comparison of oil extraction methods for algae by NMR and Chromatographic techniques

Abstract

The present study focuses on identification and compositional characterization of neutral (tri acyl glycerides, TAG; free fatty acids, FFA) and polar (glyco/ glycerophospho) lipids, and fatty acid chains constituting these lipids in the cyclohexane, dichloromethane and methanol extracts or algal oils of microalgae biomasses. Algal oils were generated by step wise Accelerated Solvent and Soxhlet extraction methods from six microalgae biomasses (Scenedesmus dimorph, Chlorella vulgaris, Spirulina, SD Flakes, Cyanothece and Chlamydomonas) obtained from commercial sources. The analytical protocol developed based on NMR (300 & 400 MHz)( 1 H & 13 C), IR, GPC, GC-FID and GC-MS techniques has provided authentic quantitative information about the nature of neutral lipids, polar lipids, fatty acid profiles, oxylipins (oxo fatty acids) and hydrocarbons present in the extracts. The analyses of fractions generated by silica column chromatographic separation of solvent extracts have facilitated demarcation of 1 H NMR chemical shift regions of functional groups corresponding to neutral and polar lipids. Specifically, α (n-3) and γ (n-6) C18:3 were differentiated in the Spirulina by critical examination of 1 H NMR spectral features of algal oils from various biomasses. The comparative results by different analytical techniques have shown that newly developed methods based on 1 H NMR techniques can provide direct and rapid quantitative results of neutral lipids components including poly unsaturated fatty acid/ester (PUFA/PUFE) in the algal oils without prior sample treatment. The neutral lipids results obtained by NMR and GPC show good agreement as compared by linear regression analyses. The results showed that nature and contents of neutral lipids, and fatty acids profile in the extracts were dependent upon the methods of extraction and the polarity index of solvent used for extraction, and specific to types of algae strains. The application of NMR and IR techniques enabled assessment of the solvent extraction efficiency towards extraction of neutral and polar lipids including types of fatty acids constituting these lipids.

Anticancer Compounds Derived from Marine Diatoms

“…The transformations of these fatty acids vary in marine algae, but are crucial for chemical protection, signaling, and responses to stresses. These are mediated by polyunsaturated aldehydes (PUAs), including decadienal (C10:2 n -3, DD), heptadienal (C7:2 n -3, HD), octatrienal (C8:3 n -1, OD), octadienal (C8:2 n -4, OD), C18:3, C22:6 (DHA), and C20:5 (EPA) [ 18 , 33 , 34 , 35 ] ( Figure 4 B). The PUAs are usually produced only when the diatom cells are damaged.…”

Biodiesel and Polyunsaturated Fatty Acid (PUFA) Potential of MicroalgaeBiomass-A Short Review

“…Without considering effects of matrix, results may be misleading due to overlapping chemical shift regions or resemblance with the matching structures in the complex matrices containing multi component system of TG, FFA and polar lipids. The Fatty acid composition profiles by NMR methods are direct and simple and quite comparable to those determined by GC-MS methods [8,41,42].…”

“…As described in the preceding sections the algal oils are transesterified in order to convert into FAMEs i.e. biodiesel and 1H NMR spectral technique could be used to monitor the process as well as determination of fatty acid profile [8,9,41,42]. This has been demonstrated in the Figure 2 in case of algal oil of Chlorella vulgaris.…”

“…Oil extraction followed by esterification is cumbersome, time consuming, and often uneconomical. Therefore, analytical methods are preferred as both total oil content and compositional information are obtained [8][9][10][38][39][40][41][42].…”

“…The accurate determination of neutral lipids in the algae biomass is a challenging task due to presence of complex multi component matrix comprising of glycerides, glycerolglyco/phospho lipids, proteins, carbohydrates and minor constituents [8,38,41,42]. Thus, there is an essential requirement for standardization of methods in order to ensure reproducibility and accurate assessment of lipid yield and productivity of produced biomass [43]…”