Backhousia Citriodora Leaf Oil is a naturally derived product made from the leaves of the "lemon myrtle" a plant belonging to the Myrtaceae family.

The name describes the structure of the molecule:

• Backhousia Citriodora is the scientific name of the plant commonly known as lemon myrtle. This plant is native to Australia and is noted for the strong lemon scent of its leaves.
• Leaf oil indicates that the product is an essential oil extracted from the leaves of Backhousia citriodora.

Industrial Production Process

Leaf collection. Backhousia Citriodora leaves are harvested during the hottest part of the year when the essential oil content, particularly citral, is at its peak.

Steam distillation. Fresh or slightly dried leaves are loaded into a distillation apparatus. Water is added and heated to generate steam, which passes through the plant material, extracting the essential oils.

Condensation. The steam laden with essential oils is passed through a condenser, where it cools and returns to a liquid state.

Separation. The essential oil separates from the distillation water (hydrosol) due to the difference in density between the two liquids. The oil, being lighter, floats on the surface and is collected.

Filtration. The essential oil may be further filtered to remove any physical impurities.

Quality control. Backhousia Citriodora leaf oil undergoes quality testing to verify the concentration of citral and to ensure the absence of contaminants.

What it is used for and where

This extract is valued for its high citral content (1), a compound that imparts a lemon aroma and possesses antibacterial, antifungal, and antioxidant properties (2). It is commonly used in skincare products for its purifying and refreshing properties. Additionally, the extract can help soothe the skin, reduce inflammation, and promote an overall sense of skin well-being. It is ideal for formulations aimed at treating oily, acne-prone skin or minimizing odor in natural deodorants.

Cosmetics - INCI Functions

Cosmetic astringent. This ingredient exerts a direct effect on the skin by tightening dilated pores by contracting stratum corneum cells and removing superfluous oil.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

CAS    84775-80-4

EC number    283-909-7

Main uses and benefits of Backhousia citriodora leaf oil

Antibacterial Properties. This extract is known for its strong antibacterial properties (3), making it effective in treating skin infections and improving overall skin health.

Aromatherapy. The characteristic lemon scent of the extract is used in aromatherapy to relieve stress and improve mood, thanks to its calming and relaxing properties.

Antioxidant. It contains antioxidants that help protect the skin from free radical damage and promote a younger, more radiant complexion.

Calming and Soothing Effects. It is effective in calming irritated and inflamed skin, making it useful in post-procedure products or for sensitive skin.

Purifying. It helps purify the skin by removing impurities and improving skin clarity, ideal for cleanser and toner formulations.

Versatile Application. It can be incorporated into a variety of skincare products, including creams, serums, masks, and body care products, leveraging its health benefits for the skin.

Safety

Products derived from Backhousia Citriodora are generally considered to be safe and of low toxicity (4).

References_____________________________________________________________________

(1) Southwell I. Backhousia citriodora F. Muell. (Lemon Myrtle), an Unrivalled Source of Citral. Foods. 2021 Jul 9;10(7):1596. doi: 10.3390/foods10071596. PMID: 34359465; PMCID: PMC8305781.

Abstract. Lemon oils are amongst the highest volume and most frequently traded of the flavor and fragrance essential oils. Citronellal and citral are considered the key components responsible for the lemon note with citral (neral + geranial) preferred. Of the myriad of sources of citral, the Australian myrtaceous tree, Lemon Myrtle, Backhousia citriodora F. Muell. (Myrtaceae), is considered superior. This review examines the history, the natural occurrence, the cultivation, the taxonomy, the chemistry, the biological activity, the toxicology, the standardisation and the commercialisation of Backhousia citriodora especially in relation to its essential oil.

(2) Lim AC, Tang SGH, Zin NM, Maisarah AM, Ariffin IA, Ker PJ, Mahlia TMI. Chemical Composition, Antioxidant, Antibacterial, and Antibiofilm Activities of Backhousia citriodora Essential Oil. Molecules. 2022 Jul 31;27(15):4895. doi: 10.3390/molecules27154895.

