Inhibition of the Fungus (Candida albicans)
using an extract from Fiji Longan
(Pometia pinnata)
Kalolaine Latu
Bio 493 Paper
Advisor: Dr Goodwill
04/23/03
Abstract
Aqueous and pure extracts of Pometia pinnata were examined for antifungal properties against Candida
albicans using the Kirby-Bauer method. Zone of inhibition was determined for 20, 30, and 40l after
incubating at 35C for 24 hrs. A 1% tolnaftate solution was used as a commercial antifungal control. The
results were evaluated by the diameter of the inhibition zone of fungal growth. The commercial antifungal
and the aqueous extracts were active against the C. albicans but the pure extract was significantly more
effective at inhibiting fungal growth.
Introduction
In developing countries, herbal medicine is used not only as a way to rescue
ancient traditions but also as an alternative solution for health problems (Martinez et al.
1996). Throughout Polynesia, medicinal plants have been used to treat a wide range of
physical ailments (Locher et al. 1995). Many are still in use today. Some of the ailments
treated by herbal medicine include topical, respiratory, reproductive, and gastrointestinal
infections caused by fungi (Jones et al. 2000).
Alectryon excelsus from the family Sapindaceae was used by Hawaiians for throat
infections. The green oil was also applied externally to sores, wounds, sore breasts,
bruises, painful joints, weak eyes, chapped skin in infants, and placed in the ear for
earache (Brooker et al. 1987). An alcoholic extract of the roots of Allophylus rubifolius
showed antibacterial activity against Staphylococcus aureus (Khan et al. 1980). The stem
bark of Dodonaea viscosa has been shown to have antibacterial activity against
Staphylococcus albus (Subbarao and Satyanarayana 1985). Extracts from the roots of
Paullinia pinnata are used for skin conditions and the dried powdered rootbark of Zanha
africana, mixed with vaseline, is rubbed over the skin for fungal infections (Chhabra et
al. 1991).
Pometia pinnata (Fiji Longan), also from the Sapindaceae family, is a tropical
forest tree. It is common in lowland rain forests, mostly below 500m elevation, often
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predominating in areas of shallow soil and in mature secondary forest. They grow to 30m
or more and have a flaky bark and a prominently buttressed trunk. The alternate
compound leaves are 18-28cm long, with 6-8 opposite pairs, strongly veined leaflets of 625cm long, and reddish when young. Flowers are tiny and inconspicuous except for the
showy red stamens (Whistler 1992a). The wood is occasionally used for construction and
furniture. The fruit is edible, tasting like Lichi chinensis (Sudarmonowati et al. 2000).
In Tonga an infusion of the bark of P. pinnata is usually given in the morning
when the stomach is empty. It is also used as an emetic for infants with mouth infection
(pala ngutu), diarrhea (fakalele), fever (mofi), diaper rash (veli), and cough (tale). An
infusion of the young P. pinnata leaves with leaves of other plants is used to rub onto the
head of infants or given as a potion to treat an unclosed fontanel (mavae ua). The bark is
boiled with several other plants to treat abdominal ailments known as kahi (Whistler
1992b).
In Fiji, P. pinnata is used to treat deep pain in the bones, migrane headaches, and
to aid in the expulsion of the placenta after childbirth. Stem bark filtrate is also used to
relieve rheumatic aching of muscles and joints and the pain and fever caused by the
parasitic disease filariasis. Fluid extracted from the inner bark is used as a cold or flu
remedy. The entire plant is used to treat an illness described as “sickness inside chest”
(Weiner 1976).
Oral thrush is a disorder caused by the yeast Candida albicans (Krauss 1993).
The signs and symptoms of oral thrush infection are the presence of cream colored to
yellow patches appearing in the mouth. To treat this infection, Tongans scrape the inner
bark from the tree trunk of P. pinnata with a sharp instrument. Two rocks are used as a
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mortar and pestle to crush the plant material. The grated or crushed plant material is
placed in the mesh-like growth found at the base of coconut fronds, or in a piece of cloth.
String is used to tie this to form a bag and the medicine is dripped directly into the mouth,
or collected in a cup and placed directly on the infected area of the mouth of infants
(personal experience).
The purpose of this study was to test whether or not the inner bark of Fiji Longan
(Pometia pinnata) contains antifungal properties against the fungus Candida albicans.
Methods
Test tissues from P. pinnata were prepared by removing the outer bark (periderm)
to obtain the inner bark (secondary phloem). About 100g of the inner-bark was crushed.
Cheesecloth was used to strain the extract and to filter the remains.
Antifungal activity on C. albicans was tested using the Kirby-Bauer method.
Candida albicans was cultured on Sabouraud dextrose medium (Locher et al. 1995). A
plate was divided into four sections. A sterile disc (6mm) was inoculated with 20l pure
sample of the P. pinnata extract and then placed on one section of the plate.
A second disk was impregnated with an extract diluted with water to form an 80%
extract of P. pinnata. The weight of bark materials used in the distilled water extract was
40g while that of the pure extract was 60g. Controls were placed on the other two
sections of the test plates. A blank disk was used as the negative control and a disk with
1% tolnaftate antifungal solution was used as the positive control. The plate was
incubated at 35ºC for 24 hrs. The above procedures were repeated using 30l and 40l
samples of each solution in order to find the most effective dosage. Five replicates were
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conducted using the 20l sample and another five for 30l sample. Twenty five
replicates were tested for the 40l sample. Even though the dosage of the 1% tolnaftate
positive control was changed, the concentration used throughout the test was the same.
