Brahim Marzouk

Antioxidant activities of the essential oils and methanol extracts from myrtle (Myrtus communis var. italica L.) leaf, stem and flower.

This study was designed to examine the chemical composition and antioxidant activity of the essential oils and methanol extracts of Myrtus communis var. italica L. leaf, stem and flower. Myrtle leaf and flower were the valuable organs for the essential oil production representing a yield of 0.61% and 0.30% (w/w), respectively. The essential oil composition of myrtle leaf and flower was characterized by high proportions of alpha-pinene, the main compound of monoterpene hydrocarbon class, with 58.05% for leaf and 17.53% for flower. Stem was rich in oxygenated monoterpenes, largely due to 1,8-cineole with 32.84%. The total phenol contents varied between different myrtle parts; leaf extract had higher total phenol content (33.67 mg GAE/g) than flower (15.70 mg GAE/g) and stem (11.11 mg GAE/g) extracts. Significant differences were also found in total tannin contents among different myrtle parts, representing 26.55 mg GAE/g in leaf, 11.95 mg GAE/g in flower, 3.33 mg GAE/g in stem. The highest contents of total flavonoids and condensed tannins were observed in stem (5.17 and 1.99 mg CE/g, respectively) and leaf (3 and 1.22 mg CE/g, respectively) extracts. The HPLC analysis indicated that the main phenolic class was hydrolysable tannins (gallotannins) in leaf (79.39%, 8.90 mg/g) and flower (60.00%, 3.50mg/g) while the stem was characterized by the predominance of flavonoid class (61.38%, 1.86 mg/g) due to the high presence of catechin (36.91%, 1.12 mg/g). Antioxidant activities of the essential oil and the methanolic extract from different myrtle parts were evaluated by using DPPH radical scavenging, beta-carotene-linoleic acid bleaching, reducing power and metal chelating activity assays. In all tests, methanolic extracts of different myrtle parts showed better antioxidant activity than essential oils.

Biochemical characterization of blood orange, sweet orange, lemon, bergamot and bitter orange

This paper reports on the composition of aroma compounds and fatty acids and some physico-chemical parameters (juice percentage, acidity and total sugars) in five varieties of citrus: blood orange, sweet orange, lemon, bergamot and bitter orange. Volatile compounds and methyl esters have been analyzed by gas chromatography. Limonene is the most abundant compound of monoterpene hydrocarbons for all of the examined juices. Eighteen fatty acids have been identified in the studied citrus juices, their quantification points out that unsaturated acids predominate over the saturated ones. Mean concentration of fatty acids varies from 311.8 mg/l in blood orange juice to 678 mg/l in bitter orange juice.

Essential Oils, Phenolics, and Antioxidant Activities of Different Parts of Cumin (Cuminum cyminum L.)

Cuminum cyminum L. roots, stems and leaves, and flowers were investigated for their essential oils, total phenolics, flavonoids, and tannins contents, individual phenolic compounds, and antioxidant activities. The essential oil was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), whereas identification and quantification of individual target polyphenolic compounds was performed by reversed-phase high-performance liquid chromatography (RP-HPLC). Essential oil yields were 0.03% in roots, 0.1% in stem and leaves, and 1.7% in flowers. Major components of the oils were bornyl acetate (23%), α-terpinene (34%), and γ-terpinene (51%) in roots, stems and leaves, and flowers, respectively. In all C. cyminum organs, total phenolics content ranged from 11.8 to 19.2 mg of gallic acid equivalents per gram of dry weight (mg of GAE/g of DW). Among the polyphenols studied, 13 were identified in roots, 17 in stem and leaves, and 15 in flowers. The major phenolic compound in the roots was quercetin (26%), whereas in the stems and leaves, p-coumaric, rosmarinic, trans-2-dihydrocinnamic acids and resorcinol were predominant. In the flowers, vanillic acid was the main compound (51%). The antioxidant activities of C. cyminum essential oils and acetone extracts obtained from the three organs were assessed using four tests [1,1-diphenyl-2-picrylhydrazyl (DPPH), β-carotene/linoleic acid, reducing power, and chelating power assays]. The acetone extract of flowers was strongly effective as a DPPH radical scavenger, lipid peroxidation inhibitor, and reducing agent, with IC(50) values of 4, 32, and 8 μg/mL, respectively. Moreover, the acetone extract of stems and leaves showed the highest chelating power. However, the essential oils exhibited moderate activities in the different tests.

