bonding

Purpose

To evaluate the effects of dentin pretreatment with chitosan-loaded oleuropein nanoparticles (CONPs) on the durability of resin-dentin bonding interfaces.

Methods

Eighty freshly extracted non-carious human third molars were randomly divided into four groups (n = 20 each): a de-ionized water (DW) group, a chitosan (CS) group, a chlorhexidine (CHX) group and a CONP group. The dentin in the DW, CS, CHX, and CONP groups were pretreated with de-ionized water, 1.0 mg/L CS solution, 2% chlorhexidine solution, and CONP suspension (prepared with 100 mg/L oleuropein), respectively, followed by the universal adhesive and resin composites. The bonded teeth of each group were randomly divided into two subgroups: an immediate subgroup and an aged subgroup. The bonded teeth of each group were then cut into the bonded beams. We measured their microtensile bond strength (μTBS), observed the characteristics of bonding interface by atomic force microscope, calculated the percentage of silver particles in a selected area for interfacial nanoleakage analysis, and evaluated the endogenous gelatinase activity within the bonding interface for in-situ zymogram analysis. Data were analyzed with two-way ANOVA and LSD multiple comparison test (P < 0.05).

Results

Regardless of after 24 h or after thermocycling, CONP exhibited better μTBS (P < 0.05) than the other three groups except that there was not a statistical significance (P > 0.05) in the CONP and CHX groups after 24 h. Besides, the CONP group presented significantly higher modulus of elasticity in the hybrid layers (P < 0.05), lower expression of nanoleakage (P < 0.05), and better inhibitory effect of matrix metalloproteinases than the other three groups before and after thermocycling.

Conclusion

Altogether, the CONPs had the potential to act as a dentin primer, which could effectively improve the dentin-resin binding durability.

Long-Term Aerobic Training Improves Mitochondrial and Antioxidant Function in the Liver of Wistar Rats Preventing Hepatic Age-Related Function Decline

Most studies on the effects of physical exercise have focused on its influence on muscle tissue, forgetting its interference in liver function. Ageing leads to the progressive impairment of hepatic functions. Several biochemical and bioenergetics parameters were determined to test the impact of a lifelong aerobic training program in the hepatic age-related and the development of an adaptative response. Liver samples were collected from 28 male Wistar rats (4-week-old, 159.4 ± 11.9 g at the beginning of the protocol), randomly distributed into two groups: non-exercised or exercised and submitted to a treadmill exercise program (60 min/day, 5 days/week, at 70% of maximal running speed), for 24 (n = 9) or 54 weeks (n = 10). A maximal running speed test was performed to determine the training speed. Antioxidant enzyme activity, cellular redox status, oxidative stress, mitochondrial respiratory chain enzymes and respiratory activity were performed in liver samples. Lifelong exercise decreased the age-associated decline in mitochondrial dysfunction, increasing the respiratory rate in state 2 (mitochondrial respiration stimulated by the substrate in the absence of added ADP) (p = 0.03) and citrate synthase enzymatic activity (p = 0.007). Complex II (p < 0.0001) and IV (p < 0.001) showed a decrease in enzymatic activity. Ageing-related oxidative stress was also attenuated by physical exercise, as showed by the increase in first-line defense antioxidant enzymes (superoxide dismutase (p = 0.07) and catalase (p = 0.03)), decreased lipid peroxidation levels (p = 0.864 for total fraction, p = 0,27 for mitochondrial fraction) and higher glutathione reduced/oxidized ratio (p = 0.02). According to our results, the regular practice of exercise can prevent the liver’s mitochondrial dysfunction and loss of antioxidant system efficacy that may arise from ageing, highlighting the benefit of lifelong aerobic exercise in preventing age-related hepatic impairment and associated diseases.

Oleuropein Improves Cognitive Dysfunction and Neuroinflammation in Diabetic Rats through the PI3K/Akt/mTOR Pathway

Objective

To explore the effect and mechanism of oleuropein on cognitive dysfunction and neuroinflammation in diabetic rats.

