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Updated 29 October 2015

Microalgae a source of antioxidants

Researchers have identified green colonial microalgae with extractable carotenoids, especially lutein – the first time that the antioxidant activity of the algae has been reported.

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“The present study indicates the antioxidant potential of B. braunii for various health supplements and nutraceuticals. This is the first report of the evaluation of the carotenoid composition and antioxidant properties of B. braunii,” wrote lead author Ambati Ranga Rao from the Central Food and Technological Research Institute in Mysore.

The research may provide the burgeoning lutein market with another extractable source of this in-demand carotenoid.

“The role of antioxidants in health and disease has been realised beyond doubt,” explained Rao. “And the search for different sources of antioxidants, especially natural ones, has acquired newer dimensions.”

Botryococcus braunii belongs to the family Chlorophycae and is known, say the researchers, for its production of hydrocarbons, exopolysaccharides and carotenoids.

How the research was done

The researchers evaluated the antioxidant activity of extracts from B. braunii using three different methods: radical scavenging (DPPH), hydroxyl radical scavenging, and assays for lipid peroxidation in both rat and human cells in vitro.

The acetone extraction method provided 2,33 micrograms of carotenoids per milligram of algae, while extraction with other solvents like a two-to-one chloroform-methanol mixture led to recovery of 7,56 micrograms of carotenoids per milligram of algae.

“Lutein was the major carotenoid (75 percent of the total carotenoids), followed by astaxanthin (18 percent), beta-carotene (six percent), alpha-carotene (0,3 percent) and zeaxanthin (0,3 percent),” wrote Rao in the Journal of Agricultural and Food Chemistry (Vol. 54, pp. 4593-4599).

For the DPPH radical scavenging assay, it was found that acetone extract exhibited a dose-dependent effect. For levels between six and ten parts per million (ppm) the free-radical activity was found to be between 56 and 68 percent. This is equivalent to about 80 to 90 percent of the activity of the synthetic antioxidant, butylhydroxyanisole (BHA), said the researchers.

In terms of hydroxyl radical scavenging activity, the effect was once again dose-dependent, with concentrations between six and ten ppm scavenging 45 to 65 percent of the hydroxyl radicals – equivalent to between 50 to 75 percent similar concentrations of BHA.

In rat cells, the carotenoid extract of the microalgae inhibited lipid peroxidation in kidney, liver and brain cells by 70, 71 and 71 percent, respectively (10 ppm dose).

In human liposomes, LDL oxidation is reported as being inhibited by 71 percent after six hours at a dose of 10 ppm.

Lipid peroxidation prevented

“The present results substantiate that B. braunii extract is capable of preventing lipid peroxidation through scavenging free radicals and hydroxy radicals in living cells,” concluded the researchers.

This result could lead to an alternative source of carotenoids, particularly lutein. Microalgae are currently farmed as a source of carotenoids such as astaxanthin. For example, Algatechnologies has been producing the carotenoid from the microalgae Haematococcus pluvialis in closed culture for some years.

There has been growing consumer awareness of lutein and its role in boosting eye health, especially against age-related macular degeneration (AMD).

Greater awareness among consumers

A recent survey from Frost and Sullivan, commissioned by Kemin Health, maker of FloraGLO-branded lutein, found that awareness of lutein has never been so high in Europe: in Italy and France it had doubled compared to last year, to 25,8 percent and 16 percent respectively.

Germans showed the greatest awareness, of 33,3 percent. The UK was the only country where it seemed to have slipped slightly, to 20 percent (compared to 25,8 in 2005). Spain had the lowest level, at 9,8 percent.

Source: Decision News Media

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