plants
Article
LC-MS Analysis and Antifungal Activity of
Turnera subulata Sm.
Jacqueline Cosmo Andrade-Pinheiro 1,2 , Celestina Elba Sobral de Souza 1 , Daiany Alves Ribeiro 1 ,
Andressa de Alencar Silva 1 , Viviane Bezerra da Silva 3 , Antonia Thassya Lucas dos Santos 1 ,
Victor Juno Alencar Fonseca 1 , Delmacia Gonçalves de Macêdo 1 , Rafael Pereira da Cruz 1 ,
José Weverton Almeida-Bezerra 1 , Antonio Júdson Targino Machado 1 , Thiago Sampaio de Freitas 1 ,
Edy Sousa de Brito 4 , Paulo Riceli Vasconcelos Ribeiro 4 , José Galberto Martins da Costa 1 ,
Henrique Douglas Melo Coutinho 1, * , Grażyna Kowalska 5 , Rafał Rowiński 5 , Radosław Kowalski 6, *
and Maria Flaviana Bezerra Morais-Braga 1
1
2
3
4
5
6
*
Citation: Andrade-Pinheiro, J.C.;
Sobral de Souza, C.E.; Ribeiro, D.A.;
Silva, A.d.A.; da Silva, V.B.; dos
Santos, A.T.L.; Juno Alencar Fonseca,
V.; de Macêdo, D.G.; da Cruz, R.P.;
Almeida-Bezerra, J.W.; et al. LC-MS
Analysis and Antifungal Activity of
Turnera subulata Sm. Plants 2023, 12,
415. https://doi.org/10.3390/
plants12020415
Academic Editors: Francesca Pintus
and Celestino Santos-Buelga
Received: 9 December 2022
Pimenta Campus, Regional University of Cariri (URCA), Av. Cel Antônio Luis, 1161, Pimenta,
Crato 63105-010, Brazil
Laboratório de Bioensaios, Federal University of Cariri (UFCA), R. Olegário Emidio de Araujo, s/n, Centro,
Brejo Santo 63260-000, Brazil
Department of Botany, Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego, 1235,
Recife 50670-901, Brazil
Embrapa Agroindústria Tropical, Tropical R. Pernambuco, 2270-Pici, Fortaleza 60511-110, Brazil
Department of Tourism and Recreation, University of Life Sciences in Lublin, 15 Akademicka Str.,
20-950 Lublin, Poland
Department of Analysis and Food Quality Assessment, University of Life Sciences in Lublin, 8 Skromna Str.,
20-704 Lublin, Poland
Correspondence: hdmcoutinho@gmail.com (H.D.M.C.); radoslaw.kowalski@up.lublin.pl (R.K.)
Abstract: Fungi of the Candida genus are responsible for invasive candidiasis, which affects people all
over the world and has high mortality rates. This is due to their virulence factors, which give them
great resistance and pathogenicity. In addition, the emergence of multidrug-resistant strains makes
it difficult to treat these infections. In this way, natural products have emerged as an alternative to
standard drugs, where plants known for their medicinal properties such as Turnera subulata become
attractive to research. The present work aimed to analyze the ethanol extract of Turnera subulata
leaves against standard strains of Candida albicans, Candida krusei and Candida tropicalis using broth
microdilution techniques. The identification of the compounds in T. subulata leaves by LC-MS
revealed the presence of a wide variety of substances such as carboxylic acids and terpenes, with
flavonoids and fatty acids being more evident. The antifungal assays showed that the extract was not
able to inhibit the growth of the tested strains at concentrations with a clinical relevance. However, at
higher concentrations, it was able to inhibit the fungal dimorphism of C. albicans and C. tropicalis. It is
possible that the T. subulata extract has potential as an inhibitor of fungal virulence factors without
affecting the cell viability. Further research should be carried out in order to assess its inhibitory
potential for other fungal virulence factors.
Revised: 9 January 2023
Accepted: 13 January 2023
Keywords: yeasts; antifungal; extract; virulence
Published: 16 January 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
1. Introduction
Fungal infections caused by Candida, Cryptococcus and Aspergillus species kill thousands of people annually. This happens because these infections are difficult to treat and
are often neglected. Although there are antifungal drugs that are widely used in medicine
with relative effectiveness, mortality rates remain high as these microorganisms are capable
of developing a resistance to this class of drugs [1,2].