Method

A diabetic rat model was constructed using streptozotocin, and the diabetic rats were divided into 3 groups with different treatment for 4 weeks, named STZ group (gavaged with normal saline), STZ+LOE group (40 mg/kg oleuropein, and STZ+SITA group (30 mg/kg sitagliptin). The fasting blood glucose (FBG), fasting serum insulin levels, and HOMA-IR index were measured in rats. After the last treatment, the Morris water maze experiment was carried out, and the rats were first subjected to training experiments for 4 consecutive days; the escape latency, number of crossing platform quadrant intersections, time spent in the target quadrant, and swimming speed were recorded. Additionally, the malondialdehyde (MDA), myeloperoxidase (MPO) content, superoxide dismutase (SOD) activity, interleukin- (IL-) 1β, tumor necrosis factor (TNF-α), and phosphatidylinositol 3-kinases (PI3K)/threonine-protein kinase (Akt)/mTOR expression levels in rat hippocampus tissues were detected.

Results

Oleuropein reduced insulin resistance, spatial learning, and memory ability in diabetic rats. It also could improve oxidative stress and inflammatory response and activate the PI3K/Akt/mTOR signaling pathway in hippocampus tissues.

Conclusion

Oleuropein ameliorates cognitive dysfunction and neuroinflammation in diabetic rats by regulating the PI3K/Akt/mTOR signaling pathway.

Age-related changes in liver metabolism and antioxidant capacity of laying hens

This study aimed to investigate the age-related changes of hepatic metabolism and antioxidant capacity of laying hens at 3 different ages. A total of 192 Hy-line Brown laying hens were assigned into 3 groups: 1) 195-day-old (D195 group); 2) 340-day-old (D340 group); 3) 525-day-old (D525 group). Each group replicated 8 times with 8 hens at the same age. Higher activity of aspartate aminotransferase and lower contents of total protein and globulin were observed in the serum of 525-day-old hens in comparison with their 195-day-old counterparts (P < 0.05). The 525-day-old hens accumulated higher contents of total cholesterol and triglyceride in the liver than 195-day-old birds. Additionally, compared with hens from D195 or D340 group, 525-day-old birds exhibited a lower circulating estradiol level (P < 0.05). For antioxidant capacity, birds in the D525 group showed a higher malondialdehyde concentration in both serum and liver as compared with D195 or D340 group (P < 0.05). The 525-day-old hens also exhibited lower glutathione peroxidase activities in both serum and liver when compared with 195-day-old birds (P < 0.05). Simultaneously, there was a decline of hepatic superoxide dismutase activity in the D525 group in comparison with D195 group (P < 0.05). Compared with 195-day-old counterparts, 340-day-old birds upregulated the mRNA abundance of nuclear factor erythroid-2 related factor 2 and glutathione peroxidase 1 in the liver (P < 0.05). In contrast, hens from D525 group showed the downregulation of hepatic nuclear factor erythroid-2 related factor 2, NAD(P)H quinone dehydrogenase 1, and superoxide dismutase 1 when compared with D340 group (P < 0.05). These results indicated that increasing age can adversely affect liver metabolism and function of laying hens.

Addition of Olive Leaf Extract to a Mixture of Algae and Extra Virgin Olive Oils Decreases Fatty Acid Oxidation and Synergically Attenuates Age-Induced Hypertension, Sarcopenia and Insulin Resistance in Rats

Olive-derived products, such as virgin olive oil (EVOO) and/or olive leaf extracts (OLE), exert anti-inflammatory, insulin-sensitizing and antihypertensive properties and may be useful for stabilizing omega 3 fatty acids (n-3 PUFA) due to their high content in antioxidant compounds. In this study, the addition of OLE 4:0.15 (w/w) to a mixture of algae oil (AO) rich in n-3 PUFA and EVOO (25:75, w/w) prevents peroxides formation after 12 months of storage at 30 °C. Furthermore, the treatment with the oil mixture (2.5 mL/Kg) and OLE (100 mg/Kg) to 24 month old Wistar rats for 21 days improved the lipid profile, increased the HOMA-IR and decreased the serum levels of miRNAs 21 and 146a. Treatment with this new nutraceutical also prevented age-induced insulin resistance in the liver, gastrocnemius and visceral adipose tissue by decreasing the mRNA levels of inflammatory and oxidative stress markers. Oil mixture + OLE also attenuated the age-induced alterations in vascular function and prevented muscle loss by decreasing the expression of sarcopenia-related markers. In conclusion, treatment with a new nutraceutical based on a mixture of EVOO, AO and OLE is a useful strategy for improving the stability of n-3 PUFA in the final product and to attenuate the cardiometabolic and muscular disorders associated with aging.

