Antifungal Activity of Stilbenes against Candida Albicans by Time Kill Assay

Candida albicans is one of the most important fungi associated with oral candidiasis and the treatment of this fungi is a serious problem today because of the resistance of these fungi against conventionally used drugs. So, there is an urgent need of alternative antifungal substances especially from the natural sources. The study was conducted to examine the MFC and time kill activity of two stilbenes [3, 4', 5-trihydroxystilbene (1) and 3,5dihydroxy-4-isopropylstilbene (2)] purified from a bacterium associated with entomopathgenic nematode against C. albicans. The activity was also compared to amphotericin B. The cytotoxicity of stilbenes was also tested against normal human cell lines (L231 lung epithelial and FS normal fibroblast). Results showed that stilbenes was effective against C. albicans with MIC and MFC of 64 and 128 μg/ml for compound 1 and 32 and 64 μg/ml for compound 2. The time kill assay of stilbenes against C. albicans was more effective than amphotericin B. No cytotoxicity was recorded for stilbenes upto 200 μg/ml. The strong antifungal activity and low cytotoxicity of stilbenes make it a promising agent for the treatment of Candida. INTRODUCTION: Candidiasis, the main opportunistic fungal infection has steadily increased over the past 30 years 1, . Among the many species, Candida albicans is the most important pathogen and oral candidiasis is an oral lesion caused by this organism. It has been estimated that more than 90% of human immunodeficiency virus (HIV) infected patients develop oral candidiasis often debilitating infection at some time during the progression of their disease 3, . Infections caused by C. albicans in immune competent individuals may include oral thrush, vulvar rash, vaginitis, conjunctivitis, endophthalmitis, diaper rash, and infections of the nail, rectum, and other skin folds . Candidas were severely affected in the treatment of patients with acute . Candida spp. are the fourth leading cause of nosocomial infections in the USA and elsewhere in the world, and in those patients with candidemia, the attributable mortality rate is up to 35% . Treatment of this fungal infection presents several problems. Besides the toxicity presented by amphotericin B, the widespread use of antifungal agents induced resistance to amphotericin B 8, . Therefore, the clear understanding of the pharmacodynamic properties of antifungal agents is important for the improvement of the treatment of oropharyngeal candidiasis. However, the choices are still limited, especially due to the resistance because of the increase in the use of drugs. For this reason identification of new drugs from natural sources are needed to fight against the candidal infection in future.