Streptomyces species from the rhizosphere of the medicinal plant Artemisia herba-alba Asso: screening for biological activities Biological activities of rhizospheric Streptomyces strains

Seven date seeds cultivars, Deglet Nour, Degla Baïdha, Fakht, Ghars, Hamraya, Tafezouin and Takermost were provided from Algerian Sahara. Some of these Algerian date seeds were studied for the first time (Fakht, Hamraya and Takermost). The biochemical characterization of these date seeds were studied, including fatty acids and minerals profiles. The results showed that date seeds are a good source of carbohydrates and crude cellulose, with averages of 66.63 and 13.20%, respectively. They are also a good source of proteins, with the cultivar Deglet Nour seeds as the richest one (9.27 ± 0.03%). The main fatty acid for all date seeds oils is oleic acid except for Deglet Nour in which lauric acid is the main one. However, the studied date seed oils could be classified as oleic-lauric oil. Potassium was the highest mineral in all date seeds cultivars, with values ranging from 2700 to 2900 mg/Kg, followed by sodium and iron. These results indicate that date seeds have good nutritional value with different compositions among cultivars. It could be concluded that date seeds could be considered as a good opportunity for their technological and industrial valorization.

Microalgae are described as a potential alternative source of bioactive compounds that are environmentally friendly. Dunaliella on its own is well known due to its potential to accumulate large amounts of carotenoids, especially β-carotene. Green and orange biomasses from a new Dunaliella salina strain DunaDZ1 isolated from an Algerian Salt Lake were evaluated for carotenoids composition and antioxidant activity. Ultrasound-Assisted Extraction (UAE) was employed using different extracting solvents. Furthermore, UAE extracts were then analyzed for their chemical composition by TLC, HPLC-DAD and for the antioxidant activity. Lutein was the main carotenoid in the green biomass, with the highest amount for ethyl acetate extract (393.19 mg/g). However, for the orange biomass, the main carotenoid was trans, β-carotene (131.83 mg/g) in the acetonic extract. Moreover, several others carotenoids were detected, belonging to xanthophylls and carotenes. Additionally, ultrasonic-assisted extraction with ethyl acetate produced the extract with the highest antioxidant activity for both D. salina biomasses. These extracts could be used as a natural antioxidant and as an ingredient for functional foods formulation.

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In recent years, intensive research has been conducted on natural carotenoids extraction using several processes. Conventional extraction methods require high amounts of solvents and a long extraction time. However, pressurized liquid extraction demonstrated to be an interesting method. The extraction efficiencies of pressurized liquid for the recovery of carotenoids, from the green and the orange biomasses of the microalga Dunaliella salina DunaDZ1, are described. Organic solvents were tested including ethanol, n-hexane, ethyl acetate and a mixture of n-hexane:ethanol (3:4). Moreover, three extraction temperatures were used (90, 120 and 150 °C) at constant pressure. Extraction efficiency and extracts characterization were conducted. Results have shown that temperature has a positive effect on extraction yield. HPLC characterization showed that β-carotene is the main carotenoid in the orange biomass, and lutein in the green biomass, with the presence of other minor carotenoids in both biomasses. The highest carotenoid amounts were found in the n-hexane orange biomass extract, with β-carotene isomers as the main carotenoid (138.54 and 357.10 mg/g of dry extract, for cis and trans isomers, respectively). Otherwise, extracts obtained at the lowest tested temperature provided the best carotenoid yields. The best results for the antioxidant activity were obtained at 120 °C for orange biomass ethyl acetate extract.