Antimicrobial Activity of Gladiolus psittacinus Bulb Extracts

International Network Environmental Management Conflicts
http://www.igetecon.org/revista/index.php/inicio/index

Qualitative Phytochemical Screening and Antimicrobial Activity Evaluation of
the Bulb Extracts of Gladiolus psittacinus Hook (Iridaceae)

François Munyemana
PhD, Professor Auxiliar, Departamento de Química, Universidade Eduardo Mondlane, Maputo,
Moçambique
E-mail: munyfranc@yahoo.co.uk ou francoism@uem.mz

Ana Paula Mondego
Mestre, Assistente, Curso de Farmácia, Instituto Superior de Ciências e Tecnologia de
Moçambique, Maputo, Moçambique

Paulo Cumbane
Licenciado, Assistente Estagiário, Curso de Farmácia, Instituto Superior de Ciências e
Tecnologia de Moçambique, Maputo, Moçambique

Abstract

In Mozambique, the bulb of Gladiolus psittacinus Hook is used in treating diarrhea, dysentery,
gonorrhea, renal and rheumatic pains, etc. In this study, was evaluated the antimicrobial activity
of different extracts and fractions of dried and fresh bulb against 6 bacterial strains:
Staphylococcus aureus ATTC 25923, Escherichia coli ATCC 25922, Klebsiella pneumoniae
ATCC 15380, Pseudomonas aeruginosa ATCC 27953, Shigella flexneri ATCC 12022 and 2
fungi: Candida albicans and Saccharomyces cerevisiae, and the interaction Ciprofloxacin –
Extract. Most of the bulb extracts and fractions showed strong inhibitory activity against Candida
albicans, Saccharomyces cerevisiae and Pseudomonas aeruginosa. The aqueous extract revealed
antagonism with ciprofloxacin while the juice (from the fresh bulb) showed additive effect.

Keywords: Gladiolus psittacinus; Iridaceae; Antimicrobial; Bulb.

Introduction

Since the antiquity, the man uses natural resources such as vegetables, for various
purposes, mainly food and medicine. In this constant man-environment interaction, the need has
become an important factor in the development of folk medicine. Plants have been used as the
basis of many traditional medicine systems throughout the world for thousands of years. They
continue to provide mankind with new remedies. Every region has its own history of traditional
medicine, for example traditional Chinese medicine, Arabic traditional medicine and African
traditional medicine.

International Network Environmental Management Conflicts, Santa Catarina – Brasil, 2(1), pp. 14-31, jan. 2013.

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Qualitative Phytochemical Screening…

Such practices are traditional because they are deeply rooted in a specific socio-cultural
context, which varies from one community to another. Each community has its own particular
approach to health and disease even at the level of ethno-pathogenic perceptions of diseases and
therapeutic behavior (Rukangira; Ochoa; Ocampo; Muñoz, 2001).
In Africa, herbal medicine gained popularity as alternative and complementary therapies,
largely as a result of cultural traditions and excessive cost of modern medicines. Traditional
remedies made from plants play an important role in the health of millions of people. Low-
income people such as subsistence farmers, people of small isolated villages and native
communities use folk medicine for the treatment of common infections (Rojas et al, 2006).
The interest in medicinal plants has grown considerably in recent years because they have
been a valuable source of products for maintaining human health, becoming potential candidates
for many applications in the pharmaceutical industry. Medicinal plants are the best sources to
obtain a variety of drugs (Santos; Ferreira; Damiao, 2010).
Mozambique, with its rich and varied flora, is one of the countries where people rely
much on the use of traditional knowledge and medicinal plants to treat various diseases.
Gladiolus psittacinus Hook (synonyms in southern Africa collections: Gladiolus natalensis and
Gladiolus dalenii) is an herbaceous and bulbous plant belonging to the family Iridaceae which
comprises about 1800 species grouped in 88 genus. Of these genus, Gladiolus and Iris are the
most representative with about 260 and 250 species respectively (Machado, 2007 & Manning,
2004). The greatest economic importance of the Iridaceae family resides in ornamentals and
medicinal use.
Phytochemical study of several species of the family Iridaceae has led to the isolation of
several secondary metabolites with high biological activity, especially, antimicrobial,
antiinflammatory, antidiarrhoeal, antidysenteric, antioxidant, antinociceptive, antifungal etc.
In the Iridaceae family occur mainly the following secondary metabolites: Flavonoids, alkaloids,
saponins, terpenoids, anthraquinones, naphthoquinones and coumarins.
The plants of the genus Gladiolus are used in different pharmacopoeias for treating
various diseases. In some regions in southern Africa plants of the genus Gladiolus are used to
treat a variety of diseases, including acute diarrhea, intestinal parasitic infections, asthma,
diabetes, constipation, impotency, headaches, relieve rheumatic pains and hemorrhoids.


