Ali Ferchichi

Antioxidant Capacities of Phenolic Compounds and Tocopherols from Tunisian Pomegranate (Punica granatum) Fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.

Physico-chemical properties and DPPH-ABTS scavenging activity of some local pomegranate (Punica granatum) ecotypes

Peels and fresh pomegranate extracts were used in the present study for the determination of the physic-chemical properties and DPPH-ABTS scavenging activities. Total sugars of juice are fructose (ca. 7 g/100 ml) and glucose (ca. 8 g/100 ml). Contents of soluble proteins in juice extracts are about 7 g/l (Bradford assays) and 22% (Kjeldhal assays) from dry pulp. Minerals in peel and juice are respectively 9.43±0.93 and 9.46±1.05 mg/100 ml for posphorus and 210.86±10.70 and 271.94±60.59 mg/100 g for potassium. The sodium contents are nearly 7 mg/100 ml in both peel and juice. Highly antioxidant contents in peels were confirmed. Free radical scavenging is about 3.58±0.38 µg/ml in peel. The antioxidant capacity value determined by ABTS was 7.364±0.403 mM Trolox equivalent antioxidant capacity/100 g dry weight. These findings implied that bio-active compounds from the peel might be potential resources for the development of antioxidant function dietary food.

Simple phenolic composition, flavonoid contents and antioxidant capacities in water-methanol extracts of Tunisian common date cultivars (Phoenixdactylifera L.)

The purpose of this study was to determine and compare the phenolic acid composition, flavonoid content and antioxidant activity of fruits from common date cultivars. The simple phenolic content ranged from 15.73 (Mermella variety) to 54.66 mg/100 g fresh weight (Korkobbi variety). Korkobbi had also the highest content of total flavonoids (54.46 quercetin equivalents/100 g fresh weight). The percentage of inhibition can reach 83% in the lipoperoxyl radical of the Korkobbi variety, while it was about 95% with the Rotbi variety for OH·. The Trolox equivalent antioxidant capacity value provided a ranking in decreasing order at 6 min: Korkobbi > Bouhattam > Baht = Smiti > Bekreri = Garn ghzal > Mermilla = Kenta > Nefzaoui = Rotbi. It seems that the highest level of flavonoids in the Korkobbi variety was principally responsible for the highest antiradical efficiency of this cultivar.

Drought effect on growth, gas exchange and yield, in two strains of local barley Ardhaoui, under water deficit conditions in southern Tunisia.

Two local barley strains cv. Ardhaoui originated from Tlalit and Switir, sourthern Tunisia were grown in pots in a glasshouse assay, under well-watered conditions for a month. Plants were then either subjected to water deficit (treatment) or continually well-watered (control). Control pots were irrigated several times each week to maintain soil moisture near field capacity (FC), while stress pots experienced soil drying by withholding irrigation until they reached 50% of FC. Variation in relative water content, leaf area, leaf appearance rate and leaf gas exchange (i.e. net CO(2) assimilation rate (A), transpiration (E), and stomatal conductance (gs)) in response to water deficit was investigated. High leaf relative water content (RWC) was maintained in Tlalit by stomatal closure and a reduction of leaf area. Reduction in leaf area was due to decline in leaf gas exchange during water deficit. Tlalit was found to be drought tolerant and able to maintain higher leaf RWC under drought conditions. Water deficit treatment reduced stomatal conductance by 43% at anthesis. High net CO(2) assimilation rate under water deficit was associated with high RWC (r = 0.998; P < 0.01). Decline in net CO(2) assimilation rate was due mainly to stomatal closure. Significant differences between studied strains in leaf gas exchange parameters were found, which can give some indications on the degree of drought tolerance. Thus, the ability of the low leaf area plants to maintain higher RWC could explain the differences in drought tolerance in studied barley strains. Results showed that Tlalit showed to be more efficient and more productive than Switir.

Screening of Natural Antioxidants from Selected Medicinal Plants

Medicinal plants contain high levels of natural antioxidants and exhibited strong antioxidant activity. In order to find new sources of natural antioxidants, a screening of natural antioxidants from some Tunisian medicinal plants commonly associated with treatment of some diseases were conducted. The total phenolic compounds, flavonoids, anthocyanins, and hydrolysables tannins were measured, and the antioxidant capacities were evaluated using DPPH and Trolox equivalent antioxidant capacity assays. Results prove that there are important quantities of these compounds in Tunisian medicinal plants. A positive linear correlation between Trolox equivalent antioxidant capacity and the phenolic compound contents suggested that these compounds were a major contributor of antioxidant activity of these plants. The results from this study will help us understand the antioxidant capacity profiles of these medicinal plants, and also investigate new sources of natural antioxidants.

Fatty acids from Tunisian and Chinese pomegranate (Punica granatum L.) seeds

Pomegranate seed oil is considered a powerful health-benefiting agent due to its anti-oxidative and anticarcinogenic properties. Lipids from 21 pomegranate cultivars (15 Tunisian and 6 Chinese) were extracted and fatty acids were identified. Total lipids (16% on a dry weight basis) are mainly unsaturated (ca. 88%). Qualitatively, the pomegranate fatty acid composition is identical. Quantitatively, the predominant fatty acid was linolenic acid (44.51–86.14%), followed by linoleic acid (3.57–13.92%), oleic acid (3.03–12.88%), palmitic acid (3.13–11.82%), stearic acid (1.68–15.64%), gadoleic acid (0.50–4.91%), lignoceric acid ( < 2.53%), arachidic acid ( < 1.70%) and myristic acid ( < 0.85%). Statistical methods revealed how Chinese and Tunisian pomegranate fatty acid contents may be affected by the sampling location.

