Nahed Fakhfakh

Variation of chemical composition of essential oils in wild populations of Thymus algeriensis Boiss. et Reut., a North African endemic Species

BackgroundThymus algeriensis is an endemic aromatic plant to Tunisia largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by the geographical location and the phase of the plant development. Therefore, the aim of the present work is to provide more information on the variation of essential oil composition of T. algeriensis collected during the vegetative and the flowering phases and from eight different geographical regions. Besides, influence of population location and phenological stage on yield and metal chelating activity of essential oils is also assessed.MethodsThe essential oil composition of Thymus algeriensis was determined mainly by GC/FID and GC/MS. The chemical differentiation among populations performed on all compounds was assessed by linear discriminate analysis and cluster analysis based on Euclidean distance.ResultsA total of 71 compounds, representing 88.99 to 99.76% of the total oil, were identified. A significant effect of the population location on the chemical composition variability of T. algeriensis oil was observed. Only 18 out of 71 compounds showed a statistically significant variation among population locations and phenological stages. Chemical differentiation among populations was high. Minor compounds play an important role to distinguish between chemical groups. Five chemotypes according to the major compounds have been distinguished. Chemotypes distribution is linked to the population location and not to bioclimate, indicating that local selective environmental factors acted on the chemotype diversity.ConclusionsThe major compounds at the species level were α-pinene (7.41-13.94%), 1,8-cineole (7.55-22.07%), cis-sabinene hydrate (0.10-12.95%), camphor (6.8-19.93%), 4-terpineol (1.55-11.86%), terpenyl acetate (0-14.92%) and viridiflorol (0-11.49%). Based on major compounds, the populations were represented by (α-pinene/1,8-cineole/cis-sabinene hydrate/camphor/viridiflorol), (1,8-cineole/camphor/terpenyl acetate), (α-pinene/1,8-cineole/camphor), (1,8-cineole/camphor/4-terpineol) and (α-pinene/1,8-cineole/cis-sabinene hydrate/camphor/4-terpineol) chemotypes. Variation of phenological stage did not have a statistically significant effect on the yield and metal chelating activity of the essential oil. These results can be used to investigate the geographical location and the harvesting time of this plant for relevant industries.

Blue-green algae (Arthrospira platensis) as an ingredient in pasta: free radical scavenging activity, sensory and cooking characteristics evaluation.

The effects of semolina enrichment with blue-green algae (Arthrospira platensis) at three different levels (1, 2 and 3 g/100 g of semolina) on the colour, cooking properties, firmness, free radical scavenging activity and sensory characteristics of pasta are reported. Microalgae addition resulted in higher swelling index and lower cooking loss than the control sample. A significant increase in pasta firmness was evidenced with an increase of added microalgae due to structural reinforcement. In addition to colouring, the use of A. platensis (2 g/100 g of semolina) can enhance the sensory quality and nutraceutical potential as evaluated by free radical scavenging activity of pasta.

Improvement of antioxidant potential in rats consuming feathers protein hydrolysate obtained by fermentation of the keratinolytic bacterium, Bacillus pumilus A1

The in vitro and in vivo antioxidant activities of feathers protein hydrolysate (FPH), produced by fermentation with the keratinolytic bacterium, Bacillus pumilus strain A1, were evaluated. The antioxidant activities of FPH, evaluated using DNA nicking and ferrozine assays, demonstrate that FPH present an important antioxidant potential. Interestingly, the addition of this hydrolysate (2.5 and 5%) to the feed of rats caused a significant decrease in the rate of thiobarbutiric acid reagent substances (TBARS) and the enzymatic antioxidants activities (superoxide dismutase, glutathione peroxidase and catalase) in liver, kidney, heart, brain and cerebella, as compared to the control. However, the supplementation of the standard food by 2.5% of untreated feather meal or 5% of soya is associated with an increase of the TBARS rate and enzymatic antioxidant activities. These results indicate that FPH may be useful as supplementary proteins and natural antioxidant in animal feed formulation.

Effect of Phenological Stage and Geographical Location on Antioxidant Activities of Tunisian Horehound: Marrubium vulgare L. (Lamiaceae)

Abstract Medicinal plants constitute an important source for a wide variety of natural antioxidants. Therefore, the aim of the present work was to compare the antioxidant activities, total phenolic and flavonoid contents of three wild populations of Marrubium vulgare L. The plant was collected from the South-East (Matmata and Thoujene) and the Central-Sahel (Melloulech) of Tunisia, at the vegetative and at the fruiting stages. The antioxidant activities were evaluated by the following methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power and metal (Fe2+) chelating activity. Ethanolic extract of M. vulgare present the highest contents of phenolics (267–325 mg GAE/g extract) and flavonoids (212–245 mg QE/g extract) at the fruiting stage, regardless the geographical location. Furthermore, the highest antioxidant activities were also obtained at the fruiting stage of M. vulgare.