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In Mozambique the plant Gladiolus psittacinus Hook is used to treat diarrhoea, dysentery,
gonorrhea, regulate the blood flow of women and as a sedative. For the treatment of diarrhea and
dysentery it is an infusion that can be administered orally or enema. As sedative, the plant is used
to calm patients with mental disorders in case of extreme agitation: two drops of fresh juice of the
bulb are applied in the nostrils of the patient.
In the present study was carried out the qualitative phytochemical screening of the bulbs
extracts of Gladiolus psittacinus Hook grown in Mozambique and evaluated the antimicrobial
activity of different extracts and fractions of dried and fresh bulb against gram-positive, gram-
negative bacteria and fungi.

Materials and Methods

Plant Material and Extraction

Fresh samples of Gladiolus psittacinus Hook bulbs were collected in Chiboene, Moamba
district, Maputo province in July 2006 and in Bilene district, Gaza province in March 2011. The
samples authentication was made in the herbarium of the Department of Biology – Eduardo
Mondlane University and in the herbarium of the Botany Department – Institute of agricultural
Research of Mozambique (voucher specimen Nr. 48529).

Samples preparation

Fresh Juice:
After collection, the fresh bulbs were washed, cut into small pieces and mechanically crushed
with the help of a centrifuge juice in order to extract the fresh juice.
Dried powdered bulb:
The fresh bulbs were washed, cut into small pieces and were dried in the oven for 7 days at a
temperature of about 50 ˚C and then ground with the help of an electric grinder.


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Preparation of extracts

Crude extracts were prepared by maceration, percolation or Soxhlet extraction using
following solvents: Methanol 90%, Methanol, Dichloromethane – methanol (1:1), Distilled
water. Fractions were obtained by solvent-solvent partition with increasing polarities (hexane or
petroleum ether, Chloroform, ethyl acetate, n-butanol).

Extraction of dried sample by percolation

300 g of dried powdered bulb was percolated for 4 days in a 500 ml percolator using as
solvent a mixture of methanol and water (9:1). The resulting extract (3 l) was filtered with suction
on a borosilicate glass funnel fitted with a filter membrane and stored at 4 ° C in a fridge for 48
hours for precipitation of the fatty material.
The extract with precipitated material was left at room temperature for 1 h and then
decanted and filtrated with Whatman ® filter paper (No. 1) and concentrated under reduced
pressure in a rotary evaporator BUCHI ® at 40 ° C until the formation of a pasty mass (methanol
extract). 100 g of the methanol extract was suspended in a volume of 200 ml of mixture methanol
/ water (1:1) in 250 ml Beaker and quantitatively transferred to a separatory funnel of 500 ml and
then submitted to liquid / liquid partition using solvents with increasing polarities (n-hexane,
chloroform, ethyl acetate and n-butanol).
The hexane fraction (HEX) was obtained by liquid / liquid partition using 3x100 ml of n-
hexane. And then separated into a 500 ml flask and concentrated in a rotary evaporator under
reduced pressure at 40oC. The chloroform fraction (CHL) was also obtained by liquid / liquid
partition with 3x100ml of chloroform. And then separated into a 500 ml flask and concentrated
to dryness in a rotary evaporator at 40o C. The hydromethanolic solution was transferred to a
round bottom flask of 500 ml and concentrated until elimination of methanol.
The aqueous extract was further entirely subjected to liquid / liquid partition with 3x100
ml of ethyl acetate, followed by 3x100 ml of n-Butanol, yielding three fractions: ethyl acetate
fraction (EA), n-butanol fraction (Bu) and aqueous fraction (Aq.Fr.) respectively. The two
organic fractions were also concentrated in a rotary evaporator under reduced pressure at 40 ° C.


