Extraction Of Oleuropein Research Articles

Polyvinylimidazole-Based Cryogel as an Efficient Tool for the Capture and Release of Oleuropein in Aqueous Media.

A polyvinylimidazole-based cryogel is presented as a pioneering solution for efficient extraction and release of partially water-soluble polyphenols from olive byproducts. Specifically, oleuropein was used as model molecule to evaluate its recovery from water. The material merges the properties of interconnected cryogel structure in adsorbing molecules via fast diffusion flux, with the strong electrostatic interactions acted by imidazole moiety. Such cryogel achieves effective oleuropein binding likely through hydrogen bonding and π-π interactions. Comprehensive assessments of static adsorption kinetics, isotherms, and desorption kinetics underscore the cryogel's efficacy in oleuropein extraction and release, highlighting its pivotal role in valorizing olive wastewater through sustainable biotechnological applications.

A Comparative Study of Oleuropein Extraction from Wild Olive Leaves (Olea europea subsp. oleaster, Hoffmanns. & Link), Its Gastrointestinal Stability, and Biological Potential

Olive leaves are the richest source of phenolic compounds, particularly oleuropein, which has many beneficial effects on human health. This study compares the effect of three extraction techniques: ultrasonic-solvent extraction, microwave-assisted extraction, and supercritical CO2 extraction of freeze-dried wild olive leaves (Olea europea subps. oleaster, Hoffmanns. & Link) on oleuropein concentration in obtained extracts. The extract with the highest concentration of oleuropein was obtained after low-frequency ultrasound solvent extraction (WOLE-S) (71.97 µg/mL). Oleuropein from that extract showed low stability after simulated gastric digestion with human gastric juices (35.66%) and high stability after 60 min of intestinal phase (65.97%). The highest antiproliferative activity of WOLE-S and pure oleuropein was detected against T24 cancer cells. The antiproliferative activity of WOLE-S against MD-MBA-123, A549, and A1235 cells was moderate, while the activity of oleuropein was high. WOLE-S significantly down-regulated the expression of IL-6 in A549 cells, indicating a possible anti-inflammatory effect in lung cancer cells. The expression of IL-8 was slightly reduced by treating the cells with WOLE-S, while the expression of IL-10 was not altered by the treatment with WOLE-S or oleuropein.

Effect of electric field on mass transfer during oleuropein extraction

The use of alternative extraction methods has increased since conventional methods have disadvantages like long processing time and limited extraction yield. It is known that the extraction yield is enhanced, and the processing time is shortened by the electric field. However, the mathematical characterization of the electrically assisted processes is needed for a better understanding and the improvement of extraction. In this study, effects of the moderate electric field extraction (MEF-E) parameters (frequencies of 1, 1000, and 2000 Hz, and wave types of sine and square) on yield, cell disintegration index (Zc), microstructure, and mass transfer coefficient (Deff) were investigated to examine mass transfer characteristics of the extraction of oleuropein from olive leaves. Correlation analysis was performed to investigate the relations between yield, Zc, Deff, and the changes in the cross section areas of palisade cells. The frequency and wave significantly affected yield, Zc, microstructural changes, and Deff values (p < 0.05). Additionally, the Zc value showed a good correlation with yield, microstructure, and Deff in both sine and square waves (p < 0.05). It was concluded that the extraction level and microstructural changes could be controlled by Zc during the MEF-E process. Two different finite element models (model 1: fixed Deff and model 2: Deff depending on the Zc) were used for mass transfer, and model 2 gave better predictions (p < 0.05). Thus, it will be possible to characterize and monitor oleuropein transfer depending on the effects of frequency and wave type applications during the MEF process. The model consisting of the Zc–Deff relationship showed that the use of Zc would be preferred for the characterization of mass transfer rather than calculating the Deff value. It is thought that the effects of electric field parameters on microstructure with the developed models will be determined and successfully characterized, thus contributing to the understanding of the effects of electric field extraction processes on mass transfer. However, it is recommended that similar studies are conducted for other plants in order to develop a valid approach on the extraction process from plants.