Olive Leaf Extract Supplementation to Old Wistar Rats Attenuates Aging-Induced Sarcopenia and Increases Insulin Sensitivity in Adipose Tissue and Skeletal Muscle

Aging is associated with increased visceral adiposity and a decrease in the amount of brown adipose tissue and muscle mass, known as sarcopenia, which results in the development of metabolic alterations such as insulin resistance. In this study, we aimed to analyze whether 3-week supplementation with a phenolic-rich olive leaf extract (OLE) to 24 months-old male Wistar rats orally (100 mg/kg) attenuated the aging-induced alterations in body composition and insulin resistance. OLE treatment increased brown adipose tissue and attenuated the aging-induced decrease in protein content and gastrocnemius weight. Treatment with OLE prevented the aging-induced increase in the expression of PPAR-γ in visceral and brown adipose tissues, while it significantly increased the expression of PPAR-α in the gastrocnemius of old rats and reduced various markers related to sarcopenia such as myostatin, HDAC-4, myogenin and MyoD. OLE supplementation increased insulin sensitivity in explants of gastrocnemius and epididymal visceral adipose tissue from aged rats through a greater activation of the PI3K/Akt pathway, probably through the attenuation of inflammation in both tissues. In conclusion, supplementation with OLE prevents the loss of muscle mass associated with aging and exerts anti-inflammatory and insulin-sensitizing effects on adipose tissue and skeletal muscle.

Olive leaf extract supplementation improves the vascular and metabolic alterations associated with aging in Wistar rats

Olive leaves are rich in bioactive substances which exert anti-inflammatory, antioxidant, insulin-sensitizing and antihypertensive effects. The aim of this study was to analyze the possible beneficial effects of an olive leaf extract (OLE) rich in secoiridoids and phenolic compounds on the aging-induced metabolic and vascular alterations. Three experimental groups of rats were used: 3-month-old rats, 24-month-old rats and 24-month-old rats supplemented 21 days with OLE (100 mg/kg). Administration of OLE to aged rats decreased the weight of adrenal glands and prevented the aging-induced loss of body weight and muscle mass. In the serum, OLE reduced the circulating levels of LDL-cholesterol and IL-6 and increased the concentrations of leptin and adiponectin. In the liver OLE attenuated the decreased gene expression of SOD-1, GSR, GCK and GSK-3β and reduced the aging-induced overexpression of NOX-4, Alox-5, iNOS and TNF-α. In aorta segments, OLE prevented endothelial dysfunction and vascular insulin resistance and improved vasoconstriction in response to KCl and NA. Improvement in vascular function was associated with the attenuation of the alterations in the gene expression of COX-2, IL-6, GPx, NOX-1 and IL-10. In conclusion, OLE exerts anti-inflammatory and antioxidant effects in aged rats and attenuates the alterations in vascular function associated with aging.

Olive Fruit Extracts Supplement Improve Antioxidant Capacity via Altering Colonic Microbiota Composition in Mice