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All fractions were stored in dry desiccator until constant weight is obtained, and after 7 days the
yield of extraction was determined.

Extraction of the dried sample by Soxhlet

20 g of the dried powdered bulb was introduced into a cellulose cartridge Whatman (30
mm x 100 mm) and subjected to Soxhlet extraction with 400 ml of the mixture dichloromethane -
methanol (1:1). After 24 hours the extract was filtered by suction on a glass funnel with a
membrane filter, then through a filter paper, and concentrated in rotary evaporator at low pressure
until dryness. The dried extract was placed in a desiccator until obtaining constant weight, and
after 7 days the yield of extraction was determined

Extraction of the fresh sample by Soxhlet

30 g of the fresh bulb, pre-treated with distilled water and cut into small fragments, was
milled in Kenwood blender and transferred quantitatively to the cellulose cartridge. Thereafter,
the material was extracted in a Soxhlet using as solvent 400 ml of distilled water. After 24 hours,
the extract was recovered from the flask, cooled to room temperature and filtered with cotton
wool in glass funnel, followed by filter paper and taken to carry out biological testing, after a
preliminary purification by filtration with sterile cellulose acetate filter (GVS Filter Technology,
USA) 0.45 mm in porosity and 25-mm diameter.

Extraction of juice in fresh bulb

50 g of the fresh bulb treated with fresh distilled water was mixed with 50 g of water and
milled in Kenwood blender. The resulting sample was transferred to a 250 ml Beaker and filtered
with cotton wool in a glass funnel. The filtrate was centrifuged and the resulting extract was
purified with cellulose acetate filter (GVS Filter Technology, USA) porosity of 0.45 mm and
diameter of 25 mm, and transferred to a sterile glass container and taken to carry out biological
testing.


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Solvent-Solvent Partition of the fresh juice

In that extraction, 20 g of fresh juice was treated with methanol (600ml) for 24 hours.
After filtration, the filtrate was evaporated to dryness in rotary evaporator, leading to a yellow
residue after total evaporation of the solvent. This residue was dissolved in distilled water (20ml)
and then proceeded to the successive extractions (3 times respectively), first with the solvent
petroleum ether (PE), then with chloroform (CHL), followed by ethyl acetate (EA ) and finally
with n-butanol (Bu) with equal volumes of 100ml each. Petroleum ether (PE), chloroform (CHL),
ethyl acetate (EA) and n-butanol (Bu) fractions were concentrated on the rotary evaporator to
give petroleum ether residue ( white ), chloroform residue (pale yellow), ethyl acetate residue
(yellow and butanolic residue (intense yellow color), which have been subjected to preliminary
phytochemical tests.

Phytochemical Analysis

The extracts and fractions were subjected to qualitative phytochemical tests for alkaloids,
tannins (hydrolysable and condensed), coumarins, iridoids, anthraquinones, flavonoids, saponins,
steroids and triterpenoids, amino acids, proteins and carbohydrates adopting the procedures
described by Gomes & Silva (2007), Duarte; Fonte & Santos (2010) and Khan et al (2010).

Antimicrobial assay

Bacterial cultures reference standard (ATCC) and the yeast Candida albicans (isolated
from vaginal discharge) were obtained from the Microbiology Laboratory of the Central Hospital
of Maputo. The yeast Saccharomyces cerevisiae was obtained from commercial packaging yeast.
The tests were performed using a standard method recommended for this purpose (NCCLS). Six
bacterial strains were used in the tests, Staphylococcus aureus (ATTC 25923), Escherichia coli
(ATCC 25922), Klebsiella pneumoniae (ATCC 15380), Pseudomonas aeruginosa (ATCC
27953), Shigella flexneri (ATCC 12022) and Salmonella typhimurium (ATCC 14028). The
culture media used were Nutrient broth, Sabouraud Dextrose Broth and Mueller – Hinton Agar.


