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AbstractBackgroundEthanolic, aqueous and lipidic extracts of Spirulina platensis were evaluated for their bioactive substances (polyphenols and fatty acids) and antioxidant activities using two different assays diphenyl-1-picrylhydrazyl (DPPH) and azino-bis (ethylbenzthiazoline-6- sulfonicacid (ABTS)).MethodsThe phenolic compounds amounts were determined by colorimetric assays and were analyzed by high-performance and liquid chromatography (HPLC) method. The identification of phenolic compounds in the extract was accomplished by comparison of their retention times with those of pure standards. The chemical composition of fatty acids in lipidic extract was determined by GC/FIDs and GC/MS method.ResultsThe obtained results revealed that using DPPH, the ethanolic extract recorded the highest activity with (IC50=449 μg/mL ± 83). It was characterized with a high levels of phenolic and flavonoid content 0.33 ± 0.01 mg GAE/g dw and 0.21 ± 0.01 mg quercetin/g dw, respectively. The ethanolic extract showed the presence of caffeic acid, syringic acid, ferulic acid, p-coumaric acid, chlorogenic acid, kaempferol, quercetin and apigenin. Those entire phenolic compounds seem participle synergistically to the pronounced higher activity. To the best of our knowledge, the apigenin (4′, 5, 7,-trihydroxyflavone), a natural compound which is famously known by its potent antiradical activity, was identified for the first time in Moroccan S. platensis only in the ethanolic extract. A high positive correlation (r=0.895) between the antioxidant activity and the chemical composition of ethanolic extract was observed. For ABTS, lipidic extract showed the highest activity with (IC50=740 μg/mL ± 12). A total of 15 fatty acids compounds, amounting 89.73% of the extract were identified. γ-linolenic acid (GLA) (39.02%) and α-linolenic acid (ALA) (13.85%) were the major component and contribute greatly to the antioxidant activity observed. The lipidic extract has a high content of unsaturated fatty acids (70.95%) which are often exhibited very high antioxidant activity since they have two or more double bonds and chain lengths. The aqueous extract either with DPPH or ABTS methods, recorded low antioxidant activity. Its correlation was r=0.499, lower than found in the ethanolic extract.ConclusionsThese results showed that Spirulina platensis could be considered as a valuable source of fatty acids and phenolics with potent antioxidant activity. It may be employed in the manufacture of pharmaceutical drugs as an alternative source of natural antioxidants.

The air-dried aerial leaves of Petroselinum crispum, Thymus satureioides and dried Spirulina platensis powder were separately extracted using a Soxhlet apparatus. The dark green solution obtained was subject to the dechlorophyllation by two techniques, the electrocoagulation and solvent extraction. The obtained absorbances, were particularly much lower for electrocoagulation process. This result showed that this technique can remove easily plant pigments in the extracts, without affecting the chemical composition on secondary metabolites.

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The cyanobacterium Arthrospira platensis (A. platensis)—a genus of nonheterocystous filamentous cyanobacteria—is used in industrial applications and as a food supply. The current research work aims to study the physicochemical characteristics of A. platensis indigenous to the Moroccan Atlantic coast at Laayoune (Foum El Oued lagoon). The contents of proteins, carbohydrates, vitamins, lipids, minerals, heavy metals, energy value, humidity, ash, pigments, and tannins in A. platensis were investigated using protocols as described in the earlier literature. The values of protein, carbohydrate, and lipid contents in A. platensis were 58.9 ± 0.07, 14.67, and 45.54% respectively. The values of vitamins B2 and B3 dosed in A. platensis were 1.31 ± 0.19 and 30.8 ± 0.001 mg/kg, respectively. The values of heavy metals including lead and chromium were 70 ± 4.5 and 5 ± 0.5 PPB (parts-per-billion), respectively; however, no trace concerning cadmium was detected. The values of energy value, humidity, and ash content were 346.48 ± 0.21, 11.6 ± 0.17%, and 9.1 ± 0.21% kcal/100 g, respectively. The results of pigment content showed the presence of chlorophyll b, chlorophyll a, and carotenoids of 37.506 ± 3.38, 26.066 ± 3.08, and 9.52 ± 0.22 mg/g, respectively. The results obtained revealed that A. platensis indigenous to the Moroccan Atlantic coast at Laayoune was found to be very rich in proteins, carbohydrates, vitamins, minerals, ash, and pigments and lower in heavy metals and saturated fats when compared with species investigated in the literature. Thus, A. platensis indigenous to the Moroccan Atlantic coast at Laayoune fulfills the requirements for being used as dietary supplements.