Amounts Of Oleuropein Research Articles

TÜRKİYE'DE DİYABET TEDAVİSİNE DESTEK OLMAK İÇİN İNSANLAR NE TERCİH EDİYOR? ZEYTİN YAPRAĞI VE DİYABET ÜZERİNE BİR ARAŞTIRMA

Objective: A questionnaire study was conducted to evaluate the applications of plants and herbal products consumed by diabetic patients for the treatment of chronic health conditions. Evaluation of the questionnaire confirmed that olive leaf is one of the most used herbs in the treatment of diabetes, in line with its traditional use in the literature. In vitro biological activity studies were performed to determine whether different olive leaf samples have antidiabetic effects. Additionally, the major component oleuropein was quantitively determined in the samples. Material and Method: The established survey was firstly approved by the ethics committee at Gazi University then the survey was conducted at the University Hospital, Department of Endocrinology between January 2021, and July 2021. Based on the result of the survey, pharmacognostic analyses, chromatographic analyses, and inhibition on diabetes-related enzymes (α-amylase, α-glucosidase, and aldose reductase) were performed on the samples of olive leaves collected from nature, obtained from herbalists, markets and pharmacies. Result and Discussion: Evaluation of the survey revealed that the patients mostly used cinnamon (29.3%) and olive leaves (21.7%) for the treatment of diabetes, and these plants were generally obtained from herbalists (51.7%). The study findings showed that aqueous and ethanolic extracts prepared from olive leaf samples contained 190.3-374.3 mg/g oleuropein. The amount of oleuropein in the ready-made olive leaf extract from herbalists was found to be much lower (50.9 mg/g) than the other olive leaf extracts. When the enzyme inhibition activity assays were evaluated, it was determined that all olive leaf samples had inhibitory effects on α-amylase, α-glucosidase, and aldose reductase enzymes. All olive leaf samples, including teas prepared by the public at home with water, were found to have capacity to decrease the blood level in other words antidiabetic activities in vitro. The oleuropein contents detected in this study once again revealed the importance of meticulous examination in herbal products.

Bioactivity, DNA damage protecting, and aroma potential of oleuropein enriched olive leaf extract by optimization of ultrasound‐assisted process

AbstractIn this study, Box–Behnken experimental design was employed to optimize Ultrasound‐assisted extraction (UAE) method to obtain oleuropein‐rich extract from olive leaf. The effect of three parameters, ethanol concentration (30%–70%), amplitude (30%–50%), and ultrasonication time (5–15 min) on oleuropein content were evaluated through experimental design. The total phenolic content, antioxidant capacity, DNA damage scavenging activity, aroma profile, and antimicrobial activity of olive leaf were also investigated. The optimum extraction condition was determined as 30% amplitude, 70% ethanol, and 5 min extraction time. The amount of oleuropein was found to be 42.621 mg/g dry leaves at the optimum condition. The total phenolic content of the optimized extract was found as 45.13 mg GAE/g dry leaves while the antioxidant capacity of the optimized extract was 216 µmol Trolox/g in DPPH and 213.19 µmol Trolox/g in ABTS method. Twenty‐three volatile compounds were identified in extracts, mainly aldehydes and alcohols. The extracts showed high antimicrobial activity against selected bacterial strains. DNA damage protecting activity of extracts on plasmid DNA was clearly demonstrated. UAE has an important effect on the phenolic content and antioxidant capacity of olive leaves. Moreover, oleuropein‐rich extract can have potential as a therapeutic agent depending on its antimicrobial and DNA‐protecting activity.

The Effect of Oleuropein on The Mitochondrial Membrane Potential and Generation of Reactive Oxygen Species on Leishmania tropica Promastigotes