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Bacterial sensitivity test by disc diffusion method

The assay was performed using the disk diffusion method where each sterile disk of
Watman filter paper of 6.0 mm in diameter was impregnated with 10 µl aliquots of the extract at
concentrations of 1 mg / disk to the total extract and the respective fractions.
The aqueous extract and juice were placed in Petri dishes containing sterile paper discs
and allowed to soak for two hours prior to testing. The suspensions containing the bacteria were
prepared separately suspending a colony of each microorganism taken from stock samples with
the aid of a platinum loop in test tubes containing nutrient broth and incubated for 24 hours at 37o
C.
After were adjusted according to the turbidity of 0.5 in McFarland scale, by visual
comparison with a standard tube containing a standardized suspension.
The adjusted suspensions were separately dispersed in a Petri dish containing Mueller – Hinton
Agar.
The Petri dish was divided into four equal portions and placed aseptically one disc of each
impregnated with plant extract in the center of each division.
Plates were also placed in the disks impregnated with ciprofloxacin, DMSO and pure distilled
water respectively. The plates were incubated for 24 h at 37 ° C and then the reading of the
diameter of zones of inhibition. All tests were done in triplicate.

Fungal sensitivity test by disc diffusion method

The suspensions of the yeasts Candida albicans and Saccharomyces cerevisiae were
prepared separately by suspending a colony of each microorganism in test tubes containing
Sabouraud Dextrose Agar (SDB) incubated at 37 ° C for 48 hours, then standardized according to
the turbidity 0 5 in McFarland scale for visual comparison with standard test tube. The dispersion
of the suspension in the plate containing the Mueller – Hinton Agar, was cleaned with sterile
cotton swab across size of Petri dish (90 mm) up to obtain a uniform inoculum. The yeast
Saccharomyces cerevisiae was isolated by suspending 1 g of yeast in 20 ml of sugar solution.
Was allowed to stand for five minutes to allow the activation of yeast and subsequently taken 200
µl of it to a test tube containing 15 ml of SDB and incubated for 48 h. Assays were performed


21

using the same procedure followed for antibacterial tests, with the exception of the positive
control, having been used in this nystatin.

Interaction Extract – Ciprofloxacin

The aqueous extract (Aq.Extr.) and juice were evaluated for the ability to interact with
ciprofloxacin. Disks were initially impregnated to saturation with the extracts and dried in sterile
medium for 30 minutes. Thereafter foi taken 10 uL of ciprofloxacin 2 mg / ml and was also added
on the disks containing extracts and aseptically transferred to Petri dishes previously inoculated
with bacteria and incubated for 24 h at 37 ° C. All tests were done in triplicates and the respective
percentages of interaction determined using the following formula: Interaction% = (Di-Dii) / Dii
x100 where: Di: mean zone of inhibition of ciprofloxacin combined with extract. Dii: mean zone
of inhibition of ciprofloxacin alone.

Results and discussion

Phytochemical Screening

The phytochemical tests carried out on the extracts, fractions and fresh juice of the bulb,
allowed the identification of the following metabolites: alkaloids, anthraquinones, flavonoids,
coumarins, saponins, hydrolysable tannins, steroids and triterpenoids, amino acids, proteins and
reducing sugars.
The phytochemical screening results showed that there is not much difference between
the chemical composition of juice and powdered dry bulb, but in practice it has been proved to be
easier to work with the dry powdered bulb than the juice in particular during the solvent / solvent
partition.
The extraction solvent / solvent of the juice extracted from the fresh bulb and powdered
dry bulb allowed to obtain less complex fractions aiming semi-purification of substances through
their polarity and solubility.


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The results of the phytochemical screening of the crude extracts are summarized in the
table 1, and the results of the phytochemical screening of the fractions from solvent-Solvent
partition were summarized in table 2.

Table 1: Phytochemical tests of Crude extracts
Dichloromethane- Aqueous
Methanol 90%
Methanol(1:1) extract (24h Juice
Phytoconstituents Extract ( fresh
Extract Soxhlet fresh (fresh bulb)
bulb)
(24h soxhlet dried bulb)
bulb)
Alkaloids + + + +
Anthraquinones + + - -
Coumarins - + - -
Flavonoids + + - -
Saponins + + - +
Tannins + + - -
Amino acids + + + +
Proteins - - - +
Reducing Sugars - + + +
+: present; -: absent

Table 2: Phytochemical tests of fractions from solvent – solvent Partition
Juice (Fresh Bulb) Powdered dry bulb
Phytoconstituents
PE/HEX CHL EA Bu PE/HEX CHL EA Bu
Alkaloids - + - - - + + -
Anthraquinones - - + - - + + -
Coumarins - + + - - + + -
Flavonoids - + + + - + + +
Iridoids - - - - - - - -
Saponins - - - + - - + +
Steroids/Terpenoids + + + + + + + +
+: present, -: absent, PE: petroleum ether fraction, HEX: hexane fraction, CHL: chloroformic
fraction, EA: ethyl acetate fraction, Bu: butanolic fraction.

