This post was most recently updated on January 5th, 2019



Eucalyptus plant is a tall tree that grows wild in warmer climate with diverse genius of trees. They are about several hundred species of eucalyptus plants.


Eucalyptus oil is an essential oil distilled from the leaves of eucalyptus plants with a strong sweet smell. It is a photochemical extracted from eucalyptus leaves by steam distillation.


The oil is divided into three major classes:


Medicinal oil

Industrial oil, and

Aromatic oil


The essential oil of eucalyptus citriodora is yellowish in color with a lemon scented aromatic smell. The leaves have antibacterial and antifungal properties.


The spread of drug resistant pathogens has caused a serious threat to the spread of infectious diseases. Escherichia coli, which is a gram negative bacteria, have prevailed in infectious diseases, with the right application of these oils, such infections can be suppress.


This oil contain essential component of organic compounds called terpenoids. Let look at what is terpenoid.

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The fresh leaves of eucalyptus citriodora hook were collected from five different locations within the University of Maiduguri Campus. The oil was extracted immediately after sample collection by steam distillation. 40g of the leaves was placed into 250ml 0f water and heated in a conical flask .The temperature was maintained at about 98 C. The process ̊ lasted for three and half hours. The distillate was yellowish in colour. Antibacterial screening was carried out using Mueller-Hinton-Agar. The Agar disc diffusion method was employed. The result of the antibacterial activity test revealed that the essential oil of eucalyptus citriodora has an antibacterial activity against Escherichia coli with inhibition zone ranging from 6mm to 15mm of both low and high concentration respectively.


Aims and objectives and Significance of the study


This research work is centered on the extraction of oil from eucalyptus citriodora hook leaf and its antibacterial effect on Escherichia coli.


A literature review of bioactive terpenoids


What are terpenoids? Plant terpenoids are used in traditional herbal remedies. Steroids and sterols are biological compounds produced from terpenoids pr4ecursors and are found to be medically useful.


Terpenes(limonene), aid in elevating the mood of an individual. They are useful in pollination and wards off insects due to their pungent smell.


The various medicinal terpenoids of medical importance and plant origin are:






















Excisanin A, and

Ardisiacrispin A


Non infectious diseases conditions including cancers can be suppressed by medicinal terpenoids. Caution should be taken when apply these substances on the body. It should be used with the Doctor’s consent.


Bioactive terpenoids are found to be useful medically and have antifungal, anti-parasitic, antiviral, anti-allergenic, anti-pasmodic, anti-inflammatory and immune modulating properties.


More than 3600 terpenoids have been identified and it is the largest class of plant’s metabolites.


Terpenoids are widely used in the production of perfumes and as insect repellents. The medicinal properties of terpenoids have been extensively studied and evaluate for it’s medical properties.


Eucalyptus plant is a very good example of the source of these terpenoids or essential oils.


Eucalyptus plant


Eucalyptus citriodora plant is naturally ever green with oil glands, but loses its leaves during the summer or the dry season. They are commonly lanceolate, petiolate and glossy green.


The most conspicuous feature of eucalyptus citriodora hook is the flower and fruit. (Capsules or gum nuts).


All annual eucalyptus put on annual layer of bark which varies with the age of the plant, the manner of bark shed, the length of the bark fibers, the degree of furrowing, the thickness, hardness and the color. They include;

Stringy bark

Iron bark,

Tessellated bark, and

Ribbon bark.


The lemon-scented gum mainly consist of citronella is used as insect repellents.  Eucalyptus oil has anti inflammatory and analgesic properties.


The cineole-based oil used as a component in pharmaceutical precipitations, to relieve the symptoms of influenza and cold.


The essential oil is used in personal hygiene, dental care, soaps and in wounds to prevents infections.


Eucalyptus oils is used as flavorings in beverages, confectionery, bake foods and meat products at low levels (0.002%). It is dangerous when taken into the mouth.


Eucalyptus oils (5% of mixture) prevent the separation problem of ethanol and petrol fuel blend.


It has a variety of industrial applications.


It is difficult to find reliable references concerning their pharmacological merits, but studies have shown that certain essential oils may have the ability to prevent the transmission of some drug resistant strain of pathogens especially staphylococcus, streptococcus and Candida.


Eucalyptus oil has a wide range of therapeutic properties including:





Stimulant and so on.


Click the link below to download the free eBook on the extraction of oil from eucalyptus citriodora hook leaf and its antibacterial effect on Escherichia coli, and check out more.


The antibacterial effects of eucalyptus oil