Functional bioactive compounds and biological activities of Spirulina platensis lipids

The compositions and concentrations of lipid classes, fatty acids, tocopherols were determined in the lipids from blue-green microalga Spirulina platensis. Total lipids (TL) recovered using chloroform: methanol (2:1, v/v) were found to be 163.5 g/kg (on dry weight basis). The level of neutral lipids was the highest, followed by glycolipids and phospholipids, respectively. Among TL and lipid classes, palmitic, gamma-linolenic and linoleic acids were the dominating fatty acids. Compared to the neutral lipids, the polar fractions were generally characterised by higher percentages of saturated fatty acids. The recovered lipids were characterised by high percentage of tocopherols, wherein a-tocopherol constitutes about 73\% of total tocopherols present, the rest being gamma-tocopherol. Spirulina platensis lipids exhibited a strong radical scavenging activity towards stable DPPH free radicals, whereas 27\% of DPPH radicals were quenched after 2 h incubation. TL and lipid classes inhibited the growth of different microorganisms except gram-negative bacteria. At high concentrations, the tested lipids appeared more effective against A. niger (28.3 +/- 1.53 mm). The information obtained in the present investigation is useful for lipid characterisation and further chemical and nutritional investigations of Spirulina platensis.