Eucalyptus - not only the favorite plant of the koalas (part 4)
After 1,8 Cineol and Pinene, we´d like to introduce three more active ingredients to you, which we have chosen because they are valuable components in eucalyptus. Please read on and find out about limonene, alpha-phellandrene and p-cymene and their properties.
Limonene is a natural substance from the group of terpenes (monocyclic monoterpenes). There are two enantiomers, the (D) - (+)-limonene and the (S) - (-)-limonene.
It is well known for its wide use in alimentary items or cleaning products, and often found as fragrance in cosmetics. It is also of great interest for health applications, as extensive studies showed a potential of limonene to aid in prevention or treatment of various diseases This is due to anti-inflammatory, antioxidant and anticancer effects described for limonene, to mention some (Vieira et al., 2018) Besides, limonene also shows antibacterial, antifungal and antiviral properties, similar to other eucalyptus compounds (e.g. cineole, beta pinene, ...). Examples for this are the effectiveness against food-borne pathogens such as S. aureus, B. cereus, E. coli and Campylobacter jejuni (Chen et al., 2008; Sandasi et al., 2008). Limonene from eucalyptus leaves is also considered to be the chemical compound associated with rust resistance of Eucalyptus spp. (Silva et al., 2019).
Alpha-Phellandrene, also known as dihydro-p-cymene, a further natural compound found in eucalyptus oil. It belongs to the class of organic compounds that are also known as menthane monoterpenoids. These are monoterpenoids that include 3 isomeric types, namely, o-, m-, or p-menthanes, with the latter, being the most common ones. Alpha-phellandrene is widely used in the food and perfume industry due to their pleasing scent.
In a study with mice, alpha-phellandrene did not show antimicrobial effects as such, but stimulated macrophage proliferation (Mac-3) and promoted their function in vivo. It also affected cellular populations of immune-associated leukocytes, increased cytotoxic effects of NK cells and stimulated B- and T-cell proliferation. Based on such observations, alpha-phellandrene seems to be able to promote the immune response, thereby indirectly suppressing intracellular bacterial growth (Lin et al., 2015; Russo & Marcu 2017
P-cymene (p-isopropyltoluene) is an aromatic organic compound found in many foods, such as orange juice, carrots, raspberries, and almost every spice and is found in volatile oils from over 100 plants, including eucalyptus. It is the biological precursor of carvacrol, compared to which it has less antimicrobial activity. This is due to a missing hydroxyl group, which is thought to play a key role in antimicrobial characteristics. (Ultee et al., 2002, Santana et al., 2011). P-cymene finds important uses in pharmaceuticals and in the production of fungicides and pesticides, mainly acting as flavoring substance (Selvaraj et al., 2002, Eaton 1997). Studies also indicate a potential for analgesic and anti-inflammatory properties in mice as wells as antioxidant properties. Such findings suggest that p-cymene could also contribute to new strategies on counteracting diseases in which oxidative stress plays an important pathophysiological role (Santana et al., 2011, Bonjardim et al., 2012, Xie et al., 2012, Oliveira et al., 2014).
Did you know?
To produce ~ 2 liters of essential oil you need about 100 kg of eucalyptus leaves.
After her study in agriculture sciences at the university of natural resources and life sciences in Vienna, Elisabeth joined the Delacon family in December 2013 as Technical Communications Manager. A position, she still exerts with pleasure after her return from maternity leave and at alongside of Anne. Elisabeth describes herself as a great animal and nature lover and prefers to spend her free time high up in the mountains with her little family, away from the hustle and bustle.