A comparative assessment for efficient oleuropein extraction from olive leaf (Olea europaea L. folium)

Since oleuropein has long been known in the health sector and is abundant directly in our country as the fourth largest olive producer, oleuropein, the predominant phenolic ingredient in olive leaves, was recovered in this study using Soxhlet extraction. The effects of different solvent types (acetonitrile, ethanol, methanol, and water), extraction period (4 cycles, 4 h, and 8 h), particle size (250-500 µm and 900-2000 µm), and pretreatment of olive leaves on the yield of oleuropein were examined to determine the maximum yield. A greater oleuropein yield was obtained when the particle size of olive leaves utilized for extraction was lowered. Furthermore, aqueous solvents revealed a higher yield of oleuropein than pure solvents and prolonging the extraction duration resulted in a significant increase in the amount of oleuropein extracted. On the other hand, pretreatment of olive leaves resulted in a reduction in oleuropein output. As a result, with 36% extraction efficiency in terms of olive leaf conversion, the highest oleuropein extraction yield was obtained as 13.35 mg g-1 dry leaf for 8 h of extraction time using olive leaves with a particle size of 250-500 µm and an 80% methanol solution as solvent.

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.

Antibacterial Finishing of Cotton Bed Sheets using Olive Leaves Extract

The main goal of this project consisted of the conceptualization and development of a product related to the olive tree chemical features to monetize the wastes of the olive fruit exploitation. The most abundant by-product of the olive fruit harvest is the olive leaves, used as the raw material in this project. By following the steps of Chemical Product Design, it was decided to pursue the idea of creating antibacterial cotton bed sheets impregnated with olive leaves extract, mainly composed of oleuropein. The production process includes a pre-treatment of the olive leaves, oleuropein extraction, and supercritical impregnation. The estimated amount of leaves required is 39 g/m2 of cotton, considering a cotton fabric with 115 GSM.

Integration of solvent extraction and membrane processes to produce an oleuropein extract from olive leaves

The integration of solvent extraction and membrane separation technology was used to recover and concentrate oleuropein from olive leaves. In this study, the effect of extraction solvent (type, composition) on the content of total phenolic compounds (TPC) extracted from olive leaves was investigated. Experimental results showed that ethanol:water, 75 %/25 % (v/v), gives the highest TPC. Thus, to establish the parameters to obtain hydroethanolic olive leaves extract with the highest content of total phenolic compounds, a Central Composite Design was performed. The extract obtained at 50 °C for 90 min, within 0.03 g/ml, was subjected to crossflow ultrafiltration (UF) to remove suspended solids in the feed and to reduce fouling phenomena, followed by a stirred dead-end nanofiltration (NF) using a commercial flat sheet membrane at different pressure (10, 20 and 30 bar). The nanofiltration (at 30 bar) showed a high rejection coefficient towards phenolic compounds and flavonoid contents. Fractions coming from UF and NF (at 30 bar) revealed that the highest content of oleuropein was 119.01 mg/g corresponding to NF retentate, high antioxidant capacity (DPPH method). Conductivity, sanity, turbidity, pH, TDS, and TSS of different fractions were also determined. It can be concluded that the integration of solvent extraction and membrane separation technology is efficient for the recovery and concentration of oleuropein and phenolic compounds from olive leaves. The obtained concentrate is of interest for preparing formulations to be used in the food, cosmetic and pharmaceutical industries.

Effect of Oleuropein Extract from Olive on Brain Oxidative Stress in Ovariectomized Diabetic Rats

Effect of Oleuropein Extract from Olive on Brain Oxidative Stress in Ovariectomized Diabetic Rats

Frequency and wave type effects on extractability of oleuropein from olive leaves by moderate electric field assisted extraction

The moderate electrical field (MEF) process was used to reduce the process time (t) of oleuropein extraction from olive leaves. MEF process was performed with methanol-water (4:1 v/v) with sine wave-SN and square wave-SQ at 30 V/cm with different frequencies (1, 1000, and 2000 Hz). The conventional extraction (CE) method was performed for 8 h in methanol-water (4:1 v/v) mixture at 40 °C. The effects of MEF conditions on t, effective electrical conductivity (EEC), cell disintegration (Zc) and extraction performance coefficient (EPC) were determined. SN provided desired extraction yield in a shorter time than SQ (p < 0.05). The necessary extraction time for target extraction yield (21.6 ± 1.0 mg Oleuropein/g dm) increased as the frequency decreased (p < 0.05). SN resulted in higher Zc values compared to SQ (p < 0.05). EPC of MEF was higher than CE (p < 0.05). It is concluded extractability of the oleuropein at any given extraction time could be improved by MEF compared to CE.