Results of antimicrobial assay

The results of the antimicrobial screening realized in this study with extracts and fractions
less complex of Gladiolus psittacinus Hook against Escherichia coli, Pseudomonas aeruginosa,
Staphylococcus aureus, Shigella flexneri, Salmonella typhimurium, Klebsiella pneumoniae,
Candida albicans and Saccharomyces cerevisiae showed interesting antimicrobial activities of
this plant as shown in table 3a and 3b.


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Table 3a. Results of antimicrobial activity tests mean diameter of inhibition zone (mm).
Micro-
NT CIP MET HEX CHL EA BU
organisms
Candida
18±0,6 20±0,6 28±0,6 25±0,6 24±0,6 23±0,6
albicans
E.coli
32±0,6 - - - - -
ATCC25922
P. aeruginosa
32±0,0 18±0,6 22±1,0 23±0,3 25±0,0 20±0,1
ATCC 27953
K. pneumoniae
30±1,0 - - - - -
ATCC 15380
S.aureus
32±0,6 - - - - 7±0,0
ATCC 25923
Saccharomyces
10±0,6 - - 20±0,3 13±0,6
cerevisiae
S. typhimurium
32±0,0 BE - BE BE BE
ATCC 14028
Shigella
flexneri 33±0,6 - - BE BE -
ATCC 12022
(_ ± _): Mean and standard deviation of triplicates; concentrations of extracts - 100 mg / disc, (-) No zone
of inhibition was observed; Positive Control : Ciprofloxacin (CIP) 2 mg / disc for bacteria and nystatin (NT )
3.2 cµg / disk for C. albicans; DMSO: solvent control; MET: crude methanol extract; HEX: hexane fraction;
CHL: chloroform fraction; EA: ethyl acetate fraction; BU: butanol fraction; Aq.frac.: aqueous fraction;
Aq.Extr.: aqueous extract; BE - bacteriostatic activity. The yeast Saccharomyces cerevisiae had not
control.

Table 3b. Results of antimicrobial activity tests (cont.)
Mean diameter of inhibition zone (mm)
CH2Cl2-
Micro-organisms NT CIP DMSO Aq.Frac. Juice Aq.Extr.
CH3OH
Candida albicans 18±0,6 - 21±0,3 - 16±0,3 -
E.coli ATCC25922 32±0,6 - - - 19±0,4 16±0,1
P. aeruginosa
32±0,0 - 15±1,0 - 12±1,0 14±0,3
ATCC 27953
K. pneumoniae
30±1,0 - - - - -
ATCC 15380
S.aureus
32±0,6 - - - - -
ATCC 25923
Saccharomyces
- 12±0,3 - 15±0,0 -
cerevisiae
S. typhimurium
32±0,0 - - - - -
ATCC 14028
Shigella flexneri
33±0,6 - - - - -
ATCC 12022
(_ ± _): Mean and standard deviation of triplicates; concentrations of extracts - 100 mg / disc, (-) : No zone
of inhibition was observed; Positive Control : Ciprofloxacin (CIP) 2 mg / disc for bacteria and nystatin (NT )
3.2 cµg / disk for C. albicans; DMSO: solvent control; MET: crude methanol extract; HEX: hexane fraction;
CHL: chloroform fraction; EA: ethyl acetate fraction; BU: butanol fraction; Aq.Frac.: aqueous fraction;
Aq.Extr.: aqueous extract; BE: bacteriostatic activity. The yeast Saccharomyces cerevisiae had not
control.


