Crimson bottlebrush (Callistemon citrinus)

Callistemon citrinus is an evergreen shrub originating from Australia and known as Crimson bottle-brush, Red bottle-brush or lemon bottle-brush. The name derives from its original shape and form, and it was given by Robert Brown (21 Dec 1773 – 10 Jun 1858), a Scottish botanist that made important contributions to botany through the use of microscope [4]. It means beautiful stamens.

The genus Callistemon belongs to family Myrtaceae, a genus that has among its 140 genera approximately 3800 species [6]. Image: Herbcyclopedia.

CALLISTEMON CITRINUS

Family: Myrtaceae
Genus: Callistemon
Common name: Crimson bottle-brush, Lemon bottle-brush, Red bottle-brush.

CALLISTEMON CITRINUS ACTIVE CONSTITUENTS

Callistemon citrinus has a total of 24 active constituents, of which the most common one is 1,8-cineole, with a 61,2% and alpha-pinene (α-pinene)in a concentration of 13,4%. Other active constituents found on this herb includes α-pinene, β-pinene, α-terpinene, linalool, trans-pinocarveol, terpinen-4-ol, geraniol and α-terpineol [6,7,8].

Callistemon viminalis, another type of Callistemon, contains a total of 12 active constituents of the most common one is 1,8-cineole, with a 83,2% and alpha-pinene in a concentration of 6,4%.

Both active constituents present in the essential oil of Callistemon citrinus and Callistemon viminalis showed in vitro antibacterial activity when confronted to 12 bacteria strains, among which S. faecalis, S. aureus, B. cereus and S. macracesens.

Mark Moss and Lorraine Oliver, two researchers from the Brain, Performance and Nutrition Research Center at Northumbria University in the UK, published the results of an experiment in which 1,8-cineole was directly and proportionally related to an improvement of the cognitive functionon twenty healthy volunteers that participated in the experiment. 1,8-cineole is also found as an active constituent of Rosemary oil (Rosmarinus officinalis).

The performance related improvement varied with the concentration of 1,8-cineole, being higher at higher concentrations of 1,8-cineole [3]. In spite the relationship between Rosemary 1,8-cineole and mood was also tested, the results were no as significant as those obtained on other cognitive function performance tests.

WHERE CAN WE FIND 1,8-CINEOLE?

In spite the study performed by Mark Moss and Lorraine Oliver was focused on Rosemary oil, the amount of 1,8-cineole present in Rosemary oil (15.74%) is significantly lower than in other herbs [4], where it is also found with other phytochemicals as camphor (27.59%), α-pinene (16.58%) and β-myrcene (10.02%) [4].

Other herbs as Anthemis pseudocotula and Anthemis creticasubspecies pontica (Asteraceae family), have higher amounts of1,8-cineole (39.40%) [5], being their other active constituents camphor (9.36%), artemisiaketone (5.68%), filifolene (5.15%), a-terpineol (4.69%), beta-caryophyllene (20.26%), azulene (14.98%), spathulenol (6.03%), and germacrene D (5.82%) [5].

Artemisia annua contained a total of 14.9% of 1,8-cineole [20]. InEucalyptus loxophleba the total content of 1,8-cineole reached 39.4% [21].

CALLISTEMON CITRINUS PROPERTIES

In spiteCallistemon citrinus has been used mainly as an ornamental plant, recent studies on the antibacterial properties of the essential oils of Callistemon citrinus [1] brought the interest of scientist on other possible uses for this plant. Other documented uses of Callistemon citrinus included the use of powdered flowers for cold malaria and cough and dry flowers in migraine [5].

ANTIBACTERIAL PROPERTIES OF CALLISTEMON CITRINUS

Among the many active constituents and phytochemicals found in Callistemon citrinus, α-pinene, β-pinene, α-terpinene, 1, 8-cineole, linalool, trans-pinocarveol, terpinen-4-ol, geraniol and α-terpineol showed certain antibacterial activity [6,7,8].

Callistemon viminalis antibacterial properties are probably exerted by this plant due to its quorum sensing inhibitory properties. Quorum sensing, also known as bacterial intracellular communication, is the mechanism by which cells are able to control basic cellular activities and coordinate their actions, and the way bacteria is able to infect our bodies in a coordinated and structured way. Breaking bacterial intracellular communication or quorum sensing, is a way to stop bacterial infections on a natural way that scientists and pharmaceutical companies have investigated since recent years to fight multi-drug resistance of certain groups of bacteria. Image right: Callistemon viminalis by mauroguanandi under Creative Common license (CC BY 2.0).

Callistemon viminalis, together with Conocarpus erectus (Combretaceae), Chamaecyce hypericifolia (Euphorbiaceae), G. Don (Myrtaceae), Bucida burceras (Combretaceae), Tetrazygia bicolor (Melastomataceae), and Quercus virginiana (Fagaceae), showed quorum sensing inhibitory properties against Chromobacterium violaceum and Agrobacterium tumefaciens bacterial strains [9].

CALLISTEMON CITRINUS SIDE EFFECTS AND PRECAUTIONS

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REFERENCES:

[1] PUBMED. Chemical composition and antibacterial activity of the essential oils of Callistemon citrinus and Callistemon viminalis from South Africa.
Oyedeji OO, Lawal OA, Shode FO, Oyedeji AO.
School of Chemistry, University of KwaZulu-Natal, Westville Campus, South Africa.

[2] Dirr's trees and shrubs for warm climates: an illustrated encyclopedia By Michael Dirr

[3] Australian wildflower paintings by Dorothy Gordon, D. Gordon, Jean Harslett, Arts Council of Australia. Meandarra Branch

[4] Wikipedia

[5] Direct Uses Of Medicinal Plants And Their Identification
By R.Vardhana

[6] Acute toxicity, brine shrimp cytotoxicity and relaxant activity of fruits of callistemon citrinus curtis Niaz Ali,corresponding author#1,2 Ghayour Ahmed,2 Syed Wadood Ali Shah,2 Ismail Shah,2 Mehreen Ghias,2 and Imran Khan3
1Department of Pharmacology, Institute of Basic Medical Sciences, Khyber Medical University, Peshawar, KPK, Pakistan 2Department of Pharmacy, University of Malakand, Chakdara, Dir, KPK, Pakistan 3Department of Biotechnology, University of Malakand, Chakdara, Dir, KPK, Pakistan.

[7] Oyedeji OO, Lawal OA, Shode FO, Oyedeji AO. Chemical Composition and Antibacterial Activity of the Essential Oils of Callistemon citrinus and Callistemon viminalis from South Africa. Molecules. 2009;14:1990–1998. doi: 10.3390/molecules14061990.

[8] Riaz M, Chaudhary FM. The chemical composition of Pakistani Callistemon citrinus oils. J Ess Oil Res. 1990;2(Suppl 6):327–328.

[9] Anti-quorum sensing activity of medicinal plants in southern Florida.
Adonizio AL, Downum K, Bennett BC, Mathee K.
Department of Biological Sciences, Center for Ethnobiology and Natural Products, CENaP, Florida International University, 11200 SW 8th Street, University Park, Miami, 33199, USA.