The development of new drugs and diagnostic tools is important to avoid these problems and requires extensive knowledge about the biology of fungal pathogens, especially
Plants 2023, 12, 415. https://doi.org/10.3390/plants12020415
https://www.mdpi.com/journal/plants
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commensals, which, under favorable conditions, develop into difficult to treat infections [2].
Species such as Candida albicans and Candida tropicalis have characteristics that make them
difficult to eradicate, such as the production of biofilms and fungal dimorphism; these
are phenomena that are often associated with virulence, aiding in the colonization, tissue
invasion and evasion of the immune system [3–5].
Researchers around the world have been looking for natural alternatives such as
medicinal plants because, due their chemical constituents, they are seen as active therapeutic sources with the potential for the development of new drugs [6]. In addition,
plant phytochemicals may be effective in combination therapies with commercial drugs,
decreasing adverse effects and reversing fungal resistance to drugs [7,8].
The Passifloraceae family is represented by 12 genera and about 220 species and is
distributed in the Americas and Africa [9–11]. In Brazil, the 2 largest genera of this family
are found, Piriqueta and Turnera, which are distributed in 155 species [12,13]. The Turnera
genus includes 135 species distributed in the tropical and subtropical regions of America
and parts of Africa [10,11].
Turnera subulata Sm. (Passifloraceae) is a herbaceous plant frequently found in the
North and Northeast of Brazil. Popularly known as “Chanana”, the species stands out for
its medicinal properties, as reported in several studies evidencing its activities as an antibacterial, by modulating the action of drugs such as amikacin, neomycin and tobramycin
against Escherichia coli [14] and gentamicin and kanamycin against Staphylococcus aureus [15];
as an antifungal, by modulating the action of metronidazole against C. tropicalis [16]; and
as an anthelmintic against Haemonchus contortus in the early stages of development [17].
According to the literature, its composition contains flavonoids, alkaloids, tannins
and phenolic compounds [18–21]; important classes that participate in the development of
the biological activities of the species and that stand out in the investigation of bioactive
compounds with a pharmaceutical potential. Therefore, and considering the medicinal
importance of this species, in this work we aimed to evaluate the antifungal action of the
ethanol extract of the leaves of Turnera subulata against the strains of Candia spp. as well as
its inhibitory potential of fungal dimorphism.
2. Results
2.1. Identification of Chemical Composition
The identification of the compounds in T. subulata leaves revealed the presence of a
wide variety of substances such as carboxylic acids and terpenes, with flavonoids and fatty
acids being more evident, as represented in the chromatogram (Figure 1). Table 1 presents
the chromatographic and mass spectral data such as the molecular ionic mass, retention
time and fragmentation pattern for the compound identification.
Of the 18 peaks observed in the chromatograms, 12 were identified; among these,
compounds 1, 2 and 3 exhibited [M-H]- at 191, 133 and 130 m/z, respectively. These
were identified as quinic acid, malic acid and leucine by an authentic comparison of the
pattern [22].
Compounds 6 and 7 showed a deprotonated [M-H]- ion at 593 m/z and 577 m/z,
respectively. Compound 6 was identified as rhamnosyl isoorientin due to the presence
of a fragment at 473 m/z corresponding with a loss of the C-hexose moiety. A fragment
at 429 corresponded with a loss of the O-rhamnose moiety and a water molecule as a
fragment ion at 327 m/z corresponded with the additional loss of the C-hexose moiety [23].
Compound 7, presenting fragments at 413 and 293 m/z that corresponded with C-glycosyl
flavones and O glycosylated in the sugar portion, was identified as rhamnosyl vitexin [24].
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Table 1. Compounds identified in the leaves of T. subulata in the negative mode of ESI.
Peak
N◦
Rt
Min
[M-H]Observed
[M-H]Calculated
Product Ions
(MS/MS)
Empirical
Formula
Ppm
Error
Putative Identification
Ref.
