Microsoft Word - Agarry et al pdf 2.doc

African Journal of Biotechnology Vol. 4 (12), pp. 1413-1414, December 2005

Available online at http://www.academicjournals.org/AJB

Short Communication

Comparative antimicrobial activities of aloe vera gel

and leaf

Agarry O.O.

, Olaleye M.T.

and Bello-Michael, C.O.

Department of Microbiology, Federal University of Technology, Akure, Nigeria

Department of Biochemistry Federal University of Technology, Akure, Nigeria

Accepted 14 October, 2005

The comparative antimicrobial activities of the gel and leaf of Aloe vera were tested against

Staphylococcus aureus, Pseudomonas aeruginosa, Trichophyton mentagraphytes, T. schoeleinii,

Microsporium canis and Candida albicans. Ethanol was used for the extraction of the leaf after

obtaining the gel from it. Antimicrobial effect was measured by the appearance of zones of inhibition.

Antimicrobial susceptibility test showed that both the gel and the leaf inhibited the growth of S. aureus

(18.0 and 4.0 mm, respectively). Only the gel inhibited the growth of T. mentagrophytes (20.0 mm), while

the leaf possesses inhibitory effects on both P. aeruginosa and C. albicans. The results of this study

tend to give credence to the popular use of both Aloe vera gel and leaf.

Key words: Antimicrobial, Aloe vera gel, Aloe vera leaf.

INTRODUCTION

Aloe vera Linne or Aloe barbadensis Miller is a succulent

from the Aloe family (400 different species) with its origin

in African continent. Its thick leaves contain the water

supply for the plant to survive long periods of drought

(Foster, 1999). The leaves have a high capacity of

retaining water also in very warm dry climates and

therefore this plant can survive very harsh circumstances

where most other vegetation disappears. When a leaf is

cut, an orange-yellow sap drips from the open end. When

the green skin of a leaf is removed a clear mucilaginous

substance appears that contains fibres, water and the

ingredient to retain the water in the leaf. This is called the

gel. A. Vera gel consists of 99.3% water. The remaining

0.7% is made up of solids with glucose and mannose

constituting for a large part. These sugars together with

the enzymes and amino acids in the gel give the special

properties as a skin care product.

The gel stimulates cell growth and as such enhances

the restoration of damaged skin. It moisturizes the skin

because it has a water holding capacity. This moist on

the skin and also has a cooling effect. As a drink it

protects the mucous membrane of the stomach

*Corresponding author. E-mail: [email protected].

especially when irritated or damaged. A. vera juice is

considered helpful for relieving many types of

gastrointestinal irritation and juice products are widely

available (Foster, 1999). In Germany, concentrated

extracts of dried Aloe leaves are used as laxative

preceeding rectal surgery and as a hemorrhoid treatment.

Aloe gel is perhaps the most widely recognized herbal

remedy in the United State today; it is used to relieve

thermal burn, sunburn and promote wound healing

(Foster, 1999). In addition, research suggests that Aloe

gel can help stimulate the body’s immune system (Davis,

1997).

Although a lot of works have been carried out on the

medicinal uses of A. vera gel, there is still little

information on the uses of the leaf. This work therefore

provides information on the comparative antimicrobial

activities of both the gel and the leaf of A. vera.

MATERIALS AND METHODS

Test organisms

Pure cultures of the bacterial and fungal isolates (Staphylococcus

aureus, Pseudomonas aeruginosa, Trichophyton mentagrophytes,

T. schoeleinii, Microsporum canis and Candida albicans) were

collected from the Microbiology Laboratory of the Federal University

1414 Afr. J. Biotechnol.

of Technology, Akure. The organisms were maintained on agar

slants stocks and were subsequently subcultured into newly

prepared nutrient agar slants. The fungal isolates were maintained

on malt extract agar, while Candida albicans was maintained on

Sabouraud dextrose agar.

A. vera gel and extracts

A. vera leaves were purchased from Akure Township in Ondo State

of Nigeria. The gel were gotten from the leaves into a clean

container and used as such. While the leaves from which the gel

have been drained were air dried, ground and soaked in ethanol for

4 days. This was later filtered and the filtrates evaporated to

dryness using a rotary evaporator. The extracts were dissolved in

sterile water and used for the antimicrobial susceptibility testing.