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Preparations of the bulb of Gladiolus psittacinus Hook are used in traditional medicine
for the treatment of various diarrheal diseases. The presence of secondary metabolites active
against microbial pathogens in the extracts of this plant has been reported.
Ameh et al (2011) demonstrated antimicrobial activity against Pseudomonas aeruginosa
and Aspergillus niger of the aqueous extract of Gladiolus bulb. The phytochemical screening of
the same extract resulted in the identification of some metabolites namely: alkaloids, tannins,
cardiotonic glycosides, flavonoids and carbohydrates.
Nguedia et al (2004) showed antifungal activity of the hydroethanolic extract of the bulb
of Gladiolus gregasius Baker against Candida albicans and Candida krusei. However, the same
extract was not active against Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris,
Staphylococcus aureus and Streptococcus faecalis. The phytochemical screening revealed the
presence of saponins, glycosides, polyphenols, phenols, triterpenes and steroids.
The crude methanolic extract exhibited an antibacterial effect against Pseudomonas
aeruginosa with an inhibition zone of 18 ± 0.6 mm and a bacteriostatic effect against Salmonella
typhimurium. An antifungal effect was shown against the yeasts Saccharomyces cerevisiae and
Candida albicans with inhibition zones of 20± 0.6 mm and 10 ± 0.6 mm respectively.
The activity of that extract against Pseudomonas aeruginosa was low compared to
ciprofloxacin used as control. However, it showed a high antifungal activity against Candida
albicans when compared to the control nystatin. The antifungal activity displayed against candida
albicans was higher than with the other yeast Saccharomyces cerevisiae. This extract was not
active against the rest of the microorganisms tested.
The hexane fraction exhibited an antibacterial effect against Pseudomonas aeruginosa
with an inhibition zone of 22 ± 0.6 mm. An antifungal effect against Candida albicans has been
shown with a zone of inhibition of 28 ± 0.6 mm. This fraction was not active at the same
concentration against other microorganisms tested. The activity of the extract against
Pseudomonas aeruginosa was low compared to the antibiotic used as control; but that was higher
than the activity of the crude methanolic extract. This fraction exhibited also an antifungal
activity against Candida albicans higher than the control nystatin and than the crude methanol
extract. In phytochemical studies performed on this fraction were identified terpenoids.
According to literature, the activity of these compounds is related to its lipid solubility
which allows them to interact with the biomembranes of microorganisms, causing rupture of the


25

cells. The solubility of these compounds in the biomembranes enables their interaction with ion
channels, carrier molecules, membranes receptors, which leads to changes in conformation and
loss of function (Lopez, 2010).
The chloroform fraction also showed an antibacterial effect against Pseudomonas
aeruginosa with a zone of inhibition of 23 ± 0.6 mm and a bacteriostatic effect against Shigella
flexneri and Salmonella typhimurium. It was also shown antifungal activity against Candida
albicans with a zone of inhibition of 25 ± 0.6 mm. This fraction was not active at the same
concentration against other microorganisms tested. The activity of the extract against
Pseudomonas aeruginosa was low compared to the control. However, the activity of this fraction
was superior to the activity of the crude methanol extract and the hexane fraction. This fraction
also showed antifungal activity against Candida albicans higher than the control, the crude
methanol extract, and the hexane fraction.
In phytochemical tests performed on this fraction by precipitation methods (Mayer and
Dragendorff) and thin layer chromatography were identified alkaloids. The presence of alkaloids
in this plant have been reported by Odhiambo et al (2010) as the active constituents present in the
extract CH2Cl2: CH3OH (1:1) against Aspergillus niger.
The ethyl acetate fraction exhibited an antibacterial activity against Pseudomonas
aeruginosa with an inhibition zone of 25 ± 0.0 mm and a bacteriostatic effect against Shigella
flexneri and Salmonella typhimurium. This fraction was also active against the yeasts Candida
albicans and Saccharomyces cerevisiae with zones of inhibition of 24 ± 0.6 ± 0.3 and 20 mm
respectively. This fraction was not active at the same concentration against other microorganisms
tested. The antibacterial activity against Pseudomonas aeruginosa of this fraction was low
compared to the control, but greater than the activity of the crude methanol extract, the hexane
and chloroform fractions. This fraction was more active against Candida albicans than against
the yeast Saccharomyces cerevisiae. It also showed antifungal activity against Candida albicans
higher than the control nystatin, crude methanol extract, hexane and chloroform fractions.
Phytochemical tests realized on this fraction showed the presence of alkaloids, coumarins and
saponins that may be associated with antimicrobial activity shown by this fraction.
The butanol fraction showed antibacterial activity against Pseudomonas aeruginosa with
a zone of inhibition of 20 ± 0.1 mm, a low activity against Staphylococcus aureus and a
bacteriostatic effect against Salmonella typhimurium. This fraction also showed antifungal