Preparation of highly purified oleuropein by combinative technology off line of HSCCC-PHPLC based on dual wavelength.

Oleuropein is the main active substance in foods or functional foods produced from olive (Olea europaea L.) leaves. In the present study, the combinative technology off line of HSCCC-PHPLC based on dual wavelength was used to separate highly purified oleuropein from oleuropein extract. Response surface methodology was used to optimize the conditions of HSCCC. Furthermore, a large amount of higher purified oleuropein was obtained through HSCCC at the wavelength of 254 nm, and oleuropein with the purity greater than 98.5% was obtained by PHPLC at the wavelength of 300 nm. Finally, the purity and structure identification of highly purified oleuropein were determined by various methods and its stability was investigated. As a result, oleuropein was stable in solution, and had good stability under the condition of dark storage at 4°C within a week or under the condition of dark storage at -20°C within one year. PRACTICAL APPLICATION: In this study, an efficient method for purification and refining of oleuropein by combinative technology off line of HSCCC-PHPLC based on dual wavelength was established. Oleuropein with the purity greater than 98.5% was macro-obtained via the technology. The highly purified oleuropein could be used to control the quality of olive products.

Supplementation Effect of Oleuropein Extract Combined with Betaine, Magnesium, and Vitamin E on Pigs' Performance and Meat Quality Characteristics.

Simple SummaryOleuropein, betaine, magnesium, and vitamin E show antioxidant and/or metabolic effects on the organism that are reflected, in many cases, in performances and meat quality. This study evaluated whether the combination of these nutrients at two doses manifest different effects on the final product. Both combinations were enough to improve the oxidative status of pigs, although performances were not affected. However, the higher doses increased n-6 and n-3 PUFA in the triglycerides and free fatty acid fractions that resulted in meat that was more susceptible to oxidation.This study evaluates the effect of the dietary combination of oleuropein extract (1200 mg/kg) and betaine (1000 mg/kg), magnesium oxide (600 mg/kg), and α–tocopheryl acetate (400 mg/kg), or a half-dose of these compounds, on pigs’ performance, oxidative status, and meat quality characteristics (drip loss, TBARS, and texture and fatty acid profile of intramuscular fat). Sixty-six barrows and females were slaughtered at 120 kg of BW. Performance and carcass yield were not changed by treatments. The high-dose mixture resulted in higher serum ferric reducing/antioxidant power (p = 0.0026), lower glucose (p = 0.03) and a tendency to have lower serum TBARS (p = 0.07) when compared to control. Percentage of drip loss, moisture content, intramuscular fat, or texture parameters were not modified by dietary treatments. Pigs supplemented with the high-dose mixture had higher PUFA (p = 0.0001), n-6 (p = 0.0001), n-3 (p = 0.0095) and lower MUFA (p = 0.0064) in the neutral lipid fraction of intramuscular fat. Free PUFA, mainly n-3 fatty acids (p = 0.0009), were also higher in the meat of pigs fed the high-dose mixture compared with the others. A higher mobilization (neutral to free fatty acids hydrolysis) of n-3 and MUFA fatty acids in the muscle from pigs fed the high-dose mixture was observed. However, dietary mixture supplementation tended to increase MUFA (p = 0.056) and decrease the total PUFA (p = 0.0074) proportions in muscle polar lipids. This specific fatty acid composition of meat from pigs supplemented with the high-dose mixture could be responsible for the higher meat lipid oxidation observed in this group when compared to the other groups. Consequently, the low-dose mixture would be more adequate for maintaining the oxidative status of pigs and, meat lipid stability.