1
1.14
191.0550
191.0556
-
C7 H11 O6
−3.1
Quinic acid *
[22]
2
1.33
133.0133
130.0137
-
C 4 H5 O 5
−3.0
Malic acid *
[22]
3
2.05
130.0863
130.0868
-
C6 H12 NO2
−3.8
Leucine *
[22]
4
3.03
409.1877
409.1862
179, 119
C21 H29 O8
3.7
Unknown
-
5
3.36
657.1106
657.1092
577, 341
C30 H25 O17
2.1
Unknown
-
6
3.65
593.1507
593.1506
473, 429, 369,
357, 327
C27 H29 O15
0.2
Rhamnosyl isoorientin
[23]
7
3.85
577.1560
577.1557
413, 293
C27 H29 O14
0.5
Rhamnosyl vitexin
[24]
8
4.17
553.3001
553.3013
507, 375
C29 H45 O10
−2.2
Unknown
-
9
4.44
305.1603
305.1600
179, 161
C14 H25 O7
1.0
Hexose derivative
[25]
10
4.78
187.0966
187.0970
125
C9 H15 O4
−2.1
Azelaic acid
[26]
11
5.35
577.1564
577.1557
269
C27 H29 O14
1.2
Apigenin
7-O-neohesperidoside
[27]
12
5.75
577.1558
577.1557
269, 431
C27 H29 O14
0.2
Apigenin 7-O-rutinoside
[27]
13
6.28
329.2322
329.2328
229, 211, 171
C18 H33 O5
−1.8
Trihydroxyoctadecaenoic
acid
[28]
14
6.63
723.1807
723.1773
269
C32 H35 O19
4.7
Apigenin derivative
[27]
15
6.82
725.1939
725.1929
453, 271
C32 H37 O19
1.4
Unknown
16
7.76
293.1766
293.1753
236, 221
C17 H25 O4
4.4
Unknown terpene
-
17
8.94
675.3601
675.3592
415, 397, 277,
235
C33 H55 O14
1.3
Digalactosylmono
acylglycerol
[29]
18
10.38
555.2793
555.2805
255
C28 H43 O11
−2.2
Unknown fatty acid
-
* Comparison with authentic standard.
Compound 9 presented a mass [M-H]- at 305 m/z; it was identified as a hexose derivative formed by the dehydration of disaccharides [25]. Compound 10, a deprotonated
molecule with a mass [M-H]- at 187 m/z, showed a prominent fragmented ion in m/z due
to the loss of the water portion and was identified as azelaic acid [26].
Compounds 11, 12 and 14 were identified as apigenin derivatives. Compound 11
produced a molecular anion in the apigenin fragment at 269 m/z, pointing to the presence
of apigenin 7-O-neohesperidoside (rhoifolin). Compound 12 was identified as apigenin
7-O-rutinoside (isorhoifolin) due to the fragment ions at 431 (M-rhamnose) m/z and 269
(M-rutinose) m/z [27].
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Figure 1. Chromatogram showing the negative mode of T. subulata leaves.
2.2. Antifungal Tests
Table 2 shows the results of the intrinsic activity performed by the broth microdilution
technique. The inhibition potential of the products tested against Candida compared with
the standard drug fluconazole was identified. The results showed that the products were
able to inhibit 50% of the microorganism population (IC50 ) only at high concentrations and
only for C. albicans and C. krusei; fluconazole
− alone was effective against the three strains
tested, where C. albicans was inhibited by 16.70
− µg/mL, C. tropicalis by 9.30 µg/mL and C.
krusei by 133.32 µg/mL.
−
Table 2. Inhibitory concentrations of 50% (IC50 ) of microorganisms (µg/mL) by ethanol extract of the
leaves of Turnera subulata and fluconazole.
Strains
Tested Products
CA INCQS 40006
CT INCQS 40042
CK INCQS 40095
Fluconazole (FCZ)
16.70 µg/mL
9.30 µg/mL
133.32 µg/mL
EELTS
7544.60 µg/mL
-
16,087.37 µg/mL
EELTS: ethanolic extract from the leaves of Turnera subulata; CA: Candida albicans; CT: Candida tropicalis; CK:
Candida krusei; INCQS: Instituto Nacional de Controle de Qualidade em Saúde.
The fungal viability curve (Figure 2) was constructed from the values obtained from an
ELISA spectrophotometer. It was found that the ethanol extract of Turnera subulata (EELTS)
against the Candida strains (CT INCQS 40006, CT INCQS 40042 and CK INCQS 40095) was
above 8192 µg/mL, showing a slight reduction in the percentage of microorganisms on the
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cell viability curve. In the minimum fungicide concentration (MFC), the absence of EELTS
results indicated a fungistatic effect on Candida (≥ 16,384 µg/mL).
Figure 2. Antifungal effect of Turnera subulata ethanol extract (EELTS) compared with standard
antifungal. FCZ: fluconazole. (A) CA: Candida albicans INCQS 40006; (B) CT: Candida tropicalis INCQS
40042; (C) CK: Candida krusei INCQS 40095. p < 0.05. * p < 0.1 and ** p < 0.01 when compared with the
growth control.
