THE ANTI-INFLAMMATORY EFFECT OF ALOE VERA GEL (Aloe barbadensis Miller)

ON YEAST-INDUCED PAW EDEMA IN ALBINO RATS (Rattus Norvegicus strain Wistar)

Nur Permatasari, BP Putra Suryana, Nor Aimi Mohd Shairy*

ABSTRACT

One of Non Steroidal Anti-inflammatory drugs (NSAID) side effect is peptic ulcer.

Aloe vera gel is mucilage obtained from parenchymal tissue which contains some active

compounds such as polysaccharides, sterol and salicylic acid. The objective of this research

is to prove that Aloe vera gel has the effect in reducing the paw edema of the albino rat

induced by yeast. This research is a true experimental design. In this research, the

measured variable was the edema volume of the rat’s hind paw that has been injected with

yeast. Twenty five male strain Wistar rats were used and had been divided into four groups

including one positive control group and three experimental groups with different dosages of

Aloe vera gel (1.0%, 2.0% and 3.0%). Data analysis resulted by One-way ANOVA showed

that Aloe vera gel had the inhibition activity thus reduced the paw edema measured in the

certain interval of time (p<0.05). Based on Pearson correlation test, there was significant

strength between different dosages of Aloe vera gel and its effect (p<0.05). These results

demonstrated that Aloe vera gel have the effect in reducing the paw edema of the right hind

paw of albino rat induced by yeast.

Keyword: Aloe vera gel, paw edema inhibition, inflammation

ABSTRAK

Salah satu efek samping penggunaan Obat Anti Inflamasi Non Steroid adalah ulkus

lambung. Gel lidah buaya merupakan lapisan terkandung dalam sel-sel parenkim daun lidah

buaya segar dan mengandung beberapa senyawa aktif, yaitu polisakarida, sterol dan asam

salisilat. Tujuan penelitian ini adalah untuk membuktikan pengaruh gel lidah buaya dalam

mengurangi edema pada telapak kaki tikus akibat induksi ragi. Penelitian ini merupakan

penelitian eksperimental murni. Variabel yang diukur pada penelitian ini adalah volume

edema pada telapak kaki tikus yang diinjeksi ragi. Dua puluh lima ekor tikus strain wistar

jantan dibagi dalam 4 kelompok yang meliputi; satu kelompok kontrol positif dan 3 kelompok

perlakuan yang diberi gel lidah buaya dalam berbagai dosis (1.0%, 2.0%, dan 3.0%). Hasil

analisa data dengan One-Way ANOVA menunjukkan bahwa gel lidah buaya dapat

menurunkan edema pada telapak kaki tikus yang telah diinjeksi ragi dalam interval masa

yang tertentu (p<0.05). Berdasarkan uji korelasi pearson diketahui bahwa terdapat pengaruh

yang kuat antara pemberian gel lidah buaya dalam berbagai dosis dengan efeknya (p<0,05).

Kesimpulan yang didapat dari penelitian ini adalah gel lidah buaya memiliki pengaruh dalam

mengurangi edema pada telapak kaki tikus albino akibat induksi ragi.

Kata kunci: gel lidah buaya, inhibisi edema pada telapak kaki, inflamasi.

INTRODUCTION

Inflammation is the most common

biological reaction to a variety of stimuli

and local injury triggered by physical or

chemical trauma, invading organisms, or

antigen-antibody reactions. This process

often resulted in swelling or edema of

tissues, pain or even cell damage

(Robbins and Cotran, 1999). Steroid drugs

such as cortisone reduce the inflammation

process through the inhibition of

phospholipase enzyme while non-steroidal

drugs such as aspirin work through the

inhibition of cyclooxygenase (Ganiswarna,

1995). Some steroidal drugs such as

cortisone may cause deleterious effect on

bone strength while some non steroidal

anti-inflammatory drugs (NSAIDs) such as

aspirin may cause irritation of the stomach

and in the long term usage may lead to

bleeding ulcers (Jonathan, 2008).

Aloe vera (Aloe barbadensis Miller)

plants grow as perennials in tropical and

sub-tropical regions, where the leaves of

these clump-forming succulents are

evergreen (Gorman and Park, 2004).

Previous phytochemical investigation of

the plant revealed the presence of sterols,

salicylic acid, polysaccharides, vitamins

and other compounds that contribute to

the therapeutic effects of Aloe vera gel in

reducing the inflammation problem. Aloe

vera sterols might have an anti-

inflammatory effect by the inhibition of

phospholipase A2. In addition, salicylic

acid in the Aloe vera gel might inhibit the

prostaglandin production through the

inhibition of cyclooxygenase (Vasquez et

al, 1996). But unlike aspirin and other anti-

inflammatory drugs, Aloe vera gel does

not cause irritation of stomach and any

other unwanted side effects (Barcroft and

Myskja, 2003). Previous studies showed

that Aloe vera gel has cytoprotective effect

on gastric mucosa by stimulating

endogenous prostaglandin production

which could inhibit the gastric acid

secretion (HCL) and promote mucus

production (Robert, 1979). Other findings

demonstrate that polysaccharide such as

Acemann in Aloe vera gel elevate IL-10

which limit tissue damage caused by

inflammation hence protect the mucosal of

gaster from any injury (Kallaya, 2006).

