When the mercury climbs, many residents like to put on a sun hat, hide in the shade of a palm tree or enjoy the cool of an air-conditioned building.
Plants do not have that option in the heat. And it is not just the high temperatures that they have to tolerate.
The biggest challenge for many plants in the UAE is salinity. The water and soil tend to have high salt content, due to factors such as high levels of evaporation that concentrate salts in the soil.
Plants adapted to these salty conditions are known as halophytes and their answer to the extreme conditions is to produce chemicals that provide protection.
Although these substances are often known as “secondary metabolites” because they are not directly involved in growth and reproduction, their role is anything but secondary.
“Just imagine, you stand very still in salty mud all day long. Normal plants cannot do that,” says Dr Mette Thomsen, an assistant professor at the Institute Centre for Energy (iEnergy) at Abu Dhabi’s Masdar Institute of Science and Technology.
“These plants are placed in that environment and there’s no escape. They have to produce a wider range of chemicals than other plants.”
Many of these substances are antioxidants, which are produced by halophytes because conditions of salt stress often lead plants to generate active forms of oxygen, which can prove harmful if they are not dealt with. Similarly, plants also produce more of these “reactive oxygen species” under conditions of heat stress.
But some of these antioxidants and other secondary metabolites are not useful only to the plants that generate them. They can also be of great value to people.
Dr Thomsen and colleagues at iEnergy, along with a researcher at Qatar University, have recently published a paper in the Emirates Journal of Food and Agriculture, which details many of the most useful substances found in halophytes, of which there are as many as 3,000 species worldwide.
The study, titled Phytochemical Composition of Some Common Coastal Halophytes in the UAE, was based on an extensive review of the scientific literature.
Although many of the halophytes in the country have not yet been studied in detail, looking at related species in other parts of the world can indicate what useful substances might be found in the plants here.
The range of chemicals is impressive. For example, Sesuvium verrucosum, a type of carpet weed adapted to salt marshes, is thought to have anti-cancer properties, while a species related to Suaeda iranshahrii, a type of seablite found in salt flats, produces a substance that combats HIV, the virus that causes Aids.
Halophytes have also been shown to produce chemicals that protect the liver, combat diabetes, treat multiple sclerosis and prevent heart disease. Other substances extracted from halophytes have been shown to be useful in cosmetics and for killing microorganisms.
Despite the lack of scientific study of UAE halophytes until now, communities have traditionally identified the potential that native plants can have for treating medical conditions.
“The local students that are working in my lab, a lot of them have stories such as, ‘My grandmother uses this for a stomach upset’. The knowledge is there,” says Dr Thomsen, who is from Denmark.
“If we don’t look into it now, that knowledge will disappear.”
Her work involves much more than searching literature to find out what useful compounds could be found in the halophytes.
She and her team have collected 15 different halophytes that grow in large quantities in the UAE, and have spent the past year carrying out chemical analyses to determine what potentially valuable substances they contain.
While the study has yet to be published, Dr Thomsen can say already that the plants appear to be rich in secondary metabolites.
“It’s no easy task and it takes a lot of time. It’s a smaller task to identify the different compounds; it’s a bigger task to quantify which compounds are there in bigger quantities,” she says.
“What is unusual here is the range of active compounds you find in one plant. Here the plants are very abundant in the array of compounds they produce.”
So far, the scientists have focused their analysis on the secondary metabolites known to be present in these types of plants, looking at their properties and potential uses. But they have also pinpointed the presence of a number of unidentified secondary metabolites, meaning that interesting discoveries are likely to be on the horizon.
“We have lots of products that have not been identified. We believe there’s potential to find new chemicals because Abu Dhabi hasn’t really been explored before and our research is new to this place,” says Dr Thomsen.
The production of active ingredients from halophytes could begin in a relatively short time, perhaps as little as a year or two.
One hurdle to overcome is developing methods to purify the plant extracts, and this process is something Dr Thomsen’s team is working on now. But there are other issues to deal with.
“Another challenge will be to find farmers to set up the farming of these plants,” she says.
Farming halophytes could also lead to mass production of biomass – in this case, largely the fibrous carbohydrates of the plants – that could be used to generate biofuels.
A parallel research project in Dr Thomsen’s lab is looking at seagrasses, which are types of flowering plant, and seaweeds, which are algae, as these also produce secondary compounds that could prove useful.
“Their chemical composition is very different and it’s something we could capitalise on,” says Dr Thomsen.
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