Titre :	Phytochemical valorization of some date palm cultivars from Ain Saleh
Type de document :	texte manuscrit
Auteurs :	Soumia Hachani, Auteur ; Mohamed Yousfi, Directeur de thèse ; Chahrazed Hamia, Directeur de thèse
Editeur :	Laghouat : Université Amar Telidji - Département des sciences de la matière
Année de publication :	2019
Importance :	171 p.
Format :	30 cm.
Note générale :	Option : Molecular Chemistry
Langues :	Anglais
Catégories :	THESES :06 chimie
Mots-clés :	Antioxidant activity  Date fruit  Morphological  Physico-chemical  Phenolic compounds  Solvent  Ultrasound extraction  Response surface methodology
Résumé :	The aim of this study is to evaluate the morphological, physico-chemical characteristics and in vitro antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, Ferric reducing antioxidant power (FRAP), total antioxidant activity, Fe-chelating activity and cupric ion reducing antioxidant capacity (CUPRAC)) of six phenolic extracts of five date cultivars (Phoenix dactylifera L) growing in Algeria, and optimizing the extraction of phenolics and antioxidants activity using ultrasound extraction. First, the fruits are characterized as being economically important via their P values, weight and quality. The highest level of total phenolic and condensed tannins contents was found in 80% methanol extracts. This level ranged from 20.38-69,85 mg GAE/100 g DW and between 3.58-60.05 mg CE/100 g DW. The highest total flavonoid contents were found in acetonic extracts. The fruits exerted different antioxidant activities and they were influenced by the extraction solvent. Although they have low phenolic contents, 70% acetone extracts gave the highest antioxidant activities. Using UHPLC-DAD-ESI-MS analysis, 19 compounds were identified, most detected compounds were found in 70% acetonic extracts. Thus, 70% acetone was found to be the best solvent to run such investigation. Due to date-pathogen, infected Tinnaser date synthesized more or new polyphenols such as O-p-coumaroylshikimic acid and apigenin pentosyl hexoside. Second, the Box-Behnken design was used to investigate the effects of three independent variables: time, temperature and solvent-to-solid ratio, on the responses of total phenolics total flavonoids and both DPPH scavenging activity and CUPRAC of date fruit methanolie extracts. Response surface analysis showed that the optimal ultrasound extraction parameters that maximized the responses were 30 min, 25 °C and 74.4 mL/g. Under optimum conditions, the experimental values for the quantification of phenolic compounds and antioxidant activities are in accordance with the predicted values, indicating the suitability of the model and the success of response surface methodology in optimizing the ultrasound extraction conditions.
note de thèses :	Thèse de doctorat en chimie

Phytochemical valorization of some date palm cultivars from Ain Saleh [texte manuscrit] / Soumia Hachani, Auteur ; Mohamed Yousfi, Directeur de thèse ; Chahrazed Hamia, Directeur de thèse . - Laghouat : Université Amar Telidji - Département des sciences de la matière, 2019 . - 171 p. ; 30 cm.
Option : Molecular Chemistry
Langues : Anglais

Catégories :	THESES :06 chimie
Mots-clés :	Antioxidant activity  Date fruit  Morphological  Physico-chemical  Phenolic compounds  Solvent  Ultrasound extraction  Response surface methodology
Résumé :	The aim of this study is to evaluate the morphological, physico-chemical characteristics and in vitro antioxidant activity (2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, Ferric reducing antioxidant power (FRAP), total antioxidant activity, Fe-chelating activity and cupric ion reducing antioxidant capacity (CUPRAC)) of six phenolic extracts of five date cultivars (Phoenix dactylifera L) growing in Algeria, and optimizing the extraction of phenolics and antioxidants activity using ultrasound extraction. First, the fruits are characterized as being economically important via their P values, weight and quality. The highest level of total phenolic and condensed tannins contents was found in 80% methanol extracts. This level ranged from 20.38-69,85 mg GAE/100 g DW and between 3.58-60.05 mg CE/100 g DW. The highest total flavonoid contents were found in acetonic extracts. The fruits exerted different antioxidant activities and they were influenced by the extraction solvent. Although they have low phenolic contents, 70% acetone extracts gave the highest antioxidant activities. Using UHPLC-DAD-ESI-MS analysis, 19 compounds were identified, most detected compounds were found in 70% acetonic extracts. Thus, 70% acetone was found to be the best solvent to run such investigation. Due to date-pathogen, infected Tinnaser date synthesized more or new polyphenols such as O-p-coumaroylshikimic acid and apigenin pentosyl hexoside. Second, the Box-Behnken design was used to investigate the effects of three independent variables: time, temperature and solvent-to-solid ratio, on the responses of total phenolics total flavonoids and both DPPH scavenging activity and CUPRAC of date fruit methanolie extracts. Response surface analysis showed that the optimal ultrasound extraction parameters that maximized the responses were 30 min, 25 °C and 74.4 mL/g. Under optimum conditions, the experimental values for the quantification of phenolic compounds and antioxidant activities are in accordance with the predicted values, indicating the suitability of the model and the success of response surface methodology in optimizing the ultrasound extraction conditions.
note de thèses :	Thèse de doctorat en chimie