A reappraisal of the use of DMSO for the extraction and determination of chlorophylls a and b in lichens and higher plants

Dimethyl sulfoxide (DMSO) and 90% acetone extracted equal amounts of chlorophyll from diatoms and blue-green algae, but DMSO was superior to 90% acetone for all green algae tested giving 2–60 times more chlorophyll depending on the species. The absorbance spectra of pure chlorophyll a (and b) from 600 nm to 750 nm were identical whether dissolved in 90% acetone or a mixture of DMSO and 90% acetone (1:1 v/v). Thus, several equations for estimating chlorophyll concentration based on extinction in 90% acetone are applicable with this solvent.

https://aslopubs.onlinelibrary.wiley.com/doi/epdf/10.4319/lo.1976.21.6.0926

Improved extraction of chlorophyll a and b from algae using dimethyl sulfoxide

Cells of the green microalga Haematococcus pluvialis were induced to accumulate the ketocarotenoid pigment, astaxanthin. This induction was achieved by the application of the following environmental conditions: light intensity (170//mol m~s~'), phosphate starvation and salt stress (NaCl 0.8%). These conditions retarded cell growth as reflected by a decrease in cell division rate, but led to an increase in astaxanthin content per cell. Accumulation of astaxanthin required nitrogen and was associated with a change in the cell stage from biflagellate vegetative green cells to non-motile and large resting cells. It is suggested that environmental or nutritional stresses, which interfere with cell division, trigger the accumulation of astaxanthin. Indeed, when a specific inhibitor of cell division was applied, a massive accumulation of astaxanthin occurred.

Astaxanthin Accumulation in the Green Alga Haematococcus pluvialis1

Fucoxanthin, one of the main marine carotenoids, is abundant in macro- and microalgae. Here, fucoxanthin was isolated and structurally identified as the major caroten- oid in the diatom Phaeodactylum tricornutum through chromatographic and spectroscopic methods, such as liquid chromatography-positive-ion atmospheric pressure chemical ioni- zation/mass spectroscopy and nuclear magnetic resonance. This pigment was quantified by reverse-phase high-performance liquid chromatography, and a number of extraction proce- dures were assessed to investigate the effect of solvent type, extraction time, temperature, and extraction method (maceration, ultrasound-assisted extraction, Soxhlet extraction, and pressurized liquid extraction). Among the investigated solvents, ethanol provided the best fucoxanthin extraction yield (15.71 mg/g freeze-dried sample weight). Fucoxanthin content in the extracts produced by the different methods was quite constant (15.42-16.51 mg/g freeze-dried sample weight) but increased steeply based on the percentage of ethanol in water, emphasizing the importance of ethanol in the extraction. The results indicate that P. tricornutum is a rich source of fucoxanthin (at least ten times more abundant than that in macroalgae) that is easily extracted with ethanol, suggesting potential applications in human and animal food, health, and cosmetics.

A Potential Commercial Source of Fucoxanthin Extracted from the Microalga Phaeodactylum tricornutum

The chlorophyte Haematococcus pluvialis accumulates large quantities of astaxanthin under stress conditions. Under either nitrogen starvation or high light, the production of each picogram of astaxanthin was accompanied by that of 5 or 3‐4 pg of fatty acids, respectively. In both cases, the newly formed fatty acids, consisting mostly of oleic (up to 34% of fatty acids in comparison with 13% in the control), palmitic, and linoleic acids, were deposited mostly in triacylglycerols. Furthermore, the enhanced accumulation of oleic acid was linearily correlated with that of astaxanthin. Astaxanthin, which is mostly monoesterified, is deposited in globules made of triacylglycerols. We suggest that the production of oleic acidrich triacylglycerols on the one hand and the esterification of astaxanthin on the other hand enable the oil globules to maintain the high content of astaxanthin esters.

Accumulation of oleic acid in haematococcus pluvialis (chlorophyceae) under nitrogen starvation or high light is correlated with that of astaxanthin esters 1

Dimethyl sulfoxide (DMSO) rapidly extracts much of the chlorophyll c and fucoxanthin from the intact thalli of brown algae. Subsequent extraction by acetone rapidly removes most of the chlorophyll a and β-carotene. An analytical procedure for these pigments has been developed, based upon this extraction sequence, followed by partition of the acetone extract between hexane and aqueous acetone. Fucoxanthin and chlorophyll c can be recovered from the DMSO extract and the aqueous acetone phase by extraction into ethyl acetate and subsequent evaporation. The DMSO-acetone extraction sequence is also effective with green algae and a few red algae, although the full scope of the method has not been investigated.

M. J. Duncan

Papers

Preparative and analytical extraction of pigments from brown algae with dimethyl sulfoxide