The zones of inhibition were measured in millimeters. The data were analyzed using the
f-test.
Results
Both 20l aqueous and pure extracts of P.pinnata showed antifungal activity in
the 20l sample (Table 1). The blank disk did not inhibit the growth of the fungus. The
1% tolnaftate antifungal (positive control) had zero inhibition. The zones of inhibition
produced by the pure extracts in the 20l sample ranged from 1.3 to 2.1 mm with a mean
of 1.78 mm, while the diluted extract produced zones that measured 0.1-1.0 mm with a
mean of 0.54 mm.
The positive control in the 30l sample showed inhibition that ranged from 1.9 to
2.5 mm with a mean of 2.14 mm (Table 2). Both pure and the aqueous extracts were
more effective than the positive antifungal control. The pure extract produced zones of
inhibition that ranged from 3.0 mm to 5.0 mm with a mean of 4.0 mm, whereas the
diluted extract showed inhibition that ranged from 2.0-3.0 mm with a mean of 2.6 mm.
The results of the tests with the 40l sample revealed that the pure extract,
dilution, positive control, and the negative control were significantly different from each
other (Table 3, Fig 1). The positive control showed inhibition that ranged from 2.0-6.0
mm with a mean of 3.1 mm. The zones of inhibition produced by the pure extract ranged
from 7.0 to 10 mm with a mean of 8.56 mm while the diluted extract ranged from 3.0-7.0
mm with a mean of 4.9mm.
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Table 1
The preliminary screening of P. pinnata bark for antifungal activity using a 20l sample. The zones of
inhibition are given in mm.
# of Plates
1
2
3
4
5
Average
St. dev
Pure extract of
P. pinnata
1.5
2.0
2.0
1.3
2.1
1.78
0.356
Diluted P.
pinnata
1.0
0.3
0.5
0.8
0.1
0.54
0.365
Antifungal
Solution
0
0
0
0
0
0
0
Blank
0
0
0
0
0
0
0
Table 2
The preliminary screening of P. pinnata bark for antifungal activity using a 30l sample. The zones of
inhibition are given in mm.
# of Plates
1
2
3
4
5
Average
St. dev
Pure extract of
P. pinnata
3.0
3.0
5.0
4.0
5.0
4
1
Diluted P.
pinnata
2.0
2.0
3.0
3.0
3.0
2.6
0.548
Antifungal
Solution
2.0
2.0
2.5
2.3
1.9
2.14
0.251
Blank
0
0
0
0
0
0
0
Table 3
The antifungal activity of bark extracts of P. pinnata using a 40l sample. The zones of inhibition is given
in mm.
# of Plates
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pure extract of
P. pinnata
7
10
8
9
8
7
9
9
8
9
9
8
10
10
Diluted P.
pinnata
4
3
3
4
4
5
5
7
6
5
4
4
6
6
Antifungal
Solution
3
3
3
3
3
2
3
4
3
3
3
6
6
6
Blank
0
0
0
0
0
0
0
0
0
0
0
0
0
0
6
Mean fungal inhibition (mm)
15
16
17
18
19
20
21
22
23
24
25
Average
Stdev
9
8
8
7
8
9
10
9
9
8
8
8.56
0.917
3.5
4
6
6
6
6
5
4
5
5
6
4.9
1.099
2
3
2
2
3
3
4
4
3
3
3
3.08
0.640
0
0
0
0
0
0
0
0
0
0
0
0
0
10
9
8
7
6
5
4
3
2
1
0
Pure extract
Aqueous
1% Tolnaf
Blank
Extracts
Fig. 1. The overall antifungal activity of each extract is expressed as the mean of inhibition zone diameters
(mm) with the 40l sample.
Discussions
The results of this study demonstrated that aqueous and pure extracts of P.
pinnata bark have antifungal activity against C. albicans. The water and pure extract had
greater antifungal activity than the positive control (1% tolnaftate topical solution). Data
also suggests that the effectiveness of pure and diluted extract of P. pinnata is dosage
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dependent. The 1% tolnaftate solution is a commercial health preparation and might be
the reason for the lack of zone inhibition in the 20l sample of positive control.
However, the positive control in the 30l and the 40l sample suggests that it might also
be dosage dependent. Further study should focus on identifying the biologically active
compounds and the appropriate concentration and dosage for fungus control. Further
research should investigate the range of fungus species affected.
Acknowledgements
I offer sincere thanks to all the Biology faculty for their revisions of this
paper. I also wish to express appreciation and thanks to Dr. Paul and Dr. Goodwill for
being my advisers. I also want to acknowledge Dr. Oba for providing the fungus and his
help with my power-point presentation and to Dr. Winget for analyzing the data, Dr.
Bruner for his help with the abstracts and the conclusions and to the BYU-H farm for
providing the plant material.
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_______ 1992b. Tongan Herbal Medicine. Honolulu: National Tropical Botanical
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