Phenolic content, antioxidant and anti-inflammatory activities of some Algerian olive stone extracts obtained by conventional solvent and microwave-assisted extractions under optimized conditions

Abstract

The recovery of food waste is a stimulating opportunity for and competitive development of agroindustries. In this context, the objective of this study was to report the antioxidant potential and phenolic compounds content of olive stones (OS) of six Algerian cultivars. Two extraction methods were used: microwave assisted extraction (MAE) and conventional solvent extraction (CSE) in order to improve the recovery of total phenolic content (TPC) and the maximization of the two extraction processes by the Box-Behnken design (BBD) from olive stone of Olea Europaea L. cv Ayemele. The optimal processing parameters obtained were (i) for MAE: 22% (v/v) ethanol, 40 s, 500 W, and ratio 65:1 (mL/g) and (ii) for CSE: 33% (v/v) ethanol, 24 min, 71 °C, and ratio 60:1 (mL/g). Phenolic compounds were then extracted from olive stones of six Algerian cultivars with MAE best extraction conditions, as it was the best strategy in term of TPC recovery. The phenolic content was different according to the olive variety. The stones of Chemlale were the richest in TPC (7.23 mg GAE/g) followed by Azeboudj (6.33 mg GAE/g), Atefah (6.04 mg GAE/g), Agraraz (5.63 mg GAE/g), Azeradj (5.35 mg GAE/g) and Ayemel (5.14 mg GAE/g). A similar profile was observed with total flavonoids content and antioxidant activities. The anti-inflammatory effects of the optimized extracts by MAE were assessed regarding their ability to prevent lipopolysaccharide-induced of reactive oxygen species and nitric oxide production in a macrophage cell line (RAW 264.7). Olive stones that are issued from the production of olive oil, and table olives can therefore be considered as renewable by-products thanks to their compounds with high added value. These bioactive compounds can target the food natural additives markets, pharmaceutical and cosmetic industries, all of which are currently very receptive such natural products.

Compostos bioativos presentes no azeite de oliva e seus subprodutos: revisão bibliográfica

“…Porém, a forma de extração dos compostos bioativos influencia muito na sua preservação, potencializando ou não seus principais atributos (Tabela 2). Por exemplo, a extração de compostos fenólicos do caroço de azeitona extraído por micro-ondas, de seis cultivares da Argélia, mostrou-se como melhor estratégia em termos de recuperação do conteúdo fenólico total quando comparado com método convencional (Djemaa-Landri et al, 2021).…”

“…Esses compostos bioativos, dos azeites e de seus subprodutos, tem abrangido tanto os mercados de aditivos naturais alimentares, farmacêuticos quanto as indústrias cosméticas, visto que a oliveira inclui trinta espécies diferentes no mundo, estando presente nos quatro continentes (Djemaa-Landri et al, 2021), podendo presumir-se que o crescente interesse atual em publicar artigos sobre o assunto possa ser justificado tanto pelos benefícios relacionados à saúde quanto a diversidade de cultivares, cada qual com suas características nutricionais e tecnológicas peculiares.…”

Effect of Microwave and Ultrasound-Assisted Extraction on the Phytochemical and In Vitro Biological Properties of Willow (Salix alba) Bark Aqueous and Ethanolic Extracts

“…Indeed, tannins and simple phenolic metabolites have been shown to have anti-inflammatory activity in Caco-2 cells in previous studies [52,53]. In macrophage cells (RAW 264.7), MAE improved the ability to contain lipopolysaccharide-induced reactive oxygen species and produce nitric oxide in Algerian olive stone extracts [54]. Overall, SA-ME treatment had a significantly lower (ρ < 0.05) permeability when compared with all other treatments (SA-C, SA-MA, SA-UE, and SA-UA) regarding the FD flux (Figure 4b).…”

Microwave-assisted extraction optimization and conventional extraction of phenolic compounds from coriander leaves: UHPLC characterization and antioxidant activity

“…It should be noted that previous works, also indicated the same results for each of the optimal conditions found in the present study, as the best for the extraction of bioactive constituents from their vegetal matrices. In particular, a solvent concentration of 50% 14,20,51 , a microwave power of 400 W [52][53][54] , an optimal irradiation time of about 2 minutes 9,51 , and a ratio close to 75 mL 6,8 .…”

“…These techniques usually require a long extraction time, which introduces the risk of thermal degradation of thermolabile active compounds 7 . In turn, in recent years, many new extraction procedures have been instigated and explored, such as microwave-assisted extraction, ultrasound-assisted extraction, pressurized liquid extraction, and pressurized hot water extraction 8 . Among these modern extraction methods, MAE was classed as one of the leading methods in terms of time efficiency, higher level of automation, quantity, and non-destruction of the extracts obtained 9 .…”