A comparative analysis of two medicinal plants used to treat common skin conditions in South Africa

Abstract

Infectious dermatological diseases are a common occurrence in southern Africa. Plants showing dermatological properties are highly sought after due to their ability to stop bleeding, speed up wound healing and to soothe skin exposed to burns (Lewis and Elvin-Lewis, 1977). An attempt was made to validate the use of Haworthia limifolia and Aloe excelsa against microbial properties from extracts of leaves against five Gram positive, four Gram negative bacteria and six species of fungi. All Gram positive bacteria were inhibited by both the ethyl acetate and acetone extracts for leaves of H. limifolia. However, only one strain of Gram negative bacteria was inhibited by the same extracts. Ethyl acetate extract of A. excelsa was only effective against three Gram positive bacteria whilst acetone extracts were effective against all bacteria except for Shigella sonnei and Enterobacter aerogene. Both ethanol and aqueous extracts of H. limifolia and A. excelsa showed antifungal activity. H. limifolia extracts showed greater antibacterial activity than A. excelsa whilst A. excelsa showed greater antifungal activity than H. limifolia. Use of either species as traditional medicine will therefore depend on the type of infection or condition presented by the patient.

Full text

African Journal of Pharmacy and Pharmacology Vol. 5(3), pp. 393-397, March 2011
Available online http://www.academicjournals.org/ajpp
DOI: 10.5897/AJPP11.048
ISSN 1996-0816 ©2011 Academic Journals
Full Length Research Paper
A comparative analysis of two medicinal plants used to
treat common skin conditions in South Africa
K. K. Naidoo and R. M. Coopoosamy*
Department of Nature Conservation, Mangosuthu University of Technology, P. O. Box 12363, Jacobs, 4026, Durban,
KwaZulu-Natal, South Africa.
Accepted 28 March, 2011
Infectious dermatological diseases are a common occurrence in southern Africa. Plants showing
dermatological properties are highly sought after due to their ability to stop bleeding, speed up wound
healing and to soothe skin exposed to burns (Lewis and Elvin-Lewis, 1977). An attempt was made to
validate the use of Haworthia limifolia and Aloe excelsa against microbial properties from extracts of
leaves against five Gram positive, four Gram negative bacteria and six species of fungi. All Gram
positive bacteria were inhibited by both the ethyl acetate and acetone extracts for leaves of H. limifolia.
However, only one strain of Gram negative bacteria was inhibited by the same extracts. Ethyl acetate
extract of A. excelsa was only effective against three Gram positive bacteria whilst acetone extracts
were effective against all bacteria except for Shigella sonnei and Enterobacter aerogene. Both ethanol
and aqueous extracts of H. limifolia and A. excelsa showed antifungal activity. H. limifolia extracts
showed greater antibacterial activity than A. excelsa whilst A. excelsa showed greater antifungal
activity than H. limifolia. Use of either species as traditional medicine will therefore depend on the type
of infection or condition presented by the patient.
Key words: Haworthia limifolia, Aloe excelsa, antimicrobial, traditional medicines.
INTRODUCTION
Infectious dermatological diseases are a common
occurrence in rural parts of South Africa. According to the
World Health Organization (WHO) more than 80% of the
world’s population relies on traditional medicine for their
primary health care needs. Traditional healing plays an
integral part of black African culture with the majority of
people consulting traditional healers (Lindsey et al.,
1999). Mander (1998) conservatively estimated that at
least 50% of the population in KwaZulu-Natal is rural and
that the frequency of indigenous medicine use is likely to
be greater than the urban areas given the limited access
to western bio-medical services in remote areas.
South Africa has a very rich plant biodiversity, many of
which are medicinally useful (Afolayan and Adebola,
2004). This rich resource is decreasing at an alarming
rate as a result of indiscriminate and unsustainable
harvesting. Demand for plant derived medicines has
*Corresponding author. E-mail: rogercoopoosamy@gmail.com.
Tel: +27 82 200 3342. Fax: +27 31 907 7665.
created a trade in indigenous plants in South Africa
conservatively estimated to be worth approximately R270
million a year (Mander, 1998). Mander (1997) estimates
that there are 27 million consumers of traditional
medicine and its supporting industry in South Africa.
Population growth coupled with rapid urbanization is
creating an ever increasing demand for traditional
medicine.
Plants showing dermatological properties are highly
sought after due to their ability to stop bleeding, speed up
wound healing and to soothe skin exposed to burns
(Lewis and Elvin-Lewis, 1977). Although skin diseases do
not usually threaten life, their unforgiving itching can
cause misery and their presence may be a social stigma.
In sub- Saharan Africa skin conditions are dominated by
bacterial and fungal infection and their clinical expression
is often modified by HIV-induced immune-suppression
(Naafs, 2004). Skin diseases may therefore constitute a
large percentage of all attendees in clinics in rural
communities in South Africa. Despite the plethora of
antibiotics afforded by lower plants such as fungi,
microbial diseases are still on the rise in developing

