Some compounds in certain essential oils made from plants such as anise, fennel and cloves could be used as natural treatments for liver and lung conditions caused by air pollution, according to a new study conducted by Miriana Kfoury and published in the journal Environmental Chemistry Letters.

The research is the first of its kind to examine the efficacy of using certain essential oil compounds to treat inflammation caused by fine particles which are common to hazy, polluted air, and known to be carcinogenic.

Plants contain various essential oils comprised of different compounds, some of which have been shown to have antioxidant properties and the ability to fight inflammation.

For example, a group of natural compounds which can be found in the essential oils of some plants – called phenylpropanoids – display promising anti-inflammatory characteristics. Some of these phenylpropanoids include estragole (found in basil), eugenol (which occurs in clove-bud oil), trans-anethole (component of anise and fennel), and isoeugenol, contained in ylang-ylang – a tropical tree from Southeast Asia.

To test their properties, the researchers collected polluted air samples containing fine particles in Beirut, Lebanon, and introduced them to human liver and lung cell cultures. This caused inflammation, evidenced in a secretion of pro-inflammatory substances called cytokines – which the body releases when fighting infections.

Next, the team introduced four compounds – trans-anethole, estragole, eugenol and isoeugenol – to the cell cultures to assess whether they could protect the liver and lung cells. They found that the essential oil compounds, significantly decreased the levels of cytokines in the cells – by up to 96% in some circumstances.

"The findings provide the first evidence that natural essential oil components counteract the inflammatory effects of particulate matter, such as that contained in polluted air," says Kfoury.