Study of phenolic composition of olive fruits: validation of a simple and fast HPLC-UV method

A high-performance liquid chromatography (HPLC) method endowed with a gradient elution and a UV detection system was established and validated for the determination of phenolic acids, phenolic alcohols, hydroxycinnamic acid derivatives, flavonoids, secoiridoids and lignans during olive (Olea europaea L.) fruit development (green, purple and black olives). Within the test range, the calibration curves exposed a good linear regression (R 2>0.9995). Detection limits ranged between 0.63 and 13.43 mg/L for the detected phenolic compounds. The presented method yielded satisfactory repeatability in terms of retention times and average concentrations of phenolic compounds (RSD < 0.3%). Verbascoside was established as the major phenolic compound in black olives. Oleuropein was established as the dominating phenolic compound in green olives, and its level decreased during maturation. Additionally, this research is the first to experimentally evidence that the flavone luteolin-7-rutinoside is the predominant flavonoid glucoside in black olives, showing the most significant variation with fruit development. The above results validate the method for an easy and fast determination of different classes of phenolic compounds present in olive fruits

Modification of pomological characteristics and flavor components of fruits and virgin olive oil following wastewater irrigation and soil tillage

BACKGROUND The experiment was carried out on olive trees cv. Chemlali, during two successive years (2013/2014). Two irrigation treatments (IT: Trees irrigated with wastewater; TRC: Trees grown under rainfed condition) were combined with two tillage practices (TTS: Trees grown in tilled soil; TNTS: Trees grown in non-tilled soil). RESULTS The results of the study showed that WW irrigation combined with soil tillage improved the pomological characteristics of olive fruits. The tree yield increase was substantial for IT and TTS. However, most of the identified phenolic compounds, especially oleuropein, mainly accumulated in olive fruits of the TC block (TNTS + TRC), suggesting a marked improvement in the nutritional value of these fruits. Moreover, fruits of TNTS had high contents of sugar compounds, required for the synthesis of the fruit storage material. The study also showed that the agronomic practices affected the amounts of some aromatic compounds responsible for the distinctive flavor notes of olive oil. CONCLUSION Hence, agronomic practices may affect considerably the commercial and nutritional values and the sensorial quality of the commodities

The Role of Dietary Intake in Type 2 Diabetes Mellitus: Importance of Macro and Micronutrients in Glucose Homeostasis

The prevalence of Type 2 diabetes (T2D) is increasing worldwide. Genetics and lifestyle, especially diet, are contributing factors. Analyses of macro- and micronutrient intake across global populations may help to explain their impact on glucose homeostasis and disease development. To this end, 420 Tunisians were enrolled in a prospective cross-sectional study of daily food consumption. Various data were collected and blood samples were drawn for biochemical assay. A 24-h recall questionnaire was obtained from participants to evaluate dietary intake. Statistical analyses were conducted using Nutrilog and R software. Biochemical analyses stratified the studied population (n = 371) into three groups: diabetics (n = 106), prediabetics (n = 192) and controls (n = 73); 49 subjects were excluded. Our results showed that Tunisians had hypercaloric diets high in carbohydrates and fat with variability in the levels of some vitamins and minerals, including riboflavin and niacin, that were statistically different among groups. The lower intake of vitamin D was associated with a greater risk of T2D. Higher vitamin A and sodium intake were associated with poor glucose homeostasis, although protein intake may improve it. In perspective, nutrigenomic studies can provide insight into problematic diets and poor eating habits and offer opportunities to analyze the effects of behavioral changes that can mitigate T2D development and progression

Modification of Phenolic Compounds and Volatile Profiles of Chemlali Variety Olive Oil in Response to Foliar Biofertilization

The main objective of this work was to studythe effects of foliar biofertilizers on individual volatile pro-files and phenolic compounds of olive oil (Olea europaeaL. cv. Chemlali). Three foliar biofertilizers were used intwo successive application seasons: T1 (rich in nitrogen,phosphorus and potassium); T2 (rich in calcium); and T3(application of both T1 and T2). Results showed that foliarfertilization with T2 increased the phenolic compound con-tents (e.g., oleuropein aglycone and decarboxymethyl lig-stroside aglycone) of Chemlali olive oil. It also enhancedthe levels of many volatile compounds responsible for thegoodflavor of olive oil such as hexanal. However,T1-tested fertilizer led to a significant decrease in the con-tent of phenolic compounds, although they seemed toimprove significantly the levels of the majority of volatilecompounds, especially hexanal. Based on these results, asignificant relationship between plant nutrition and qualityof oil was observed. Our results demonstrated a potentialpositive influence on the concentration of sensory qualitycompounds under T2 (Ca2+-based fertilizer). This resultshould be considered in the design of foliar nutrient appli-cation management strategies for olive trees

Modification of Phenolic Compounds and Volatile Profiles of Chemlali Variety Olive Oil in Response to Foliar Biofertilization

