1
Laboratório de Micologia Médica e Molecular, Departamento de Análises
Clínicas e Toxicológicas, Universidade Federal do Rio Grande do Norte,
Natal, Rio Grande do Norte, Brazil
2 Departamento de Farmácia, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
3 Departamento de Análises Clínicas, Universidade Estadual de Maringá, Maringá, Paraná, Brazil
4 Departamento de Infectologia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
2 Departamento de Farmácia, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
3 Departamento de Análises Clínicas, Universidade Estadual de Maringá, Maringá, Paraná, Brazil
4 Departamento de Infectologia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
BMC Complementary and Alternative Medicine 2015, 15:6
doi:10.1186/s12906-015-0522-x
The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1472-6882/15/6
The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1472-6882/15/6
| Received: | 20 October 2014 |
| Accepted: | 14 January 2015 |
| Published: | 5 February 2015 |
© 2015 Silva-Rocha et al.; licensee BioMed Central.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Abstract
Background
Candida albicans is a diploid yeast that in some circumstances may cause oral or oropharyngeal infections.
Yeasts virulence factors contribute for both the maintenance of colonizing strains
in addition to damage and cause tissue invasion, thus the establishment of infection
occurs. The limited arsenal of antifungal drugs for the treatment of candidiasis turn
the investigation of natural products mandatory for the discovery of new targets for
antifungal drug development. Therefore, tropical countries emerge as important providers
of natural products with potential antimicrobial activity. This study aimed to investigate
morphogenesis and secretion of hydrolytic enzymes (phospholipase and proteinase) in
the presence of the CE of Eugenia uniflora.
Methods
The isolates were tested for their ability to form hyphae in both solid and liquid
media under three different conditions: YPD + 20% FBS, Spider medium and GlcNac and
the ability to secrete phospholipase and proteinase in the presence of 2000 μg/mL
of E. uniflora.
Results
The CE of E. uniflora inhibited hypha formation in both liquid and solid media tested. It also impaired
hydrolytic enzymes production.
Conclusions
This was the first study to describe the interaction of a natural product with the
full expression of three different factors in C. albicans. E. uniflora may be an alternative therapeutic for oral candidiasis in the future.
Keywords:
Candida albicans ; Oral candidiasis; Kidney transplant recipients; Morphogenesis; Hydrolytic enzymes; Eugenia unifloraBackground
Candida species are the most common human fungal pathogens, whereas Candida albicans is the most prevalent species isolated in fungal infections of the oral mucosa [1]-[3]. In the human oral cavity, these yeasts colonize from 20 to 80% of adults without
evidences of infection [3]-[5]. However, in some circumstances which involve both pathogen attributes of virulence
as well as host immunity; specific groups of patients, such as those with AIDS, transplant
recipients and patients submitted to broad spectrum antibiotics may become susceptible
to develop oropharyngeal candidiasis [6]-[8].
Oral candidiasis is a fungal opportunistic infection commonly observed in kidney transplant
recipients, where the prevalence of the disease ranges from 9.4 to 46% in different
group of patients, being C. albicans the most frequently isolated species [6],[9]-[13].
C. albicans virulence factors contribute for both the maintenance of colonizing strains and tissue
invasion, thus the establishment of infection occurs [14]-[16]. Among the main virulence attributes of C. albicans are the ability of cells transition from yeast to hyphae, a phenomenon called morphogenesis,
which contributes to tissue invasion [17]. Morphogenesis is a well-recognized virulence factor in C. albicans, because mutants unable to form pseudohyphae or true hyphae are attenuated in virulence
[18],[19].
Merson-davies and Odds [20] proposed a quantitative index based on the shape of the cells to differentiate blastoconidia,
pseudohyphal and true hyphal forms of growth. Yeast cells have a morphology index
(MI) between 1.0 to 1.5, pseudo hyphae from 2.5 to 3.4 and true hyphae greater than
3.4 [21]. This index, based on a complex image analysis measurements can be substituted with
an approximated score system to generate information on morphology distributions [22],[23].
The secretion of hydrolytic enzymes such as phospholipases, which degrade glycerolphospholipids
of cell membranes, is important for host cells destruction [24]. In addition, C. albicans possesses secreted aspartic proteinases (Saps), able to target several important
substrates, such as albumin, immunoglobulins and extracellular matrix proteins [14],[25],[26].
The limited arsenal of antifungal drugs for the treatment of candidiasis includes
mainly polyenes, azoles and echinocandins [27]-[29]. Nevertheless, these drugs have narrow therapeutic index, low bioavailability, week
intestinal absorption and serious side effects [30]. In addition, the excessive and indiscriminate use of antifungal agents favors the
development of resistant strains [31]. Although C. albicans has been reported as less resistant to antifungal drugs than other Candida species, resistance to azoles [32] and echinocandins [33] have been reported. Therefore, due to the increase of resistance of pathogenic fungi
to antifungal drugs currently used, there is a necessity for the prevention of oral
fungal infections and the development of alternative therapies [34],[35].
The use of natural products aiming the treatment of several diseases has increased
in the last few years, related to the high diversity of plants distributed around
the planet [36]. Nevertheless, there are only a few studies about the use of vegetal extracts to
treat fungal infections, including candidiasis [37]-[39]. In addition, very little is known about the action of plant extractive compounds
in the virulence attributes of C. albicans.
Concerning to the world biodiversity, the American flora is one of the most rich source
of plants with pharmacological activities [40] In this context, Brazil emerges as an important provider of botanical material for
the international pharmaceutical market [40]. Eugenia uniflora, (known in Brazil as “pitangueira”) is a native Brazilian plant belonging to the
family Myrtaceae, which includes species that have phenolic compounds as the predominant constitution
[41]. The infusion of E. uniflora leaves has application in popular medicine mainly due to its properties as antioxidant,
hypotensive, modulator of antibiotics and antifungal drugs [42]. Actually, anti-Candida activity of E. uniflora has been previously described [42],[43].
The present study aimed to evaluate the action of the crude extract (CE) of E. uniflora in some C. albicans virulence factors, including morphogenesis and hydrolytic enzymes (proteinase and
phospholipase) activities of clinical oral isolates of C. albicans obtained from kidney transplant recipients in Brazil.