Oxidative stress, one of the most common biological dysfunctions, is usually associated with pathological conditions and multiple diseases in humans and animals. Chinese olive fruit (Canarium album L.) extracts (OE) are natural plant extracts rich in polyphenols (such as hydroxytyrosol, HT) and with antioxidant, anti-hyperlipidemia, and anti-inflammatory potentials. This study was conducted to investigate the antioxidant capacity of OE supplementation and its related molecular mechanism in mice. Mice (25.46 ± 1.65 g) were treated with 100 mg/kg body weight (BW) OE or saline solution for 4 weeks, and then the antioxidant and anti-inflammatory capacities of mice were examined. The results showed that OE supplement significantly increased the serum antioxidative enzyme activities of total antioxidant activity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase and decreased the serum malondialdehyde (MDA) level, indicating that OE treatment enhanced the antioxidant capacity in mice. qPCR results showed that the transcriptional expression of antioxidant SOD1, CAT, Gpx1, and Gpx2 were significantly down-regulated in the small intestine (jejunum and ileum) after OE administration. Meanwhile, OE treatment significantly decreased the T-AOC and increased the MDA level in the small intestine. Furthermore, OE administration dramatically reduced the mRNA expression of pro-inflammatory cytokines (TNF-α and IL-1β), which confirmed its antioxidant and anti-inflammatory capacities with OE administration. Using amplicon sequencing technology, 16S rRNA sequencing results showed that OE supplement significantly increased the colonic Firmicutes/Bacteroidetes ratio, which also had a negative correlation with the serum MDA level and positively correlated with serum GSH-Px activity through Pearson correlation analysis. Besides that, Alloprevotella was negatively correlated with serum T-AOC. Colidextribacter was positively correlated with serum MDA and negatively correlated with serum T-AOC, SOD, and GSH-Px levels. In summary, this study showed that treatment with 100 mg/kg BW polyphenol-rich OE could alter colonic microbiota community, which was strongly associated with improved antioxidant capacity in mice.

Thyroid-Modulating Activities of Olive and Its Polyphenols: A Systematic Review

Olive oil, which is commonly used in the Mediterranean diet, is known for its health benefits related to the reduction of the risks of cancer, coronary heart disease, hypertension, and neurodegenerative disease. These unique properties are attributed to the phytochemicals with potent antioxidant activities in olive oil. Olive leaf also harbours similar bioactive compounds. Several studies have reported the effects of olive phenolics, olive oil, and leaf extract in the modulation of thyroid activities. A systematic review of the literature was conducted to identify relevant studies on the effects of olive derivatives on thyroid function. A comprehensive search was conducted in October 2020 using the PubMed, Scopus, and Web of Science databases. Cellular, animal, and human studies reporting the effects of olive derivatives, including olive phenolics, olive oil, and leaf extracts on thyroid function were considered. The literature search found 445 articles on this topic, but only nine articles were included based on the inclusion and exclusion criteria. All included articles were animal studies involving the administration of olive oil, olive leaf extract, or olive pomace residues orally. These olive derivatives were consistently demonstrated to have thyroid-stimulating activities in euthyroid or hypothyroid animals, but their mechanisms of action are unknown. Despite the positive results, validation of the beneficial health effects of olive derivatives in the human population is lacking. In conclusion, olive derivatives, especially olive oil and leaf extract, could stimulate thyroid function. Olive pomace residue is not suitable for pharmaceutical or health supplementation purposes. Therapeutic applications of olive oil and leaf extract, especially in individuals with hypothyroidism, require further validation through human studies.

Microbiological and Antioxidant Activity of Phenolic Compounds in Olive Leaf Extract

According to many reports, phenolic compounds isolated from olive leaves have very good biological activities, especially antimicrobial. Presently, the resistance of microorganisms to antibiotics is greater than ever. Therefore, there are numerous recent papers about alternative solutions for inhibiting their influence on human health. Olive leaf is studied as an important source of antimicrobials with low cost and used in medicine. Numerous publications on involving green technologies for isolation of active compounds from olive leaves have appeared over the past few decades. The present review reports on current knowledge of the most isolated phenolic compounds from olive leaf extract as well as methods for their isolation and characterization. This paper uses recent research findings with a wide range of study models to describe the antimicrobial potential of phenolic compounds. It also describes the vast range of information about methods for determination of antimicrobial potential focusing on effects on different microbes. Additionally, it serves to highlight the role of olive leaf extract as an antioxidants and presents methods for determination of antioxidant potential. Furthermore, it provides an overview of presence of enzymes. The significance of olive leaves as industrial and agricultural waste is emphasized by means of explaining their availability, therapeutic and nutritional effects, and research conducted on this field.