Extraction of oleuropein from olive leaves and applicability in foods

Oleuropein is a phenolic compound found in all parts of the olive tree (Olea europaea L.), although at higher levels in the leaves. The health benefits associated with the consumption of oleuropein include the prevention of cardiac diseases, improvement in lipid metabolism, and decrease in obesity-related disturbs, among others. In addition, several studies have shown that oleuropein presents antimicrobial, antioxidant, and inflammatory properties. The scientific interest in the methods for the extraction of oleuropein from olive leaves has markedly increased in recent years, aiming to extend its application in foods, cosmetics, and drugs. In this review, the extraction procedures available in the literature are described according to their advantages and disadvantages that directly affect the extraction yield. The applicability of oleuropein in food products is also discussed.

Dietary oleuropein extract supplementation and its combination with α-tocopheryl acetate and selenium modifies the free fatty acid profile of pork and improves its stability.

Olive-derived antioxidants have been shown to affect the oxidative status of meat and have also been associated with greater consumption of glucose, which might affect glycogen stores and muscle characteristics. This study evaluated the effect of oleuropein extract supplementation (OLE) versus vitamin E + Se (VE), and their combination (VEOLE), in pig diets, on pH, drip loss, the proportion of free fatty acids, and meat stability, and their prediction by blood oxidative status markers. The drip loss of muscle was lower in antioxidant-supplemented groups when compared with controls. α-Tocopherol concentration and total fatty acids profile were not affected by dietary oleuropein supplementation. However, OLE and VEOLE had lower free n-3 polyunsaturated fatty acid (PUFA) levels when compared with VE and tended to have higher free monounsaturated fatty acid (MUFA) levels. Furthermore, the VEOLE group had lower free n-6 PUFA levels when compared with controls or VE, whereas the OLE group had intermediated values. Muscle samples from pigs subjected to the antioxidant-mixed supplementation (VEOLE) had lower malondialdehyde concentration when compared with the others. The VE and OLE groups showed intermediate malondialdehyde values. Chilled meat stability was highly correlated with antioxidant status in vivo. The administration of 96 mg oleuropein kg-1 feed produced similar meat quality characteristics as the use of 100 mg kg-1 α-tocopheryl acetate +0.26 mg kg-1 sodium selenite and it would be an interesting alternative in Mediterranean countries. The VEOLE group was the most effective for reducing lipid oxidation and for the production of polyunsaturated free fatty acids in meat, which would result in lower rancidity formation and better aroma development in products. © 2020 Society of Chemical Industry.

Abstract 1872: Oleuropein reduces Prdx1 expression, cell proliferation and viability in K562 human leukemia cells

Abstract Oleuropein is one of the two main phenolic compounds derived from olive leaves. Numerous studies have found that the polyphenols contained in olive leaves possess strong antioxidant properties, and increase apoptosis in many types of cancer cells, suggesting its possible efficacy as an anti-cancer treatments. The purpose of our study was to examine the effects of oleuropein extract on cell growth and viability of the K562 human leukemia cell line, and to investigate possible molecular mechanisms of action. Oleuropein of 98% purity was used for our studies. We first demonstrated that K562 cells treated with 200 and 400 μg/ml oleuropein exhibited a significant reduction in cell growth and viability after four days as compared to ethanol-treated controls. Cells treated with 200μg/ml oleuropein showed decreased cell proliferation and viability after two days, and exhibited approximately 90% reduction in cell density and viability after four days of treatment. A concentration of 400 μg/ml oleuropein resulted in 100% toxicity by day four. We also examined the effects of oleuropein on cellular cytotoxicity using an LDH release assay and found a two-fold elevation in LDH release within 24 hours of treatment with 200 μg/mL oleuropein. To begin to explore a mechanisms of action, we used western blotting to examine known antioxidant and signaling pathways for possible regulation by oleuropein in these cells. We examined expression of the Peroxiredoxin (Prdx) family of proteins, a group of thiol-specific antioxidants found to be elevated in many types of cancer. We found that 200 ug/ml oleuropein reduced Prdx1 expression by about 50% after eight and twenty-four hours, while having no significant effect on expression levels of Prdx-2, -3, -4, and -6. We are currently investigating the mechanism of cell death induced by oleuropein, as well as the role of Prdx1 in oleuropein-induced toxicity. Together with previously reported cancer-cell specific effects, this research provides a promising new avenue for the use of natural products as anti-cancer agents. Citation Format: Natalie Fulco, Sophia Fagan, Shelley A. Phelan. Oleuropein reduces Prdx1 expression, cell proliferation and viability in K562 human leukemia cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1872.

