Olive leaf extract inhibits lead poisoning-induced brain injury

Olea europaea L. (olive) leaf extract ameliorates learning and memory deficits in streptozotocin-induced diabetic rats

Objective

The aim of the present study was to assess olive leaf extract (OLE) effects on learning and memory deficits in a model of diabetes induced by streptozotocin (STZ) in rats.

Materials and methods

The rats were divided as: (1) control rats, (2) diabetic rats, and (3-6) diabetic rats treated by 100, 200, and 400 mg/kg of OLE or metformin. Using the passive avoidance test (PA), we investigated fear learning and memory behaviors. In cortical and hippocampus tissues, total levels of malondialdehyde (MDA) and thiol were measured along with the activity of catalase (CAT) and superoxide dismutase (SOD).

Results

Learning and memory behavior impairment were significantly developed in diabetic rats as shown by the impairment of the PA task compared to the control group (p<0.001). In addition, elevated levels of MDA and reduced overall concentrations of thiol, CAT and SOD activity were obvious in diabetic rats' cortex and hippocampus tissues (p<0.01-p<0.001). Meanwhile, OLE in a dose-dependent manner, improved memory deficit and cognitive performance that was attributed to a reduction of lipid peroxidation and elevation of total thiol concentration, and CAT and SOD activity levels in the brain tissues (p<0.05-p<0.001).

Conclusion

OLE could be effective in improving cognitive impairment in STZ-induced diabetes by oxidative stress depression.

Phenolic and Antioxidant Analysis of Olive Leaves Extracts (Olea europaea L.) Obtained by High Voltage Electrical Discharges (HVED)

Background: The aim of this study was to evaluate high voltage electrical discharges (HVED) as a green technology, in order to establish the effectiveness of phenolic extraction from olive leaves against conventional extraction (CE). HVED parameters included different green solvents (water, ethanol), treatment times (3 and 9 min), gases (nitrogen, argon), and voltages (15, 20, 25 kV). Methods: Phenolic compounds were characterized by ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS), while antioxidant potency (total phenolic content and antioxidant capacity) were monitored spectrophotometrically. Data for Near infrared spectroscopy (NIR) spectroscopy, colorimetry, zeta potential, particle size, and conductivity were also reported. Results: The highest yield of phenolic compounds was obtained for the sample treated with argon/9 min/20 kV/50% (3.2 times higher as compared to CE). Obtained results suggested the usage of HVED technology in simultaneous extraction and nanoformulation, and production of stable emulsion systems. Antioxidant capacity (AOC) of obtained extracts showed no significant difference upon the HVED treatment. Conclusions: Ethanol with HVED destroys the linkage between phenolic compounds and components of the plant material to which they are bound. All extracts were compliant with legal requirements regarding content of contaminants, pesticide residues and toxic metals. In conclusion, HVED presents an excellent potential for phenolic compounds extraction for further use in functional food manufacturing.

The Effects of Olive Leaf Extract on The Testis, Sperm Quality and Testicular Germ Cell Apoptosis in Male Rats Exposed to Busulfan

Background

Busulfan (BU) has a destructive effect on the male reproductive system. The goal of this study was to assess the effects of olive leaf extract (OLE) as a source of antioxidants and phenolic compounds, on BU-induced damages in rat testes.

Materials and Methods

In this experimental study, 40 male Wistar rats were randomly divided into 5 groups. The control group (CTL) received a single intraperitoneal (i.p.) injection of dimethyl sulfoxide (DMSO), followed by oral administration of distilled water for 5 weeks. In BU group, BU (10 mg/kg) was administrated i.p. once. In co- treatment groups, first, received BU (10 mg/kg, a single i.p. injection) then, OLE was administrated orally at different doses of 250 mg/kg (BU+OLE 250), 500 mg/kg (BU+OLE 500) and 750 mg/kg (BU+OLE 750), for 5 weeks. Next, blood and sperm samples were collected. The left testis was removed to investigate testicular parameters and apop- tosis by using H&E and TUNEL staining, respectively. All data were analyzed by SPSS software and a P<0.05 was considered significant.