Olive leaf extract modulates glycerol-induced kidney and liver damage in rats

The present study was conducted to examine the protective effect of olive leaf extract (OLE) against glycerol-induced oxidative stress in rats. Sixty male albino rats were used and allocated randomly into four groups, each of 15 rats. Groups (1) and (2) were administered intraperitoneally (i.p.) a single dose of 500 μL normal saline and hypertonic glycerol solution (10 mL/kg b.wt., 50% v/v, in sterile saline), respectively, followed by a 24-h period of water deprivation. Group (3) was orally given OLE (500 mg/kg b.wt.) for 22 days and glycerol as mentioned above on the 14th day of OLE administration followed by a 24-h period of water deprivation. Group (4) was administered OLE alone. Five rats from each group were sacrificed and samples were collected 1, 5, and 8 days after water deprivation. Alterations in hematobiochemical parameters, renal and hepatic oxidative stress markers, as well as histopathology of the kidney and liver, were evaluated. Glycerol treatment resulted in significant hematological and biochemical alterations as well as significant renal and hepatic oxidative stress. Administration of OLE has significantly ameliorated renal dysfunction, morphological alterations of kidney and liver, and relieved the oxidative stress. These findings show obviously the role of oxidative stress and its relevance to renal dysfunction and suggest the ameliorative impact of OLE in glycerol-induced acute kidney damage in rats, possibly due to its antioxidant properties.

Efficacy of olive leaf extract-containing cream for facial rejuvenation: A pilot study

BACKGROUND

Olive leaf extract (OLE), a naturally extracted product from olive leaves, contains oleuropein and other bioactive phenolic compounds. Oleuropein was identified to have various medical properties. It was also found to inhibit the effects of both acute and chronic UVB-induced skin damage as well as accelerate wound healing activity.

AIMS

To evaluate the efficacy of olive leaf extract-containing cream on facial rejuvenation.

METHODS

This is a prospective pilot study with a total of 36 participants, who presented with photoaging skin. All participants applied the olive leaf extract-containing cream (SUPERHEAL™ O-Live Cream, PhytoCeuticals, Inc, USA) to their whole face twice daily for 2 months. Primary outcomes measured in the study were the changes in the biophysical properties of the skin assessed with the following parameters: melanin and erythema index, transepidermal water loss (TEWL), skin hydration, skin pH, sebum level, texture, and wrinkles.

RESULTS

After 2 months, TEWL decreased significantly (P = .007) and maintained the results 1 month after discontinuation of the treatment (P = .007). Skin hydration also increased significantly after 2 months (P = .004). Wrinkles improved significantly on all follow-ups (P < .001, P = .001, P = .001, respectively). An image of the skin captured using Visioscan® showed improvement of the skin texture 2 months after treatment. Majority of the participants (64%) noted improvement in their skin texture.

CONCLUSION

Olive leaf extract-containing cream provided benefits on skin rejuvenation in human skin.

Pleiotropic Biological Effects of Dietary Phenolic Compounds and their Metabolites on Energy Metabolism, Inflammation and Aging

Dietary phenolic compounds are considered as bioactive compounds that have effects in different chronic disorders related to oxidative stress, inflammation process, or aging. These compounds, coming from a wide range of natural sources, have shown a pleiotropic behavior on key proteins that act as regulators. In this sense, this review aims to compile information on the effect exerted by the phenolic compounds and their metabolites on the main metabolic pathways involved in energy metabolism, inflammatory response, aging and their relationship with the biological properties reported in high prevalence chronic diseases. Numerous in vitro and in vivo studies have demonstrated their pleiotropic molecular mechanisms of action and these findings raise the possibility that phenolic compounds have a wide variety of roles in different targets.

Effect of oleuropein on morphine-induced hippocampus neurotoxicity and memory impairments in rats

Oleuropein, as an olive leaf extract antioxidant polyphenol, has been reported to be a free radical scavenger. This study was done to investigate the effects of oleuropein, against morphine-induced hippocampus neurotoxicity and memory impairment in rats. The Morris water maze (MWM) test was used to assess the effect of oleuropein (5, 15, and 30 mg/kg, i.p., co-administrated with morphine) on spatial learning and memory of male Wistar rats which were treated with morphine sulfate (45 mg/kg, s.c., 4 weeks). In order to evaluate the cleaved caspase-3, Bax, and Bcl2 protein expression (as biochemical markers of apoptosis) in CA1 area of hippocampus tissue, the western blot test was used. Also, to evaluate the oxidative stress status of hippocampus CA1 area tissue, the malondialdehyde (MDA) level, superoxide dismutase (SOD) activity, and glutathione peroxidase (GPx) activity were assessed. The data showed that oleuropein treatment (15 and 30 mg/kg) improves the spatial learning and memory impairments in morphine-treated animals. Also, oleuropein treatment decreased the apoptosis and oxidative stress levels in the hippocampus CA1 area of morphine-treated rats. Oleuropein can prevent the spatial learning and memory impairments in morphine-treated rats. Molecular mechanisms underlying the observed effects could be at least partially related to the inhibition of neuronal apoptosis and oxidative stress in the hippocampus CA1 area of morphine-treated rats.