Optimization of Oleuropein and Luteolin-7-O-Glucoside Extraction from Olive Leaves by Ultrasound-Assisted Technology

The olive orchard cultivation in Mediterranean countries results in huge amounts of lignocellulosic biomass residues. One of the main residues are olive leaves. Olive leaves contain high concentrations of bioactive antioxidant compounds like oleuropein and luteolin-7-glucoside. The production of biactive compounds from olive leaves requires treatments capable of breaking the lignocellulosic structure. Current research focuses on use of inexpensive, quick, and not harmful to the environment treatments, searching a more simplified large-scale operation approach. Recently, advances in applied chemistry have led to possible new emerging industrial techniques like ultrasound-assisted extraction (UAE). This technology is a promising candidate as a green treatment solution for olive leaves utilization in a biorefinery. However, this application goes through prior optimization of technique and operating conditions. The goal of this study was to optimize the extraction of oleuropein and luteolin-7-glucoside from olive leaves through an investigation of the influence of key factors of ultrasound-assisted extraction using an experimental central composite design, in comparison with conventional Soxhlet extraction. The highest extraction efficiency and antioxidant capacity were obtained under optimal increment of temperature and amplitude conditions (40 °C and 30%, respectively). Values for oleuropein, luteolin-7-glucoside were 69.91 g/kg and 1.82 g/kg, respectively.

Green alcoholic solvent and UAE extraction of oleuropein from the Olea europaea L.leaves: Experimental design, optimization, and comparison with Pharmacopoeia method

ABSTRACT Solvent extraction and UAE were studied for the extraction of the polyphenolic compounds from the olive leaf in MeOH/H2O and EtOH/H2O solvent systems. Box Wilson-CCRD design was used under RSM for the experimental design of alcoholic solvent extraction. Multi-response optimization was solved with the help of pareto areas and optimal input variable values were determined by the desirability function, optimization by fuzzy similar precedable ratio method. It is seen that the developed solvent extraction methods are more advantageous to the European Pharmacopoeia method for especially oleuropein and the other phenolics which have synergetic effect in olive leaf extract.

Extraction of oleuropein and luteolin-7-O-glucoside from olive leaves: Optimization of technique and operating conditions

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Oleuropein reduces Prdx1 expression, cell proliferation and viability in K562 human leukemia cells

Oleuropein is one of the two main phenolic compounds derived from olive leaves. Numerous studies have found that the polyphenols contained in olive leaves possess strong antioxidant properties, and increase apoptosis in many types of cancer cells, suggesting its possible efficacy as an anti‐cancer treatments. The purpose of our study was to examine the effects of oleuropein extract on cell growth and viability of the K562 human leukemia cell line, and to investigate possible molecular mechanisms of action. Oleuropein of 98% purity was used for our studies. We first demonstrated that K562 cells treated with 200 and 400 μg/ml oleuropein exhibited a significant reduction in cell growth and viability after four days as compared to ethanol‐treated controls. Cells treated with 200μg/ml oleuropein showed decreased cell proliferation and viability after two days, and exhibited approximately 90% reduction in cell density and viability after four days of treatment. A concentration of 400 μg/ml oleuropein resulted in 100% toxicity by day four. We also examined the effects of oleuropein on cellular cytotoxicity using an LDH release assay and found a two‐fold elevation in LDH release within 24 hours of treatment with 200 μg/mL oleuropein. To begin to explore a mechanisms of action, we used western blotting to examine known antioxidant and signaling pathways for possible regulation by oleuropein in these cells. We examined expression of the Peroxiredoxin (Prdx) family of proteins, a group of thiol‐specific antioxidants found to be elevated in many types of cancer. We found that 200 ug/ml oleuropein reduced Prdx1 expression by about 50% after eight and twenty‐four hours, while having no significant effect on expression levels of Prdx‐2, ‐3, ‐4, and ‐6. We are currently investigating the mechanism of cell death induced by oleuropein, as well as the role of Prdx1 in oleuropein‐induced toxicity. Together with previously reported cancer‐cell specific effects, this research provides a promising new avenue for the use of natural products as anti‐cancer agents.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Pretreatment and optimization of processing conditions for extraction of oleuropein from olive leaves using central composite design

