Evaluation of essential oils

used in aromatherapy with

specific reference to

antimicrobial activity

Dr. Mohd Mujeeb

Faculty of Pharmacy,Jamia

Hamdard, New Delhi

Introduction

Essential oils are the odorous principles found in various

plant parts.Because they evaporate when exposed to the

air at ordinary temperatures,they are called as volatile

oils. They are

commercially important as the basis of natural perfumes

and also of spices and flavourings in food industry.

Chemically they may be hydrocarbon, phenol, ketone,

aldehyde,ester,alcohol etc.

Antimicrobial potential of essential oils

Anti-bacterial

Anti-fungal

Anti-viral

Anti-infectious

Anti-dandruff

Anti-acne

History:

Anti-Infectious Properties

This is the most widely studied area of essential oils; this

property is the only one that is really well-known and used

regularly. In fact, many people associate ‘aromatherapy’ with

‘anti-infectious therapy’

The capacity of essential oils to neutralize germs is now

irrefutable. Experimental studies were undertaken in France

by Chamberland as early as 1887. In 1888, Cadeac and

Meunier published the results of their own research (Annales

de l’Institut Pasteur). Many in-vitro confirmations were

performed by pharmacists and doctors; results were

conclusive. In his book, Anti septiques Essentials, published

in 1938,

Phytoconstituents of essential oils have anti-infectious potential

Anti-bacterial ,Antifungal and Anti-viral

Phenols: Carvacrol, thymol and eugenol

Alcohols: Geraniol, linalool, thujanol and myrcenol,

terpineol, menthol and piperitol

Aldehydes: Neral and geranial (citrals), citronnellal and

cuminal

Ketones: Verbenone, thujone, borneone (camphor),

pinocamphone, cryptone, fenchone, menthone,

piperitone and carvone.

Ethers: estragole and anethole

Oxides: Oxides are mildly anti-infectious. Phtalids are

strongly antibacterial. Other molecular groups

have no antibacterial effects.

Phenol:

Thymol: Trachyspermum ammi (Ajowan)

thymol

Carvacrol: Origanum compactum (Oregano) Origanum

heracleoticum (Greek Oregano) Corydothymus capitatus

(Spanish Oregano) Satureja montana (Winter or mountain

savory) Thymus serpyllum (Wild thyme or mother-of-thyme)

Eugenol: Eugenia caryophyllus (Clove tree) Cinnamomum verum

– leaf (Ceylon Cinnamon)

Ocimum gratissimum (Hot or shrubby basil)

Gaiacol: Guajacum officinalis (Gaiac wood)

Antimicrobial essential oil containing medicinal plants

Alcohol:

Linalool: Aniba rosaeodora (Rosewood)

Coriandrum sativum (Coriander)

Lavandula reydovan

Geraniol: Cymbopogon martinii (Palmarosa)

Thujanol: Origanum majorana (Sweet marjoram or oregano)

Borneol: Thymus satureioides (Thym borneol-carvacrol type)

Inula graveolens (Sweet inula)

Menthol: Mentha piperita (Peppermint)

Mentha arvensis (Field mint or cornmint)

Citronnellol: Pelargonium asperum (Geranium)

Terpineno1 : Melaleuca alternifolia (Tea Tree)

Origanum majorana (Sweet marjoram or oregano)

Alpha Terpineol: Ravensara aromatica (Ravensara)

Eucalyptus radiata (Black or narrow-leaf peppermint eucalyptus

Aldehyde:

Cinnamaldehyde:

• Cinnamomum verum or zeylandicum (bark) (Ceylon

cinnamon (bark))

• Cinnamomum cassia (bark) (Chinese cinnamon (bark)

• Cinnamomum loureirii (bark) (Vietnamese cinnamon (bark)

Cuminal:

• Cuminum cyminum (Cumin)

• Eucalyptus polybractea CT cryptone (Blue mallee

eucalyptus cryptone type)

Phellandral:

• Eucalyptus polybractea CT cryptone (Blue mallee

eucalyptus cryptone type)

Gram+ve bacteria Gram-ve bateria Fungi

Staphylococcus

aureus

Escherichia coli Candida albicans

Diplococcus

pneumoniae

Klebsiella

pneumoniae Aspergillus niger

Micrococcus flavus Haemophilus

influenzae Absidia glauca

Streptococcus

pyogenes

Microorganisms used in study

General Methods for Anti-

microbial Screening

Diffusion Method Cup-plate

Cylinder-plate

Disc-Plate

Dilution Method/Turbidity

Media used : Solid Agar and liquid broth culture media C and D

Cultures: Aspegillus niger, Aspergillus flavus, Candida

albicans, Candida tropicalis, Cryptococcus neoformans and

Trichophyton lignorum etc.

Disc Diffusion Method

Sterile medium D(20 ml )

Culture medium (2 ml)

Prepare a disc of Whatma-1( 6 mm diameter)

Moist disc with test drug, standard and DDSW and

place disc on the surface of the plate

Incubate all petriplates at particular Temp for one week

and measure zone of inhibition

Cup Plate Method

Sterile medium D(20 ml )

Culture medium (2 ml)

Made holes of uniform diameter with sterile borer in solidified medium

Fill holes with test drug, standard and DDSW/DMSO (0.3l)

Incubate all petriplates at particular Temp for one week

and measure zone of inhibition

Anti-microbial activity (Zone

of inhibition)

Drugs

Chloramphenicol

Amoxycyclin

Gentamycin

Sulfonamide

M/o

E.coli

S.aureus

Salmonella

Anti-microbial activity(cup-plate

Model)

Anti-microbial activity (Zone of inhibition)

(Zone of inhibition)

Anti-microbial activity (Zone of inhibition)

Turbidity Method

Sterile medium-C previously seeded with the test organism (9 ml )

Test drug, standard and DDS (1 ml each for each test tube)

Incubate all test tubes at particular Temp for 48 hrs

Measure absorbance at 530 nm

Anti-microbial activity(Turbidity

Model)

Dilutions

Determination of OD

Spectrophotometer

Colony Counter