Results

There was a significant decline in sperm viability (P=0.017), number of primary spermatocyte (PS) (P=0.001) and Leydig cells (P=0.023) in the BU group versus the CTL group. OLE at three doses could repair these defects ver- sus BU group. Increases in apoptotic spermatogonia cells (SG) due to BU were significantly reduced by OLE 250 and 500 mg/kg (P<0.01). A reduction in germinal epithelium height and an increase in apoptotic SG were observed in BU+OLE 750 group vs. other groups (P<0.01) and alkaline phosphatase (ALP) was at the highest level, also Aspartate aminotransferase (AST) increased markedly vs. CTL (P=0.024).

Conclusion

Oral administration of OLE at the doses of 250 and 500 mg/kg could be helpful in ameliorating BU- induced toxicity in rat testes, while OLE 750 mg/kg not only did not cause positive effects, but also could exacerbate the harmful effects.

Indigofera oblongifolia Prevents Lead Acetate-Induced Hepatotoxicity, Oxidative Stress, Fibrosis and Apoptosis in Rats

The current study was aimed to evaluate the preventive effects of Indigofera oblongifolia leaf extract (IOLE) on lead acetate (PbAc)-induced hepatotoxicity in adult male Wistar rats. PbAc was intraperitoneally injected at a dose of 20 mg/kg body weight for 5 days alone or in combination with the IOLE (100 mg/kg). Liver lead concentration and oxidative stress markers such as lipid peroxidation, hydrogen peroxide, nitric oxide, and glutathione content were investigated in addition to the enzymatic antioxidant activities. PbAc injection caused a significant elevation in the liver function parameters, lead level, lipid peroxidation, hydrogen peroxide, and nitric oxide, with a concomitant decline in the glutathione content compared with the control, accompanied by a significant inhibition of antioxidant enzyme activities. The induction of oxidative stress, lead accumulation, and histological alterations in the liver were successfully minimized by pre-administration of IOLE. In addition, the PbAc group showed increase in the levels of Bax, caspase-3, and matrix metalloproteinase-9 proteins, while the expression of Bcl-2 protein was decreased. Prior administration of IOLE significantly mitigated apoptosis and fibrosis in the liver. Finally, the major components in I. oblongifolia extract were identified as polyphenols, flavonoids, and organic acids using liquid chromatography coupled mass spectroscopy. Thus, the findings of the current study revealed that I. oblongifolia had protective, anti-fibrotic, antioxidant, and anti-apoptotic activities on PbAc-induced hepatotoxicity. The beneficial effects of I. oblongifolia were in part mediated by Nrf2/HO-1 pathway.

Oleuropein-Enriched Olive Leaf Extract Affects Calcium Dynamics and Impairs Viability of Malignant Mesothelioma Cells

Malignant mesothelioma is a poor prognosis cancer in urgent need of alternative therapies. Oleuropein, the major phenolic of olive tree (Olea europaea L.), is believed to have therapeutic potentials for various diseases, including tumors. We obtained an oleuropein-enriched fraction, consisting of 60% w/w oleuropein, from olive leaves, and assessed its effects on intracellular Ca²⁺ and cell viability in mesothelioma cells. Effects of the oleuropein-enriched fraction on Ca²⁺ dynamics and cell viability were studied in the REN mesothelioma cell line, using fura-2 microspectrofluorimetry and MTT assay, respectively. Fura-2-loaded cells, transiently exposed to the oleuropein-enriched fraction, showed dose-dependent transient elevations of cytosolic Ca²⁺ concentration ([Ca²⁺]_i). Application of standard oleuropein and hydroxytyrosol, and of the inhibitor of low-voltage T-type Ca²⁺ channels NNC-55-0396, suggested that the effect is mainly due to oleuropein acting through its hydroxytyrosol moiety on T-type Ca²⁺ channels. The oleuropein-enriched fraction and standard oleuropein displayed a significant antiproliferative effect, as measured on REN cells by MTT cell viability assay, with IC₅₀ of 22 μg/mL oleuropein. Data suggest that our oleuropein-enriched fraction from olive leaf extract could have pharmacological application in malignant mesothelioma anticancer therapy, possibly by targeting T-type Ca²⁺ channels and thereby dysregulating intracellular Ca²⁺ dynamics.