Link between cardiac function and the antioxidative defense mechanism in aged rats

Aging presents profound structural and physiological changes in the cardiovascular system. Oxidative stress, a major contributing factor during the aging process, has been involved in various age-related cardiovascular pathologies. Nevertheless, the underlying mechanism of oxidative stress in the aging heart is still unclear. This study was designed to determine whether changes in cardiac structure and function in aged rats were associated with decreases in the antioxidative defense mechanism. Young (3-month-old) and aged (24-month-old) rats were used in this study, and the differences in function, structure, antioxidative capacity and the expression of antioxidative-related proteins between the two groups were compared. By using echocardiography, we observed that compared to young rats, the left ventricular internal end-diastolic diameter (LVID; d) and left ventricular volume at diastole (LV Vol; d) were significantly increased in aged rats, while the MV E/A (E wave and A wave ratio, the ratio of peak velocity of early to late filling of mitral inflow), which represents heart diastolic function, was significantly decreased in aged rats. In addition, we observed degenerative histological modifications and an increased number of apoptotic cells in aged rats. We further detected the protein expression of catalase (CAT), glutathione synthetase (GSS), superoxide dismutase-1 (SOD-1), heme oxygenase-1 (HO-1) and NADPH: quinone oxidoreductase 1 (NQO1) in cardiac tissue. Western blot results showed that the expression of GSS was significantly decreased and that the expressions of CAT, SOD-1, and HO-1 were slightly decreased in aged rats. Immunohistochemistry results further confirmed the decreased expression of GSS, SOD-1 and NQO1 in cardiomyocytes in aged rats. Taken together, our data suggest that aging may affect the morphology and function of the heart by oxidative stress and the antioxidative defense mechanism.

6-gingerol ameliorates age-related hepatic steatosis: Association with regulating lipogenesis, fatty acid oxidation, oxidative stress and mitochondrial dysfunction

The prevalence of NAFLD increases with age. As the main active ingredient of ginger, 6-gingerol significantly improves lipid metabolism abnormalities in adult rodents. However, few studies have reported its effect on age-related NAFLD. This study was to investigate the effects of 6-gingerol on age-related hepatic steatosis and its potential targets. As expected, 6-gingerol dramatically normalized the hepatic triglyceride content, plasma insulin and HOMA-IR index of ageing rats. Mechanistically, 6-gingerol affected lipid metabolism by increasing β-oxidation and decreasing lipogenesis through activation of PPARα and CPT1α and inhibition of DGAT-2. Furthermore, 6-gingerol reversed the decreases in citrate, Cs and ATP, lessened the damage caused by ROS, and upregulated mitochondrial marker enzymes NOX, SDH, and SIRT3 in the ageing liver, indicating its ability to strengthen mitochondrial function. Our results showed 6-gingerol exerted a positive effect on insulin sensitivity by regulating Akt. In conclusion, the hepatic anti-steatotic effect of 6-gingerol is associated with inhibition of de novo lipogenesis, upregulation of fatty acid oxidation, reduction in oxidative stress and synergistic enhancement of mitochondrial function.