Leishmania parasites, which are reported to be endemic in 98 countries around the world, infect humans as well as wild and domestic carnivores and small mammals, and are transmitted by sand flies (Phlebotomus, dwarf sandflies). It is reported that 350 million people are at risk and two million new cases are seen in the world every year. It has been reported that different drugs (topical paromomycin, oral miltefosine, ketoconazole, rifampin, and zinc) have been tried in studies especially in endemic regions in the treatment of cutaneous leishmaniasis, and response to treatment has been obtained at different rates. Today, the search for alternative treatments continues and many studies have been carried out for this purpose. For centuries, olive leaf extracts have been used to maintain health. Oleuropein has numerous health benefits, including antioxidant, antimicrobial, anti-inflammatory, antiatherogenic, anticarcinogenic, antiviral activities, cardio- and neuroprotective, hepatoprotective effects. The aim of this study was to determine and understand the mode of action of oleuropein, the cell death mechanisms caused by oleuropein in L.tropica promastigotes. In this study, the phenolic and flavonoid content of oleuropein was determined by HPLC method. The antioxidant capacity and the amount of oleuropein were determined. Afterwards, morphological and physiological (mitochondrial membrane potential, formation of reactive oxygen species, Annexin V binding) changes triggered by oleuropein in L.tropica promastigotes were investigated using flow cytometry. Our studies revealed that apoptotic properties such as mitochondrial dysfunction, production of reactive oxygen species, flip-flop action of phosphatidylserine could induce cell death in L.tropica promastigotes. It has been observed that oleuropein induced typical apoptotic morphological features in L.tropica promastigotes. Total phenolic content and total flavonoid content values of oleuropein extract were determined as 33 mg/g and 229 mg/g. The radical removal method was used to investigate the antioxidant capacity of methanol extracts against free radicals. Total antioxidant content of oleuropein extract was determined as 87%. In addition, the amount of oleuropein in the oleuropein extract was determined as 21. 1% by HPLC. The oleuropein dose that killed 50% of L.tropica promastigotes, that is the IC50 value, was detected as 46.6 µg/mL after 24 hours. It was observed that the parasites in the control group preserved their typical morphological features with a single nucleus, flagella, kinetoplast and narrow cell body at both 24 and 48 hours. It was observed that as oleuropein concentrations increased, the and kinetoplasts of L.tropica promastigotes could not be distinguished from each other, they moved away from the narrow cell body structure, they lost their flagella and turned into a round form, and they moved away from the typical form of the parasite. The percentage of Annexin V+ apoptotic cells was found to be 2.9 ± 0.4% in the untreated control group, and 38.1 ± 6.9% in the oleuropein-treated group. Polarization in the mitochondrial membrane of healthy promastigotes caused an approximately 1.7-fold change in the direction of depolarization in oleuropein-treated promastigotes. According to these findings, oleuropein triggered mitochondria-related death in L.tropica promastigotes. Moreover, 1.4 ± 0.2 fold increase in reactive oxygen species production was detected in oleuropein-treated promastigotes compared to the untreated control group. Comparisons between groups were made using the independent sample t test method. In conclusion, phenolic compounds of olive leaf extract oleuropein induced apoptotic cell death in L.tropica promastigotes. Our results support that olive products such as oleuropein may have anti-parasitic effects.

A non-targeted metabolomics study on Xylella fastidiosa infected olive plants grown under controlled conditions

In the last decade, the bacterial pathogen Xylella fastidiosa has devastated olive trees throughout Apulia region (Southern Italy) in the form of the disease called “Olive Quick Decline Syndrome” (OQDS). This study describes changes in the metabolic profile due to the infection by X. fastidiosa subsp. pauca ST53 in artificially inoculated young olive plants of the susceptible variety Cellina di Nardò. The test plants, grown in a thermo-conditioned greenhouse, were also co-inoculated with some xylem-inhabiting fungi known to largely occur in OQDS-affected trees, in order to partially reproduce field conditions in terms of biotic stress. The investigations were performed by combining NMR spectroscopy and MS spectrometry with a non-targeted approach for the analysis of leaf extracts. Statistical analysis revealed that Xylella-infected plants were characterized by higher amounts of malic acid, formic acid, mannitol, and sucrose than in Xylella-non-infected ones, whereas it revealed slightly lower amounts of oleuropein. Attention was paid to mannitol which may play a central role in sustaining the survival of the olive tree against bacterial infection. This study contributes to describe a set of metabolites playing a possible role as markers in the infections by X. fastidiosa in olive.

Evaluation of the phenolic antioxidants of olive (Olea europaea) leaf extract obtained by a green approach: Use of reduced graphene oxide for electrochemical analysis

Deep Eutectic Liquids (DELs) have been specially designed, and used for the extraction of bioactive natural products from a bio-waste, since they have attracted much attention from economic and ecological aspects. In this study, an easy, accurate and sensitive detection method has been developed towards a trace amount of oleuropein which is one of the most significant components of the olive leaf extract. TiOx-modified reduced graphene oxide electrode (TiOx-RGO@GCE) has been used as the sensing electrode for the quantitative detection of oleuropein. The structural characterization of TiOx-RGO@GCE has been performed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and atomic force microscopy (AFM) techniques. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques have been implemented to investigate the electrochemical behavior of oleuropein. The electrochemical experiments revealed that the quasi-reversible reaction is the dominant mechanism on the electrode/electrolyte interface. The linear concentration range of 1–12 µM was obtained with the detection limit of 18.7 nM for oleuropein.

Identification of Predominant Phytochemical Compounds and Cytotoxic Activity of Wild Olive Leaves (Olea europaea L. ssp. sylvestris) Harvested in South Portugal.