METHODOLOGY

This research is a true experimental

design (one group pre test, post test

design) aimed to prove that Aloe vera gel

has the effect in reducing the paw edema

of the albino rat induced by yeast. The

independent variable in this research was

the dosage of Aloe vera gel (1.0%, 2.0%

and 3.0%) while the dependent variable

was the paw edema volume of the rat

measured in milliliter at certain interval of

time.

Aloe vera gel is the colourless leaf

pulp or mucilage obtained from the

parenchymal tissues that make up the

inner portion of the leaves.

Yeast is the dry yellow powder that

has yeast odor, soluble in water and was

injected on the right hind paw of the rat to

induce edema.

Edema is the increasing of the paw

sizes measured by subtracting the paw

edema volume before and after treatment

in certain interval of time at every dosages

group (1.0%, 2.0% and 3.0%).

Yeast-induced edema test

The Aloe vera gel activity was

evaluated on Rattus Norvegicus in groups

of five animals for each dose. The gel at

dosages of 1.0%, 2.0% and 3.0% were

administered orally an hour before the

subcutaneous injection of 0.2 ml of yeast

(5%) in the right hind paw of the rat

(Sekiguchi et al, 2008). The control group

received distilled water. Paw volumes

were measured by soaking the right hind

paw of the rat into a measuring cylinder

filled with 20ml of water 30 min before

yeast injection, and then thereafter every

30 minutes until the interval of time reach

180 minutes. The paw edema volume

changes were calculated by subtracting

the volume of the paw edema after yeast

injection with the paw edema volume

before yeast injection.

Percentages of inhibition were

obtained for each group and at each

record using the following ratio (Vasquez

et al, 1996):

(Vt – Vo) control – (Vt – Vo) treated x100

(Vt – Vo) control

Where “Vt” is the mean paw volume for

each group after yeast treatment and “Vo”

is the mean paw volume obtained for each

group before yeast treatment.

RESEARCH RESULTS

The anti-inflammatory effect of the

gel was evaluated by measuring the

increasing of the inflamed paw volume.

The volume measurement was taken for 3

hours with 30 minutes of time interval. The

result obtained was then calculated for the

percentage inhibition as the standard data

analysis showed in the table below.

Table 5.2 The percentage inhibition (%) of the paw

edema volume of the rats in certain interval of times

Group/

Time

(min)

0’ 30’ 60’ 90’ 120’ 150’ 180’

Control 0 0 0 0 0 0 0

1.0% 0 0 0 27.59 33.38 24.24 20.59

2.0% 0 0 0 48.28 48.28 36.36 32.35

3.0% 0 0 0 41.37 30.30 27.27 17.64

The data was then plotted in the graph

below.

Graph 5.1 the percentage inhibition of the paw

edema (%) in the interval of time (min).

0

20

40

60

0' 30' 60' 90'120'150'180'

Per

cen

tage

inh

ibit

ion

of

the

paw

ed

ema

volu

me

Time/min

1.0%

2.0%

3.0%

Control

Based on the graph 5.1, it shown

that 1.0% dosage of Aloe vera gel had

started to show the response at 90

minutes and reached the maximum effect

at 120 minutes; while dosage of 2.0% start

to show the response at 60 minutes and

reached the maximum effectiveness at 90

minutes. According to table 5.1, it is

shown that for dosage of 3.0%, whenever

it reaches the maximum effect, it will then

decrease for next time interval. From the

graph of 5.1, it shown that the effect of

3.0% of dosage of Aloe vera gel reaches

its peak gradually and after that, it starts to

decline. Therefore, for the dosage of

3.0%, it is assumed that the graph is

actually shifted to the left whereby the

maximum effect occurs at less than 90

minutes.

As the conclusion, the pattern of

the percentage of inhibition is highest at

dosage 2.0% followed by dosage 1.0%

and then dosage 3.0% after three hour of

experiment with the percentage of

inhibition of 32.35%, 20.59% and 17.64%

respectively.

Data obtained were analyzed using

the SPSS version 16.0. The statistical

tests used to process and evaluate the

collected data were One Way ANOVA.

From the normality test, the data of paw

edema volume in certain time interval

according to different dosage of Aloe vera

gel were normally distributed with p>0.05.

The data also were homogenous with

p>0.05. These two tests fulfilled the

ANOVA test condition. One-way ANOVA

analysis has been done to compare

between the paw edema volumes with the

different dosage of Aloe vera gel given. As

p>0.05, the data showed there that there

were significant different between the paw

edema volume measurement in every

different dosages of Aloe vera gel given.

Post Hoc Tukey’s LSD showed that there

were significant differences between the

groups of Aloe vera gel dosage with the

paw edema volume measurements of the

rats (p<0.05). In addition, correlation test

resulted in significant value of 0.020

(p<0.05) with -0.197 of coefficient

correlation. This showed that there were

significant strengths of association

between the dosages of Aloe vera gel and

their effect in reducing the paw edema

volume of the rats.

