Growing rates of fungal infections and increasing resistance against standard antifungal drugs can cause serious health problems. There is, therefore, increasing interest in the potential use of medicinal plants as novel antifungal agents. This study investigates the antifungal properties of crude plant extracts from ten medicinal plant species. Crude samples were extracted using the hot water extraction process. The minimum inhibitory concentrations (MIC) and diameter zone of inhibition were determined in each extract against ten fungal strains, and fluconazole was used as a positive control. The cytotoxicity of crude extracts on in vitro human skin fibroblast (HSF) cell models was determined by MTT assay. Of the ten crude extracts, Psidium guajava L. exhibited the highest antifungal activity, diameter zone of inhibition, and percentage HSF cell viability. Although all extracts exhibited antifungal activity, Psidium guajava L. had the greatest potential for developing antifungal treatments. 1. Introduction Despite the intensive prophylactic use of antifungal drugs, the incidence of fungal infections has increased due to growing resistance [1, 2]. Therefore, the possibility of finding novel antifungal agents from crude plant extracts has been explored. Many edible plants are known to have beneficial and medicinal properties to humans, and plant extracts have been used as a source of alternative medication for their antioxidative, antifungal, and anticancer properties [3]. Ten plants commonly used in Thai traditional medicine were selected for this study: Garcinia mangostana L., Piper betel L., Camellia sinensis, Morus alba Linn., Aegle marmelos L., Garcinia atroviridis Griff., Andrographis paniculata (Burm.f.) Wall.ex Nees, Schefflera leucantha R. Vig., Carthamus tinctorius L., and Psidium guajava L. The objective of this study was to evaluate the in vitro antifungal activities of crude extracts of these edible plant species in a systematic and consistent manner against clinical pathogens. The results indicate that there are potential benefits of using crude plant extracts for the treatment of fungal infections. 2. Materials and Methods 2.1. Preparation of Plant Sample Extracts The ten plant species used in this study can be divided into four categories according to their active ingredients. The first category is condensed tannins, which is obtained from the peel of Garcinia mangostana L. (mangosteen). The second is hydrolysable tannins, obtained from the leaf of Piper betel L. (betel vine) and Camellia sinensis (green tea). The third category is
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