Content area
Full text
Received Dec 2, 2017; Revised Mar 4, 2018; Accepted Mar 21, 2018
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Candida albicans is the most common pathogenic fungus in human and could cause a series of skin and superficial mucosal tissue infections, including oral thrush and vaginitis, as well as the lethal invasive systemic candidiasis [1]. Recent years have witnessed the increase in the morbidity and mortality of C. albicans infections, due to the increased use of immune-suppression therapies (resulting from cancer therapies and organ transplantation), the rise in acquired immune deficiency syndrome (AIDS) patients, and the emergence of drug resistance [2, 3]. Among the nosocomial bloodstream infections, C. albicans is the fourth most common pathogenic agent [4].
Among the many virulence factors, the capacity of C. albicans to switch from yeast form to hyphal form and to form biofilms on abiotic and biotic surfaces plays a critical role in the pathogenesis [5, 6]. The hyphae of C. albicans could secrete Candidalysin which could damage the epithelial cells and facilitate the survival in and the escape from the macrophages [7, 8]. C. albicans biofilms are complex structures consisted of different types of cells (yeast, hyphal, and pseudo-hyphal forms) encased by the extracellular exopolysaccharide (EPS) generated by the cells within biofilms [9]. The cells in biofilm are much more resistant to antifungal therapies compared to their planktonic counterparts [9]. The biofilm growth is responsible for the majority of C. albicans infections, especially those associated with medical devices such as catheters, pacemakers, dentures, and prosthetic joints [9, 10]. This fungal pathogen causes a large burden on social economy and public health, while there is a dearth of antifungal drugs. The development of drug resistance is making this worse. Therefore, developing novel antifungal agents, especially those effective against biofilm, is a pressing mission.
Natural products have been considered as a huge reservoir for developing new antifungal drugs [11, 12]. Huangshanyao (Chinese name) saponin extract (HSE) is the saponin extract from rhizomes of Dioscorea panthaica Prain et Burk, a traditional medicinal herb that is grown in Southwest part of China such as Yunnan, Sichuan,...