New biotechnological method gives hope for treatment of AMD

Special substances extracted from seaweed using enzymes have been shown in laboratory tests to have a protective effect against the eye disease AMD.

The incurable eye disease AMD—Age-related Macular Degeneration—affects thousands of elderly persons in Denmark every year, and is the most frequent cause of blindness and loss of vision in elderly persons in the Western world.

The current treatment consists of injections of medicine into the eyeball itself, which primarily dries out the retina, but does not cure the disease. However, new research shows that the substance fucoidan, which is a complex carbohydrate, found only in seaweed, can have a protective effect against the eye disease. 

Fucoidan is found in common seaweed such as sweet tangle, yellowish brown bladder wrack, which are both used as food ingredients. Fucoidan is a group of complex carbohydrates which are built into the cellular walls of seaweed. To examine and exploit the effect of fucoidan, it is important to extract the substances from seaweed in a precise manner.

In fact, fucoidan is difficult to obtain in clean form without destroying its structure, as it is encapsulated in the walls of the seaweed cells and is closely tangled up with another type of polysaccharide—alginate—which makes it difficult to extract it without destroying the natural structure of fucoidan.

But a new biotechnology method developed by researchers at DTU Bioengineering—headed by Professor Anne S Meyer—makes precisely this extraction possible. In their method, enzymes are used to cut fucoidan from seaweed very precisely in its natural structure. Firstly, the enzymes cut the other carbohydrates—which include alginate—from the cellular walls of the seaweed, and the researchers can then extract the fucoidan structures in intact form without having to untangle them from other carbohydrate structures.

Ophthalmologists from Kiel in Germany have now tested the fucoidan structures against AMD in ocular cells, and their tests have shown that fucoidan is effective in preventing AMD-promoting mechanisms in ocular cells. The tests also showed that the protective treatment of the ocular cells was only effective for the fucoidan extracted from seaweed using the researchers’ new method, and it offers hope that the newly developed method can be used to develop prevention of or a simple cure for AMD:

“If it is possible to drip eyes with this enzymatically extracted fucoidan from seaweed, it opens up for the possibility of developing a simple, gentle, and inexpensive method for AMD prevention and treatment”, says Professor Anne S. Meyer from DTU Bioengineering, who has been developing the enzyme method together with Postdoc Maria Dalgaard Mikkelsen and a team of PhD students from Vietnam.

Anne S Meyer says that it is a completely new discovery that an enzymatic seaweed extract can be good for the eyes. Even though the enzyme technology for extracting fucoidan is well tested and can be scaled up to industrial production, she finds that there is still some way to go before the efficacy of the fucoidan substances has been documented in clinical trials and they can be offered to patients.

Seaweed industry in Denmark

The results also show the way towards utilizing local seaweed plants for medicinal products:

“Commonly occurring seaweed such as sweet tangle and bladder wrack can turn out to be new valuable raw materials and spark an industry in which seaweed is grown in our part of the world. The type of seaweed from which we extract fucoidan and alginate is normally produced in South America and Southeast Asia, which means that there are potentially both large climate-friendly transport cost reductions and great possibilities for developing new processes for this type of seaweed,” says Anne S. Meyer.

The results from the AMD eye tests have been published in the article Effects of a Newly Developed Enzyme-Assisted Extraction Method on the Biological Activities of Fucoidans in Ocular Cells in thejournal Marine Drugs and have been presented at the virtual ABC Conference  Algae Bioactive Compounds – from Research to Innovation on 25-26 August 2020.