26

activity against Candida albicans with a zone of inhibition of 23 ± 0.6 mm and a moderate
activity against the yeast Saccharomyces cerevisiae with a zone of inhibition of 13 ± 0.6 mm.
The activity of this fraction against Pseudomonas aeruginosa was low compared to the
antibiotic used as control; but it was higher than the crude methanol extract. It also showed
antifungal activity against Candida albicans higher than the control nystatin and the crude
methanol extract. The phytochemical tests of this fraction made possible the identification of
saponins. The presence of these compounds in the extracts of this plant has also been evidenced
by Odhiambo; Siboe; Lukhoba; Dossaji, (2010).
The extract CH2Cl2: CH3OH (1:1) showed antibacterial activity against Pseudomonas
aeruginosa with an inhibition zone of 15 ± 1.0 mm. It also showed activity against candida
albicans and Saccharomyces cerevisiae with zones of inhibition of 21 ± 0.3 mm and 12 ± 0.6 mm
respectively. The activity of the extract against Pseudomonas aeruginosa was low compared to
the antibiotic used as control. Furthermore, their activity against Candida albicans was higher
than the control.
The activity demonstrated by the extract against Candida albicans was higher than that
displayed against Saccharomyces cerevisiae. Phytochemical Tests carried out on this extract
made possible the identification of alkaloids, amino acids, anthraquinones, flavonoids, tannins
and saponins.
The quinolinic compounds are capable of forming irreversible complexes with
nucleophilic amino acids in proteins, often leading in inactivating proteins and consequent loss of
function, which explains the high antimicrobial effect of these compounds (Lopez, 2010). The
biological role of tannins in plants has been investigated and it is believed that they are involved
in chemical defense of plants against attack by herbivores and against pathogens (Oliveira et al,
2007). Not surprisingly, extracts containing tannins show activity against microorganisms.
Flavonoids are compounds synthesized by the plants in response to microbial infection (Dixon;
Dey; Lamb, 1983), so it is not surprising to demonstrate antimicrobial activity in vitro against a
broad range of microorganisms. This activity is probably due to the ability to form complexes
with extracellular soluble proteins and the bacterial cell wall. The more lipophilic flavonoids can
also disrupt microbial membranes.
In studies realized by Odhiambo et al (2010), was also identified the presence of alkaloids
in the extract CH2Cl2 – CH3OH (1:1) which were attributed the potent antifungal activity


27

demonstrated by this extract against Aspergillus niger. The activity exhibited by this extract
against Candida albicans can probably also be associated with these compounds identified.
The juice from the fresh bulb showed an antibacterial activity against Escherichia coli and
Pseudomonas aeruginosa with inhibition zones of 19 ± 0.4 and 12 ± 1.0 mm respectively. It was
also active against candida albicans and Saccharomyces cerevisiae with respective zones of
inhibition of 16 ± 0.3 and 15 ± 0.0 mm. The activity of the extract against Escherichia coli and
Pseudomonas aeruginosa was low compared to the control. Its activity against Candida albicans
was also lower than control.
Phytochemical tests carried out on this extract, have made possible the identification of
amino acids, proteins, alkaloids and saponins. The activity shown by this extract may be
associated with these compounds.
The aqueous extract of the fresh bulb was active against Pseudomonas aeruginosa and
Escherichia coli with the respective zones of inhibition of 16 ± 0.1 and 14 ± 0.3 mm. However
was inactive against the rest of the tested bacteria. No antifungal effect was demonstrated in this
extract. The activity of the extract against Escherichia coli and Pseudomonas aeruginosa was
low compared to the antibiotic used as control.
Phytochemical tests carried out on this extract made possible the identification of
alkaloids. The study realized by Ameh et al (2011), reported the presence of alkaloids in the
aqueous extract of the bulb of Gladiolus obtained by the same method. However, the above
extract was found to be slightly active against Pseudomonas aeruginosa and Aspergillus niger
and inactive against Candida albicans.
The bacteria Escherichia coli was susceptible to aqueous extract and juice, which are
generally used in traditional medicine for the treatment of diarrhea, gonorrhea and other intestinal
disturbances. This activity may explain its traditional use in the treatment of diarrhea of various
origins.
The results of the interaction Extract-Ciprofloxacin show an additive effect for the
combination Juice + Ciprofloxacin in case of E. coli, S. flexneri, K. pneumoniae and P.
aeruginosa; Indifference in case of S. aureus and S. typhimurium. In the case of the combination
of Ciprofloxacin + aqueous extract, the antagonistic effect was observed for all microorganisms
tested. The results of the interaction Extract – Ciprofloxacin are summarized in table 4.