The images presented in Figure 3 show the growth control and the control of the
effect of fluconazole on the fungal dimorphism. In the micromorphology reading, it could
be observed that the properly depleted medium stressed the Candida strains, driving the
morphological transition and causing the emission of hyphae and pseudohyphae.
When cultivated in the growth medium added to the ethanolic extract of the leaves of
Turnera subulata, C. krusei did not show any changes in its dimorphic potential at any of
the concentrations tested. The presence of hyphae and pseudohyphae was recorded, as
seen in Figure 4. For C. albicans and C. tropicalis, there was inhibition only at the highest
HSA-8192 µg/mL concentration.
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Figure 3. Growth control and fluconazole effect in Candida morphological transition assays. (1–3):
Candida growth control; (4–6): effect of fluconazole. View from a 40 × objective. CA: Candida albicans;
CK: Candida krusei; CT: Candida tropicalis.
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Figure 4. Effect of ethanol extract from Turnera subulata leaves on Candida morphological transition. CK: Candida krusei; CT: Candida tropicalis; CA: Candida albicans; INCQS: Instituto Nacional
de Controle de Qualidade em Saúde. (1,4,7): concentrations of 512 µg/mL; (2,5,8): 2048 µg/mL;
(3,6,9): 8192 µg/mL.
3. Discussion
Fungal infections affect people all over the world. In most of these infections, the
isolated fungi are of the Candida genus, with C. albicans being the most common. However,
many non-albicans Candida species are pathogenic. This pathogenicity is due to virulence
factors such as the ability to develop biofilms, which gives them a great resistance. In
addition, these fungi can develop a drug resistance [30,31]. Thus, natural products represent
an alternative in the treatment of these infections, which can promote a reduction in the
fungal virulence or even promote the action of drugs in combined therapies [32].
In a study carried out by Santos et al. [16] using an ethanol extract of T. subulata leaves,
there was no clinically relevant antifungal activity against strains of C. albicans ATCC
40227, C. krusei ATCC 40147 and C. tropicalis ATCC 13803 when the MIC of the product
was ≥1024 µg/mL. In addition, in a combined activity with drugs, the extract did not
product
was
≥ 1024 in
μg/mL.
In addition,
in
show
any
changes
the MIC
when associated
with amphotericin B and nystatin, but
showed a potentiating effect of antifungal activity against C. tropicalis when associated with
metronidazole.
In a study carried out by Morais [33], the crude extract as well as the hexane fractions
and ethyl acetate from T. subulata also did not show a significant antifungal activity against
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strains of C. albicans ATCC 90028, Candida dubliniensis CBS 7987, C. tropicalis ATCC 13803,
Candida parapsilosis ATCC 22019, Candida glabrata ATCC 2001, C. krusei ATCC 6258 and
Candida rugosa ATCC 10571.
Similarly, the present work showed that EELTS did not show an antifungal activity
against the three tested Candida strains, although flavonoids were the main component
of the extract. It is known that flavonoids exhibit diverse biological activities, including
antifungal activities [34]. These activities are extensively reported in the literature and,
according to Jin et al. [35], flavonoids can act on the cell wall as well as biofilm formation
and fungal dimorphism. This may elucidate the results obtained, where EELTS was able
to inhibit the development of hyphae at the highest concentrations against C. albicans and
C. tropicalis.
Fatty acids present in EELTS may also have contributed to the inhibition of fungal
dimorphism in C. albicans and C. tropicalis. Studies show that fatty acids can reduce the
virulence of these fungi such as biofilm formation, hyphae growth and cell aggregation [36].
The plasticity of the fungal cells of the genus Candida has been frequently associated with
an increase in the virulence and, for this reason, there is great interest in researching
the compounds capable of inhibiting these factors. It is more favorable to reduce the
virulence of fungi without interfering with their cell viability, thus being able to prevent
the development of resistance [3,5].
Interestingly, although the fluconazole activity was effective against C. krusei, it was
still more resistant than C. albicans and C. tropicalis. According to Sampaio et al. [37], this
difference in the antifungal activity of fluconazole between Candida species may be due
to subtle changes between them, which give them resistance. In agreement, Arendrup
and Patterson [38] reported that this resistance in Candida does not occur in the same
way among their species. For C. albicans, the prolonged use of antifungals followed by
recurrent infections such as chronic mucocutaneous candidiasis increases the chances of an
acquired resistance. For several non-albicans Candida species such as C. krusei, there is less
susceptibility to several classes of antifungals.