DISCUSSION

The injection of 0.2 ml of 5% yeast

provoked acute inflammation process

characterized by edema formation. The

yeast caused the disturbance of

phospholipid membrane through the

action of phospholipase A2 which results in

the formation of arachidonic acid (Carolyn,

2008). The arachidonic acid formed the

prostaglandin through the cyclooxygenase

pathway thus increased capillary

permeability and caused the accumulation

of fluid in the extravascular space thereby

promoting the edema formation (Katzung,

2004). This reaction can be observed in

the control group of the experiment.

The Aloe vera gel showed the

effect in reducing the paw edema volume

of the rat. It is assumed that Aloe vera gel

has the anti-inflammation effect. This is

supported by the previous research which

revealed that Aloe vera gel contain

salicylic acid that has the effect on

inhibiting the cyclooxygenase (Vasquez et

al, 1996). In addition, Aloe vera gels also

contain sterols that might have anti-

inflammatory effect due to their structural

similarity with the anti-inflammatory

steroids (Suga et al, 1983). Besides that,

there might be some other active

constituents such as polysaccharides and

many others substance that have the anti-

inflammatory effect which played roles in

inhibiting the edema formation in this

experiment. This reaction can be observed

in the intervention group which received

dosages of 1%, 2% and 3% of Aloe vera

gel.

In the intervention group using

Aloe vera gel dosage 1.0%, the effect

started to show at 90 minutes and reached

the maximum effect at 120 minutes which

was slower than the other two dosages

groups while dosage 2.0% started to show

the effect faster than dosage 1.0% at 60

minutes and reached the maximum

effectiveness at 90 minutes. Meanwhile

dosage 3.0% had started reach its peak

gradually at 90 minutes and show no more

increment or plateau phase recorded after

it reached the peak effect. These showed

that the duration of action shortens with

the increase of dosage. This is assumed

to happen because there are other active

constituents inhibited the actions of

salicylic acid, sterols and other anti-

inflammatory substances. These actions

resulted in the shortening of anti-

inflammatory effect. Thus, there is no

dose-response and time-dependent effect

can be observed in this experiment.

The mechanism of action of this

Aloe vera gel in reducing the paw edema

volume depends on the active constituents

involved. Salicyclic acid reduced the paw

edema progression by the inhibition of the

cyclooxygenase hence controlled the

excess formation of prostaglandins

(Vasquez et al, 1996). This caused the

decreasing of the capillary permeability

thereby reducing the edema progression

on the rat’s paw. In addition, sterols inhibit

phospholipase A2 enzyme which

responsible for arachidonic acid liberation

thus reduced the prostaglandin production

and the paw edema progression (Suga et

al, 1983). Meanwhile, there are also

unknown active constituents in Aloe vera

gel which could act as anti-inflammatory

agents with different mechanism of action.

From this research we can

conclude that Aloe vera gel is effective in

reducing the paw edema volume of the

yeast-induced albino rat. The percentage

of edema inhibition was highest for the

dosage of 2.0% followed by 1.0% and

3.0%.

However there were several

limitations in this experiment. The graph of

3.0% reaches its peak gradually and after

that it starts to decline. Therefore, it is

assumed that the graph is actually shifted

to the left thus the yeast should be

injected less than 60 minutes in order to

obtain the actual maximum effectiveness

of the gel. In addition, the time interval

between each paw edema measurements

should be narrowed from 30 minutes to 15

minutes to obtain the actual onset of

action of the gel. In this research also, we

only focused the effect of Aloe vera gel on

decreasing the edema induced by

inflammation. Other signs of inflammation

response such as color (increased heat),

rubor (redness), dolor (pain) and function

laesa (loss of function) were not studied in

this experiment. Besides that, the active

constituents and their proportion which

played the role in reducing the

inflammation process are still unknown.

Perhaps the active constituents work

individually or together with other active

constituent in reducing the inflammation

process.

CONCLUSION

From the research result, it can be

concluded that;

1. Aloe vera (Aloe barbadensis miller)

gel could reduce the paw edema of

the yeast-induced albino rat.

2. There was no dose-response and

time-dependent anti-inflammation

effect because Aloe vera gel may

has many active constituents that

have different activity and different

onset of action.

3. There are many active constituents

in the Aloe vera gel such as

salicylic acid, sterols,

polysaccharides, vitamins and

other substances that may acted

as anti-inflammatory agents.

SUGGESTIONS

From this experiment, the suggestions for

future research are:

1. Further research is needed to

know the exact mechanism of

action of Aloe vera gel in

reducing the inflammation

process.

2. Further research is needed to

elucidate the components or

active constituents in Aloe vera

gel that responsible in reducing

the inflammation process.

3. Further study is needed to

know the effect of Aloe vera gel

on the other kind of

inflammation signs such as

color, rubor and function laesa.

4. Yeast should be injected lesser

than 60 minutes and the time

interval between each paw

edema measurements should

be narrowed from 30 minutes

to 15 minutes to obtain the

actual onset of action of the

gel.

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