394 Afr. J. Pharm. Pharmacol.
Table 1.Traditional uses of Aloe excelsa.
Plant Part Uses Preparation Used
Leaves Skin burns Leaf exudates
Leaves Rashes Diluted tea from leaf exudates.
Leaves Sun burns Diluted tea from leaf exudates.
Leaves Laxatives Leaf exudates
Leaves Blood purifers Leaf exudates
Leaves Skin irritants Leaf exudates
Leaves Moisturizers Diluted tea from leaf exudates
Leaves Immune boosters Diluted tea from leaf exudates
countries due to the relative unavailability of medicines
and the emergence of wide scale drug resistance (Okeke
et al., 2005). The fleshy leaves and roots of most species
within the Aloe family are used in many traditional
treatments (Mabberley, 1987). Traditional healers and
indigenous people utilize mainly the leaf sap of this genus
widely for the treatment of wounds, burns, rashes,
cracked lips, and cracked skin (Cera et al., 1980).
Another much used species, exhibiting similar properties,
is Haworthia limifolia. In this study we attempted to
confirm the antimicrobial activity of crude extracts of H.
limifolia and A. excelsa currently being used for the
treatment of skin diseases. Both these species are widely
available in multi markets although increased use as
resulted in pressure on wild populations, thus, escalating
trade prices.
MATERIALS AND METHODS
All plant material was collected and a voucher specimen was stored
as Cooper03/2009 (Aloe excelsa) and Cooper02/2010 (H. limifolia)
at Mangosuthu University of Technology. Specimen verification was
done with the help of Plant Specialists at Ezemvelo KZN Wildlife.
Antibacterial assay
Methods used in extraction of plant extract by tradtitional healers
was performed according to Coopoosamy et al. (2010). Briefly,
according to Coopoosamy et al. (2010), leaf material of H. limifolia
and A. excelsa were collected from the field and dried in an oven at
60°C until sufficiently dried (4 days). One kilogram of dried material
for each specimen was then crushed and placed in a 2 L conical
flask containing one of three mediums that is water, ethyl acetate
and acetone, for extraction. The media except the boiled medium
(method used by traditional healers) were left for 72 h in an orbital
shaker at 20 shakes per minute. After 72 h the extracts were
filtered. The boiled medium was placed on a hot plate at constant
800c for a period of 4 hours after which it was filtered. The extracts
were then used for further tests.
The plant extracts were then tested for antibacterial properties
against five strains of Gram-positive (Bacillus subtilis, Micrococcus
kristinae, Bacillus cereus, Staphylococcus aereus, Staphylococcus
epidermidis) and four strains of Gram-negative bacteria
(Escherichia coli, Proteus vulgaris, Enterobacter aerogenes, and
Shigella sonnei) for antibacterial activity. Each organism was
prepared by diluting in 24 h old broth cultures with sterile nutrient
broth. The cultures were then diluted 100 fold to give approximately
106 bacteria ml-1.
Antifungal assay
H. limifolia and A. excelsa leaves (approximately 1 kg) were cut into
small pieces and crushed in a homogenizer. Different extraction
methods were use to determine the most suitable for extraction of
compounds for testing against microbials. Each method would
result in different compounds being extracted as per the polarity of
the solvents. The plant materials were soaked in ethanol (95% v/v)
and in distilled water in 2 L conical flasks for 3 weeks. The extracts
(water and ethanol) obtained were evaporated at reduced pressure
(45°C) to a residue. Extracts for testing ethanol and aqueous
extracts were prepared in three different concentrations. The stock
solutions were prepared by dissolving 100 mg of dry extract in 1 ml
of ethanol and water separately in order to obtain a concentration of
100 mg/ml dilutions (1:10, 1:100, 1: 500). These stock solutions
were then used in phosphate buffer at pH 6.0 to evaluate the
antifungal activity (Champion et al., 1992). The solutions were then
tested for antifungal activity using the following fungal cultures:
Aspergillus flavus, Aspergillus glaucus, Candida albicans, Candida
tropicalis, Trichophyton mentagrophytes, and Trichophyton rubrum.
Plates containing potato dextrose agar were used to serve as
controls.
RESULTS AND DISCUSSION
In Southern Africa as well as in China and Mexico, the
leaf gel or exudates of Aloe sp. are used in various
dermatological remedies, such as, minor skin irritations
(Grindley and Reynolds, 1986). Although used as
medicinal remedies for centuries, the only three common
uses that predominate are the laxative effect, blood
purifying effects as well as external treatment of skin
infections or injuries (Table 1).
The traditional use of H. limifolia involves use both in
spiritual as well as traditional medicinal practices (Table
2). The traditional use has been linked to sores, burns
and sun-burns. Skin diseases occur in various forms,
basically classified as non-contagious diseases, the
primary of which are bacterial, fungal, viral and parasitic
diseases. These diseases occur throughout the world,
but are prevalent in the rural and tropical regions (Davies