Drought effects on polyphenol composition and antioxidant activities in aerial parts of Salvia officinalis L.

Salvia officinalis L. is a medicinal plant containing several compounds with important pharmacological activity. In this study, we investigated the effects of water deficit (moderate and severe water deficits) on the contents of total and individual polyphenols of the aerial parts. Also, we studied the effect of drought on the antioxidant activity of methanolic extracts. Our results showed that water deficiency, as estimated by the decrease in water potential, resulted in a reduction of the biomass, plant height and total chlorophyll contents. In general, drought increased the level of total and individual polyphenols and this increase was more pronounced under moderate water deficit. These findings suggest that S. Officinalis is a sensitive species and that a severe water deficit could result in a decline in the activity of enzymes involved in the biosynthesis of phenolic compounds. On the other hand, our results showed an enhancement of reducing power and the radical scavenging activity as assessed using the DPPH assay with increasing stress severity. Finally, the evaluation of the chelating capacity of the extracts was found to be altered significantly under severe treatment by 39.71%. Based on these results, it seems that drought tolerance of S. officinalis is related to the capacity of the plant to modulate its phenolics in order to face to oxidative stress caused by water limiting conditions.

Juice components and antioxidant capacity of four Tunisian Citrus varieties

BACKGROUND Juices from four Citrus species of Tunisia were investigated mainly for quality parameters and antioxidant capacity. RESULTS Citrus reticulata (mandarin) juice had the highest content of total flavonoids (85.33 mg CE L(-1)). The latter also occurred in high quantity (82.01 mg CE L(-1)) in Citrus lemon (lemon) juice which was also marked by its richness in total aroma (70.16 µg mL(-1)) and in total fatty acids (48.10 µg mL(-1)). Mandarin and lemon juices had the highest antioxidant activity, as determined b the β-carotene bleaching assay (26.67% and 22.67%, respectively). Citrus aurantium (bitter orange) juice was characterised by the highest content of total polyphenols (784.67 mg GAE L(-1)) and by the greatest inhibition of DPPH (96.10%). Citrus sinensis (blood orange) juice was only marked by the high quantity of ascorbic acid (36.90 mg mL(-1)). GC/MS analysis of juice aroma showed the predominance of limonene (48.85-69.59%) in mandarin and in bitter and blood oranges, but of camphene (89.05%) in lemon. GC analysis of juice fatty acids revealed their richness in oleic acid (23.13-39.52%). HPLC analysis of juice phenolics indicated the predominance of phenolic acids (73.13-86.40%). CONCLUSION The Citrus species used in this study were considered valuable varieties from the point of view of antioxidant capacity and nutrition.

Effects of water-deficit on lipids of safflower aerial parts.

Three-week-old plants of safflower (Carthamus tinctorius L.) were subjected to a water-deficit stress. The lipid composition of the shoot parts of both control (well-watered) and water stressed plants was analyzed. Experimental data revealed that moderate stress induced an increase in total lipid content within all lipidic classes. However, severe water-deficit induced a sharp decrease in the total lipid content and specially in polar lipids, particularly in phosphatidylethanolamine, phosphatidylcholine, monogalactosyl-diacylglycerol and digalactosyl-diacylglycerol. Also, the content of neutral lipids was increased. Concerning the fatty acid composition, water-deficit induced a decrease in their degree of unsaturation expressed by a reduction in the proportions of linolenic (18:3) and linoleic (18:2) acids and most of lipidic classes.

Essential oils and fatty acids composition of Tunisian and Indian cumin (Cuminum cyminum L.) seeds: a comparative study