4. Materials and Methods
4.1. Plant Collection
Fresh leaves of Turnera subulata were collected from the Araripe National Forest
(FLONA; Araripe Apodi) in a locality known as Barreiro Grande (07◦ 21′ S and 039◦ 28′ W),
located in the municipality of Crato in the south of the State of Ceará (Brazil, Crato).
4.2. Preparation of Ethanol Extract
A total of 500 g of fresh leaves of Turnera subulata was crushed and then subjected to an
exhaustive removal in 95% ethanol for 72 h. The extraction solution was subjected to solvent
distillation on a rotary evaporator under a reduced pressure at an average temperature of
50 ◦ C [39]. After distilling the solvent to dryness, the ethanolic extract of the fresh leaves of
Turnera umifolia (EELTS) was obtained, with a percentage yield of 1.1%.
4.3. LC-MS Conditions
The analyses were performed using an Acquity UPLC (Waters, Milford, MA, USA)
system coupled to a Xevo Quadrupole and Time-of-Flight mass system (QTOF, Water,
Milford, MA, USA). A Waters Acquity BEH C18 column was used for the separation
condition (150 mm × 2.1 mm; 1.7 µm) and set at 40 ◦ C. An injection volume of a 5 µL
aliquot of ethanolic extract was subjected to an exploratory gradient. The mobile phase was
composed of deionized water (A) and acetonitrile (B) and both contained formic acid (0.1%
v/v). The extracts were subjected to an exploratory gradient as follows: 2–95% B (15.0 min),
100% B (15.01–17.0 min) and 2% B (17.1–19.0 min), with a flow rate of 0.22 mL min−1 .
Mass spectrometry analyses were performed using a mass spectrometer equipped
with an ionization source (QTOF, Water, Milford, MA, USA) with an electrospray ionization
source in the negative mode of ESI acquired in the range of 110–1200 Da. The optimized
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instrumental parameters were as follows (to negative): capillary voltage at 2.8 kV, cone
voltage at 50 V, source temperature at 120 ◦ C, desolvation temperature at 350 ◦ C, flow cone
gas at 20 L h−1 and desolvation gas flow at 500 L h−1 . The mode of acquisition was MSE .
The system was controlled using MassLynx 4.1 software (Waters Corporation, Milford,
MA, USA).
4.4. Antifungal Assays
4.4.1. Microorganisms
For the evaluation of the antifungal activity, three standard strains obtained from the
Oswaldo Cruz Culture Collection of the National Institute for Quality Control in Health
(INCQS) were used: C. albicans CA INCQS 40006; C. krusei CK INCQS 40095; and C. tropicalis
CT INCQS 40042.
4.4.2. Growth Media
A Sabouraud Dextrose Agar (SDA) medium purchased from HIMEDIA® was prepared
according to the manufacturer’s instructions. Sabouraud Dextrose Broth (CSD), purchased
from KASVI® and doubly concentrated, was used in the assays to evaluate the antifungal
activity. For the analysis of fungal dimorphism, a potato dextrose agar (PDA) medium,
purchased from Difco® , was used. The growth media were solubilized with distilled water
and sterilized in an autoclave at 121 ◦ C for 15 min.
4.4.3. Inoculum Preparation
The strains were initially kept in test tubes containing SDA under refrigeration (8 ◦ C).
For the minimum inhibitory concentration (MIC) and minimum fungicide concentration
(MFC) tests, the fungi were initially cultivated in Petri dishes containing SDA and incubated
at 37 ◦ C for 24 h (overnight). After this, the suspensions of microorganisms were prepared
in tubes containing 4 mL of a sterile solution (0.9% NaCl). These suspensions were then
shaken in a vortex mixer and the turbidity was compared and adjusted according to
the 0.5 McFarland scale, which corresponded with an inoculum of approximately 105
colony-forming units (mL–CFU/mL) [40].
4.4.4. Drugs and Reagents
Dimethylsulfoxide (DMSO-Dynamic) was used to dilute the extract. The antifungal
fluconazole at a dose of 150 mg (PRATI-Donaduzzi) was diluted in distilled water and
used as a reference drug for the antifungal tests. In the preparation of the matrix solution
of the extract, 0.15 g was weighed and then solubilized in 1 mL of DMSO. The extract
and fluconazole were diluted again in sterile distilled water in order to obtain the desired
concentration for the tests (16,384 µg/mL). The assay was performed using DMSO with
a final concentration lower than 10% (the pilot assay performed in the lab indicated that
DMSO concentrations lower than 10% did not affect the final results).