Antimicrobial susceptibility testing

Sterile agar (at 45°C) was poured into sterile petri dishes, which

had been inoculated with the test organisms. The plates were

allowed to gel for an hour. Wells (10 mm diameter) were made with

the aid of flamed cork borer on the surface of the agar plates. About

0.1 ml of each of the gel and the leaf extracts were delivered into

each of the wells. These were incubated at 37°C for 24 h.

Sabouraud dextrose agar plates were used for C. albicans. They

were incubated at 25°C for 5 days. The presence of zones of

inhibition was regarded as the presence of antimicrobial action.

From the inhibition zones seen, antimicrobial activity was expressed

in terms of average diameter of the zones of inhibition measured.

Table 1. Antimicrobial activities of A. vera gel and leaf extract

(25 mg/ml).

Zone of inhibitory mm

Organisms

Gel leaf

Staphylococcus aureus

18.0 4.0

Pseudomonas aeruginosa

0.0 4.0

Trichophyton mentagrophytes

20.0 0.0

Trichophyton schoeleini

0.0 0.0

Microsporum canins

0.0 0.0

Candida albicans

0.0 3.0

RESULTS AND DISCUSSION

The results showed that both the gel and the leaf have

inhibitory effect on S. aureus with zone of inhibition 18.0

and 4.0 mm, respectively. Among the bacteria and fungi

tested, A. vera gel possesses greatest inhibitory effect on

the S. aureus. This result could be responsible for the

popular use of A. vera gel and leaf to relieve many types

of gastrointestinal irritations (Foster, 1999; Grindlay and

Reynolds, 1986) since S. aureus form part of the normal

microbial flora of the skin, upper respiratory tract and

intestinal tract (Cheesbrough, 1984). Also the gel is also

said to promote wound healing due to the presence of

some components like anthraquinones and homones

(Davis, 1997), which posses antibacterial antifungal and

antiviral activities. However, most of the constituents are

found in the gel and not in the leaf; hence the gel is likely

to be more active than the leaf.

The gel also inhibited the growth of T. mentagrophytes

(zone of inhibition: 20.0 mm) while the leaf has no effect

on the organism. This result indicates that gel and the

leaf are made up of different constituents, which is

manifested in antimicrobial activities. However, the leaf

possesses inhibitory effect on P. aeruginosa (zone of

inhibition: 4.0 mm) while the gel had no effect. P.

aeruginosa is known to cause skin infection especially at

burns sites, wounds, pressure sores and ulcers. The

inhibitory effect of the leaf of A. Vera on the growth of P.

aeruginosa gives an explanation of its reputation as a

healing plant for burns.

The growth of C. albicans was also inhibited by A. vera

leaf but was not affected by the gel. Many different

clinical forms of candidiasis are known involving primarily

the mucosa surface (thrush gastrointestinal or urogenital

tract) and deep-seated infections such as candidaemia or

meningitis. Candida vaginitis is a common infection

during pregnancy. Candida infection of the mouth and

esophagus are common in those with HIV disease

(Cheeshrough, 1984). Davis (1997) in his experiment

challenged the medical views of the relationship between

AIDS and HIV infections and A. vera. He sees a

promising role for this natural brood spectrum healing

plant because of its immunodulatory properties can also

act as an immune stimulant. The results of inhibitions

effect on C. albicans also established that the A. vera gel

and leaf, though share certain components, are distinct

from one another (Foster 1999).

In conclusion, more work should also be carried out on

the leaf to reveal some of its potentials. This investigation

shows that both the gel and the leaf are useful and that

they can complement one another in their medicinal

capabilities.

REFERENCES

Cheesbrough M (1984). Medical Laboratory Manual for Tropical

Countries. Vol. 11, first edition. Printed and bond in Great Britain by

the university Press, Cambridge. pp. 372-391

Davis HR (1997) Aloe vera: A Scientific Approach Published by

VantagePress(NewYork, SA<http://www.aloevera.co.uk/rhdavis.htm>

Foster S (1999) Aloe vera: The succulent with skin soothing cell-

protecting properties. Herbs for Health magazine. Health

WorldOnline. <http://www.healthy.net/library/articles/hfh/aloe.htm>

Grindlay D, Reynadds T (1986) “The Aloe vera Phenomenon. A review

of the properties and modern uses of the leaf parenchyma gel. “J.

Ethnopharmacol.16: 117-151.