Background: The extraction methods used for isolation of biomolecule from Olive leaves show risk of residual solvent and less extraction efficiency. Hence, there is a need to develop novel techniques to encapsulate the risks headed with extraction process. Objective: The goal was to unravel the effect of novel extraction techniques on the extraction efficiency of Oleuropein from Olea europaea, a major secoiridoid resided in Olive leaf. Materials and Methods: Olive leaves were collected, authenticated, and subjected to proximate, phytochemical analysis to contemplate the source of active moiety. The precised solvent, i.e., water: glycerol (3:1%v/v) was functionalized to depict the influence of independent variable on response using central composite design. For hot blanching, the independent factors selected were treatment temperature (50°C–70°C) and duration of blanching (10–30 min) whereas the observed response is percentage extraction efficiency of Oleuropein. The hot blanched leaves were subjected to extraction by cold maceration, microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE). The content of Oleuropein was analyzed by high-performance thin-layer liquid chromatography. Results: From the design space, the model is stable at a range of 0.002–0.80 which indicates lack of fit is very less and more curvature effects are clearly visualized with P = 5% level of significance. Maximum response was attained at a temperature of 60°C–65°C and duration of 15–20 min. Microstructural changes in leaf were observed through scanning electron microscopy studies. From the study, pretreated leaves followed by UAE result in higher yield of Oleuropein compared to MAE and maceration. Conclusion: Hot blanching technique shows a significant linear upswing in the concentration of Oleuropein when compared to direct extraction techniques. Blanching of Olive leaves causes deactivation of enzymes, and further exposure to ultrasonic waves enhances mass transfer of solvent and promotes the release of Oleuropein.

Abstract 4388: Anti-cancer effects of oleuropein olive leaf extract in K562 leukemia cells

Abstract Olive leaves come from a Mediterranean plant that many believe to have positive effects on human health, including anti-cancer properties. Oleuropein is one of the two main phenolic compounds derived from olive leaves, and it has been shown to increase apoptosis in many types of cancer cells. Numerous studies have found that the polyphenols contained in olive leaves possess strong antioxidant properties, suggesting that the compound could be effective in anti-cancer treatments. The purpose of this study was to examine the effects of oleuropein extract on cell growth and viability in K562 human leukemia cells, and begin to investigate possible molecular mechanisms of action. We purified our own extract from olive leaves for these studies. Oleuropein was microwave extracted from olive leaf powder using methanol and water as solvent. The oleuropein was successfully identified using HPLC to characterize elution time in comparison to an authentic standard. HPLC was then used in purification and fractions were lyophilized. Isolated oleuropein was greater than 94% in comparison to the authentic standard. We next demonstrated that K562 cells treated with 50-150 ug/ml of oleuropein exhibited significant reduction in cell growth and cell viability after four days when compared to 70% ethanol-treated controls. This effect was markedly greater after 6 days . Current studies are being conducted to determine the most effective concentration and duration of treatment for oleuropein-induced cell death. We are also examining cellular cyytotoxicity and cell cycle progression in these experiments using LDH assay and cell cycle staging, and further studies are being conducted to examine inflammatory and antioxidant pathways for their involvement in the anti-cancer effect of the compound in these cells. Given the observation that many of the cytotoxic effects of oleuropein are cancer-cell specific, this research provides a promising new avenue for the use of natural products as anti-cancer agents. Citation Format: Sophia Fagan, Natalie Fulco, Justin Gilbertson, Aaron R. Van Dyke, Shelley A. Phelan. Anti-cancer effects of oleuropein olive leaf extract in K562 leukemia cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4388.