Dietary fiber from Tunisian common date cultivars (Phoenix dactylifera L.): chemical composition, functional properties, and antioxidant capacity.

The dietary fibers (DF) of 10 date varieties from Tunisian oases have been investigated. Further knowledge on the content, composition, and technological applications of those fibers could support their genetic variability and promote the socioeconomical development of growing areas. The composition, water- and oil-holding capacities, solubility, and antiradical activity have been determined. The DF content ranged from 4.7% (Matteta, Rochdi) to >7% (Deglé Nour, Garen Gaze, Smeti). Composition varied significantly among cultivars, and the results evidenced that uronic acids and lignin determine to a great extent the organoleptic quality of dates. Many of the varieties that have been studied (Garen Gaze, Matteta, Kenta, Rochdi, Mermella, Korkobbi, Eguwa) were selected because of great interest from technological and functional points of view. Among their physicochemical characteristics, these samples presented water- and oil-holding capacities of higher than 17 and 4 mL/g fiber, respectively, which make them suitable for use as additives in fiber-enriched foods. Also, DF of Garen Gaze, Smeti, Mermella, and Eguwa had a high antiradical capacity (>230 Trolox equiv/kg fiber). It was concluded that some of these varieties could be grown as potential sources of DF, which could be included in the formulation of fiber- and antioxidant-enriched foods.

The Use of ISSR and RAPD Markers for Genetic Diversity among South Tunisian Barley

Random amplified polymorphic DNA (RAPD) and intersimple sequence repeat (ISSR) were assayed to determine the genetic diversity of 80 barley specimens from South Tunisia. The ISSR primers showed variation in the percentage of polymorphism, band informativeness (Ib), and resolving power (Rp). The percentage of polymorphism is 66.67%, the average Ib ranged from 0.24 to 0.39, while Rp ranged from 0.74 to 1.16. In RAPD analysis, three primers yielded a total of 17 scorable bands, which are all polymorphic. The three polymorphic primers exhibited variation with regard to average band informativeness (AvIb) and resolving power (Rp). RAPD and ISSR marker systems were found to be useful for the genetic diversity among the barley specimens. The two dendrograms obtained through these markers show different clustering of 80 barely specimens, but we noted that some clusters were similar in some cases. A poor correlation (𝑟=0.12) was found between both sets of genetic similarity data, suggesting that both sets of markers revealed unrelated estimates of genetic relationships. Therefore, the ISSR and RAPD molecular markers show two genetic grouping of studied barely specimens.

Health‐promoting compounds of broccoli (Brassica oleracea L. var. italica) plants as affected by nitrogen fertilisation in projected future climatic change environments

BACKGROUND The complex interactions between CO2 increase and salinity were investigated in relation to decreased N supply, in order to determine the nutritional quality of broccoli (Brassica oleracea L. var. italica) plants under these conditions. Three different decreased N fertilisation regimes (NO3(-)/NH4(+) ratios of 100:0, 50:50 and 0:100 respectively) were combined with ambient (380 ppm) and elevated (800 ppm) [CO2 ] under non-saline (0 mmol L(-1) NaCl) and saline (80 mmol L(-1) NaCl) conditions. Nutrients (minerals, soluble protein and total amino acids) and natural antioxidants (glucosinolates, phenolic acids, flavonoids and vitamin C) were determined. RESULTS In NH4(+) -fed broccoli plants, a marked growth reduction was shown and a redistribution of amino acids to cope with NH4(+) toxicity resulted in higher levels of indolic glucosinolate and total phenolic compounds. However, the positive effect of the higher [CO2] - ameliorating adverse effects of salinity--was only observed when N was supplied as NO3(-). Under reduced N fertilisation, the total glucosinolates were increased by a decreased NO3(-)/NH4 (+) ratio and elevated [CO2] but were unaffected by salinity. CONCLUSION Under future climatic challenges, such as increased salinity and elevated [CO2], a clear genotypic dependence of S metabolism was observed in broccoli plants. In addition, an influence of the form in which N was supplied on plant nutritional quality was observed; a combined NO3(-)/NH4(+) (50:50) supply allowed broccoli plants not only to deal with NH4(+) toxicity but also to modify their glucosinolate content and profile. Thus, for different modes of N fertilisation, the interaction with climatic factors must be considered in the search for an optimal balance between yield and nutritional quality.

Microbiological and chemical characterisations of organic and conventional date pastes (Phoenix dactylifera L.) from Tunisia

Chemical and microbiological properties of organic and conventional date pastes produced from the Deglet Nour cultivar were investigated. Significant differences were observed in water content, sugar profiles, and pH among the date pastes. The low moisture and the high acidity of organic date paste were two important positive attributes for its storage and potential manufacturing uses. Before pasteurisation, moulds CFU’s of the organic paste was significantly (P <0.01) lower than those of the conventional one but no significant differences were observed for yeasts, coliforms and the total aerobic flora among the two date pastes. Considerable interest has developed on the preservation of conventional date paste by the use of natural additives such asJuniperus phoenicea and olive oil (conditioned paste). At a given mixture ofJuniperus and olive oil and after pasteurisation, mould CFU’s were reduced by 95% (P <0.01) whereas the reduction was only 84% for the yeast populations, after 45 days at 25 °C.