Naidioo and Coopoosamy 395
Table 2. Traditional uses of H. limifolia.
Plant Part Uses Preparation Used
Whole Plant
Removal of evil Plant used as a charm
Leaves Blood purifiers Diluted tea from leaf exudates.
Leaves promote pregnancy Diluted tea from leaf exudates.
Leaves Treatment of sores Leaf exudates
Leaves Treatment of superficial burns Leaf exudates
Leaves Treatment of sun burns Leaf exudates
Leaves Cleansing of digestive system Diluted tea from leaf exudates
Table 3. Minimal inhibitory concentration (MIC) of H. limifolia antibacterial assay on crude extract (Controls:
Chloramphenicol and Streptomycin sulfate) n = 3.
Bacteria
(106 Bacteria/ml) Gram +/- Medium (MIC) (mg/ml) Control (µg/ml)
Cold water Ethyl acetate Acetone Chlora Streptb
Bacillus subtilis + Na 3.0 3.0 <2.0 <2.0
Micrococcus kristinae + Na 4.0 5.0 <2.0 <2.0
Bacillus cereus + Na 4.0 4.0 <2.0 <2.0
Staphylococcus aureus + Na 4.0 5.0 <2.0 <2.0
Staphylococcus. epidermis + Na 5.0 5.0 <2.0 <2.0
Escherichia coli - Na 5.0 5.0 <2.0 <2.0
Proteus vulgaris - Na Na Na <2.0 <2.0
Shigella sonnei - Na Na Na <2.0 <5.0
Enterobacter aerogene - Na Na Na <2.0 <2.0
Na = No activity, All tests were done in triplicates and the averages are indicated, Chlora = Chloramphenicol, Strept b=
Streptomycin sulphate.
et al., 1986).
All gram positive bacteria were inhibited by both the
ethyl acetate and acetone extracts of leaves of H. limifolia
(Table 3). However, only one strain of gram negative
bacteria was inhibited by the same extracts. In contrast,
there were no inhibitory effects on Gram positive and
negative bacteria with aqueous extracts (Table 3). Gram
positive bacteria often cause human diseases such as
colds, wounds and sores (Waihenya et al., 2002).
Medically relevant Gram negative cocci cause sexually
transmitted diseases, meningitis and respiratory
symptoms whilst bacilli species primarily cause
respiratory, urinary and gastrointestinal problems. It is
therefore evident that leaf extracts from H. limifolia may
play a valuable role in treating various skin conditions
caused by Gram positive bacteria. Traditional healers
tend to boil large quantities of leaf material of H. limifolia,
thereby possibly releasing the bioactive compounds that
are involved in the treatment process.
Ethyl acetate extracts of A. excelsa were only effective
against three Gram positive bacteria whilst acetone
extracts were effective against all bacteria except for
Shigella sonnei and Enterobacter aerogene (Table 4).
The ability of Aloe to inhibit growth of micro-organisms
has been demonstrated by rapid clearing of infected
tissue after induction of therapy. In a study of Aloe in the
treatment of tuberculosis during the early stages, it was
found that moderate antibacterial activity was exhibited
from the leaf sap (Droscoll et al., 1974; Ghannam et al.,
1986).
Both ethanol and aqueous extracts of H. limifolia and A.
excelsa showed antifungal activity (Table 5). The
antifungal activity of the ethanol was shown to be slightly
more effective than the aqueous extracts with the 1:10
dilution producing the maximum rates of inhibition.
Growth inhibition (zone of inhibition) was recorded as
very high (++++), high (+++), medium (++), and low (+),
which indicated zones of inhibition between 41 to 50, 31
to 40, 21 to 30, and 11 to 20 mm, respectively
(Coopoosamy, et al., 2010). It was evident that extracts
from A. excelsa possessed greater antifungal activity
across the dilution range (Table 5). It is therefore not
surprising that there has been a recent explosion of Aloe
products on the market, mostly cream based, which is
used frequently to treat dry skin, sun burns, itching,
irritated skin, rashes, scabies etc.
Skin fungus infections include itching, redness and
thickened skin of fungal infections can look like other
burn occurs, the patient loses the protective epithelial
layer of skin and as a result is prone to infection by