BACKGROUND Cumin (Cuminum cyminum L.) seeds of two geographic origins, Tunisia (TCS) and India (ICS), were studied regarding their fatty acid and essential oil composition. RESULTS Oil yields were 17.77 and 15.40% for TCS and ICS respectively. Petroselinic acid (C18:1n-12) was the major fatty acid in both varieties, with a higher proportion being found in TCS (55.90% of total fatty acids (TFA)) than in ICS (41.42% TFA). Moreover, the most predominant fatty acids were palmitic, petroselenic and linoleic acids, accounting for more than 91% TFA in both varieties. The unsaturated fatty acid content was high: 70.95% TFA in TCS and 62.17% TFA in ICS. Essential oil yields differed significantly (P < 0.05) between the two varieties: 1.21 and 1.62% for ICS and TCS respectively. A total of 40 compounds were identified, 34 of which were present in both essential oils. The two varieties displayed different chemotypes: γ-terpinene/1-phenyl-1,2-ethanediol for TCS and cuminaldheyde/γ-terpinene for ICS. CONCLUSION The study revealed that the biochemical composition of cumin seeds is origin-dependent and that cumin seeds are rich in an unusual fatty acid, petroselinic acid. Besides, cumin essential oil is a rich source of many compounds, including cuminaldehyde and γ-terpinene. The overall results suggest the exploitation of cumin seeds as a low-cost renewable source for industrial processing in the fields of cosmetics, perfumes and pharmaceuticals.

Characterization of Bioactive Compounds in Tunisian Bitter Orange (Citrus aurantium L.) Peel and Juice and Determination of Their Antioxidant Activities

Citrus aurantium peel and juice aroma compounds were investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS), whereas phenolic compounds analysis was performed by reversed-phase high-performance liquid chromatography (RP-HPLC). Limonene was the major volatile compound of bitter orange peel (90.25%) and juice (91.61%). HPLC analysis of bitter orange peel and juice methanolic extracts indicated that phenolic acids constitute their main phenolic class representing 73.80% and 71.25%, respectively, followed by flavonoids (23.02% and 23.13%, resp.). p-Coumaric and ferulic acids were the most abundant phenolic compounds representing 24.68% and 23.79%, respectively, in the peel, while the juice contained 18.02% and 19.04%, respectively. The antioxidant activities of bitter orange peel and juice methanolic extracts have been evaluated using four in vitro assays, and the results were compared with the standard antioxidants (BHT, BHA, and ascorbic acid). Our findings demonstrated that Citrus aurantium peel and juice possess antioxidant activities which were less effective than those of antioxidant standards. Both extracts may be suggested as a new potential source of natural antioxidant.

Thermal stability of corn oil flavoured with Thymus capitatus under heating and deep‐frying conditions

BACKGROUND The thermal stability of corn oil flavoured with thyme flowers was determined and compared with that of the original refined corn oil (control). The oxidative stability index (OSI) was measured and samples were exposed to heating (30 min at 150, 180 and 200 °C) and deep-frying (180 °C). Changes in peroxide value (PV), free fatty acid (FFA) content, specific absorptivity values (K(232) and K(270)), colour and chlorophyll, carotenoid and total phenol contents were monitored. RESULTS The OSI and heating results showed that thyme incorporation was effective against thermal oxidation based on the increased induction time observed for the flavoured oil (6.48 vs 4.36 h), which was characterised by lower PV, FFA content, K(232) and K(270) than the control oil after heating from 25 to 200 °C, with higher red and yellow colour intensities and chlorophyll, carotenoid and total phenol contents. The deep-frying test showed the accelerated deterioration of both oils in the presence of French fries. CONCLUSION Compared with the control oil, the thyme-flavoured oil showed improved thermal stability after heating. This could be attributed to the presence of thyme pigments and antioxidant compounds allowing extended oil thermal resistance.

Variation in Phenolic Composition and Antioxidant Activity during Flower Development of Safflower (Carthamus tinctorius L.)

This work was aimed to study the effect of extraction solvent system with varying polarities on polyphenol, flavonoid and proanthocyanidin contents and DPPH scavenging activity. Obtained results showed that phenolic contents and antioxidant activities varied considerably as function of solvent polarity. The extraction with acetone/water (2:8) showed the highest flower polyphenol content (15.09 mg GAE/g DW). Moreover, antiradical capacities against DPPH, chelating power and lipid peroxidation assay were maximal in acetone/water (2:8) of flower extract. Significant variation in antioxidant properties was observed between different development stages of Carthamus tinctorius flowers; the highest antioxidant activity was observed at stage III (full flowering) while phenolic composition reached its maximum at stage II (flower formation). Gallic acid was the most abundant phenolic compound in C. tinctorius orange flowers, accounting for about 102.57 (μg/g DW). Findings underline the potential health benefits as a result of consuming C. tinctorius flowers and suggest that it could be used as valuable flavor with functional properties for food or nutraceutical products on the basis of the high polyphenol contents and antioxidant activities.