Protective Effects of Olive Leaf Extract on Acrolein-Exacerbated Myocardial Infarction via an Endoplasmic Reticulum Stress Pathway

Many studies reported that air pollution particulate matter (PM) exposure was associated with myocardial infarction (MI). Acrolein representing the unsaturated aldehydes, the main component of PM, derives from the incomplete combustion of wood, plastic, fossil fuels and the main constitute of cigarette smoking. However, the effect of acrolein on MI remains not that clear. In the current study, the effect of acrolein-exacerbated MI was investigated. In vivo, male Sprague–Dawley rats received olive leaf extract (OLE) followed by acrolein, then isoprenaline (ISO) was received by subcutaneous injection to induce MI. Results showed that the expression levels of GRP78 and CHOP, two major components of endoplasmic reticulum (ER) stress were higher in the combination of acrolein and ISO than those in ISO treatment. The apoptosis marker, Bax, was also higher while the anti-apoptosis indicator, Bcl2 expression was lower both at protein and mRNA levels in the combination group. Also, the acrolein-protein adducts and myocardial pathological damage increased in the combination of acrolein and ISO relative to the ISO treatment. Besides, cardiac parameters, ejection fraction (EF) and fractional shortening (FS) were reduced more significantly when acrolein was added than in ISO treatment. Interestingly, all the changes were able to be ameliorated by OLE. Since hydroxytyrosol (HT) and oleuropein (OP) were the main components in OLE, we next investigated the effect of HT and OP on cardiomyocyte H9c2 cell apoptosis induced by acrolein through ER stress and Bax pathway. Results showed that GRP78, CHOP and Bax expression were upregulated, while Bcl2 expression was downregulated both at the protein and mRNA levels, when the H9c2 cells were treated with acrolein. In addition, pretreatment with HT can reverse the expression of GRP78, CHOP, Bax and Bcl2 on the protein and mRNA levels, while there was no effect of OP on the expression of GRP78 and CHOP on the mRNA levels. Overall, all these results demonstrated that OLE and the main components (HT and OP) could prevent the negative effects of acrolein on myocardium and cardiomyocytes.

Oleuropein attenuates cognitive dysfunction and oxidative stress induced by some anesthetic drugs in the hippocampal area of rats

The present study was designed to evaluate the antioxidant effects of oleuropein against oxidative stress in the hippocampal area of rats. We used seven experimental groups as follows: Control, Propofol, Propofol-Ketamine (Pro.-Ket.), Xylazine-Ketamine (Xyl.-Ket.), and three oleuropein-pretreated groups (Ole.-Pro., Ole.-Pro.-Ket. and Ole.-Xyl.-Ket.). The oleuropein-pretreated groups received oleuropein (15 mg/kg body weight as orally) for 10 consecutive days. Propofol 100 mg/kg, xylazine 3 mg/kg, and ketamine 75 mg/kg once as ip was used on the 11th day of treatment. Spatial memory impairment and antioxidant status of hippocampus were measured via Morris water maze, lipid peroxidation marker, and antioxidant enzyme activities. Spatial memory impairment and lipid peroxidation significantly increased in Xyl.-Ket.-treated rats in comparison to the control, propofol, Ole.-Pro. and Ole.-Pro.-Ket. groups. Oleuropein pretreatment significantly reversed spatial memory impairment and lipid peroxidation in the Ole.-Xyl.-Ket. group as compared to the Xyl.-Ket.-treated rats. There was no significant difference between the control and the propofol group in lipid peroxidation and spatial memory status. Superoxide dismutase and catalase activities both significantly decreased in Xyl.-Ket.-treated rats when compared to the control, propofol, Ole.-Pro., Ole.-Pro.-Ket., and Ole.-Xyl.-Ket. groups. In contrast, glutathione peroxidase activity in Xyl.-Ket.-treated rats significantly increased as compared to the control, propofol, Pro.-Ket., Ole.-Pro., and Ole.-Pro.-Ket. groups. We concluded that xylazine in combination with ketamine is an oxidative anesthetic drug and oleuropein pretreatment attenuates cognitive dysfunction and oxidative stress induced by anesthesia in the hippocampal area of rats. We also confirmed the antioxidant properties of propofol as a promising antioxidant anesthetic agent.

Effects of exercise training on hepatic oxidative stress and antioxidant status in aged rats

This study investigated the effects of exercise training on oxidative stress, and antioxidant defense markers in the liver tissues of young and aged rats. Two age groups of 4-(young) and 20-months-(aged) old male Wistar rats were performed exercise training program consisted of swimming exercise for 8 weeks. The biomarkers of pro/antioxidant status malondialdehyde (MDA), protein carbonyl (PC), 8-hydroxy-2'-deoxyguanosine (8-OHdG), total glutathione (GSH) and superoxide dismutase (SOD) were assessed by commercially available kits. PC levels were higher in the untrained aged rats compared to the young groups and exercise training decreased PC levels (p < 0.05). 8-OHdG levels were higher in the aged groups (p < 0.05). MDA and GSH levels and SOD activity did not differ significantly between the groups (p > 0.05). The present findings indicate that exercise training prevents aging-induced hepatic oxidative damage especially in the proteins.