This study has been aimed at providing a qualitative and quantitative evaluation of selected phytochemicals such as phenolic acids, flavonoids, oleuropein, fatty acids profile, and volatile oil compounds, present in wild olive leaves harvested in Portugal, as well as at determining their antioxidant and cytotoxic potential against human melanoma HTB-140 and WM793, prostate cancer DU-145 and PC-3, hepatocellular carcinoma Hep G2 cell lines, as well as normal human skin fibroblasts BJ and prostate epithelial cells PNT2. Gallic, protocatechuic, p-hydroxybenzoic, vanillic acids, apigenin 7-O-glucoside, luteolin 7-O-glucoside, and rutin were identified in olive leaves. The amount of oleuropein was equal to 22.64 g/kg dry weight. (E)-Anethole (32.35%), fenchone (11.89%), and (Z)-3-nonen-1-ol (8%) were found to be the main constituents of the oil volatile fraction, whereas palmitic, oleic, and alpha-linolenic acid were determined to be dominating fatty acids. Olive leaves methanol extract was observed to exerted a significant, selective cytotoxic effect on DU-145 and PC-3 cell lines. Except the essential oil composition, evaluated wild olive leaves, with regard to their quantitative and qualitative composition, do not substantially differ from the leaves of other cultivars grown for industrial purposes and they reveal considerable antioxidant and cytotoxic properties. Thus, the wild species may prove to be suitable for use in traditional medicine as cancer chemoprevention.

A study of the effects of cultivation variety, collection time, and climate on the amount of oleuropein in olive leaves

Summary Effects of cultivation variety, collection time, and climate on amounts of oleuropein (OE), a strong antioxidant, in olive leaves were studied. A modified ultrasound-assisted method was used for efficient and quantitative extraction of OE from olive leaf samples before their analysis by a rapid HPLC method. Under the optimized conditions, the extraction was performed in two successive steps with an RSD better than 2.95% (n = 5) and a detection limit of 0.02 μg OE. The amount of OE was determined in twelve samples of olive leaves from Mary Zeitoon, Koroneiki, and Sevillana varieties cultivated in three different regions of Iran after collection in two different seasons. The results confirmed that the amounts of OE varied in different olive varieties with mean values of 127, 115, and 144 μg g−1, respectively, although statistical tests indicated a significant interaction of collection time and climate with olive variety. In general, the OE concentration was significantly higher in the cold season an...

Assessment of susceptibility of olive cultivars to the Bactrocera oleae (Gmelin, 1790) and Camarosporium dalmaticum (Thüm.) Zachos & Tzav.-Klon. attacks in Calabria (Southern Italy)

Within the framework of research concerning the application of techniques alternative to chemical pesticides for control of parasites, the C.R.A. Experimental Institute for Olive Growing for many years has been performing a large investigation in order to detect sources of genetic resistance in olive germplasm. In the present study we observed the behavior related to the olive fly (Bactrocera oleae) infestation and Camarosporium dalmaticum infection of ten olive cultivars farmed under the same agronomic and climatic conditions in Calabria, Southern Italy. The sampling and the data collecting were carried out in three different ripening times.The drupe amount of oleuropein and cyanidine was detected by laboratory analyses in order to verify a possible correlation between these molecules and the level of infestation/infection of the above-mentioned parasites. The obtained data were submitted to analysis of variance. In relation to the fungal infection the results displayed that cvs Tonda nera dolce showed the lowest susceptibility, while the cv Giarraffa turned out to be the most susceptible. The less susceptible cultivars to the phytophagous were Tonda nera dolce and Bhardi Tirana. Since the less susceptible cultivar to olive fly attacks are the same observed in relation to the susceptibility to olive fruit rot, it is suggested a relation between the olive fly infestation and the fungal infection. It suggests the utility to achieve these results both to transfer directly to the farmers' world and to emphasize ecosystem health and biodiversity conservation.

Factors Affecting the Contents of Iridoid Oleuropein in Olive Leaves (Olea europaea L.)

In this study, for the first time, the impact of the genetic factor on the contents of oleuropein in olive leaves was not only evaluated but the influence exerted by the color/age of leaves (green, green-yellowish, and yellow) and the collecting period (spring or autumn) was also evaluated. A repetitive high-resolution gas chromatographic quantitation method and an accurate high-performance liquid chromatographic method were developed. These analytical methods gave results showing a highly linear relationship. Samples of olive leaves were taken from seven major Italian olive cultivars, such as Dritta, Leccino, Caroleo, Coratina, Castiglionese, Nebbio, and Grossa di Cassano. Such a vegetal raw material could actually be exploited for recovering oleuropein, considered to be a high-added value molecule. This could be converted into hydrxytyrosol, a compound known to possess strong bioactive properties. Olive leaves showed considerable contents of oleuropein, which with some cultivars were even higher with respect to those present in the corresponding olive fruits (reported in the literature). The amounts of oleuropein in the collected leaves were markedly modified by the color/age and genetic factors, whereas meaningless variations were ascribable to the quantitation method and the collecting period factors. Various chemometrics, applied to the obtained analytical data, appeared to be effective in discriminating the samples on the basis of the above-examined experimental factors, thus confirming how these should be taken into account in future industrial recovery of oleuropein from olive leaves.