scholarly journals Optimizing Total Phenolic and Oleuropein of Chinese Olive (Olea europaea) Leaves for Enhancement of the Phenols Content and Antioxidant Activity

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 686
Author(s):  
Bixia Wang ◽  
Shian Shen ◽  
Jipeng Qu ◽  
Zhou Xu ◽  
Shiling Feng ◽  
...  

China, as a contrary climate to the Mediterranean-climate region, is massive in planting olive (Olea europaea) cultivation as an important oil crop. Nonetheless, Chinese olive leaves have received little attention and there is little information about the phenols content. Therefore, in this study, a multiple-response optimization was performed to maximize the total phenolic and oleuropein content (TPC and OEC) by ultrasound-assisted extraction, and the aged and young leaves prepared from six Chinese cultivars from January to December were investigated concerning seven main phenolic composition. Under optimal conditions (power 260 W, time 10 min, liquid-solid ratio 30 mL/g, and 50% ethanol), the highest TPC (197.32 mg/g DM) and OEC (74.68 mg/g DM) were obtained. Findings revealed that the optimal olive leaves for phenolic compounds were the young leaves in spring and winter, being oleuropein and luteolin-4′-O-glucoside present in higher level, and the “Koroneiki” and “Jiufeng” cultivars were relatively stable. Furthermore, antioxidant potential of the phenol extract and oleuropein was also evaluated based on the reducing power and scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH)and superoxide radical assays, and a higher antioxidant effect of oleuropein was observed compared to the phenol extract. In addition, oleuropein showed anticancer activity against HeLa cells, with a minimum inhibitory concentration (EC50) value of 0.19 mg/mL at 48 h. These findings revealed an attractive source of biological substances for further development and utilization of Chinese olive leaves.

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2513 ◽  
Author(s):  
Bixia Wang ◽  
Jipeng Qu ◽  
Siyuan Luo ◽  
Shiling Feng ◽  
Tian Li ◽  
...  

Olea europaea leaves are the major byproduct of olive farming. In this study, ultrasound-assisted extraction of flavonoids from olive leaves was optimized using response surface methodology, and the flavonoid compounds and their antioxidant and anticancer activities were investigated by high performance liquid chromatography. The results showed that the optimized conditions for achieving the maximum yield of flavonoids (74.95 mg RE/g dm) were 50 °C temperature, 270 W power, 50 min time, and 41 mL/g liquid-solid ratio. There was a significant difference in the total flavonoid content between the aged and young leaves harvested in April and July, and six main components were quantified. Among them, luteolin-4’-O-glucoside was the most predominant flavonoid compound, followed by apigenin-7-O-glucoside and rutin. Olive leaves also contained small amounts of luteolin, apigenin, and quercetin. Additionally, excellent antioxidant activity was exhibited when tested with the DPPH assay; superoxide radical-scavenging ability and reducing power was also tested. The anticancer activity of the flavonoids was assessed using HeLa cervical cancer cells, and it was observed that increasing concentrations of olive leaf flavonoids resulted in decreased cancer cell viability. These results suggest that the flavonoids from olive leaves could be used as a potential source of natural antioxidants for the pharmaceutical and food industries.


2019 ◽  
Vol 15 (6) ◽  
pp. 583-587
Author(s):  
Abderrahim Benslama ◽  
Amirouche Deghima ◽  
Nadjat Righi

Background: Ficus carica and Olea europaea are two medicinal plants which are widely distributed in Algeria, and used in food and traditional medicine. Objective: The objective of this work is the evaluation of the antioxidant capacity of different extracts of F. carica and O. europaea, for ends of flora valorization in Algeria. Methods: The dried leaves of the concerned plants Ficus carica and Olea europaea were submitted to sequential extraction with solvents of increasing polarity to give hexane, chloroform, ethyl acetate and methanolic extracts. The total phenolic and flavonoids were determined spectrophoto-metrically. The antioxidant activity of extracts was evaluated using 1,1’-Diphenyl-1-Picrylhydrazyl (DPPH) radicalscavenging and ferric reducing power test. Results: The results of the quantitative analysis show that the Methanolic Extract (ME) gives the highest yield with 16.43% and 19.98% for F. carica and O. europaea respectively. The analysis show that the highest amount of phenolic compounds was recorded in the ME of O. europaea (171.40±6.79 µg GAE/ mg E), when the the highest amount of flavonoids was recorded in the CHE of the F. carica (34.06± 0.05 µg QE/ mg E). In addition, the results show that the Ethyle Acetat Extract (EAE) exhibit the highest antiradical activity against DPPH free radical with an EC50=45.21±1.12 and 8.20±0.37 µg/ml for F. carica and O. europaea, respectively. Moreover, the EAE of the two plants present the highest reducing effect compared to other extracts at concentration of 200 µg/ml. Conclusion: The obtained results revealed the presence of a strong correlation between the antioxidant activity of the extract and its total phenolic content. Furthermore, they reported that the EAE have a considerable antioxidant capacity. This can be considered as an alternate natural source of antioxidants used generally as additives in food and pharmaceutical preparation.


2020 ◽  
Author(s):  
Cristiane Marangoni ◽  
Alexandre José Cichoski ◽  
Juliano Smanioto Barin

Foods ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 10 ◽  
Author(s):  
Djamel Djenane ◽  
Diego Gómez ◽  
Javier Yangüela ◽  
Pedro Roncalés ◽  
Agustín Ariño

Oleaster (wild olive tree) by-products represent a renewable and low-cost source of biopolyphenols. Leaf extracts (sylv.OLE) of Algerian oleaster, locally called a’hachad (Olea europaea subsp. europaea var. sylvestris), were applied at 1 and 5% (v/w) to raw Halal minced beef (HMB) in order to test its safety and shelf-life prolongation during retail/display. The total phenolic compound content in the extract was 198.7 ± 3.6 mg gallic acid equivalent. Ten compounds were identified in the sylv.OLE by High Performance Liquid Chromatography/Diode Array Detector (HPLC/DAD), of which oleuropein was the most abundant (43.25%). Samples treated with 5% sylv.OLE had significantly higher antimicrobial and antioxidant effects than those treated with 1% extract (p < 0.05). The addition of sylv.OLE reduced psychrotrophic counts as well as the level of pathogens (Salmonella enterica ser. Enteritidis and Shiga toxin-producing Escherichia coli O157:H7). A thiobarbituric acid reactive substance (TBARS) value of 2.42 ± 0.11 was reached throughout six days of retail/display in control samples, while the addition of 5% sylv.OLE reduced TBARS value by 58% (p < 0.05). The presence of sylv.OLE at the tested concentrations did not negatively influence the overall acceptability and bitterness of HMB.


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