396 Afr. J. Pharm. Pharmacol.
Table 4. Minimal inhibitory concentration (MIC) of A. excelsa antibacterial assay on crude extract (Controls:
Chloramphenicol and Streptomycin sulfate) n = 3.
Bacteria
(106 Bacteria/ml) Gram +/- Medium (MIC) (mg/ml) Control (µg/ml)
Cold water Ethyl acetate Acetone Chlora Streptb
Bacillus subtilis + Na 3.0 2.0 <2.0 <2.0
Micrococcus kristinae + Na 4.0 1.0 <0.2 <2.0
Bacillus cereus + Na 2.0 2.0 <2.0 <2.0
Staphylococcus aureus + Na Na 1.0 <2.0 <2.0
Staphylococcus. epidermis + Na Na 1.0 <2.0 <2.0
Escherichia coli - Na Na 3.0 <2.0 <2.0
Proteus vulgaris - Na Na 2.0 <2.0 <2.0
Shigella sonnei - Na Na Na <2.0 <5.0
Enterobacter aerogene - Na Na Na <2.0 <2.0
Na = No activity, All tests were done in triplicates and the averages are indicated, Chlora = Chloramphenicol, Strept b=
Streptomycin sulphate.
Table 5. Effect of ethanol and aqueous extracts obtained from H. limifolia and A. excelsa on different fungal specimens.
Fungal species
H. limifolia A. excelsa
Ethanol extract Aqueous extract Ethanol extract Aqueous extract
1:10 1:100 1:500 1:10 1:100 1:500 1:10 1:100 1:500 1:10 1:100 1:500
Aspergillus flavus +++ ++ + + + - ++++ +++ ++ ++++ +++ ++
Aspergillus glaucus +++ + + + + - ++++ +++ +++ +++ +++ +++
Candida albicans +++ ++ + + - - ++ + - ++ + -
Candida tropicalis +++ ++ + + + - +++ ++ ++ +++ ++ +
Trichophyton
mentagrophytes ++ + + + - - +++ ++ ++ ++ ++ +
Trichophyton
rubrum ++ + + - - - ++ ++ + ++ + +
- = Negative antifungal activity, + = Positive antifungal activity (low inhibition), ++ = Positive antifungal activity (medium inhibition), +++ = Positive antifungal
activity (high inhibition), ++++ = Positive antifungal activity (very high inhibition). N.B.: Plates containing Potato dextrose agar only served as controls.
Control did not show any inhibition of any of the test fungal species.
Table 6. Minimal inhibitory concentration observed in different concentrations prepared from stock solution of 100 mg/ml of aqueous and
ethanol extracts of H. limifolia and A.excelsa (n = 3).
Fungal species H. limifolia A. excelsa
Ethanol extract Aqueous extract Ethanol extract Aqueous extract
Aspergillus flavus 1:500 1:100 1:500 1:500
Aspergillus glaucus 1:500 1:100 1:500 1:500
Candida albicans 1:500 1:10 1:100 1:100
Candida tropicalis 1:500 1:100 1:500 1:500
Trichophyton mentagrophytes 1:500 1:10 1:500 1:500
Trichophyton rubrum 1:500 1:10 1:500 1:500
opportunistic infection such as C. albicans. C albicans is
readily introduced into burn wounds because this yeast is
commonly a member of the normal flora found on
mucous membranes. Anecdotal evidence suggests that
when Aloe is used on patient’s burns, the frequency of
fungal infections decrease (Lee et al., 1999). The minimum
inhibitions observed are given in Table 6.
Conclusion
It was clearly evident from the study that both H. limifolia

and A. excelsa possess antibacterial and antifungal
properties. However, H. limifolia extracts showed greater
antibacterial activity than A. excelsa whilst A. excelsa
showed greater antifungal activity than H. limifolia. Use of
either species as traditional medicine will therefore
depend on the type of infection or condition presented by
the patient.
ACKNOWLEDGEMENT
The authors would like to thank Mangosuthu University,
Directorate of Research for funding towards this
investigation.
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