The main objective of this work was to studythe effects of foliar biofertilizers on individual volatile pro-files and phenolic compounds of olive oil (Olea europaeaL. cv. Chemlali). Three foliar biofertilizers were used intwo successive application seasons: T1 (rich in nitrogen,phosphorus and potassium); T2 (rich in calcium); and T3(application of both T1 and T2). Results showed that foliarfertilization with T2 increased the phenolic compound con-tents (e.g., oleuropein aglycone and decarboxymethyl lig-stroside aglycone) of Chemlali olive oil. It also enhancedthe levels of many volatile compounds responsible for thegoodflavor of olive oil such as hexanal. However,T1-tested fertilizer led to a significant decrease in the con-tent of phenolic compounds, although they seemed toimprove significantly the levels of the majority of volatilecompounds, especially hexanal. Based on these results, asignificant relationship between plant nutrition and qualityof oil was observed. Our results demonstrated a potentialpositive influence on the concentration of sensory qualitycompounds under T2 (Ca2+-based fertilizer). This resultshould be considered in the design of foliar nutrient appli-cation management strategies for olive trees

Genetic characterization of suspected MODY patients in Tunisia by targeted next-generation sequencing

International audienceAIMS: Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes with autosomal dominant inheritance pattern. The diagnosis of MODY and its subtypes is based on genetic testing. Our aim was investigating MODY by means of next-generation sequencing in the Tunisian population.METHODS: We performed a targeted sequencing of 27 genes known to cause monogenic diabetes in 11 phenotypically suspected Tunisian patients. We retained genetic variants passing filters of frequency in public databases as well as their probable effects on protein structures and functions evaluated by bioinformatics prediction tools.RESULTS: Five heterozygous variants were found in four patients. They include two mutations in HNF1A and GCK that are the causative genes of the two most prevalent MODY subtypes described in the literature. Other possible mutations, including novel frameshift and splice-site variants were identified in ABCC8 gene.CONCLUSIONS: Our study is the first to investigate the clinical application of targeted next-generation sequencing for the diagnosis of MODY in Africa. The combination of this approach with a filtering/prioritization strategy made a step towards the identification of MODY mutations in the Tunisian population

Association of apolipoprotein A5 gene variants with metabolic syndrome in Tunisian population.

International audienceAIM OF THE STUDY : APOA5 has been linked to metabolic syndrome (MetS) or its traits in several populations. In North Africa, only the Moroccan population was investigated. Our aim is to assess the association between APOA5 gene polymorphisms with the susceptibility to MetS and its components in the Tunisian population. MATERIALS AND METHODS : A total of 594 participants from the Tunisian population were genotyped for two polymorphisms rs3135506 and rs651821 located in APOA5 gene using KASPar technology. Statistical analyses were performed using R software. RESULTS : The SNP rs651821 increased the risk of MetS under the dominant model (OR=1.91 [1.17-3.12], P=0.008) whereas the variant rs3135506 was not associated with MetS. After stratification of the cohort following the sex, only the variant rs651821 showed a significant association with MetS among the women group. The influence of the geographic origin of the studied population on the genotype distribution of APOA5 variants showed that the variant rs651821 was significantly associated with MetS only for the Northern population. The association analyses of the variants rs651821 and rs3135506 with different quantitative traits of MetS showed a significant association only between the variant rs3135506 and triglycerides levels. CONCLUSION : This is the first study reporting the association of APOA5 gene variants with MetS in Tunisia. Our study emphasizes the role of APOA5 variants in the regulation of the triglycerides blood levels. Further studies are needed to confirm the clinical relevance of these associations and to better understand the physiopathology of the MetS

Pharmacogenetic landscape of Metabolic Syndrome components drug response in Tunisia and comparison with worldwide populations

<div><p>Genetic variation is an important determinant affecting either drug response or susceptibility to adverse drug reactions. Several studies have highlighted the importance of ethnicity in influencing drug response variability that should be considered during drug development. Our objective is to characterize the genetic variability of some pharmacogenes involved in the response to drugs used for the treatment of Metabolic Syndrome (MetS) in Tunisia and to compare our results to the worldwide populations. A set of 135 Tunisians was genotyped using the Affymetrix Chip 6.0 genotyping array. Variants located in 24 Very Important Pharmacogenes (VIP) involved in MetS drug response were extracted from the genotyping data. Analysis of variant distribution in Tunisian population compared to 20 worldwide populations publicly available was performed using R software packages. Common variants between Tunisians and the 20 investigated populations were extracted from genotyping data. Multidimensional screening showed that Tunisian population is clustered with North African and European populations. The greatest divergence was observed with the African and Asian population. In addition, we performed Inter-ethnic comparison based on the genotype frequencies of five VIP biomarkers. The genotype frequencies of the biomarkers rs3846662, rs1045642, rs7294 and rs12255372 located respectively in <i>HMGCR</i>, <i>ABCB1</i>, <i>VKORC1 and TCF7L2</i> are similar between Tunisian, Tuscan (TSI) and European (CEU). The genotype frequency of the variant rs776746 located in <i>CYP3A5</i> gene is similar between Tunisian and African populations and different from CEU and TSI. The present study shows that the genetic make up of the Tunisian population is relatively complex in regard to pharmacogenes and reflects previous historical events. It is important to consider this ethnic difference in drug prescription in order to optimize drug response to avoid serious adverse drug reactions. Taking into account similarities with other neighboring populations, our study has an impact not only on the Tunisian population but also on North African population which are underrepresented in pharmacogenomic studies.</p></div