28

Table 4 - Results of the interaction Extract - Ciprofloxacin
Mean diameter of the inhibition zone (mm)
Distilled CIP+
Microorganism CIP Juice Juice+CIP Aq.Extr.
water Aq.Extr.
E.coli
- 31±0,6 19±0,6 33±0,6 16±0,0 28±0,3
ATCC25922
S.aureus
- 33±0.3 - 33±0,6 - 30±2,6
ATCC 25923
Shigella flexneri
- 32±1,0 - 34±1,0 - 30±0,6
ATCC 12022
S. typhimurium
- 32±0.3 - 32±0,3 - 31±0,6
ATCC 14028
K. pneumoniae
- 29±0,0 - 30±1,6 27±1,0
ATCC 15380
P. aeruginosa
- 30±1,0 28±0.5 34±0,6 19±1,0 25±0,3
ATCC 27953
Purified distilled water: Negative control; CIP: Ciprofloxacin - positive control; CIP + Aq.Extr.:
ciprofloxacin combined with aqueous extract; Juice + CIP: ciprofloxacin combined with juice.

Diameters of inhibition of ciprofloxacin when tested in combination with the juice show a
slight increase. Only in the case of Staphylococcus aureus and Salmonella typhimurium, the
combination showed indifference. However, the aqueous extract had an opposite effect, the
diameters of inhibition of the control showed a reduction when used in combination with the
aqueous extract for all tested microorganisms.
According to Nwze & Eze (2009), the convention suggests to use additive when the
percentage of the increase of the diameter of inhibition of the plant extract combination with the
antibiotic is less than or equal to 19%; indifferent, when the diameter of inhibition of the
antibiotic combination with the extract is equal to the diameter of inhibition when the antibiotic
is tested alone, and there is an antagonistic effect in case of loss of inhibition diameter when the
antibiotic control is used in combination with the extract.
This work was based on the same convention. An additive effect was observed in the
following microorganisms: Escherichia coli with 6.45% addition, Shigella flexneri with addition
of 6.25%, Klebsiella pneumoniae with 3.45% of addition and Pseudomonas aeruginosa with
addition of 13.33% when the juice combined with ciprofloxacin. Moreover, the bacteria
Salmonella typhimurium and S. aureus were indifferent to the combination. The combination of
the antibiotic with the aqueous extract showed an antagonistic effect for all the microorganisms
tested.


29

It is important to note that the action of medicinal plants can never be fully understood by
analyzing its components separately. Proponents of this theory argue that the properties are due to
interactions between multiple components (Wink, 2008). For example, the saponins present in
many medicinal plants, enhance the absorption and activity of other substances. The saponins of
Sapindus mukorossi increase the intestinal absorption of certain natural antibiotics. Therefore,
positive interaction found in the combination of the juice with ciprofloxacin can be associated
with the presence of saponins in the plant, which can essentially increase the absorption of
ciprofloxacin through the biological membranes of the bacteria, thereby enhancing its effect.

Conclusion

Qualitative phytochemical analysis of the extracts and fractions of the bulb revealed the
presence of: alkaloids, anthraquinones, tannins, saponins, flavonoids, terpenoids, steroids,
cumarins, reducing sugar, aminoacids and proteins.
Most of the bulb extracts and fractions showed strong inhibitory activity against Candida
albicans, Saccharomyces cerevisiae and Pseudomonas aeruginosa. The determination of the
interaction Ciprofloxacin - aqueous extract and Ciprofloxacin - juice revealed an antagonism
between ciprofloxacin and the aqueous extract and an additive effect between Ciprofloxacin and
juice.
Phytochemical and antimicrobial test results obtained in this work in combination with
the previously reported in literature by different authors validate to some extent the use of the
bulb of Gladiolus psittacinus Hook in traditional medicine in treating diseases of microbial
origin, thus demonstrating the potential of this plant.

References

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31

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