Abstract. The essential oil of Backhousia citriodora, commonly known as lemon myrtle oil, possesses various beneficial properties due to its richness in bioactive compounds. This study aimed to characterize the chemical profile of the essential oil isolated from leaves of Backhousia citriodora (BCEO) and its biological properties, including antioxidant, antibacterial, and antibiofilm activities. Using gas chromatography-mass spectrometry, 21 compounds were identified in BCEO, representing 98.50% of the total oil content. The isomers of citral, geranial (52.13%), and neral (37.65%) were detected as the main constituents. The evaluation of DPPH radical scavenging activity and ferric reducing antioxidant power showed that BCEO exhibited strong antioxidant activity at IC50 of 42.57 μg/mL and EC50 of 20.03 μg/mL, respectively. The antibacterial activity results showed that BCEO exhibited stronger antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis) than against Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). For the agar disk diffusion method, S. epidermidis was the most sensitive to BCEO with an inhibition zone diameter of 50.17 mm, followed by S. aureus (31.13 mm), E. coli (20.33 mm), and K. pneumoniae (12.67 mm). The results from the microdilution method showed that BCEO exhibited the highest activity against S. epidermidis and S. aureus, with the minimal inhibitory concentration (MIC) value of 6.25 μL/mL. BCEO acts as a potent antibiofilm agent with dual actions, inhibiting (85.10% to 96.44%) and eradicating (70.92% to 90.73%) of the biofilms formed by the four tested bacteria strains, compared with streptomycin (biofilm inhibition, 67.65% to 94.29% and biofilm eradication, 49.97% to 89.73%). This study highlights that BCEO can potentially be a natural antioxidant agent, antibacterial agent, and antibiofilm agent that could be applied in the pharmaceutical and food industries. To the best of the authors' knowledge, this is the first report, on the antibiofilm activity of BCEO against four common nosocomial pathogens.

(3) Wilkinson JM, Hipwell M, Ryan T, Cavanagh HM. Bioactivity of Backhousia citriodora: antibacterial and antifungal activity. J Agric Food Chem. 2003 Jan 1;51(1):76-81. doi: 10.1021/jf0258003. 

Abstract. Backhousia citriodora products are used as bushfoods and flavorings and by the aromatherapy industry. The antimicrobial activity of 4 samples of B. citriodora oil, leaf paste, commercial tea (0.2 and 0.02 g/mL), and hydrosol (aqueous distillate) were tested against 13 bacteria and 8 fungi. Little or no activity was found to be associated with the leaf tea and hydrosol, respectively. Leaf paste displayed antimicrobial activity against 7 bacteria including Clostridium perfringens, Pseudomonas aeruginosa, and a hospital isolate of methicillin resistant Staphylococcus aureus (MRSA). The 4 essential oils were found to be effective antibacterial and antifungal agents; however, variation was apparent between oils that did not correlate with citral content. The antimicrobial activity of B. citriodoraessential oils was found to be greater than that of citral alone and often superior to Melaleuca alternifolia essential oil. B. citriodora has significant antimicrobial activity that has potential as an antiseptic or surface disinfectant or for inclusion in foods as a natural antimicrobial agent.

(4) Hayes AJ, Markovic B. Toxicity of Australian essential oil Backhousia citriodora (Lemon myrtle). Part 1. Antimicrobial activity and in vitro cytotoxicity. Food Chem Toxicol. 2002 Apr;40(4):535-43. doi: 10.1016/s0278-6915(01)00103-x. 

Abstract. The antimicrobial and toxicological properties of the Australian essential oil, lemon myrtle, (Backhousia citriodora) were investigated. Lemon myrtle oil was shown to possess significant antimicrobial activity against the organisms Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, methicillin-resistant S. aureus (MRSA), Aspergillus niger, Klebsiella pneumoniae and Propionibacterium acnes comparable to its major component-citral. An in vitro toxicological study based on the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) cytotoxicity assay was performed. In vitro cytotoxicity testing indicated that both lemon myrtle oil and citral had a very toxic effect against human cell lines: HepG2 (a hepatocarcinoma-derived cell line); F1-73 (a fibroblast cell line derived from normal skin) and primary cell cultures of human skin fibroblasts. Cytotoxicity IC50 (50% inhibitory concentration) values ranged from 0.008 to 0.014% (w/v) at 4 h to 0.003-0.012% (w/v) at 24 h of exposure. The no-observed-adverse-effect level (NOAEL) for lemon myrtle oil was calculated as 0.5 mg/l at 24 h exposure and the RfD (reference dose) was determined as 0.01 mg/l. A product containing 1% lemon myrtle oil was found to be low in toxicity and could potentially be used in the formulation of topical antimicrobial products.