4.4.5. Intrinsic Activity of the Antifungal Effect of EELTS and Fluconazole
An antifungal test with EELTS and fluconazole was performed using the broth microdilution technique and 96-well polystyrene plates. A total of 100 µL of a double-concentrated
SDB medium was added to each well, plus the fungal suspension (10%). Subsequently,
100 µL of the natural product at a concentration of 16,384 µg/mL was deposited in the first
well, from which the serial microdilution was carried out until the penultimate well; the
concentrations ranged from 8192 to 8 µg/mL. The last well was reserved for the growth
control. Controls for the sterility of the medium and the dilution of the natural product
and fluconazole were also performed [41].
The plates were incubated at 37 ◦ C for 24 h. After this period, they were taken
to be read in an ELISA spectrophotometer device (Termoplate® ) with a wavelength of
630 nm [42]. The results provided the minimum inhibitory concentration (MIC) of the
tested products as well as the IC50 . The tests were performed in quadruplicate.
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4.4.6. Determination of the Minimum Fungicide Concentration
With the aid of a sterile rod, the aliquots were transferred from each well of the MIC
test plate, where the concentrations varied from 8192 to 8 µg/mL, to Petri dishes containing
SDA. The plates were incubated at 37 ◦ C for 24 h. After this period, the plates were checked
for the growth of Candida colonies. The MFC was defined as the lowest concentration of
the natural product capable of inhibiting the growth of fungal colonies [43].
4.4.7. Effect of EELTS on the Fungal Dimorphism of Candida spp.
In the observation of the morphological alterations of the Candida strains against
the EELTS extract, the technique of microculture for yeasts was used, using the depleted
PDA medium in humid chambers. Intrinsic activity concentrations were considered, with
concentrations of 8192 µg/mL being evaluated as HSA (a higher concentration assessed) as
well as 2048 µg/mL (HSA/4) and 512 µg/mL (HSA/16). A total of 3 mL of the medium
associated with the product tested was poured onto glass slides in a humid chamber. After
the solidification of the medium, the yeast was seeded with the aid of a calibrated loop of
1 µL; two parallel streaks were then drawn, which were covered with sterile coverslips.
The plates were incubated at 37 ◦ C. After 24 h, the slides were observed under an optical
microscope with a 40 × objective. A yeast growth control was performed as well as a
fluconazole control for comparative purposes. The microcultures were photographed with
an attached camera with a 5 x zoom. The tests were performed according to Sidrim and
Rocha [44] and Mendes [45], with a few modifications.
4.5. Statistical Analysis
Quadruplicates were performed for each test and a two-way ANOVA analysis of
variance with Fisher’s test was applied to each sample. The IC50 values were computed
by a linear regression for the interpolation into standard curves relating to the percentage
(%) of the growth values and the product concentration in µg/mL using GraphPad Prism
software, version 5.0.
5. Conclusions
Although EELTS did not affect the cell viability of the three tested Candida strains, it
was possible to observe, at high concentrations, an inhibitory effect on dimorphism in C.
albicans and C. tropicalis. These results suggested that the product could act on these fungi
directly on their virulence factors without affecting the cell viability. Further studies are
needed to check its activity against other virulence factors such as biofilm formation. In
addition, it is possible that this product could modulate the action of drugs, enhancing
their activity.
Author Contributions: Conceptualization, J.C.A.-P. and C.E.S.d.S.; methodology, D.A.R., D.G.d.M.,
A.J.T.M. and R.P.d.C.; software, J.W.A.-B. and P.R.V.R.; validation, T.S.d.F.; formal analysis, A.d.A.S.;
investigation, J.C.A.-P., A.T.L.d.S., A.d.A.S. and V.J.A.F.; resources, J.C.A.-P., M.F.B.M.-B., H.D.M.C.,
R.K. and J.G.M.d.C.; data curation, J.C.A.-P.; writing—original draft preparation, J.C.A.-P.; writing—
review and editing, J.C.A.-P.; visualization, V.B.d.S., G.K., E.S.d.B. and R.R.; supervision, M.F.B.M.-B.,
H.D.M.C., R.K. and J.G.M.d.C.; funding acquisition, M.F.B.M.-B., H.D.M.C., R.K. and J.G.M.d.C. All
authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement: Not applicable.
Informed Consent Statement: Not applicable.
Data Availability Statement: Not applicable.
Acknowledgments: Universidade Regional do Cariri.
Conflicts of Interest: The authors declare no conflict of interest.
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