The extraction of phenolic compounds of olive leaves : A Part from the Book Chapter : Antioxidant Properties and Protective Effect of Phenolic Extracts of Olive Leaves and Olive Mill Wastewater against Lipid Peroxidation

olive mill wastewater

A test portion of 100 ml of delipidated OMWW is mixed with 100 ml of solvent (ethanol 75%). The mixture is then stirred for 4 hours followed by evaporation to dryness of the solvent at 50°C. The obtained dry extract was stored at -20°C.

The extraction of phenolic compounds of olive leaves was based on a modified method described by Ma et al.,. Ten (10 g) grams of dried olive leaves were macerated with 100 mL of ethanol (70%). The mixture was homogenized under magnetic stirring conditions at 150 rpm for 24h at room temperature and protected from light. This mixture was filtered and subsequently dried at 50°C. The obtained dry extract was then stored at a low temperature (- 20°C).

The level of total phenolic content of olive leaves and olive mill wastewater extracts was determined using Folin-Ciocalteu reagent based on a method described by Singleton et al.,. 500 μL of each extract, at increasing concentrations ranging from 0.125 to 0.5 mg/mL, was mixed with 500 μL of Folin-ciocalteau reagent (1/10 with distilled water). After 5min incubation in the dark, 1.5 mL of 7.5% Na2CO3 was added. The resulting mixture was again incubated for 30 minutes in the dark, at room temperature. The absorbance was measured at a 760 nm wavelength. A standard curve of gallic acid was drawn with a concentration range of 3.125 x 10–3 to 5 x 10–2 mg/mL. The content of the total phenolics was expressed as mg of gallic acid equivalents per gram of dried extract (mg GAE/g of dried extract). All determinations were carried out in triplicate.

Author(s) Details:

Fatiha Abdellah

Laboratory of Research on Local Animal Products at Ibn Khaldoun University, Tiaret, Algeria.

Also See : The Most Recent Review of Pteridophyte Flora : A Part from the Book Chapter : Pteridophyte Flora of Western Ghats- A Review

Recent Global Research Developments in Beneficial Effects of Olive Oil on Human Health

Phenolic Compounds in Olive Oil:

  • Olive oil (Olea europaea) contains monounsaturated fatty acids (such as oleic acid), polyunsaturated fatty acids (like linoleic acid), and minor compounds, including phenolic compounds like hydroxytyrosol.
  • Hydroxytyrosol, in particular, has been studied for its anti-inflammatory, antioxidant, and antiproliferative properties.
  • These phenolic compounds are of interest in clinical practice, especially in the context of hematological neoplasms (both solid and blood-related cancers) [1].

Cancer-Preventive Effects:

  • Numerous epidemiological studies across diverse populations consistently highlight olive oil’s potential in mitigating cancer risk.
  • Extra virgin olive oil, rich in phenolic content, is particularly beneficial [1].

Bioavailability and Microbiota Impact:

  • Studies have also explored the bioavailability of olive oil compounds and their impact on gut microbiota.
  • Biomarkers related to olive oil intake have been described [2].

Cardiovascular and Metabolic Benefits:

  • Olive oil has protective effects against cardiovascular diseases, diabetes, metabolic syndrome, and certain cancers [3].


  1. Campo, C., Gangemi, S., Pioggia, G., & Allegra, A. (2024). Beneficial Effect of Olive Oil and Its Derivates: Focus on Hematological Neoplasm. Life, 14(5), 583.
  2. de Aguiar Sobral, P., Miyahira, R.F. & Zago, L. Health Outcomes Related to the Consumption of Olive Products: A Brief Review. Plant Foods Hum Nutr 78, 643–653 (2023).
  3. Hernáez, Á., Valussi, J., Pérez-Vega, A., Castañer, O., Fitó, M. (2019). Olive Oil and Health Effects. In: Mérillon, JM., Ramawat, K.G. (eds) Bioactive Molecules in Food. Reference Series in Phytochemistry. Springer, Cham.
  4. Boskou D, Clodoveo ML. Olive Oil: Processing Characterization, and Health Benefits. Foods. 2020; 9(11):1612.

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