Olive polyphenol effects in a mouse model of chronic ethanol addiction

OBJECTIVES

Alcohol addiction elicits oxidative imbalance and it is well known that polyphenols possess antioxidant properties. We investigated whether or not polyphenols could confer a protective potential against alcohol-induced oxidative stress.

METHODS

We administered (per os) for two months 20 mg/kg of olive polyphenols containing mostly hydroxytyrosol in alcoholic adult male mice. Hydroxytyrosol metabolites as hydroxytyrosol sulfate 1 and hydroxytyrosol sulfate 2 were found in the serum of mice administered with polyphenols with the highest amount in animals treated with both polyphenols and alcohol. Oxidative stress was evaluated by FORT (free oxygen radical test) and FORD (free oxygen radical defense) tests.

RESULTS

Alcoholic mice showed a worse oxidative status than nonalcoholic mice (higher FORT and lower FORD) but polyphenol supplementation partially counteracted the alcohol pro-oxidant effects, as evidenced by FORT.

CONCLUSIONS

A better understanding of the antioxidant protection provided by polyphenols might be of primary interest for drug discovery and dietary-based prevention of the damage associated with chronic alcohol abuse.

Neuroprotective effects of oleuropein against cognitive dysfunction induced by colchicine in hippocampal CA1 area in rats

Alzheimer's disease is a progressive neurodegenerative disorder with decline in memory. The role of oxidative stress is well known in the pathogenesis of the disease. The purpose of this study was to evaluate pretreatment effects of oleuropein on oxidative status and cognitive dysfunction induced by colchicine in the hippocampal CA1 area. Male Wistar rats were pretreated orally once daily for 10 days with oleuropein at doses of 10, 15 and 20 mg/kg. Thereafter, colchicine (15 μg/rat) was administered into the CA1 area of the hippocampus to induce cognitive dysfunction. The Morris water maze was used to assess learning and memory. Biochemical parameters such as glutathione peroxidase and catalase activities, nitric oxide and malondialdehyde concentrations were measured to evaluate the antioxidant status in the rat hippocampus. Our results indicated that colchicine significantly impaired spatial memory and induced oxidative stress; in contrast, oleuropein pretreatment significantly improved learning and memory retention, and attenuated the oxidative damage. The results clearly indicate that oleuropein has neuroprotective effects against colchicine-induced cognitive dysfunction and oxidative damage in rats.

Dry olive leaf extract counteracts L-thyroxine-induced genotoxicity in human peripheral blood leukocytes in vitro

The thyroid hormones change the rate of basal metabolism, modulating the consumption of oxygen and causing production of reactive oxygen species, which leads to the development of oxidative stress and DNA strand breaks. Olive (Olea europaea L.) leaf contains many potentially bioactive compounds, making it one of the most potent natural antioxidants. The objective of this study was to evaluate the genotoxicity of L-thyroxine and to investigate antioxidative and antigenotoxic potential of the standardized oleuropein-rich dry olive leaf extract (DOLE) against hydrogen peroxide and L-thyroxine-induced DNA damage in human peripheral blood leukocytes by using the comet assay. Various concentrations of the extract were tested with both DNA damage inducers, under two different experimental conditions, pretreatment and posttreatment. Results indicate that L-thyroxine exhibited genotoxic effect and that DOLE displayed protective effect against thyroxine-induced genotoxicity. The number of cells with DNA damage, was significantly reduced, in both pretreated and posttreated samples (P < 0.05). Comparing the beneficial effect of all tested concentrations of DOLE, in both experimental protocols, it appears that extract was more effective in reducing DNA damage in the pretreatment, exhibiting protective role against L-thyroxine effect. This feature of DOLE can be explained by its capacity to act as potent free radical scavenger.